Quark Matter 2019 - the XXVIIIth International Conference on Ultra-relativistic Nucleus-Nucleus Collisions

Asia/Shanghai
Wanda Reign Wuhan Hotel

Wanda Reign Wuhan Hotel

No. 138 Donghu Road, Shuiguohu Street, Wuchang District, Wuhan, China
Ben-Wei Zhang (Central China Normal University), Enke Wang (South China Normal University), Feng Liu (Central China Normal University)
Description

Quark Matter 2019 - the XXVIIIth International Conference on Ultra-relativistic Nucleus-Nucleus Collisions - will be held in Wuhan, China, during November 4-9, 2019. The conference will take place in the "Wanda Reign" hotel located in the center of Wuhan. Quark Matter 2019 will consist of five and a half days of conference, beginning the morning on Monday, November 4, and ending early afternoon on Saturday, November 9. The conference is preceded by a Student Day on Sunday, November 3, at the Science Hall on the campus of Central China Normal University (CCNU).

Quark Matter 2019 brings together physicists from around the world to discuss new developments in high energy heavy-ion physics. The focus is on the fundamental understanding of strongly-interacting matter at extreme conditions of high temperature and density, as formed in ultra-relativistic nucleus-nucleus collisions. In these conditions, which also characterised the early Universe, matter appears as a Quark-Gluon Plasma, with quarks and gluons not confined within hadrons.

Public WebsiteQM2019 (Maybe not accessed due to the server maintenance sometime!)

Host institutions:  

  • Key Laboratory of Quark and Lepton Physics (MOE) and Institution of Particle Physics, Central China Normal University
  • Institute of Quantum Matter, South China Normal University
Participants
  • Aaron Capon
  • Abhijit Majumder
  • Adam Bzdak
  • Adam Kisiel
  • Adam Takacs
  • Adrian Amatus Weber
  • Adrian Fereydon Nassirpour
  • Adrian Rodriguez
  • Agnieszka Wergieluk
  • Ahsan Mehmood Khan
  • Aihong Tang
  • Ailec de la Caridad Bell Hechavarria
  • Akihiko Monnai
  • Aleksas Mazeliauskas
  • Alessandro De Falco
  • Alessandro Grelli
  • Alexander Milov
  • Alexander Philipp Kalweit
  • Alexander Rothkopf
  • Alexandra Neagu
  • Alexandre Lebedev
  • Alexandru Florin Dobrin
  • Alexandru Parvan
  • Alina Czajka
  • Alwina Liu
  • Amaresh Jaiswal
  • Amit Kumar
  • Anar Rustamov
  • Andre Govinda Stahl Leiton
  • Andrea Dainese
  • Andrea Danu
  • Andrea Dubla
  • Andrea Rossi
  • Andreas Ipp
  • Andreas Morsch
  • Andrey Seryakov
  • Angela Badala
  • Angelika Magdalena Tefelska
  • Anjali Sharma
  • Anke Lei
  • Anna Schäfer
  • Anne Marie Sickles
  • Anping Huang
  • Anthony Frawley
  • Anthony Hodges
  • Anton Lymanets
  • Anton Motornenko
  • Antonio Ortiz Velasquez
  • Anurag Tiwari
  • Ao Luo
  • Arabinda Behera
  • Aradhya Shukla
  • Arghya Chatterjee
  • Arthur Gal
  • Arvind Khuntia
  • Ashish Pandav
  • Attila Pasztor
  • Austin Alan Baty
  • Axel Drees
  • Ayaka Suzuki
  • Azumi Sakai
  • Azwinndini Muronga
  • Baidyanath Sahoo
  • Baochi Fu
  • Barbara Jacak
  • Barbara Trzeciak
  • Bedangadas Mohanty
  • Ben-Wei Zhang
  • Benjamin Audurier
  • Benjamin Doenigus
  • Benjamin Schweid
  • Benjamin Schüller
  • Berndt Mueller
  • Biao Zhang
  • Bing-feng JIANG
  • Bjoern Schenke
  • Bojana Ilic
  • Boleslaw Wyslouch
  • Bong-Hwi Lim
  • Borge Nielsen
  • Boris Hippolyte
  • Boris Tomasik
  • Bowen Xiao
  • Brett Fadem
  • Brian Cole
  • Caio A. G. Prado
  • Caio Brito
  • Cameron Dean
  • Carlos A. Salgado
  • Carsten Greiner
  • Catalin Ristea
  • Cesar Bernardes
  • changfeng li
  • ChanJui Feng
  • Chanwook Park
  • Chao Guo
  • Charles Gale
  • Chathuranga Sirimanna
  • Cheng Zhang
  • Chenlu Hu
  • Chi Ding
  • Chi Yang
  • Chihiro Sasaki
  • Chowdhury Aminul Islam
  • Christian Fischer
  • Christian Fischer
  • Christoph Blume
  • Christopher Mc Ginn
  • Christopher Plumberg
  • Chuan Sun
  • Chun Shen
  • Chunjian Zhang
  • Cindy Mordasini
  • cong li
  • Constantin Loizides
  • Cristina Terrevoli
  • Daicui Zhou
  • Daiki Sekihata
  • Daiki Suenaga
  • daimei zhou
  • Daniel Brandenburg
  • Daniel Pablos
  • David Coelho
  • David Morrison
  • David Stewart
  • De-Xian Wei
  • Debasish Mallick
  • Deepa Thomas
  • Defu Hou
  • Denes Molnar
  • deng wan
  • Dennis Bollweg
  • Dennis Perepelitsa
  • Derek Teaney
  • Dhananjaya Thakur
  • Di Yang
  • Dieter Roehrich
  • Dimitar Lubomirov Mihaylov
  • Dimitra Andreou
  • DING CHEN
  • dingwei zhang
  • Dirk Rischke
  • Dmitri Kharzeev
  • Dmitrii Dementev
  • Dmitry Sosnov
  • Dmytro Oliinychenko
  • Dominik Karol Derendarz
  • Dominique Dittert
  • Dong Jo Kim
  • Dongdong hu
  • Dongfang Wang
  • Douglas Wertepny
  • Dukhishyam Mallick
  • Dusan Zigic
  • Duxin Zheng
  • Dániel Kincses
  • Edmond Iancu
  • Eduardo Grossi
  • Edward Shuryak
  • Eero Aleksi Kurkela
  • Ejiro Naomi Umaka
  • Elisa Meninno
  • Enrico Scomparin
  • Enrico Speranza
  • Esther Bartsch
  • Evgeny Kashirin
  • Evgeny Zabrodin
  • Fan Si
  • Farid Taghinavaz
  • Federico Antinori
  • Fei Sun
  • Felipe Andres Garcia Rosales
  • Felix Reidt
  • Felix Reidt
  • Felix Ringer
  • Feng Li
  • Feng Liu
  • Feng-lei Liu
  • fenglan shao
  • Fengxian Liu
  • Fernando Antonio Flor
  • Fernando Torales Acosta
  • Filip Erhardt
  • Flemming Videbaek
  • Florian Cougoulic
  • Florian Seck
  • Francesco Becattini
  • Frank Geurts
  • Frederique Grassi
  • Freja Thoresen
  • Frithjof Karsch
  • fu chuan
  • Fu-Hu Liu
  • Fuqiang Wang
  • Gabor David
  • Gabriel Denicol
  • Gang Chen
  • Gang Wang
  • Gaoqing Cao
  • Georgios Krintiras
  • Gergely Gabor Barnafoldi
  • gezheng zhou
  • Gian Michele Innocenti
  • Gianluca Usai
  • Gojko Vujanovic
  • Gokce Basar
  • Gongming Yu
  • Govert Nijs
  • Grecia Castelazo Martinez
  • Greg Jackson
  • Grzegorz Stefanek
  • Guang-You Qin
  • Gunther Roland
  • Guo-yun Shao
  • Guojun Huang
  • Guruprasad Kadam
  • Guy Paic
  • Gwang-Jun Kim
  • Gyeonghwan Bak
  • Gábor Bíró
  • Gábor Papp
  • Haavard Helstrup
  • Haavard Helstrup
  • Hai Wang
  • Hannah Elfner
  • Hanseul Lee
  • Hanzhong Zhang
  • Hao Qiu
  • Hao-Lei Chen
  • Haohao Peng
  • Haojie Xu
  • Harald Appelshaeuser
  • Harsimranjeet Singh
  • Hayato Aoi
  • He-Xia Zhang
  • Helen Caines
  • Hendrik Roch
  • Heng Miao
  • Heng-Tong Ding
  • Hengne Li
  • Henner Buesching
  • Henrique Jose Correia Zanoli
  • Henry Klest
  • Hermann Franz Degenhardt
  • Hideki Hamagaki
  • Hideki Okawa
  • Hidetoshi Taya
  • Hirotsugu Fujii
  • Hiroyuki Sako
  • Hong-Zhong Wu
  • Hongxi Xing
  • Horst Sebastian Scheid
  • Horst Stoecker
  • Hua Pei
  • Huan Chen
  • huan zhong huang
  • Hui Li
  • Hui Liu
  • Hui Liu
  • Hui Zhang
  • Hyunchul Kim
  • Ian Gardner Bearden
  • Ievgenii Kres
  • Ilya Selyuzhenkov
  • In Kwon Yoo
  • Ingo Martin Deppner
  • Ionut Cristian Arsene
  • Irfan Siddique
  • ismail soudi
  • Itzhak Tserruya
  • Iurii Mitrankov
  • Ivan Vitev
  • Ivan Vorobyev
  • Jaebeom Park
  • Jagbir Singh
  • Jakub Cimerman
  • Jakub Kvapil
  • Jamal Jalilian-Marian
  • James Dunlop
  • James Lawrence Nagle
  • Jamie Stafford
  • Jan Fotakis
  • Jan Hammelmann
  • Jan M. Pawlowski
  • Jan Otto
  • Jan Steinheimer
  • Jan Vanek
  • Jana Crkovska
  • Jana N. Guenther
  • Jarkko Peuron
  • Jarkko Peuron
  • Jasmine Brewer
  • Jasper Parkkila
  • Jean-Bernard Rose
  • Jean-Francois Paquet
  • Jean-Paul Blaizot
  • Jean-Yves Ollitrault
  • Jens-Jorgen Gaardhoeje
  • Jeongsu Bok
  • Jerome Jung
  • Jessica Churchill
  • Jhuma Ghosh
  • Ji-Chong Yang
  • Jia Chen
  • Jian Deng
  • Jian Zhou
  • Jian-Hua Gao
  • Jiangyong Jia
  • Jianhui Zhu
  • Jianing Li
  • Jianqiao Wang
  • jiaxing zhao
  • Jiayin Sun
  • Jiayu Wu
  • Jie Zhao
  • Jihye Song
  • Jim Thomas
  • jin gui
  • jin gui
  • Jin Hu
  • Jin Huang
  • Jin Joo Seo
  • Jin Wu
  • Jinfeng Liao
  • Jing Wang
  • Jing Zhang
  • Jinghua Fu
  • Jingyi Chao
  • Jinjin Pan
  • Jishnu Goswami
  • Joachim Stroth
  • Joel Anthony Mazer
  • Johanna Stachel
  • John Lajoie
  • John William Harris
  • Jonatan Adolfsson
  • Jonathan Runchey
  • Jonghan Park
  • Jorge Noronha
  • Joseph Adams
  • Jovan Milosevic
  • Julia Velkovska
  • Jun Xu
  • Junjie He
  • Junjie ZHANG
  • Junlee Kim
  • Jurgen Schukraft
  • Jussi Viinikainen
  • Justin Mohs
  • Kaede Kamano
  • Kai Zhou
  • KaiJia Sun
  • Karoly Uermoessy
  • Katarina Krizkova Gajdosova
  • Kaya Tatar
  • Kayman Gonçalves
  • ke mi
  • Keming Shen
  • Kenichi Tadokoro
  • Kenji Fukushima
  • Kenshi Kuroki
  • Kenta Shigaki
  • Kentaro Nishimura
  • Kie Sang Jeong
  • Kirill Lapidus
  • Kishora Nayak
  • Klaudia Maj
  • Koichi Murase
  • Konrad Tywoniuk
  • Kosuke Okubo
  • Kouki Nakamura
  • Kousik Naskar
  • Krishna Rajagopal
  • Krista Smith
  • Kristjan Gulbrandsen
  • Krzysztof Redlich
  • Kun Jiang
  • Kurt Keys Hill
  • Langtian Liu
  • Lanlan Gao
  • Larisa Bravina
  • Larry McLerran
  • Laszlo Pal Csernai
  • Laura Brittany Havener
  • Laura Fabbietti
  • le zhang
  • Lei Wang
  • Lei Wang
  • Lei Yin
  • Leif Lönnblad
  • Leonhardt Heinrich Viebach
  • Leszek Kosarzewski
  • Li Yan
  • Liang Zheng
  • Lianyi He
  • Lihan Liu
  • Lijuan Ruan
  • lijuan zhou
  • Liliana Apolinario
  • Lilin Zhu
  • Lin Chen
  • Ling Huang
  • Lingfeng Chen
  • Lingxiao Wang
  • Lipei Du
  • liqiang zhu
  • Liuyao Zhang
  • Livio Bianchi
  • Lixin Yang
  • Lokesh Kumar
  • Long Ma
  • Long-Gang Pang
  • Luca Barioglio
  • Luca Micheletti
  • Lucas Altenkamper
  • Lucia Anna Husova
  • Lucia Oliva
  • Luciano Musa
  • Luciano Rezzolla
  • Lukas Kramarik
  • Lukas Kreis
  • Ma Guo-Liang
  • Maciej Rybczynski
  • Magdalena Djordjevic
  • Maitreyee Mukherjee
  • Maja Katarzyna Mackowiak-Pawlowska
  • Mamiya Kawaguchi
  • man xie
  • mao shijun
  • Maowu Nie
  • Marc Borrell Martinez
  • Marcel Lesch
  • Marco Van Leeuwen
  • Maria Paola Lombardo
  • Maria Sergeeva
  • Martin Rybar
  • Martin Spousta
  • Masahiro Takamura
  • Masakiyo Kitazawa
  • Masayuki Asakawa
  • Matt Durham
  • Matthew Kelsey
  • Matthew Luzum
  • Matthew Nickel
  • Matthew Sievert
  • Matthias Kaminski
  • Mattia Faggin
  • Mauricio Hippert
  • Maximiliano Puccio
  • Megan Connors
  • Meng Zhou
  • Mengke Cai
  • Mengquan Yang
  • Mesut Arslandok
  • Michael Florian Wondrak
  • Michael Joseph Peters
  • Michael Phipps
  • Michael Weber
  • Mihaela Gabriela Besoiu
  • Mike Henry Petrus Sas
  • Mike Lisa
  • Miklos Gyulassy
  • Miklós Horváth
  • Min He
  • Ming Li
  • Ming Shao
  • Ming Xiong Liu
  • Mingrui Zhao
  • Misha Stephanov
  • Mohammad Nasim
  • Molly Taylor
  • Mubarak Alqahtani
  • Muhammad Usman Ashraf
  • Muhammed Ikram Shahzad
  • Mustafa Anaam
  • Nadia Barnard
  • Najmul Haque
  • Nicole Apadula
  • Nicole Bastid
  • NIHAR RANJAN Sahoo
  • Niklas Mueller
  • Nikolay Geraksiev
  • Nikolay Karpushkin
  • Nima Zardoshti
  • Nina Kersting
  • Ning Yu
  • NingBo Chang
  • Niseem Abdelrahman
  • Nora Weickgenannt
  • Norbert Novitzky
  • Norbert Willi Herrmann
  • Nu Xu
  • Olaf Kaczmarek
  • Oleg Golosov
  • Oleksandr Vitiuk
  • Olga Evdokimov
  • Oliver Matonoha
  • Omar Vazquez Rueda
  • Oskari Antti Matti Saarimaki
  • Osnan Maragoto Rodriguez
  • Panos Christakoglou
  • Paolo Parotto
  • Pasquale Di Nezza
  • Patrick Huhn
  • Patrick Pfistner
  • Paul Caucal
  • Paula Hillmann
  • Pavel Larionov
  • Peifeng Liu
  • Peng Liu
  • Peng Ru
  • Pengfei Wang
  • Pengqi Yin
  • Pengyao Cui
  • Pengyu Ren
  • Peter Alan Steinberg
  • Peter Braun-Munzinger
  • Peter Christiansen
  • Peter Martin Jacobs
  • Peter Senger
  • Petja Paakkinen
  • Philipp Gubler
  • Pierre Moreau
  • Pierre-Alain Loizeau
  • Prabhakar Palni
  • Pragya Singh
  • Prakhar Garg
  • Prashant Kumar Srivastava
  • Prithwish Tribedy
  • Qian Chen
  • Qian Yang
  • Qiang Hu
  • Qiao Xu
  • Qing Zhang
  • Qingfei Han
  • Qiye Shou
  • Qun Wang
  • Raghav Kunnawalkam Elayavalli
  • Raghunath Sahoo
  • Raimond Snellings
  • Rainer Fries
  • Raju Venugopalan
  • Ralf Averbeck
  • Ralf-Arno Tripolt
  • Ran Bi
  • Ran Xu
  • Randhir Singh
  • Ranjit Nayak
  • Rashmi Raniwala
  • Rasmus Larsen
  • Rene Bellwied
  • Renjie Wang
  • Renu Bala
  • Richard Lednicky
  • Rishi Sharma
  • Rob Pisarski
  • Robert Greifenhagen
  • Roberta Arnaldi
  • Roman Zhokhov
  • Ron Soltz
  • Rongrong Ma
  • Rosi Reed
  • Roy Lacey
  • Ruben Kara
  • Ruiqin Wang
  • RURI OTSUKA
  • Rutuparna Rath
  • Sa WANG
  • Saehanseul Oh
  • Samuel Belin
  • Sandeep Chatterjee
  • Sandra Padula
  • Sanghoon Lim
  • Sangyong Jeon
  • Sarah Porteboeuf
  • Satoshi Yano
  • Sebastian Tapia Araya
  • Sergei Voloshin
  • Seyed Farid Taghavi
  • Seyoung Han
  • Shahin Iqbal
  • Shaifali Mehta
  • Shaista Khan
  • Shan-Liang Zhang
  • Shangxing Li
  • shanjin wu
  • Shanshan Cao
  • Shanzhen Chen
  • Shaowei Lan
  • Sheng-Qin Feng
  • Shengli Huang
  • Shengquan Tuo
  • Shengtai Li
  • Shi Pu
  • Shi Pu
  • Shi-Yong Chen
  • Shile Chen
  • Shingo Sakai
  • Shinichi Esumi
  • Shinichi Hayashi
  • Shiori Kajimoto
  • Shiyi Zhang
  • Shiyong Li
  • Shizheng Yang
  • Shota Imaki
  • Shreyansh Shankar Dave
  • Shu HE
  • Shuai Liu
  • Shuai Wang
  • Shuang Li
  • Shuqing Li
  • Shusu Shi
  • Shuwan Shen
  • shuxiang ma
  • Shuzhe SHI
  • Shyam Kumar
  • Sigtryggur Hauksson
  • Silvia Masciocchi
  • Silvia Pisano
  • Sitian Qian
  • Siyu Tang
  • Sizar Aziz
  • Soeren Schlichting
  • Somadutta Bhatta
  • Somnath Kar
  • Song Shi
  • Song Zhang
  • Songkyo Lee
  • Sonja Kabana
  • Sooraj Krishnan Radhakrishnan
  • sora oh
  • Soumya Mohapatra
  • Sourav Kundu
  • Sourendu Gupta
  • Souvik Priyam Adhya
  • Stefan Floerchinger
  • Stefano Trogolo
  • Steffen A. Bass
  • Subhash Singha
  • SUBHASIS SAMANTA
  • Subikash Choudhury
  • Subrata Pal
  • Sudhir Pandurang Rode
  • Sudhir Raniwala
  • Sumit Kumar Saha
  • Sunil Jaiswal
  • Sushant Kumar Singh
  • Sushanta Tripathy
  • Swagato Mukherjee
  • Szymon Harabasz
  • Taesoo Song
  • Takahiro Miura
  • Takahito Todoroki
  • Takashi Hachiya
  • Taku Gunji
  • Takumi Osako
  • Tamas Biro
  • Tan Luo
  • Tang Shi'an
  • Tapan K. Nayak
  • Tatsuya Chujo
  • Tetsufumi Hirano
  • Tetyana Galatyuk
  • Thomas Hemmick
  • Tianhao Shao
  • Tiantian Cheng
  • Tianyu Dai
  • Timothy Rinn
  • Tiziano Virgili
  • Tom Reichert
  • Tomas Herman
  • Tomasz Bold
  • Tong Liu
  • Toru Kojo
  • Toshihiro Nonaka
  • Travis Dore
  • Tribhuban Parida
  • UKACHUKWU UGOCHUKWU
  • Umut Gursoy
  • Urs Wiedemann
  • Vadim Babkin
  • Valerii Kondratev
  • Veronica Canoa Roman
  • Verônica Dexheimer
  • Victor Roy
  • Victoria Greene
  • Viktor Klochkov
  • Vincent Gaebel
  • Vit Kucera
  • Vito Manzari
  • Vladimir Skokov
  • Volker Koch
  • Vytautas Vislavicius
  • Wanbing He
  • wang fen
  • Wei Chen
  • Wei Dai
  • Wei Li
  • Wei-jie Fu
  • Wei-Liang Qian
  • Weihu Ma
  • Weixi Kong
  • Weiyao Ke
  • Wen-Jing Xing
  • Wenbin Zhao
  • Wenchang Xiang
  • Wenchao Zhang
  • Wenda Guo
  • WenHao Zhou
  • Wenjing Zhang
  • Wenkai Fan
  • Wenkai Zou
  • Wenqing Fan
  • Wilke Van Der Schee
  • William Alexander Horowitz
  • William Zajc
  • Wojciech Broniowski
  • Wojciech Florkowski
  • Wu Kejun
  • Xiang Li
  • Xiang-Yu Wu
  • Xianglei Zhu
  • Xiangrong Zhu
  • Xiao-Dan Wang
  • Xiao-Liang Xia
  • Xiaofeng Luo
  • Xiaojun Yao
  • Xiaoli Luo
  • Xiaolong Chen
  • Xiaoming Zhang
  • Xiaozhi Bai
  • Xiaozhou Yu
  • Xin An
  • Xin Dong
  • Xin-li Sheng
  • Xin-Nian Wang
  • Xing Long Li
  • Xingrui Gou
  • Xingyu Guo
  • Xinye Peng
  • Xinyue Ju
  • Xionghong He
  • Xiujun Li
  • Xiuxiu Jiang
  • Xu-Guang Huang
  • Ya Zhu
  • Yacine Mehtar-Tani
  • Yafei Wang
  • Yalei Tan
  • Yan Huang
  • Yan Lu
  • Yanbing Cai
  • Yanchun Ding
  • Yanfang Liu
  • Yang He
  • Yangguang Yang
  • Yao Li
  • Yapeng Zhang
  • Yaping Wang
  • Yasuki Tachibana
  • Yasuyuki Akiba
  • Yaxian Mao
  • Yayun He
  • Ye Lu
  • Yen-Jie Lee
  • Yeonju Go
  • Yi Chen
  • Yi Chen
  • Yi Yang
  • Yi Yin
  • yian li
  • Yifei Zhang
  • Yifeng Sun
  • Yiheng Luo
  • yilin cheng
  • Yilong Xie
  • Yilun Du
  • Yin Jiang
  • Yingjie Zhou
  • Yingying SHI
  • Yitao Wu
  • Yogesh Kumar
  • Yoko Minato
  • Yongzhen Hou
  • Yorito Yamaguchi
  • Yoshitaka Hatta
  • You Zhou
  • Youngil Kwon
  • Yu Fu
  • Yu Shi
  • Yu Zhang
  • Yu Zhang
  • Yu-Chen Liu
  • Yuangfang Wu
  • Yuanjing Ji
  • Yuansheng Zhao
  • Yuanyuan Zhang
  • Yue Hang Leung
  • Yue Liang
  • Yufei Liu
  • Yufu Lin
  • Yuji Hirono
  • Yuki Fujimoto
  • Yuki Gogun
  • Yukinao Akamatsu
  • Yuko Sekiguchi
  • Yukun Song
  • Yun Guo
  • Yuri Murin
  • Yuri Sato
  • Yuto Yoshida
  • Yuuka Kanakubo
  • Yuxin Liu
  • yuxin xiao
  • Yuxing Dang
  • Yves Schutz
  • Zaochen Ye
  • Ze Fang Jiang
  • Zebo Tang
  • Zehao Sun
  • Zeyan Wang
  • Zeyu Zhai
  • Zhan Bai
  • Zhan Gao
  • Zhandong Sun
  • Zhangbu Xu
  • Zhanna Khabanova
  • zhao zhang
  • Zhaozhong Shi
  • Zhe Xu
  • Zhen Liu
  • zhen wang
  • Zhengyu Chen
  • Zhenyu Chen
  • Zhenyu Ye
  • Zhenyu Zhu
  • Zhenzhen YANG
  • Zhiwei Du
  • Zhong Yang
  • Zhong-Bao Yin
  • Zhoudunming Tu
  • Zi-Wei Lin
  • Ziming Liu
  • Ziyang Li
  • Ziyue Wang
  • Zoltan Varga
  • Zubayer Ahammed
  • Zuo-Yun Wang
  • Zuzana Moravcova
  • Émilien Chapon
    • 09:00 17:30
      Student Day Science Hall at CCNU campus

      Science Hall at CCNU campus

      Conveners: Mei Huang (University of Chinese Academy of Sciences), Bowen Xiao (Central China Normal University)
    • 09:00 10:40
      Plenary Session I Wanda Han Show Theatre

      Wanda Han Show Theatre

      Convener: John William Harris (Yale University (US))
      • 09:00
        Welcome 10m
        Speaker: TBD
      • 09:10
        Quark Matter - Status & Challenges 40m
        Speaker: Barbara Jacak (University of California Berkeley (US))
      • 09:50
        Highlights from the ALICE experiment 25m
        Speaker: Michael Weber for the ALICE Collaboration (Stefan Meyer Institute for Subatomic Physics (SMI), Austrian Academy of Sciences (AT))
      • 10:15
        Highlights from the ATLAS experiment 25m
        Speaker: Martin Spousta for the ATLAS Collaboration (Charles University)
    • 10:40 11:00
      Coffee Break 20m Wanda Han Show Theatre

      Wanda Han Show Theatre

    • 11:00 12:40
      Plenary Session II Wanda Han Show Theatre

      Wanda Han Show Theatre

      Convener: William Zajc (Columbia University)
      • 11:00
        Highlights from the CMS experiment 25m
        Speaker: Émilien Chapon for the CMS Collaboration (CERN)
      • 11:25
        Highlights from the LHCb experiment 20m
        Speaker: Benjamin Audurier for the LHCb Collaboration (Universita e INFN, Cagliari (IT))
      • 11:45
        Highlights from the PHENIX experiment 20m
        Speaker: Megan Connors for the PHENIX Collaboration (Georgia State University)
      • 12:05
        Highlights from the STAR experiment 25m
        Speaker: Zhangbu Xu for the STAR Collaboration (Shandong University & Brookhaven National Laboratory)
    • 12:40 14:00
      Lunch Break 1h 20m
    • 14:00 16:30
      Plenary Session III Wanda Han Show Theatre

      Wanda Han Show Theatre

      Convener: Maria Paola Lombardo (INFN)
      • 14:00
        New developments in lattice QCD 30m
        Speaker: Heng-Tong Ding (Central China Normal University)
      • 14:30
        An experimenter’s assessment of correlations and flow in small systems 30m
        Speaker: James Lawrence Nagle (University of Colorado Boulder)
      • 15:00
        Dynamics of critical fluctuation 30m
        Speaker: Derek Teaney (Stony Brook University)
      • 15:30
        A new laboratory to study hadron-hadron interactions 30m
        Speaker: Laura Fabbietti (Technische Universitaet Muenchen (DE))
      • 16:00
        Machine learning in heavy-ion physics 30m
        Speaker: Long-Gang Pang (lbnl)
    • 16:30 18:00
      Poster Session Wanda Han Show Theatre & Wanda Reign Wuhan Hotel

      Wanda Han Show Theatre & Wanda Reign Wuhan Hotel

      • 17:40
        "Mid-rapidity J/ψ production as a function of charged-particle multiplicity in proton-proton collisions at √s=13 TeV." 20m

        Previous ALICE studies have shown a stronger than linear relative increase of the inclusive J/ψ production at mid-rapidity as a function of the mid-rapidity charged-particle multiplicity in proton-proton collisions. Studies on Monte Carlo simulations with PYTHIA 8 attributed this behavior to
        autocorrelation effects. In this regard, interesting results were obtained studying the correlation of
        the J/ψ production with the charged-particle multiplicity in different regions of the azimuthal angle
        with respect to the flight direction of the J/ψ meson.
        With experimental data on proton-proton collisions at √s=13 TeV, collected with ALICE during
        Run 2 of data taking at the LHC, latest results of the relative J/ψ yield, measured at mid-rapidity
        (|y|<0.9), in the di-electron decay channel, as a function of the charged-particle multiplicity will be
        shown and compared to predictions from the PYTHIA8 Monte Carlo generator and other available
        theoretical models.

        Speaker: Ms Ailec Bell Hechavarria (Westfälische Wilhelms-Universität Münster)
      • 17:40
        $\it{R}_{\rm{AA}}$ of electrons from beauty-hadron decays in Pb-Pb collisions at 5.02 TeV with ALICE 20m

        In relativistic heavy-ion collisions, heavy quarks (charm and beauty) are predominantly produced in the early stage of the collisions via hard partonic scattering processes. Therefore, they experience the full evolution of hot and dense QCD matter in which quarks and gluons are de-confined (Quark-Gluon Plasma, QGP) created by such collisions, and can be an effective probe to study the QGP properties. In particular, while traversing the medium, partons can loose energy via both collisional and radiative processes, and in-medium parton energy loss is expected to depend on the parton color charge and mass. Since beauty quarks are heavier than charm quarks, the mass dependence of the in-medium parton energy loss can be studied by the comparison between nuclear modification factors ($\it{R}_{\rm{AA}}$) of charm and beauty hadrons.
        In the ALICE experiment, beauty production is studied by means of non-prompt D mesons and electrons from beauty-hadron decays at mid-rapidity. The electrons are identified using the Time Projection Chamber, the Time-Of-Flight and the Electromagnetic Calorimeter, and the tracks are reconstructed using the Inner Tracking System and the Time Projection Chamber. In this poster, the $\it{R}_{\rm{AA}}$ of electrons from beauty-hadron decays in 0-10% and 30-50% Pb-Pb collisions at 5.02$\,$TeV will be presented.

        Speaker: Jonghan Park (Inha University (KR))
      • 17:40
        $\pi^0$ Azimuthal Anisotropy in Central d+Au Collisions Measured with PHENIX at RHIC 20m

        The study of anisotropic flow provides strong constrains to the evolution of the medium produced in heavy ion collisions and its event-by-event geometry fluctuations. These observables have long been related to collective behaviour in the formed medium. Recent results both at RHIC and LHC provide strong evidence for the formation of such medium in smaller systems.

        RHIC has had a broad program to study the physics of small systems by systematically varying the collision energy and Ion configuration for a better understanding of the underlying physics. PHENIX recorded data from d+Au collisions at 200GeV and smaller energies in 2016 using a special trigger which enhances statistics for the very central collisions. Here we show our recent anisotropic flow measurements for fully reconstructed $\pi^0$ at $-0.35<\eta<+0.35$ in d+Au collisions.

        Speaker: Axel Drees
      • 17:40
        $\rm \Xi_{c}^{0}$ reconstruction via hadronic decay channel in pp collisions at $\sqrt{s}=$ 13 TeV 20m

        The high collision energies available at the LHC allow for an abundant production of heavy quarks (charm and beauty), which are sensitive probes for investigating the properties of the Quark-Gluon Plasma (QGP) formed in high-energy heavy-ion collisions. Due to their large masses, they are produced in initial hard parton scattering processes on a timescale shorter than the QGP formation time and experience the whole system evolution. There have been extensive researches regarding the production of charm mesons, such as $\rm D^{0}$, $\rm D^{+}$, $\rm D^{*+}$, $\rm D^{+}_{s}$, in order to investigate the interactions of charm quarks with the QGP constituents and the transport properties of the medium. The measurement of charm-baryon production, and in particular the baryon-to-meson ratios, provides unique information on hadronisation mechanisms, constraining the role of coalescence and testing the predicted presence of diquark states in the QGP.

        Measurements of charm-baryon production in pp collisions are important to set up a benchmark for Pb-Pb collisions and provide essential tests of pQCD calculations and models of charm hadronisation process. In this poster, the status and performance of the $\rm \Xi_{c}^{0}$ baryon measurements via the hadronic decay channel $\rm \Xi_{c}^{0} \rightarrow \pi^{+} \Xi^{-}$ (and its charge conjugate) in pp collisions at $\sqrt{s}=$ 13 TeV will be reported.

        Speaker: Jianhui Zhu (Central China Normal University CCNU (CN))
      • 17:40
        $K^*(892)^0$ and $\overline{K^*}(892)^0$ production in p+p interactions at SPS energies from NA61/SHINE 20m

        The NA61/SHINE hadron physics program focuses on a search for the critical point and on studies of the properties of the onset of deconfinement in strongly interacting matter. For this purpose the phase diagram is scanned by changing the collision energy (from 13A to 150/158A GeV/c) and the size of the colliding system (from p+p to Pb+Pb).

        The main topic of this talk are preliminary results on $K^*(892)^0$ and $\overline{K^*}(892)^0$ meson production in p+p interactions at beam momentum 40-158 GeV/c obtained by the NA61/SHINE experiment. The analysis of $K^*(892)^0$ was performed with a novel template method in the $K^+\pi^-$ decay channel. The results include the double differential spectra $d^2n/(dydp_T)$, $d^2n/(m_Tdm_Tdy)$ as well as yields dn/dy. The measured mass of the $K^*(892)^0$ as a function of transverse momentum is also presented and compared to other published results. Finally, the multiplicity of $K^*(892)^0$ and the ratio of <$K^*(892)^0$>/<$K^{+/-}$> as a function of system size will be presented together with the results from other experiments.

        Speaker: Angelika Magdalena Tefelska (Warsaw University of Technology (PL))
      • 17:40
        (Non-)Strange particle production at RHIC and LHC energies using HYDJET++ 20m

        Recent experimental and theoretical obsevations suggest that production of (multi-)strange hadrons and charged hadrons in (non-)deformed nuclei is a complex physical process. The properties of charged hadrons produced in deformed nucleus collisions at RHIC and LHC energies contradict many of the theoretical models result including two-component Monte Carlo Glauber model. Unlike light hadrons, the production mechanism of (multi-)strange hadrons is quite involved as they do not simply produce according to their statistical weights as described in grand canonical ensemble. In recent past, several efforts have been made to provide a mechanism for (non-)strange hadron production in symmetric and asymmetric heavy ion collision experiments. However, an unified theoretical or simulation model which reproduce the multiplicity distribution of (multi-)strange hadrons alongwith multiplicity of charged hadrons is still lacking. In this article, we have used HYDJET++ model to calculate multiplicity distribution of (non-)strange hadrons with various control parameter in symmetric collision of (non-)deformed nuclei at RHIC and LHC energies. We have calculated the pseudorapidity distribution, transverse momentum distribution and elliptic flow distribution of charged hadrons with different control parameters.We observed that HYDJET++ along with certain parameters can adequately provide a unified model for light as well as strange hadron production in various type of collisions.

        Speaker: Mr Arpit Singh (Banaras Hindu University)
      • 17:40
        [Poster] Using Ξ(1820) baryons to test for parity doubling at ALICE 20m

        We report the first measurement of the Ξ(1820) baryon at LHC energies by reconstructing its decay to Λ-Κ in pp collisions at 13 TeV. Recent lattice calculations on parity doubling indicate that the masses of negative-parity particles, such as Ξ(1820), may decrease at the critical temperature, while the masses of positive-parity partners, i.e. the Ξ(1530), do not. Furthermore, the lifetime of the Ξ(1820) is short enough that it may be suppressed in high-multiplicity collisions, as has been observed for K*(892) and ρ(770). Studying Ξ(1820) also allows us to gain a better understanding of the spectrum of excited hyperon states, with implications for our understanding of the hadron resonance gas. We have successfully reconstructed the Ξ(1820) using ALICE data from 2015-2018 and measured its mass, width, and yield as a function of the transverse momentum and collision multiplicity. These studies performed in small collision systems will serve as a baseline for future measurements of the Ξ(1820) in p-Pb and Pb-Pb collisions.

        Speaker: Corey James Myers (University of Houston (US))
      • 17:40
        A Comprehensive Study of Bottomonium Production in Heavy-ion Collision 20m

        One of the important goals of heavy-ion collision experiments is to test the predictions of Quantum Chromodynamics(QCD). One such QCD prediction is the formation of Quark-Gluon Plasma(QGP) in the heavy-ion collision experiments. Quarkonia suppression has been suggested as a sign of formation of QGP in heavy ion collision, where it could exist as a transient state. We have developed a model to predict the suppression of quarkonia in QGP. It incorporates quarkonia production and suppression due to hot nuclear matter effects like color screening, collisional damping, gluonic dissociation and cold nuclear matter effect namely, nuclear shadowing. We have considered the possibility of regeneration of quarkonia due to correlated/uncorrelated quark and anti-quark pair in QGP medium. Since our model had employed Bjorken's (1+1)-dimensional hydrodynamics, we were restricted to predict suppression at mid-rapidity only. A complete rapidity dependence of suppression was also missing in our previous work. Both of these shortcomings are taken care by switching to (3+1)-dimensional relativistic hydrodynamics using MUSIC, a C++ code. MUSIC uses Kurganov-Tadmor algorithm to solve hydrodynamic conservation equations. In the present work, we compare the bottomonium suppression calculated by using our current (3+1)-dimensional expansion based model with the experimentally measured suppression, $R_{AA}$ as a function of centrality, transverse momentum, and rapidity.

        Speaker: Mr Nikhil Hatwar (Birla Institute of Technology and Sciences, Pilani campus)
      • 17:40
        A hydrodynamic approach for multiplicity fluctuations in heavy-ion collisions 20m

        It is understood that multiplicity fluctuations serve as one of the important observables for the study of the critical endpoint in the beam energy scan program of RHIC.
        As a matter of fact, the problem is rather subtle, and many different factors may potentially affect the observable in question.
        In this work, we take into consideration the thermal fluctuations, resonance decay, as well as the hydrodynamic expansion of the system.
        In particular, we focus on the noncritical aspects of the topic and investigate the multiplicity fluctuations in heavy-ion collisions by using a hydrodynamic model.
        Subsequently, we evaluate the effects of initial state fluctuations and resonance decay.
        The obtained results are compared to those obtained by the statistical model as well as the experimental data.

        Speaker: Wei-Liang Qian (Federal University of Ouro Preto)
      • 17:40
        A MAPS based Inner Tracking System of the Multi-Purpose Detector at the NICA collider 20m

        The Multi-Purpose Detector (MPD) is being constructed to study the properties of extremely dense nuclear matter formed in relativistic nucleus-nucleus collisions at NICA energies. The yields of strange and charmed particles are the important observables sensitive to critical phenomena in phase transitions of the QGP-matter at high net-baryon density. Highly efficient registration of such short-lived products of nuclear interactions using vertex silicon detectors will play a key role in the analysis of the possible onset of deconfinement in nuclear matter.
        An Inner Tracking System (ITS) based on the Monolithic Active Pixel Sensors (MAPS) is under design by the emerging MPD ITS collaboration in Dubna and Wuhan. The ultra-light carbon fiber structure carries five layers of CMOS ALPIDE sensors recently elaborated by the ALICE collaboration. The two layers of the Outer Barrel (OB) are built out of 42 staves developed for the new ALICE ITS to be installed at CERN next year. The MPD ITS mainframe mechanics and the OB installation is planned to be completed in 2023. The Inner Barrel (IB) will use novel MAPS sensors of enlarged area and reduced thickness to be developed together with the ALICE collaboration within 2020-2025 and installed after the reduction of the diameter of the MPD beam pipe to optimal value of 38 mm will become possible. The poster presents the main details of the MPD ITS layout, computer simulations of the pointing resolution gained with the system, as well as a quality assessment of the MPD tracking system including ITS and Time Projection Chamber used for the reconstruction of the multi-strange hyperons and the D-mesons produced in the central Au-Au collisions at \sqrt{S_{NN}} = 9 GeV.

        Speaker: Dr Yuri Murin (JINR, Dubna)
      • 17:40
        A multivariate approach to measuring low-mass dielectrons in p-Pb collisions at sqrt(sNN) = 5.02 TeV with ALICE 20m

        Correlated dielectron pairs are a very promising probe to study the quark-gluon plasma, a deconfined state of quarks and gluons predicted by lattice quantum chromodynamics calculations in ultra-relativistic heavy-ion collisions. Electrons reach the detector without significant final state interactions. In addition, the low-mass dielectron spectrum comes from various sources, i.e. Dalitz and resonance decays of pseudoscalar and vector mesons, semi-leptonic decays of charm and beauty hadrons, as well as the radiation from the thermalised system, which are produced at all stages of the collision. Therefore, dielectron pairs can be used to study the space-time evolution of the system.

        While pp collisions provide an important baseline measurement in vacuum for heavy-ion studies, p-Pb collisions can be used to disentangle cold from hot nuclear matter effects. Moreover, recent studies in small colliding systems (pp and p-Pb) showed intriguing collective behaviours similar to observations previously done in heavy-ion collisions. They require further investigations in particular as a function of the event charged-particle multiplicity. Searching for the thermal signatures through dielectrons is also important in small systems to disentangle the initial and final state effects.

        In this poster the latest status of the dielectron analysis with ALICE in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV will be presented. Data recorded in 2016 are used. Furthermore, it will be discussed how a multivariate approach can be useful for the measurements of low-mass dielectrons.

        Speaker: Aaron Capon (Stefan Meyer Institute for Subatomic Physics (SMI), Austrian Academy of Sciences (AT))
      • 17:40
        An object-oriented software framework for anisotropic flow analysis 20m

        We present an object-oriented software framework for performing the anisotropic flow analysis in collisions of ions and hadrons. The framework operates on flow Q-vectors and provides an abstraction layer for the analysis of two and multi-particle correlation functions. Its modular design and flexible interface allows to use it as an external software package, which fits the scope of any experimental setup.

        The current version implements commonly used flow observables, multi-differential corrections of Q-vectors with the possibility for data preprocessing to account for detector azimuthal non-uniformity. The extension of the core functionality and the definition of new observables and correction steps is straightforward. The framework supports multi-differential flow analyses with statistical uncertainty propagation based on subsampling and/or bootstrapping algorithms. To illustrate the flexibility and powerful functionality of the framework, examples of application to data analyses of ALICE at the LHC, NA49 and NA61/SHINE at SPS, and the future CBM experiment at FAIR will be shown.

        Speaker: Lukas Kreis (GSI - Helmholtzzentrum für Schwerionenforschung GmbH (DE))
      • 17:40
        Analytical solutions and attractors of relativistic viscous hydrodynamics for Bjorken flow 20m

        We consider causal higher order theories of relativistic viscous hydrodynamics in the case of one-dimensional boost-invariant expansion and study the associated dynamical attractor. We obtain the evolution equations for inverse Reynolds number as a function of inverse Knudsen number. The solutions of these equations exhibit attractor behavior which we analyze in the context of Lyapunov exponents from several different techniques. We also compare attractors of second-order Muller-Israel-Stewart (MIS) theory, transient DNMR theory, third-order theory and exact solution of Boltzmann equation in the relaxation-time approximation. We demonstrate that the third-order theory provides a better approximation to the exact kinetic theory attractor compared to MIS and DNMR theories. Further, we find analytical solutions for these higher-order theories by assuming different forms of shear relaxation time and use these solutions to study the analytical attractors. Finally, we propose a new way to characterize and uniquely determine the hydrodynamic attractors, as well as the Lyapunov exponents, by studying the universal behavior of these solutions at small as well as large Knudsen numbers.

        Speaker: Sunil Jaiswal (Tata Institute of Fundamental Research)
      • 17:40
        Anisotropic flow measurements from the NA61/SHINE and NA49 beam momentum scan programs at CERN SPS 20m

        The NA61/SHINE experiment at the CERN SPS has recently extended its program for the energy scan with Pb ions. In the past, the NA49 experiment, which preceded the NA61/SHINE, has also recorded data for Pb–Pb collisions at different energies. Together, the two experiments cover wide range of collision energies in the beam momentum range of 13–150A GeV/c provided by CERN SPS. Analysis of the new NA61/SHINE data and revision of the existing NA49 using modern measurement techniques allow for a new comprehensive systematic study of the collective flow relative to the spectator plane. The measurements at the lowest energy available at the SPS are also relevant for the preparation of the Compressed Baryonic Matter (CBM) heavy-ion experiment at the future FAIR facility in Darmstadt.

        We will present new NA61/SHINE results on directed and elliptic flow measurement in Pb–Pb collisions at 13 and 30A GeV/c relative to the spectator plane determined with the Projectile Spectator Detector. Also a new analysis of 40 and 158A GeV data collected by the NA49 experiment using forward spectator calorimeters (VETO and RCAL) will be shown. The flow coefficients are reported as a function of rapidity and transverse momentum in different classes of collision centrality. The new results are compared with existing results from previous NA49 analysis and the STAR data at RHIC.

        Speaker: Evgeny Kashirin (MEPhI)
      • 17:40
        Anomaly Effects in Transport Coefficients 20m

        Recently anomaly related transports have attracted lot of interests in various fields. Ranged from low energy physics and in condensed matter up to high energy physics and in heavy ion collisions, physicists are interested to study the effects of microscopic anomaly over the macroscopic scales. Historically this stream is initiated by the work of Vilenkin in 1979 [ A.~Vilenkin, Phys. Rev. D 20, 1807 (1979)] and afterwards physicists try to study these anomalous transports in various subjects such as in weak regime by using the Chiral Kinetic Theory (CKT) or in strong regime using the ADS/CFT correspondence and fluid-gravity conjecture. Based on this motivation, I want to review our recent works in our groups which study anomaly related issues by using CKT approach and chiral hydrodynamics. To this purpose, first I want to mention about hydro modes for relativistic anomalous fluid and then introduce the notion of equilibrium frame. After that I will try to address the magneto transports in an anomalous fluid by using the linear response theory. For weakly interacting particles this study will be performed by using the CKT, while for strongly interacting matter this will be done by using the gauge/gravity duality and the notion of magnetized brane.

        Speakers: Dr Farid Taghinavaz (IPM), Dr Navid Abbasi (IPM), Mr Omid Tavakol (Sharif University of Technology)
      • 17:40
        Anomaly with a non-relativistic dispersion relation 20m

        We use several methods to study the case of chiral anomaly with a non-relativistic dispersion relation $H=\frac{p^2}{2m}+\lambda\sigma\cdot p$, which might be useful in special condensed matter state. where $H$ means halmitonian.$\lambda$ is just a constant coeffecient.

        we will show the results with different explanations in each methods. For example, the anomaly disappears for the lack of UV divergence in one loop feynman diagram with field theory method. And in wigner function methods, it canceled in intergration of 4-D momentum.

        we will also show the chiral kinetic equation for quasi-particles by effective field theory, and the looked-like anomaly in it.

        Speaker: Ms Lanlan Gao (Fudan University)
      • 17:40
        Application of Principal Component Analysis on Collective Flow 20m

        Various flow observables, defined based on the Fourier decomposition, have provided valuable information on the initial state fluctuations, final state correlations and the QGP properties. In spite of the success of the flow measurements and the hydrodynamic descriptions, one essential question is why the Fourier expansion is a natural way to analyze the flow data. In this talk, I will address this question with one of the machine learning techniques, called the Principal Component Analysis (PCA). In more details, we will investigate if a machine (unsupervised learning technique) could directly discover flow from the huge amount of data of the relativistic fluid systems without explicit instructions from human beings.

        After apply PCA to the raw data of hydrodynamic simulations, we found that the obtained PCA eigenvectors are similar to but not identical with the traditional Fourier bases. Correspondingly, the PCA defined flow harmonics vn are also similar to the traditional vn for n = 2 and 3, but largely deviated from the Fourier ones with n≥4 . A further study on the symmetric cumulants and the Pearson coefficients indicates that mode-coupling effects are reduced for these flow harmonics defined by PCA. Our work also demonstrated the hydrodynamic system is not highly non-linear as generally believed before, which should be reevaluated with such PCA bases for the flow definition.

        [1] Z. Liu, W. Zhao and H. Song, arXiv:1903.09833 [nucl-th]

        Speaker: Huichao Song (Peking U)
      • 17:40
        Azimuthal anisotropy correlations and fluctuations in PbPb collisions at the LHC energies from HYDJET++ and AMPT model 20m

        Flow correlations and fluctuations are sensitive probes to the initial geometry and the quark-gluon plasma (QGP) in relativistic heavy ion collisions. Model comparisons are essential to decipher the properties of the QGP. In this talk, we study the correlations between flow harmonics $v_2$, $v_3$, and $v_4$ over a wide centrality range with two-particle correlations in PbPb collisions at $\sqrt{s_{_{\mathrm{NN}}}}=2.76$ TeV simulated by the HYDJET++ and AMPT models. We compare the model results to the experimental data from ATLAS and find both models are in good agreement with data for $v_2$-$v_3$ correlation. For $v_2$-$v_4$ and $v_3$-$v_4$ correlations, while AMPT is still in good agreement, HYDJET++ gives stronger slopes in the correlations than the ATLAS data. The AMPT model qualitatively predicts a boomerang-like shape in the correlations as observed in the experimental data, however, they quantitatively disagree. The HYDJET++ model fails completely to reproduce such a boomerang shape. We study flow fluctuations by the $v_2$ obtained with different Q-cumulant orders, namely $v_2\{2\}, v_2\{4\}, v_2\{6\},$ and $v_2\{8\}$. In particular, we study the skewness, a measure of the asymmetry of the $v_2$ distribution, by the ratio of
        $v_{2}\{6\} - v_{2}\{8\}$ and $v_{2}\{4\} - v_{2}\{6\}$. The HYDJET++ model
        calculation shows good agreement with results reported by the CMS and ALICE
        experiments. However, more data statistics are needed in order to draw firm
        conclusions.

        Speaker: Dr Jovan Milosevic (Vinca Institute of Nuclear Sciences, University of Belgrade, Mike Petrovica Alasa 12-14, 11351 Vinca, Belgrade, Serbia)
      • 17:40
        Azimuthal anisotropy measurement of strange hadrons in Au+Au collisions at $\sqrt{s_{NN}}$ = 27 and 54.4 GeV at STAR 20m

        The hadronic interaction cross section for (multi)strange hadrons are expected to be small. Hence, the study of azimuthal anisotropy of (multi)strange hadrons allows one to access the collective properties of early stages in heavy-ion collisions. The STAR experiment recently recorded high statistics data for Au+Au collisions at a new centre-of-mass energies ($\sqrt{s_{NN}}$) of 54.4 GeV ($\sim$1.3 billion events) and 27 GeV ($\sim$600 million events). The newly installed Event Plane Detector (EPD) allows one to measure the azimuthal anisotropy of particles with high precision and less non-flow contributions using event plane with large gaps in rapidity.

        In this poster, we will present the second-order azimuthal anisotropy ($v_{2}$) of (multi)strange hadrons ($K^{0}_{S}$, $\phi$, $\Lambda$, $\Xi$, $\Omega$) measured at midrapidity ($|y|$ $< $0.5) as a function of transverse momentum ($p_{T}$) and centrality at $\sqrt{s_{NN}}$=27 and 54.4 GeV. Measurement will be carried out using event planes from both Time Projection Chamber ($|\eta|$$<$1.0) and EPD (2.1$<$$|\eta|$$<$5.1). High precision test of the number of constituent quark scaling of $v_{2}$ (including light hadrons) will be shown. The results will be compared to transport-based model calculations. Finally, the physics goals of such measurements at the other $\sqrt{s_{NN}}$ = 19.6, 11.5, 9.2 and 7.7 GeV of beam energy scan phase II will be discussed.

        Speaker: Mohammad Nasim (IISER Berhampur)
      • 17:40
        Azimuthal anisotropy of heavy-flavour decay electrons in p-Pb collisions with ALICE 20m

        Two-particle angular correlations are used to investigate properties of the Quark-Gluon Plasma (QGP) formed in high-energy heavy-ion collisions. They are sensitive to different effects of the evolution of the collision, such as collective effects, initial conditions and jet properties.

        In small systems (such as pp or p--A collisions), an unexpected double-ridge structure has been observed in the two-particle angular correlations of charged hadrons. The double-ridge is similar to the one observed in A--A collisions, where the physical origin is usually credited to collective behaviour. This structure can be quantified using a Fourier decomposition of the $\Delta \varphi$ distribution. These Fourier coefficients can be factorized to single-particle $v_n$ coefficients, related to the azimuthal distribution of the particles. The interpretation of this phenomena in small system is still in debate, especially concerning the role of hydrodynamics and initial conditions. Extending this measurement to heavy-flavour particles could provide further insight on the initial and final-state origin of the anisotropies in these collision systems.

        In this poster, the results of the heavy-flavour hadron decay electron $v_2$ in high-multiplicity p--Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV will be presented. The measurement was performed with ALICE at mid-rapidity ($|\eta| < 0.8$). The $v_2$ was obtained by calculating two-particle correlations between heavy-flavour hadron decay electrons and unidentified charged particles in high-multiplicity collisions. The jet contribution to the two-particle correlation distribution was subtracted using the using low-multiplicity collisions.

        Speaker: Henrique Jose Correia Zanoli (Utrecht University (NL))
      • 17:40
        b-jet quenching in Pb+Pb collisions measured by the ATLAS detector 20m

        The measurement of modification of jet yields in heavy-ion collisions provides a powerful method to probe the dynamics of the hot, dense medium formed in these collisions at the LHC. Jet quenching in heavy-ion collisions is expected to depend on the flavor of the fragmenting parton. For light partons, energy loss via gluon bremsstrahlung is expected to dominate, while in the case of heavy-quark-initiated jets, collisional energy loss may play a more important role. In this poster, we report in detail the new measurement of b-tagged jets production reconstructed from a jet-associated muon in $pp$ and Pb+Pb at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV collision energy using the large statistics of the recently collected 2018 ATLAS data.

        Speaker: ATLAS Collaboration
      • 17:40
        Background study of the CME-related correlations in heavy-ion collisions within a multiphase transport mode 20m

        The Chiral Magnetic Effect (CME) manifests itself via a separation of electric charge along the direction of the magnetic field, produced by spectator protons in heavy-ion collisions. The experimental searches for the CME, based on the charge-dependent angular correlations [1] have, however, remained inconclusive till date, because the observed features of charge separation in data are also compatible with non-CME background sources. Recently, the CMS collaboration attempted to disambiguate the origin of charge separation by measuring charge-dependent angular correlations or $\gamma$-correlators with respect to second-order ($\Psi_{2}$) and third-order ($\Psi_{3}$) symmetry planes defined as $\gamma_{112}$ and $\gamma_{123}$ respectively, in p+Pb and Pb+Pb collisions [2]. The idea is that an equality is expected in $\frac{\Delta\gamma_{112}}{\Delta\delta \times v_{2}}$ ($\kappa_{112}$) and $\frac{\Delta\gamma_{123}}{\Delta\delta \times v_{3}}$ ($\kappa_{123}$), if the charge separations are dominated by non-CME backgrounds \cite{CMS_3p}. The CMS measurements indeed reveal such equality across light-ion and heavy-ion collision systems, suggesting the observed charge separation in data arises from non-CME background contributions to a large extent. However, the signals and backgrounds in data are so entangled that such an interpretation may be naive. Instead, non-CME background models could provide a testing ground to verify or falsify such relations. In this poster, we will present results of different harmonics of $\gamma$-correlators calculated from a charge-conserved version of a multiphase transport (AMPT) model. In contrary to the CMS expectation, the AMPT model calculations show $(\kappa_{132} \approx 1) < (\kappa_{112} \approx 1.3) < (\kappa_{123} \approx 2)$.

        References
        [1] “Parity violation in hot QCD: how to detect it”, S. Voloshin, Phys. Rev. C70, 057901 (2004).
        [2]“Constraints on the chiral magnetic effect using charge-dependent azimuthal correlations in pPb and PbPb collisions at the LHC, The CMS Collaboration”, Phys. Rev. C 97, 044912 (2018).

        Speakers: Dr Subikash Choudhury (Fudan University), Dr Wanbing He (Fudan University)
      • 17:40
        Baryon number fluctuations from DSEs 20m

        We present new results for fluctuations of the baryon number for QCD with
        Nf=2+1 quark flavours at non-zero temperature and chemical potential [1].
        These are extracted from a framework based on a combination of lattice QCD
        and Dyson-Schwinger equations. In previous works ([2], see [3] for a review)
        we found a critical end point in the region ($T^c,\mu_B^c$)=(120,500) MeV.
        We discuss the changes of ratios of fluctuations up to fourth order along
        and below the transition line for temperatures and baryon chemical potential
        up to and beyond the critical end point.
        Comparing with preliminary STAR data for the skewness and kurtosis ratios,
        our results are compatible with the scenario of a critical end point at
        large chemical potential and slightly offset from the freeze-out line.
        We also discuss the caveats involved in this comparison.

        [1] P.Isserstedt, M.Buballa, C.S.Fischer, P.Gunkel, arXiv:1906.11644
        [2] C.S.Fischer, J.Luecker and C.A.Welzbacher, Phys. Rev. D 90 (2014) no.3, 034022
        [3] C.S.Fischer, Prog. Part. Nucl. Phys. 105 (2019) 1

        Speaker: Prof. Christian Fischer (JLU Gießen)
      • 17:40
        Beam test results of the sPHENIX HCal prototype 20m

        The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) will quantify the properties of quark-gluon plasma created in relativistic heavy ions collisions with a focus on the measurements of jets and Upsilon states. A crucial component to the sPHENIX detector design for jet measurements is the hadronic calorimeter (HCal) which is located outside of the solenoid magnet and composed of alternating layers of tapered steel plates and scintillator tiles. sPHENIX has performed four tests of the HCal prototypes at Fermilab since 2015 and pre-production design of the EMCal and HCal in the η∼1 configuration was tested at the Fermilab Test Beam Facility as experiment T-1044 in the spring of 2018. We will present the results of 2018 HCal prototype beam test, the results of sPHENIX-like calorimeter system and corresponding GEANT4 simulations. The energy linearity and resolution of pions and electrons will also be presented.

        Speaker: sPHENIX Collaboration
      • 17:40
        Beam Test Results of the sPHENIX HCal Prototype 20m

        sPHENIX is a planned upgrade at RHIC designed to quantify the properties of quark-gluon plasma created in relativistic heavy ions collisions with a particular focuses on the measurements of jets and upsilon states. A crucial component to the sPHENIX detector design for jet measurements is the hadronic calorimeter (HCal) which is located outside of the solenoid magnet and composed of alternating layers of tapered steel plates and scintillator tiles.

        sPHENIX has performed four tests of the HCal prototypes at Fermilab
        since 2015 and pre-production design of the EMCal and HCal in the $\eta\sim$1 configuration was tested at the Fermilab Test Beam Facility as experiment T-1044 in the spring of 2018.
        This poster will present the results of 2018 HCal prototype beam test, the results of sPHENIX-like calorimeter system and corresponding GEANT4 simulations. The energy linearity and resolution of pions and electrons will also be presented in this poster.

        Speaker: Dr Xu Sun (Georgia State University)
      • 17:40
        Beam-energy dependence of spatial and temporal characteristics of shape-selected events in Au+Au collisions at STAR 20m

        Femtoscopic measurements can be leveraged to gain insight into the expansion dynamics of the hot and dense medium created in heavy-ion collisions. This poster presentation will report and discuss excitation functions for shape-selected two-pion HBT radii ($R_{out}$, $R_{side}$ and $R_{long}$) measured for a a broad range of collision centrality and average pair transverse momentum ($k_{T}$) with the STAR detector. The shape selections were accomplished via cuts on the distributions of the second-order $Q_2$ vector [1]. The excitation functions, which span the full range of the RHIC beam energy scan ($\sqrt{s_{NN}}$ = 7.7-200 GeV), indicate clear sensitivities to the magnitude of the $Q_2$ vector which give insight into the expansion dynamics. The connection between the magnitude of the $Q_2$ vector and the spatiotemporal characteristics of the quark-gluon plasma produced in the collisions will be discussed.

        [1] J. Schukraft, A. Timmins, and S. A. Voloshin, Phys. Lett. B 719 (2013) 394.

        Speaker: Benjamin Schweid (Stony Brook University)
      • 17:40
        Beyond scattering and hypernuclei experiments: $p-\Lambda$ and $p-\Sigma^0$ correlation studies at ALICE 20m

        Recent ALICE results have demonstrated that femtoscopic measurements in pp and p-Pb collisions provide an unprecedented opportunity to study the short range part of the strong interaction.

        Femtoscopy is a technique to extract information on the emission source and interaction potential from correlations between particles with low relative momentum. In this talk we will use femtoscopy to study the $p-\Lambda$ and $p-\Sigma^0$ interactions on the scale of the particle emitting source, which is 1 fm or smaller.

        Existing data on the $p-\Lambda$ interaction from scattering experiments only probe large energies, and are not sensitive to the opening of the $N-\Sigma$ channel. In this talk we will show that ALICE data from high-multiplicity pp collisions allows us to measure the $p-\Lambda$ correlation function with exceptional precision at low momentum and at the $N-\Sigma$ threshold, and are thus capable of providing quantitative constraints to existing theoretical models, such as chiral effective theory calculations.

        Furthermore, no $p-\Sigma^0$ scattering data exist, and as a result the theoretical models are poorly constrained. The ALICE data allow us to perform the first ever measurement of the $p-\Sigma^0$ correlation function and make comparisons to state-of-the-art theoretical models.

        Speaker: Laura Fabbietti (Technische Universitaet Muenchen (DE))
      • 17:40
        Bottom and Charm production in $p$+$p$ collisions at $\sqrt{s}$=200 GeV measured by PHENIX 20m

        The study of the charm and bottom interacting with the QGP strongly relies on the precise measurement of their yields in p+p collisions, since the theoretical calculations of the yields have large uncertainties. The PHENIX collaboration has measured the semi-leptonic decay yields of charm and bottom hadrons and the non-prompt $J/\psi$ yield from B meson decays in 200 GeV $p$+$p$ collisions, using the distance-of-closest approach measured in the vertex detectors installed at mid ($|y|<0.35$) and forward ($1.2<|y|<2.2$) rapidities. This presentation will show the final results on the semi-leptonic decays of charm and bottom hadrons at mid-rapidity and the status of the analysis of non-prompt $J/\psi$ and other measurements at forward rapidity.

        Speaker: Julia Velkovska (Vanderbilt University (US))
      • 17:40
        Bottomonia Suppression in Heavy-Ion Collisions from AdS/CFT 20m

        We compute for the first time the suppression of bottomonia in a strongly coupled QGP and compare the results to those from a weakly coupled QGP and to data. Using imaginary time techniques we numerically determine the real and imaginary parts of the binding energy of $\Upsilon$(1S) in (complex) potentials derived from AdS/CFT and from pQCD. We confirm the strong coupling binding energies by independently deriving the meson spectrum in AdS/CFT using semiclassical, rotating open strings.

        We then implement the complex binding energies in a suppression model to determine the $\Upsilon$(1S) nuclear modification factor in $\sqrt{s}_{NN}=2.76$ TeV Pb+Pb collisions. The simplest strong-coupling, $p_T$-independent potential leads to a significant oversuppression of $\Upsilon$(1S) compared to data while the results from the pQCD-derived potential are consistent with data. Lastly, we investigate the consequences of the different velocity dependencies of potential models on the bottomonia $R_{AA}(p_T)$.

        Speaker: Nadia Barnard (University of Cape Town)
      • 17:40
        Bottomonium anisotropic flow from an escape mechanism 20m

        Bottomonia are produced mostly in the initial stage of a heavy ion collision. Once created, any subsequent interaction with the medium can as a first approximation be dealt with as leading to dissociation. In that picture, the bottomonia surviving until the final state are those that escaped any interaction with the medium.
        We compute the anisotropic flow of bottomonia arising from their differential survival probability in an asymmetric medium of massless particles, using different assumptions for the microscopic details of the latter. In particular, we show that the Fourier coefficients $v_n$ for the bottomonium flow are sensitive to the initial eccentricities of both the bulk medium geometry and the bottomonium distribution.

        Speaker: Nina Kersting (Bielefeld University)
      • 17:40
        Bottomonium production in p+p and Pb+Pb collisions with ATLAS 20m

        Bottomonium, a bound state of a bottom quark and its antiquark, is an excellent probe of the hot and dense medium created in heavy-ion collisions at LHC. The ATLAS collaboration collected the large datasets of $pp$ and Pb+Pb collisions in 2017 and 2018 corresponding to integrated luminosities of 242 pb$^{-1}$ and 1.39 nb$^{-1}$ respectively, at a centre-of-mass energy per nucleon pair of 5.02 TeV. In this poster, bottomonium states are reconstructed via the dimuon decay channel in the rapidity range of $|y| < 1$, and their production in PbPb collisions is compared to that in pp collisions to extract the nuclear modification factor, $R_{AA}$, as a function of event centrality and transverse momentum. In addition, the relative suppression of the excited states Y(nS) to the ground state Y(1S) is studied.

        Speaker: Songkyo Lee (Iowa State University (US))
      • 17:40
        Bulk properties of QCD matter using S-matrix based hadron resonance gas model 20m

        Ideal Hadron Resonance Gas (HRG) model is a well-known tool to describe hadron multiplicities in relativistic nuclear collisions and for modelling hadronic equation of state. The model relies on the assumption that all hadronic resonances are free particles, which is valid, given that their decay widths are negligible. However, when the temperature is close to the crossover region, the model does not agree with lattice QCD data for observables like second order charge susceptibility ($\chi^2_Q$), the difference between second and fourth order baryon susceptibility ($\chi^2_B -\chi^4_B$) and the baryon-strange correlator ($C_{BS}$). Interaction among constituent hadrons is expected to affect these observables. We have implemented interactions among hadrons in the HRG model using $S$-matrix framework. The elements of $S$-matrix are related to the two body scattering phase shifts of interacting hadrons. The positive phase shifts, related to attractive interactions are calculated using $K$-matrix formalism while the negative phase shift, related to repulsive interactions are obtained from experimentally measured phase shifts. We observe a good agreement between results from our $S$-matrix formalism and lattice QCD data for the aforementioned higher order susceptibilities along with bulk properties like the speed of sound and interaction measure etc. Further, we use the $S$-matrix formalism to calculate the temperature ($T$) and baryon chemical potential ($\mu_B$) dependence of transport coefficients (shear viscosity, bulk viscosity, heat conductivity and diffusion coefficient) for the multi-component system of hadrons. Our calculation predicts lower values of shear viscosity coefficient as a function of temperature as compared to previous results in the literature.

        Speaker: Ashutosh Dash
      • 17:40
        Can jet quenching constrain the evolution history of parton showers? 20m

        In the soft and collinear limit, the choice of evolution scale in a parton shower algorithm is ambiguous and several options have been implemented in existing Monte Carlo event generators for proton-proton collisions. However, the resulting space-time evolution could result in subtle differences depending on the particular choice. In this work we quantify measurable consequences of the choice of the evolution variable and show how the implications of such a choice propagates into jet quenching observables.
        We have developed a parton shower algorithm for a general evolution variable, that includes the virtuality, angle, transverse momentum and formation time. We study the interplay between the shower history for different evolution variables and the phase space affected by parton energy loss. In particular, we implement effects of jet quenching in the dense and dilute medium limits, and highlight the role of color coherence effects [1,2]. We compare the results of the different evolutions to existing Monte Carlo shower implementations on the parton level by analyzing primary and secondary Lund planes. Finally, we study the sensitivity of quenched jets to the choice of evolution variable by confronting our results for certain key observables, such as the inclusive jet spectrum, the (groomed) momentum sharing fraction or the jet mass, against theoretical expectations and experimental data.

        [1] D. Pablos and K. Tywoniuk, JHEP 1611, 174 (2016).
        [2] Y. Mehtar-Tani and K. Tywoniuk, Phys. Rev. D98, 051501 (2018).

        Speaker: Ádám Takács (Wigner Research Centre for Physics)
      • 17:40
        Causality and dissipation in relativistic polarizeable fluids 20m

        We examine the relativistic perfect fluid limit, defined as the fastest possible local equilibration,
        in a medium with polarizeability, defined as a non-zero local equilibrium partition of angular
        momentum into spin and vorticity. We show that the Lagrangian approach is best suited to
        analyzing this situation, as it can be used to efficiently avoid issues such as the breakdown of
        isotropy, the ambiguity of the energy-momentum tensor definition and the lack of closure of
        conservation equations. We obtain the Lagrangian and the equations of motion of an ideal
        relativistic fluid with polarization, linearize them, and show that to restore causality a relaxation
        term linking vorticity and polarization, analogous to the Israel-Stewart term linking viscous forces
        and gradients,is required. We close with an discussion of the phenomenological applicability of the
        hydrodynamics with polarization developed here, focusing on the recent finding of Lambda
        polarization and resonance spin alignement, and discussing weather observables sensitive to earlytime polarization exist .

        Speaker: Mr David Montengro (Instituto de F ́ısica Te ́orica (IFT/UNESP), UNESP - S ̃ao Pau lo State University)
      • 17:40
        Central Membrane Studies for the sPHENIX TPC 20m

        sPHENIX is an ongoing upgrade to the PHENIX detector which is planned to explore the quark-gluon plasma formed in heavy ion collisions through the measurements of jets and Upsilons at RHIC in the 2020’s. The experiment will feature a charged particle tracking system along with electromagnetic and hadronic calorimeters and also a 1.4 Tesla superconducting solenoid magnet. A TPC with a GEM-based readout will form the core of the sPHENIX tracking system. The central membrane of the TPC is an important part of the TPC and several simulation studies ranging from tracking performance of single particles to jet fragmentation studies were done with different proposed designs of the TPC membrane. The details of these extensive simulation studies on the sPHENIX TPC membrane will be presented here.

        Speaker: sPHENIX Collaboration
      • 17:40
        Centrality dependence of bottom and charm production at PHENIX 20m

        Bottom and charm production is a powerful tool to investigate the properties of
        quark gluon plasma created in high energy heavy ion collisions. Heavy flavor production is calculable by perturbative QCD because of their large mass.
        Once produced, they traverse the QGP and suffer the hot medium effects such as
        energy losses. The collisional and radiative mechanisms play an important role of the energy losses
        for low and high $p_T$, respectively. Therefore, it is crucial to measure the medium modifications of bottom and charm production with broad $p_T$ ranges.
        PHENIX experiment at RHIC studied the heavy flavor production in Au+Au collisions
        using the measurement of single electrons from the heavy flavor decays. The Silicon vertex detector, VTX, provides the precise tracking capability, enabling the separation of electrons from the bottom and charm decays by measuring the distance of the closest approach to the collision vertex. Recently, we updated the $p+p$ baseline measurement of bottom and charm productions with high statistics.
        In this presentation, we will present the centrality dependence of bottom and charm production with the new $p+p$ baseline and discuss their modifications.

        Speaker: Takashi Hachiya (Nara Women's University and RIKEN)
      • 17:40
        Centrality determination with the Event Plane Detector for fluctuation measurements from STAR 20m

        Event-by-event fluctuation of conserved quantities such as net baryon, net strangeness or net charge is considered to be a powerful tool to find the critical point (CP) on the Quantum Chromodynamics (QCD) phase diagram. To map out the QCD phase diagram, the Beam Energy Scan I (BES-I) program has been carried out at RHIC and non-monotonic behavior of the 4th-order net-proton cumulants was found around low collision energy, which could be a signature of the CP. In order to further investigate the behavior of conserved quantities, BES-II has started in 2019 focusing on lower collision energies. For the experiment, a new detector named Event Plane Detector (EPD) was installed. The EPD is a scintillation detector located in the large rapidity region and expected to improve the determination of collision centrality with less self-correlation effect in the fluctuation measurements. In this poster, results of fluctuation measurements in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=27\ \textrm{GeV}$ will be shown and new centrality determination with the EPD will be discussed.

        Speaker: Yuri Sato (University of Tsukuba)
      • 17:40
        Challenges and prospects for the Silicon Tracking System of CBM in the first tests with heavy ions collisions 20m

        The Compressed Baryonic Matter (CBM) experiment at the FAIR facility aims to explore the QCD phase diagram at very high baryon densities, where a first order phase transition from hadronic to partonic matter as well as a chiral phase transition is expected to occur.
        The Silicon Tracking System is the central detector for momentum measurement and charged-particle identification. It is designed to measure up to 1000 charged particles in A+A collisions between 0.1 and 10 MHz interaction rate, to achieve a momentum resolution in a 1 Tm dipole magnetic field of better than 2%, and to be capable of identifying complex particle decays topologies, e.g., such with strangeness content. The STS employs high-granularity double-sided silicon strip sensors matching the non-uniform track density, and fast self-triggering electronics with a free streaming data acquisition system and online event selection. With the resulting 1.8 million readout channels, it poses the most demanding requirements regarding bandwidth and density of all CBM detectors.
        In the context of FAIR phase 0, the mini-CBM (mCBM) project aims to prove the concept of free-streaming data generation, transport and reconstruction, as well as to provide a test setup for all CBM subsystems using the existing GSI/FAIR accelerator facilities. The STS deployed a demonstrator of one small tracking station with full readout chain. The prototype, called mSTS, has been operated in Ag+Au collisions at energies above 1.59 AGeV and overall interaction rates up to 40 MHz, which is similar to a realistic experimental scenario. This allows evaluating the detector performance integrated with other subsystems into a free-streaming DAQ. This presentation aims to describe the main technical challenges and prospects for the STS and to summarize the results of the latest test campaign.

        Speaker: Adrian Rodriguez Rodriguez (Goethe University Frankfurt am Main)
      • 17:40
        Characterization and operation of the front-end electronics of the CBM Silicon Tracking System 20m

        The Compressed Baryonic Matter (CBM) experiment is a fixed-target heavy-ion physics experiment at the Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany. The CBM physics program aims at exploring the QCD phase diagram at very high baryon densities. For high-statistics measurements of rare probes, CBM is designed to cope with very high interaction rates up to 10 MHz. To achieve this high rate capability, the CBM experiment will be equipped with fast and radiation hard detectors employing free-streaming readout electronics. The Silicon Tracking System (STS) is the essential component for tracking up to 1000 charged particles per event in A+A collision. The experimental conditions pose demanding requirements in terms of channel density and read-out bandwidth. The STS-XYTER is a dedicated ASIC for the readout of the double-sided silicon micro-strip sensors. It is a low power, self-triggering ASIC with 128 channels, 5-bit ADC charge and 14-bit timing information. It needs to be fully integrated into a very confined space and it should perform in a highly irradiated environment with strong magnetic field. Several tests are carried out to check chip functionalities, full detector modules performance and integration aspects. An overview of the frontend electronic, module tests and experimental results, for different data taking scenarios, will be presented, including first measurements with a full system test-setup in heavy-ion collisions at SIS18.

        Speaker: Mr Osnan Maragoto Rodriguez (GSI Helmholtz Center for Heavy Ion Research)
      • 17:40
        Charge dependent flow and the search for the chiral magnetic wave at the LHC with ALICE 20m

        One of the novel anomalous chiral effects, the chiral magnetic wave (CMW), has been experimentally searched by using the charge-dependent anisotropic flow in recent years. The observed linear dependence between the charge asymmetry and the flow of the positively and negatively charged hadrons, however, still remains inconclusive owing to the existence of background effects such as local charge conservation entwined with the collectivity of the collision system.

        In this poster, we present the method and the preliminary measurements of the charge asymmetry dependence of elliptic and triangular flow, as well as the corresponding three-particle correlation for charged hadrons in Pb-Pb and p-Pb collisions at the TeV energy region with the ALICE detector. The results are partly compared with that of other experiments and the theoretical estimations from the signal and background. Our measurements provide more insights into the study of CMW as well as the collective behavior of the Quark-Gluon Plasma.

        Speaker: Qiye Shou (Fudan University)
      • 17:40
        Charge separation in Au+Au collisions at $\sqrt{{\it{s}}_{NN}} = 200$ GeV at STAR 20m

        In this poster, we will present measurements of event-by-event charge separation in Au+Au collisions at $\sqrt{{\it{s}}_{NN}} = 200$ GeV using Sliding Dumbbell Method (SDM). The charge dependent three-particle correlator ($\gamma = \langle cos(\phi_{a} + \phi_{b} - 2.{\Psi}_{RP}) \rangle$) which is the observable for Chiral Magnetic Effect (CME) [1] is investigated for each centrality interval which is further divided into ten bins depending on the charge separation based on SDM. An attempt is made to get CME enriched sample for each centrality. The background estimation is obtained by reshuffling the charges of particles and also by randomising the azimuthal angles of particles in an event. Physics implications will be discussed.

        [1] S.A.Voloshin, Phys. Rev. C 70 (2004) 057901.

        Speaker: Jagbir Singh (Panjab University)
      • 17:40
        Charged particle multiplicity dependence of $\Lambda(1520)$ production in pp collisions at $\sqrt{s}$ = 13 TeV with ALICE at the LHC 20m

        Resonances are useful tools to study the properties of the hadronic medium produced in high energy heavy-ion collisions, due to their short lifetime. In particular, the baryonic resonance $\Lambda(1520)$ is important because of its lifetime ($\tau \sim$ 12.6 fm/$\it c$), which lies in between the lifetimes of $ K^*$ and $\phi$ resonances.
        Its study will indicate the dominance of re-scattering or regeneration in the yields and support results obtained for other resonances having different lifetimes. The reconstruction of $\Lambda(1520)$ as a function of multiplicity in pp collisions at $\sqrt{s}$ = 13 TeV has been performed via its hadronic decay channel. New measurements of the transverse momentum ($p_{\rm{T}}$) spectra, $p_{\rm{T}}$-integrated yield ($\langle dN/dy\rangle$), $\langle p_{\rm{T}}\rangle$ and $\Lambda(1520)/ \Lambda$ yield ratio in different multiplicity classes will be presented and discussed. The results obtained are expected to provide more information on strange resonance production and the system-size evolution of the hadronic phase in small systems. Furthermore, these results are important for studies of the multiplicity-dependent enhancement of multi-strange hadrons in small systems.

        Speaker: Dr Pragati Sahoo (Indian Institute of Technology Bombay)
      • 17:40
        Charged-particle multiplicity dependence of $\rm K^{*}(892)^{\rm \pm}$ resonance production in pp collisions at $\sqrt{\rm s}$ = 13 TeV with ALICE 20m

        Hadronic resonances have been shown to be good probes to investigate the late-stage evolution of ultra-relativistic heavy-ion collisions. Their lifetimes are comparable with the time scale of the fireball generated in these collisions. Therefore they are sensitive to the competing re-scattering and regeneration effects occurring in the hadronic phase, which modify particle momentum distributions and yields after hadronization.
        Recent measurements of resonance production in high-multiplicity proton-proton (pp) and proton-lead (p-Pb) collisions have shown the onset of phenomena typical of heavy-ion (Pb-Pb) collisions even in those smaller collision systems. In particular, there are hints of suppression of the $\rm K^{*}(892)^{\rm 0}$/$\rm K$ ratio with increasing charged-particle multiplicity. A study of $\rm K^{*}(892)^{\rm \pm}$ production can provide further evidence to confirm the observed trend.
        In this poster the measurement of $\rm K^{*\rm \pm}$ production at mid-rapidity in pp collisions at 13 TeV as a function of the charged-particle multiplicity will be presented and discussed. The measurements will be compared to results for the $\rm K^{*\rm 0}$, other collision systems and energies, and to theoretical models.

        Speaker: Daniele Pistone (Universita e INFN, Catania (IT))
      • 17:40
        Charged-particle multiplicity dependence of $\Sigma(1385)^{\pm}$ and $\Xi(1530)^{0}$ production in pp collisions at 13 TeV with ALICE at the LHC 20m

        Strangeness enhancement has been observed for several multi-strange hadrons in proton-proton (pp) collisions with increasing charged-particle multiplicity and is in remarkable agreement with measurements in p-Pb collisions. The yields of resonances with short lifetimes are sensitive to regeneration and re-scattering processes in the hadronic phase between chemical and kinetic freeze out. It is therefore interesting to study these resonances in pp collisions as a function of multiplicity to see if we can observe signs of a hadron-gas phase even in small collision systems. In this poster, the strange hyperon resonances $\Sigma(1385)^{\pm}$ ($c\tau=5-5.5$ fm/$c$) and $\Xi(1530)^{0}$ ($c\tau=21.8$ fm/$c$) are studied as a function of charged-particle multiplicity in pp collisions at $\sqrt{s}=13$~TeV. The $p_{\mathrm{T}}$ spectra, mean $p_{\mathrm{T}}$ and integrated yields and their ratios to long-lived hadrons will be reported and compared to measurements in other collision systems and to theoretical models.

        Speaker: Bong-Hwi Lim (Pusan National University (KR))
      • 17:40
        Charged-particle production as function of event multiplicity in ALICE 20m

        The ALICE experiment at the LHC is designed to investigate the properties of the Quark-Gluon Plasma by studying high-energy pp, p--Pb, Pb--Pb and Xe--Xe collisions. Medium effects like parton energy loss can be examined by measuring the production of charged particles and their nuclear modification at high transverse momentum ($\textit{p}_{\text{T}}$).
        In this poster, we report on charged-particle $\textit{p}_{\text{T}}$-spectra as a function of the event multiplicity. Detector efficiency and resolution effects are corrected for using an iterative unfolding procedure. Particle production is compared for different collision energies and systems.
        In particular, we focus on investigating the energy and system size dependence of the unfolded $\textit{p}_{\text{T}}$-spectra as a function of event multiplicity by means of the evolution of the inverse slope parameter of the $\textit{p}_{\text{T}}$-spectra at high $\textit{p}_{\text{T}}$. All results are compared with QCD-inspired models.

        Speaker: Patrick Huhn (Johann-Wolfgang-Goethe Univ. (DE))
      • 17:40
        Charm and beauty isolation in heavy flavor electron measurements in Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV at RHIC 20m

        Heavy quarks (charm and beauty) are believed to be produced predominately in hard scattering processes at early stage of the collisions before the QGP production so they can pass through the hot-dense medium completely, and their production yields can be calculated by perturbative-QCD, which makes them ideal probes for QGP. According to the theoretical prediction, energy loss of heavy quarks is less than that of light quarks due to the suppression of the gluon radiation angle by the quark mass. Heavy quarks could be more difficult to be thermalized than light quarks in the hot-dense medium and moved following the collective flow during the expansion of the partonic matter. Because of its three times larger mass compared with that of charm, beauty could have different properties in terms of its interactions with QGP medium from charm.

        We develop a data-driven method to isolate charm and beauty contributions from the inclusive heavy flavor electrons based on the most recent open charm hadron measurements in minimum bias Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV at RHIC. The individual electron nuclear modification factor ($R_{\rm AA}$) and elliptic flow ($v_2$) from charm and beauty decays will be reported. Model comparisons and discussions will also be given.

        Speaker: Mr Fan Si (USTC)
      • 17:40
        Charm baryon production measurements in small systems with the ALICE experiment at the LHC 20m

        Heavy quarks (charm and beauty) are an effective tool to study the properties of the Quark-Gluon Plasma (QGP) formed in heavy-ion collisions at the LHC. Due to their large mass, they are produced during the early stages of the collisions in hard-scattering processes, on a time interval shorter than the QGP formation time. Thus, they experience the whole evolution of the system. The baryon-to-meson ratio is sensitive to the hadronisation mechanism. In particular, it is expected to be enhanced with respect to the proton-proton baseline if charm quarks hadronise via recombination with the surrounding light quarks in the QGP. Measurements of charm-baryon production in small systems (pp and p--Pb collisions) provide the reference necessary for interpreting results in Pb--Pb collisions. In addition, in pp collisions, they allow to study the hadronisation of charm quarks, and allow testing QCD calculations. Measurements in p--Pb collisions are fundamental to disentangle cold nuclear matter effects from those deriving from the presence of the QGP.

        In this contribution, the latest ALICE measurements on the $\Lambda_c$ baryon production and the $\Lambda_c / \rm D^0$ ratio in pp and p--Pb collisions at $\sqrt{s}$ = 5.02 TeV will be presented. Results will be compared with theoretical expectations. In addition, the latest results on the multiplicity dependent production of the $\Lambda_c$ baryon in pp collisions at $\sqrt{s}$ = 13 TeV will be discussed. Furthermore, the measurement of the $\Xi_c$ baryon in pp collisions at $\sqrt{s}$ = 7 TeV will be presented. Finally, the latest updates on the measurements of the $\Xi_c$ baryon in pp and p--Pb collisions at 5.02 TeV will be discussed together with the status of the measurement of the $\Sigma_c$ baryon.

        Speaker: Cristina Terrevoli (University of Houston (US))
      • 17:40
        Charm production in pp and p-Pb collisions with ALICE at the LHC 20m

        Charm quarks are effective probes used for the investigation of the Quark-Gluon Plasma (QGP) created in high-energy heavy-ion collisions. They are produced in hard scattering processes on a timescale shorter than the QGP formation time and experience the whole system evolution.
        The measurement of charm-baryon production, and in particular the baryon-to-meson ratios, provides unique information on hadronisation mechanisms, constraining the role of coalescence and testing the predicted presence of diquark states in the QGP.
        Measurements of charm-baryon production in pp and p-Pb collisions are essential to establish a baseline for Pb-Pb collisions. In addition, the measurements in pp collisions provide critical tests of $p$QCD calculations and models of charm hadronisation in vacuum, while the measurements in p-Pb collisions are useful to study cold nuclear matter effects and the possible evolution with charged-particle multiplicity of the modification of charm hadronisation.
        In this poster, ALICE results of $\Lambda_{\rm c}^{+}~$ measurements in pp and p-Pb collisions will be presented. The comparison with model calculations will be discussed. Furthermore, the latest updates on the measurement of the total charm cross-section in pp and in p-Pb collisions will be discussed.

        Speaker: Dr Elisa Meninno (Stefan Meyer Institute for Subatomic Physics, Vienna)
      • 17:40
        Charmonia production in pPb collisions at LHCb 20m

        We present LHCb results on charmonia production in proton-lead collisions, using the data collected in 2016 at sqrt(s_NN) = 8.16 TeV nucleon-nucleon centre-of-mass energy, in the forward region (pseudorapidity between 2 and 5), covering forward (pPb configuration) and backward (Pbp configuration) rapidities. Measurements include prompt and from-b-decay components which are disentangled. The large increase in size of the data sample, compared to the 5 TeV sample collected in 2013, allows a remarkable improvement in the accuracy of the studies of nuclear matter effects.

        Speaker: Jana Crkovska (Los Alamos National Laboratory (US))
      • 17:40
        Chiral Kinetic Theory from High Density Effective Theory and Reparametrization Invariance 20m

        We redevelop the chiral kinetic theory (CKT) by exploiting the effective field theory method and find some disagreements at higher order of ($1/\mu$) from the earlier results. However, these disagreements are the same which have been pointed out by the off-shell effective theory formalism after identifying a cut-off. We address the discrepancies and by using the reparametrization invariance, we show that these disagreements are in fact expected due the choices of different degrees of freedom in effective theory and field theory. Further, we show that both methods yield the similar dynamics for chiral fermions.

        Speaker: Aradhya Kumar Shukla (School of Physics and Astronomy, Sun Yat-Sen University, Guangzhou, China)
      • 17:40
        Chiral Magnetic Hydrodynamics 20m

        Be based on Heavy Ion Collisions, I focus on the chiral anomaly effect eg:CME or CVE in magnetic hydrodynamics. Due to chiral anomaly ,there will be many special features ,I will introduce possible new wave models with the CVE in magnetic hydrodynamics.

        Speaker: Mr Shuai Wang
      • 17:40
        Chiral soliton lattice in dense matter under rotation 20m

        We study the anomaly-induced effects of dense matter under rotation. We show that the chiral perturbation theory under rotation has the topological term that accounts for the chiral vortical effect. We find that, due to the presence of this new term, the ground state of QCD under rotation is the chiral soliton lattice (CSL) of the neutral pion or $\eta^{\prime}$ meson. This state is a periodic array of topological solitons which spontaneously breaks parity and continuous translational symmetries. In particular, at high density, the CSL of the $\eta^{\prime}$ meson is energetically more favorable than the color-flavor locked color superconducting phase and its critical angular velocity is proportional to the QCD anomaly in the flavor symmetric case.

        Speaker: Kentaro Nishimura (Keio University)
      • 17:40
        Chiral Vortices and Pseudoscalar Condensation due to Rotation 20m

        We investigate the influence of rotation on the chiral condensate in strongly interacting matter. We develop a self-consistent theoretical framework to study the inhomogeneous chiral condensate and the possible chiral vortex state in rotating finite-size matter in four-fermion interaction theories. For sufficiently rapid rotation, the ground state can be a chiral vortex state, a type of topological defect in analogy to superfluids and superconductors. The vortex state exhibits pion condensation, providing a new mechanism to realize pseudoscalar condensation in strongly interacting matter.

        Speaker: Mr Lingxiao Wang (University of Tokyo)
      • 17:40
        Cold Nuclear Matter Effects on J/$\psi$ and $\Upsilon$ Productions at RHIC with the STAR Experiment 20m

        Quarkonia are excellent probes for studying the properties of quark-gluon plasma formed in relativistic heavy-ion collisions at RHIC. In order to fully understand the observed suppression of quarkonium production in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV, it is essential to understand well the cold nuclear matter (CNM) effects on the quarkonium production. Collisions of p+Au at the same energy can be used to study the CNM effects since these effects are expected to be dominant in such systems.

        In this poster, we present measurements of inclusive J/$\psi$ and $\Upsilon$ cross-sections in p+p collisions and their modification in p+Au collisions (the nuclear modification factor $R_{pAu}$) at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV. The results are extracted from data recorded by the STAR experiment in 2015 using the di-electron decay channel of the quarkonia. Comparisons are made to results from other experiments as well as to model calculations and physics implications are also discussed.

        Speakers: Ziyue Zhang, Zhenyu Ye (University of Illinois at Chicago)
      • 17:40
        Collective effects in pp collisions with the balance function of the identified particles 20m

        Experiments at RHIC and the LHC have lately reported intriguing results that indicate the presence of collectivity in small collision systems. The first hints originated from two-particle azimuthal correlations studies. The charge dependent part of such correlations is studied using the balance function in the relative pseudorapidity (∆η) and azimuthal angle (∆φ) of the particle pair. This measurement has been used as an effective tool to investigate the properties of the system created in high-energy heavy-ion collisions such as the hadronization time, the freeze-out conditions and to characterise its collective motion. In addition, the study of the balance function for different particle species in A-A collisions provides valuable insight to the chemical evolution of the QGP.

        In this poster, we report the measurement of the balance function of identified particles in pp collisions at √sNN = 5.02 TeV recorded by ALICE. This analysis, performed as a function of multiplicity, is an important piece in understanding if the underlying physics phenomena of particle production are of a common origin across collision systems.

        Speaker: Ms Zhanna Khabanova (Nikhef)
      • 17:40
        Collision energy dependence of the freeze-out in nuclear collisions at RHIC BES and the LHC 20m

        We reconstruct the freeze-out state of the fireball produced in central Au+Au or Pb+Pb collisions in the energy range from 7.7 GeV up to 2760 GeV per colliding nucleon pair. The data stem from the RHIC beam energy scan programme and from the LHC. Transverse momentum spectra of protons, antiprotons, charged pions and kaons have been fitted. Blast-wave model is used. Resonance decays are fully taken into account and the fitting procedure uses Bayesian method with Gaussian process emulator. It is assumed that the fireball freezes-out chemically at chemical freeze-out temperature and then evolves in partial chemical equilibrium. We present how different resonance decays contribute to the spectrum at different energies. The freeze-out temperature decreases with increasing collision energy, while the transverse expansion velocity grows. The decrease of the freeze-out temperature seems to stop at the collision energy of 130 GeV; afterwards the temperature stays constant or grows slightly.

        Speaker: Boris Tomasik (Univerzita Mateja Bela (SK))
      • 17:40
        Collision-system dependence of charge separation relative to the second- and third-order event planes; Implications for the Chiral Magnetic Effect in STAR 20m

        Validation of the Chiral Magnetic Effect (CME) in the quark-gluon plasma (QGP) produced in heavy-ion collisions can provide key insights into anomalous transport in QGP and the connections between chiral symmetry restoration, axial anomaly and gluonic topology. Recently, a charge-sensitive correlator, $\mathrm{R_{\Psi_m}(\Delta S)}$ [1], designed to discern between background- and CME-driven charge separation was used to carry out a detailed set of charge separation measurements, relative to both the $2^{\mathrm{nd}}$- ($\Psi_2$) and $3^{\mathrm{rd}}$-order ($\Psi_3$) event planes for several collision systems (A+A(B)). The measurements indicate nearly flat to convex $\mathrm{R_{\Psi_m}(\Delta S)}$ distributions for the measurements relative to $\Psi_3$ and those relative to $\Psi_2$ for the p(d)+Au systems, consistent with the essentially random $\vec{B}$-field orientations for these measurements. By contrast, the A+A measurements relative to $\Psi_2$ show concave-shaped $\mathrm{R_{\Psi_2}(\Delta S)}$ distributions suggestive of a CME-driven charge separation. Results for U+U collisions at $\sqrt{s_{NN}}$= 193 GeV and p(d)+Au, Cu+Au, Cu+Cu and Au+Au collisions at $\sqrt{s_{NN}}=$ 200 GeV will be presented and discussed in this poster.

        [1] N. Magdy, et al., Phys. Rev. C 97 (2018) 061901.

        Speaker: Niseem Abdelrahman (University of Illinois at Chicago)
      • 17:40
        Comparison of Chemical freeze-out parameters in p+p, p+Pb, Xe+Xe and Pb+Pb collisions at LHC energies 20m

        In this work, we have presented the collision energy, multiplicity and system size dependence of chemical freeze-out parameters such as chemical freeze-out temperature ($T_{\rm ch}$) and strangeness saturation factor ($\gamma_{s}$). These parameters are obtained by analysing the particle ratios at different Large Hadron Collider (LHC) energies using statistical thermal model (THERMUS). Here, we consider the particle ratios obtained recently in pp collisions at $\sqrt{s}$ = 13 TeV, p+Pb at $\sqrt{s_{\rm NN}}$ = 5.02 TeV, Xe+Xe at $\sqrt{s_{\rm NN}}$ = 5.44 TeV and Pb+Pb at $\sqrt{s_{\rm NN}}$ =5.02 TeV. In addition, we look into the energy dependence of chemical freeze-out parameters by comparing with pp collisions at $\sqrt{s}$ = 7 TeV and Pb+Pb at $\sqrt{s_{\rm NN}}$ =2.76 TeV results in our study. The particle production from small to large systems has been addressed by considering two ensembles namely, canonical and grand canonical. The results obtained in this study shows a clear multiplicity dependence of $T_{\rm ch}$ and $\gamma_{s}$. The values obtained in high multiplicity pp collisions are similar to the peripheral Pb+Pb collisions. In future, high multiplicity triggered pp events will add more insight about the strangeness chemical equilibrium and to understand the particle production mechanism in smaller collision systems.

        Speaker: Arvind Khuntia (Indian Institute of Technology Indore (IN))
      • 17:40
        Conserved charge fluctuations at vanishing net-baryon density from Lattice QCD 20m

        Cumulants of net charge fluctuations and their correlations at vanishing values of the charge chemical potentials ($\mu_{B,Q,S}=0$) provide the basis for Taylor expansions of various thermodynamic observables at non-zero values of the chemical potentials. At $\mu_{B,Q,S}=0$ continuum extrapolated results for these cumulants can directly be compared with charge fluctuations and correlations currently being measured by the ALICE collaboration at the LHC.
        We present here continuum extrapolated results for all second order and some of the fourth order cumulants of net baryon-number, strangeness and electric charge fluctuations as well as their cross-correlations obtained by the HotQCD collaboration. As the chemical freeze-out temperature at LHC is found to be close to the pseudo-critical temperature for the QCD chiral transition these cumulants potentially probe remnants of critical behavior in the crossover region. Using results from calculations with smaller than physical quark masses we estimate the singular part contributing to these second and fourth order cumulants. Furthermore, we will show comparisons of our results with hadron resonance gas (HRG) model calculations and argue that particularly in the electric charge sector there is evidence for strong modifications of the resonance spectrum in the transition region.
        We also will use the updated results of HotQCD on higher order cumulants to constrain the radius of convergence of Taylor series as estimator for the location of a possible critical point in the QCD phase diagram.

        Speaker: Jishnu Goswami (Bielefeld University)
      • 17:40
        Constraining Particle Production in Au+Au Collisions at RHIC Energies Using A Multi Phase Transport Model 20m

        We study the production of pions, kaons, and (anti-) protons in A Multi Phase Transport (AMPT) Model in Au+Au collisions at $\sqrt{s_{NN}}=$ 7.7, 27, and 200 GeV. We present the centrality and energy dependence of bulk observables such as invariant yields as a function of transverse momentum $p_T$, particle yields $dN/dy$, average transverse momentum $\langle p_T \rangle$ and various particle ratios, and compare them with experimental data. Both default and string melting (SM) versions of the AMPT model are used with three different sets of initial conditions. We observe that neither the default nor the SM model could consistently describe the centrality dependence of all observables at the above energies with any one set of initial conditions. The energy dependence behavior of the experimental observables for 0--5\% central collisions is in general better described by the default AMPT model using the default HIJING parameters for Lund string fragmentation and 3mb parton scattering cross-section.

        Speaker: Dr Lokesh Kumar (Panjab University (IN))
      • 17:40
        Constraining the initial stages of heavy-ion collisions with high-$p_{\perp}$ theory and data 20m

        Commonly, only low-$p_{\perp}$ sector is used to infer the features of initial stages before QGP thermalization. On the other hand, recently acquired wealth of high-$p_{\perp}$ experimental data paves the way to utilize the high-$p_{\perp}$ particles energy loss in exploring the initial stages. However, the results of such explorations are up to now either inconclusive or questionable. We here concentrate on high-$p_{\perp}$ $R_{AA}$ and $v_2$ observables, and study the effects of four different commonly considered initial stages scenarios, which have the same temperature profile after - but differ in the temperature profiles before - thermalization. For the study, we use our recently developed DREENA framework, which is a fully optimized computational procedure in which our state-of-the-art dynamical energy loss is employed. Contrary to the common expectations, we surprisingly obtain that high-$p_{\perp}$ $v_2$ is insensitive to the initial stages of medium evolution, being unable to discriminate between different scenarios. On the other hand, $R_{AA}$ is notably sensitive to these conditions, strongly preferring later thermalization times and free streaming during the initial stages of QGP formation. Moreover, we also reconsider the validity of widely-used procedure of fitting the energy loss parameters for different initial-stage cases to reproduce the experimentally observed $R_{AA}$. We here find that the reported sensitivity of $v_2$ to different initial-stage scenarios is mainly an artifact of the $R_{AA}$ fitting, with no real physical process to support it. Therefore, such a procedure may lead to erroneous conclusions, masking the underlying nature of jet-medium interactions. Consequently, the simultaneous study of high-$p_{\perp}$ $R_{AA}$ and $v_2$ is necessary for imposing reliable constraints on the initial stages.

        Speaker: Dr Bojana Ilic (Blagojevic) (Institute of Physics Belgrade)
      • 17:40
        Cross-correlators of conserved charges in QCD 20m

        We present our continuum extrapolated lattice QCD results for the cross-correlators of baryon number, electric charge and strangeness, and compare them to calculations from the Hadron Resonance Gas (HRG) model with the most up-to-date hadronic spectrum. We analyze the contributions to these observables from hadronic correlations and self-correlations, and their relation to experimentally measurable quantities. We study the dependence of the cross-correlators on the kinematic cuts, and suggest novel observables to allow for a model-independent comparison to experimental results. We perform the direct comparison to available experimental results, for observables related to net-$\Lambda$ and net-kaon fluctuations.

        Speaker: Paolo Parotto (University of Wuppertal)
      • 17:40
        Curing the numerical Cherenkov instability in 3+1D Glasma simulations 20m

        We present our results on genuinely 3+1D simulations of the Glasma in heavy ion collisions. By incorporating nuclei with finite thickness along the beam axis, we naturally break boost invariance and obtain Gaussian-like rapidity profiles of energy densities already at the tree level [1]. The profiles resemble strong coupling results and agree surprisingly well with experimental data of pion multiplicities as obtained at RHIC. The applicability of these simulations is limited by the numerical Cherenkov instability. We construct a new lattice action which allows us to cure this instability along one lattice direction [2]. This paves the way for simulations at higher energies and better resolution.

        [1] AI, D. Müller, Phys.Lett. B771 (2017) 74-79, arXiv:1703.00017
        [2] AI, D. Müller, Eur.Phys.J. C78 (2018) no.11, 884, arXiv:1804.01995

        Speaker: Andreas Ipp (TU Wien)
      • 17:40
        D + meson production as a function of charged- particle multiplicity in pp collisions at √s =13 TeV with ALICE 20m

        Charm and beauty are heavy quarks with observed masses of
        1.28 GeV/c 2 and 4.18 GeV/c 2 respectively. They are produced
        in initial hard scattering processes. Due to their small
        formation time (∆t~0.1 fm/c) as compared to the formation
        time of QGP ( ∆t~0.3 fm/c) at the LHC, they experience all the
        stages occuring during the time evolution of the hot and dense
        medium produced in heavy-ion collisions. Therefore, the
        measurement of open charm and beauty production allows
        probing QGP properties and investigating the color charge and
        mass dependence of the parton in-medium energy loss.
        Moreover, due to their large masses (m c , m b >> Λ QCD ) their pp
        production cross-sections are calculable within the domain of
        perturbative QCD constituting an excellent test of pQCD
        calculations.
        The study of D-meson yield in pp collisions as a function of
        charged-particle multiplicity helps to understand the processes
        involved in the production of charm quarks. Moreover,
        analyzing the charm production processes could help in
        learning the basic differences between hard and soft processes
        of particle production. Along with that, they also serve as a
        reference for the similar measurements in p-Pb and Pb-Pb
        collisions.
        In this contribution, D + meson yield as a function of charged-
        particle multiplicity will be presented. Furthermore, the
        comparison with J/ψ yield at 7 TeV, 13 TeV and to D + -meson
        yield at 7 TeV in pp collisions will be shown.

        Speaker: Randhir Singh (University of Jammu (IN))
      • 17:40
        D+ meson production in pp, p--pb and Pb--Pb collisions at √s= 5 TeV with ALICE 20m

        Heavy quarks (charm and beauty) are effective probes to investigate the properties of the hot and dense strongly-interacting medium created in heavy-ion collisions as they are produced in high-energy hard partonic scattering processes occurring in the early stages of the collision. Due to their long life time, they probe all the stages of the medium evolution interacting with its constituents and losing energy via gluon radiation and elastic collisions. In pp collisions, heavy quarks serve as a fundamental test of perturbative QCD calculations and also provide reference for measurements in p--Pb and Pb--Pb collisions. Pb--Pb collisions give the possibility of studying the properties of strongly-interacting matter at high temperature and density, while p-Pb collisions allow us to disentangle cold nuclear effects (such as kT broadening, nuclear modification of parton distribution functions, parton saturation at small Bjorken-x etc.) and to study the origin of the collective-like effects evidenced in high-multiplicity pp and p--Pb collisions.
        The ALICE apparatus has excellent capabilities for heavy-flavour measurements in all the collision systems. Open heavy-flavour production is measured at mid-rapidity via the hadronic decays of D mesons (D0, D+, D∗+ and Ds+) and Λc+, the semileptonic decays to electrons of charm and beauty hadrons and also semileptonic decays to electrons of Λc+ and Ξc0.
        In this contribution, the measurement of D+ meson production in pp, p--Pb and Pb--Pb collisions will be presented. The results will also be compared with various theoretical models

        Speaker: Dr Renu Bala (University of Jammu (IN))
      • 17:40
        D-meson production in Pb--Pb collisions with ALICE at the LHC 20m

        The production of charm quarks occurs predominantly in hard scattering processes in the earliest stages of a heavy-ion collision, and due to their relatively long lifetimes they experience the full evolution of the system. In ALICE, charmed mesons ($D^0$,$D^+$,$D^{*+}$ and $D_{s}^{+}$) are reconstructed in their hadronic decay channels, allowing the full kinematic information of the original particle to be retained. Their nuclear modification factor ($R_{\rm AA}$) evaluated as the modification of the D meson production $p_{\rm T}$ spectra in Pb--Pb collisions with respect to the one in proton--proton collisions gives insight into the energy loss mechanisms charm quark undergoes as it traverses the strongly interacting medium (QGP). In particular comparisons with lighter hadrons give insight into the possible mass and flavour dependence of the in-medium energy loss. Comparative studies between particle species in Pb--Pb and pp collision systems allow us to test possible differences in the production of different charge states and resonances such as $D^{*+}$.

        Furthermore, charmed hadrons with strangeness content, such as $D_{s}^{+}$, are of particular interest as they allow us to probe the effect of the hot and dense medium on charm hadronisation such as the possible recombination of charm and strange quarks in the strangeness-rich QGP. In this case one expects a difference in the $R_{\rm AA}$ of strange and non-strange D mesons.

        In this contribution will be presented the latest ALICE results for the production of strange and non-strange D mesons in Pb--Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV, using the data provided by the 2018 run of the LHC. The nuclear modification factor of strange and non-strange D-mesons will be shown, along with the relative production ratios of the strange and non-strange D-meson species. Of particular interest is the extremely low $p_{\rm T}$ reach ALICE is able to achieve on the measurement of the production of $D^0$ mesons in Pb--Pb collisions that allows to evaluate the $D^0$ $R_{\rm AA}$ down to $\sim$ 0 $p_{\rm T}$ and opens the possibility to determine the total $D^0$ production cross-section in heavy-ion collisions.

        Finally, comparisons of the measurements with theoretical model calculations and lighter-flavour particles will be discussed.

        Speaker: Stefano Trogolo (Universita e INFN, Padova (IT))
      • 17:40
        D0-meson elliptic flow using event-shape-engineering technique in Au+Au collisions at √sNN = 200 GeV from STAR 20m

        Because of their early production, charm quarks are sensitive to the entire evolution of the system created in ultra-relativistic collisions of heavy ions. In particular, charm quark elliptic flow (v2) is a valuable tool for study of charm transport in the quark-gluon plasma (QGP). Recent results from the STAR experiment show that in 10-40% central Au+Au collisions at the top RHIC energy the D0-meson v2 follows the Number-of-Constituent-Quark(NCQ) scaling similarly as light-flavor hadrons. To gain more insight into the charm quark dynamics it is of interest to study their flow in events with different initial conditions.

        In this poster, we will present D0-meson v2 measurement with the event-shape-engineering technique applied in Au+Au collisions at sNN = 200 GeV by the STAR experiment. The measurement utilizes the STAR Heavy Flavor Tracker and the combined datasets recorded during RHIC 2014 + 2016 runs. D0 v2 will be reported as a function of the reduced flow vector q2 and compared to that of light-flavor and strange hadrons. Furthermore, we utilize the Forward Meson Spectrometer (FMS) detector covering the range of 2.5 < η < 4. The large η-gap helps to reduce the non-flow contribution in the D0 v2 measurement. These results will be compared to model calculations and physics implications on the charm quark diffusion coefficient will be discussed.

        Speaker: Yue Liang (Kent State Univesrsity & Lawrence Berkeley National Laboratory )
      • 17:40
        Data-driven constraints on the drag and diffusion of light partons 20m

        Interactions between hard partons and the quark-gluon plasma range from frequent soft collisions to rare large angle scatterings. The larger number of soft interactions makes possible an effective stochastic description of parton-plasma interactions in terms of drag and diffusion transport coefficients [1]. We build on the methodical division between soft and hard parton-plasma interactions derived in Ref. [2] and present a first Monte-Carlo implementation of this reformulated parton energy loss model. We discuss the model's dependence on the scale separating soft and hard interactions, both for small and large values of the strong coupling constant.

        Using the model's systematic separation between the transport (soft) sector of the parton energy loss and harder vacuum-like interactions, we perform a Bayesian analysis to calibrate the model to jet measurements and extract the transport properties of light partons propagating in a strongly-coupled quark-gluon plasma. We constrain the drag and diffusion coefficients alongside the strong coupling constant and the scale separating soft and hard parton-plasma interactions, and discuss the physical interpretation of the phenomenologically-constrained soft/hard scale.


        [1] Moore and Teaney, Phys.Rev.C71:064904 (2005)
        [2] Ghiglieri, Moore and Teaney, JHEP1603:095 (2016)

        Speaker: Tianyu Dai (Duke University)
      • 17:40
        Development and characterization of high-density interconnection technologies for the CBM Silicon Tracking System at FAIR 20m

        The Compressed Baryonic Matter (CBM) experiment at the future Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany, aims to explore the quantum chromodynamics phase diagram for highest baryon densities.
        One of the core detectors of CBM is the Silicon Tracking System (STS). The STS is the key detector for measuring the momentum and tracks of up to 1000 charged particles produced in Au+Au collisions which happen at interaction rates up to 10 MHz on a fixed target. Due to the required momentum resolution for the STS of Δp/p ~ 1.5%, the material budget of STS has to be minimized as much as possible. In order to keep the read-out electronics, cooling and mechanical infrastructure out of the detector acceptance, the sensors are connected to the self-triggering front-end electronics by means of low-mass flexible microcables with a length up to 50 cm. In combination with the large double-sided sensors with a size up to 124 mm x 62 mm, the detector module becomes a highly complex structure, which in turn leads to a challenging module assembly procedure.
        To mitigate risk, two high-density interconnection technologies have been developed for the STS modules, based on ultra-thin aluminium and copper mircocables, respectively. Capacitance simulations and measurements of the microcables and full detector material budget simulations have been performed. Next to the individual steps involved in the respective interconnection technologies, the electrical performance of the assembled modules, including a thorough noise analysis, will be presented.

        Speaker: Patrick Pfistner (KIT)
      • 17:40
        Development of a Muon Chamber System at the CBM Experiment at FAIR 20m

        The Compressed baryonic matter (CBM) experiment at the future acceleratorFacility for anti-proton and ion research (FAIR) in GSI Germany aims to explore the QCD phase diagram in the very high net-baryon density. The Muon Chamber (MuCh) system would facilitate detection of probes like charmonium (J/ψ) and low mass vector mesons (LMVM) via di-leptonic decay channel. The CBM experimental conditions require detectors to be high radiation tolerant and with high rate capability. Under these circumstances, the MuCh system will be based on segmented absorbers with detectors placed in between them. The first two stations of MuCh system will be based on gas electron multiplier (GEM) technology where the particle ratereachesup to about 1 MHz/cm2for minimum bias Au-Au collisions at SIS100 energy. On the other hand, the 3rdand 4thstationswill be resistive plate chamber (RPC) based where particle ratereduces to 4 KH/cm2. In the present presentation, we will discuss detail design parameters of the MuCh system. Prototype test results of two different subsystems (GEM and RPC) using self-triggered electronics custom-built for CBM will also be presented.

        Speaker: Dr subhasis chattopadhyay (Variable Energy Cyclotron Centre)
      • 17:40
        Development of Hadron Identification Detector Using MRPC for J-PARC E16 Experiment 20m

        In J-PARC E16 experiment, for the first beam time in the coming February 2020, the sophisticated detector system for measuring hadron spectra via $e^{+}$ $e^{-}$ pair decay, for example $\phi$ $ \rightarrow $ $e^{+}$ $e^{-}$, is being installed and commissioned. In addition to these detectors, hadron identification detector using time-of-flight technique with MRPC devices, is under development. These devices would expand capabilities to study changes of the hadron properties in the various status of matter, with the scope to measure the chiral symmetry restoration in the matter. In this presentation, the latest status of development and the performance are presented and discussed.

        Speaker: Hiroyuki Sako
      • 17:40
        Development of large area silicon pixel detector assembly for heavy-ion collision experiments 20m

        Based on the state-of-the-art Monolithic Active Pixel Sensor (MAPS) technology, the silicon pixel detector has been successfully applied in the STAR Heavy Flavor Tracker (HFT) for the first time since early 2014. The HFT allows precise measurements of open heavy flavor hadron production in heavy-ion collisions over a wide range of transverse momentum at RHIC. After the 2$^{\rm{nd}}$ long shutdown (LS2) during 2019 to 2020, the ALICE detector will be upgraded to enable the read-out of all interactions and accumulate more than 10 nb$^{-1}$ of Pb+Pb collisions in Run 3 (2021 - 2023) and Run 4 (2026 - 2029). One of the key components of the ALICE LS2 upgrade programme is that a new low material and high-resolution silicon pixel detector for the Inner Tracking System (ITS) based on the next generation of MAPS technology will be built, which has been adopted by sPHENIX and NICA/MPD experiments for faster vertex detector development in coming years.
        The Chinese group has constructed a complete assembly line and built an experienced team on large area pixel chip integration and testing at CCNU. As one of five ALICE ITS Outer Barrel (OB) Hybrid Integrated Circuit (HIC) construction sites, CCNU has completed the OB HIC construction with a yield of about 80\%, approximately 20\% of the ITS OB HIC modules (equal share planned over 5 sites). The positioning accuracies of chip alignment and wire-bonding are well controlled within 5 $\mu$s ($@3\sigma$). Development of the MAPS-based pixel detector for the HIC experiments at CCNU is introduced in this poster, and the advanced techniques involved in the detector assembly and test are described. We will also report the plan in China on the Inner Tracker (IT) construction for the NICA/MPD experiment, and the MAPS-based IT detector will enable MPD to measure charm production at NICA energies and benefit clean measurement of multi-strange hadron spectra.

        Speaker: Biao Zhang (Central China Normal University CCNU (CN))
      • 17:40
        Dielectron Production in Au+Au Collisions at $\sqrt{s_\textrm{NN}}=$ 27 GeV with the STAR Experiment 20m

        Dielectron production is suggested as an excellent probe of the hot, dense and strongly interacting medium (QGP) created in relativistic heavy-ion collisions due to their minimal interactions with the medium and the final state hadrons. Dielectrons can be produced at different evolution stages of the collision system. Different invariant mass ranges are sensitive to different physics processes. In the low mass region ($M_{ee}$<$M_{\phi}$), dielectron production is sensitive to the in-medium modifications of vector mesons which could provide an access to the chiral symmetry restoration. In the intermediate mass region ($M_{\phi}$<$M_{ee}$<$M_{J/\psi}$), the dielectron production from the medium thermal radiation is sensitive to the medium temperature, thus can serve as a thermometer of the medium. However, the dominant source in this mass region, semi-leptonic decays of open heavy flavor hadrons, makes the extraction of the thermal radiation contribution very challenging.

        In this poster, we will present the results from the $1.5$ B minimum-bias events taken in 2018 Au+Au collisions at $\sqrt{s_{\text{NN}}}=$ 27 GeV. This data sample is more than 10 times larger than that from the STAR Beam Energy Scan phase I program and allows a much more precise measurement of the in-medium modification of $\rho$ mesons. The much lower open charm production rate at this energy compared to RHIC top energies greatly reduces their contributions to the dielectron spectrum at the intermediate mass region, providing a better opportunity to extract the medium temperature. The results will be compared to the measurements from other collision energies and the theoretical model calculations.

        Speaker: Zaochen Ye for STAR Collaboration (Rice University)
      • 17:40
        Dielectron production in Au+Au collisions at $\sqrt{s_{\rm {NN}}}=54$ GeV at STAR 20m

        Dielectrons are excellent probes of the Quark-Gluon Plasma (QGP) created in high-energy heavy-ion collisions. Because they can be produced at all stages of the collision system evolution and do not interact with the medium strongly, dielectrons carry the information from the initial stage to the final stage. In the low mass region (LMR, $\rm M_{ee} < M_{\phi}$), the mass spectra of vector mesons will be modified by the hot and dense medium which is related to the chiral symmetry restoration in the medium. In the intermediate mass region (IMR, $\rm M_{\phi} < \rm M_{ee} < \rm M_{J/\psi}$), QGP thermal radiation can be used as a QGP thermometer. However, it is hard to measure the QGP thermal radiation because of the heavy flavor semi-leptonic decay contributions.

        In this poster, we will present the dielectron production in Au$+$Au collisions at $\sqrt{s_{\rm {NN}}}=54$ GeV at STAR. With a 10 times larger data sample than that at 62 GeV from the first phase of the STAR Beam Energy Scan (BES-I) program, in-medium $\rho$ modification can be studied with better precision and compared to different theoretical predictions. With lower heavy flavor semi-leptonic decay contributions compared to those at RHIC top energies, QGP thermal radiation in the IMR will be discussed. Furthermore, physics implications of these measurements will be discussed.

        Speaker: Mr zhen wang (Shandong University)
      • 17:40
        Differential measurements of global polarization of $\Lambda$ hyperon in Au+Au collision at $\sqrt{s_{\mathrm{NN}}}$ = 54.4\ GeV\ with STAR 20m

        The medium generated by non-central nuclear-nuclear collision would have a large angular momentum. Due to the spin-orbit coupling, spin directions of particles formed by recombining quarks from the plasma could reflect the spin direction aligned with the angular momentum of the system. Global polarization is expected to lead to the understanding of the physical properties of QGP because it is caused by the vorticity of the system. Global polarization has been measured from 7.7 GeV to 200 GeV via $\Lambda$ hyperon decay. In this poster, various differential studies including different event planes and azimuthal dependences of the global polarization measurements in Au+Au collision at 54.4 GeV will be reported.

        Speaker: Kosuke Okubo (University of Tsukuba)
      • 17:40
        Dijet invariant mass in pp and p--Pb collisions with ALICE 20m

        Oskari Saarimäki for the ALICE collaboration

        We present the dijet invariant mass distribution in pp and p--Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$ TeV measured by ALICE. We study the dependence of the dijet invariant mass on event multiplicity in both collision systems, to explore cold nuclear matter effects or possible medium modifications in small collision systems. We measure charged jets using central tracking detectors in ALICE and correct the results for detector effects using unfolding procedure. Previous two-particle correlation studies from RHIC and the dijet asymmetry studies from LHC indicate that the dijet invariant mass can be sensitive to modifications caused by the QGP medium.

        Speaker: Oskari Antti Matti Saarimaki (Helsinki Institute of Physics (FI))
      • 17:40
        Directed flow of pions, kaons and protons in Au+Au collisions at $\sqrt{s_{NN}} $= 54.4 GeV in STAR 20m

        Rapidity-odd component of directed flow ($v_{1}$) measurement at various beam energy gives a new insight on the properties of the medium created in heavy-ion collisions. Both hydrodynamic and nuclear transport models indicate that $v_{1}$(y) is sensitive to the details of expansion during the early stages of collision fireball. In this poster, we will present directed flow ($v_{1}$) as a function of rapidity of identified particles ($\pi^{+}$, $\pi^{-}$, $K^{+}$, $K^{+}$, $p$ and $\bar{p}$) at 54.4 GeV in Au+Au collisions at RHIC-STAR. The $v_{1}$(y) slope will be discussed and compared with results from Beam Energy Scan I.

        Speaker: Shaoqiu Fan (Central China Normal University)
      • 17:40
        Discharge propagation in GEM detectors 20m

        Micropattern gaseous detectors (MPGDs) are a group of modern gaseous ionizing detectors consisting of microelectrode structures developed to overcome many of the difficulties of traditional gaseous detectors such as multiwire proportional chambers. The gas electron multiplier (GEM) is one of the most prolific MPGDs currently in use and slated to be used for many future detectors or current detector upgrades. Recent research conducted on discharges in GEM detectors will be presented. Delayed propagating discharges to the readout plane are a potential threat to the stable operation of GEM detectors and can cause permanent damage to the detector. An experimental setup enabling simultaneous electrical and optical measurements is used to provide novel insights regarding the physical mechanism of the delayed discharge, including the microsecond time delay between the primary and secondary discharges. Based on these measurements, indicators of the onset of the delayed propagating discharge are identified by means of the charge transfer to the readout electrode and potential methods to prevent or mitigate the delayed discharge propagation are proposed.

        Speaker: Filip Erhardt (University of Zagreb (HR))
      • 17:40
        Dissipation and causality in fluids with polarization 20m

        We examine the relativistic perfect fluid limit,
        defined as the fastest possible local equilibration, in a medium with
        polarizeability, defined as a non-zero local equilibrium partition of
        angular momentum into spin and vorticity.
        We show that the Lagrangian approach is best suited to analyzing this situation, as
        it can be used to efficiently avoid issues such as the breakdown
        of isotropy, the ambiguity of the energy-momentum tensor definition and
        the lack of closure of conservation equations.
        We obtain the Lagrangian and the equations of motion of an ideal
        relativistic fluid with polarization, linearize them, and
        show that to restore
        causality a relaxation term linking vorticity and polarization,
        analogous to the Israel-Stewart term linking viscous forces and
        gradients,is required.
        We close with an discussion of the phenomenological applicability
        of the hydrodynamics with polarization developed here, focusing on the recent
        finding of Lambda polarization and resonance spin alignement, and discussing
        weather observables sensitive to early-time polarization exist.

        Based on https://arxiv.org/abs/1807.02796
        and previous work by the same authors

        Speaker: Mr David Montenegro (IFT, Unesp, Sao Paulo)
      • 17:40
        DREENA framework as a multipurpose tool for QGP tomography 20m

        DREENA framework is based on our dynamical energy loss formalism, which takes into account finite size, finite temperature QCD medium consisting of dynamical (moving) partons. Both radiative and collisional energy losses are calculated under the same theoretical framework in the dynamical energy loss formalism, which is applicable to both light and heavy flavor observables. We generalized the formalism to the case of finite magnetic mass, running coupling, and towards removing widely used soft-gluon approximation. Importantly, DREENA provides a natural framework where temperature profile from any medium evolution can be straightforwardly implemented. We exploit this by implementing different state-of-the-art medium evolutions (both event-by-event hydrodynamics and kinetic transport theory) within DREENA framework. DREENA does not use free parameters, i.e. its only input is the temperature profile that comes directly from various hydrodynamic and kinetic theory models. This opens possibility to use DREENA on both light and heavy flavor to test and differentiate between different available QGP evolution models, including both large and smaller systems, making DREENA a multipurpose QGP tomography tool. Our results on these tests will be presented, which enables us to gain a better understanding of the bulk QGP medium created at RHIC and LHC. As a highlight, contrary to the existing models, which for full hydro evolution models lead to $v_2$ puzzle, with DREENA we surprisingly obtain a very good joint agreement between $R_{AA}$ and $v_2$ data. This well known puzzle therefore appears to be a consequence of a simplified energy loss commonly used by other models once a proper description of parton-medium interactions is used, $v_2$ puzzle is abolished. While a widely accepted paradigm is that proper medium evolution description dominates in explaining high $p_{\perp}$ data, this result strongly suggests that proper description of parton-medium interactions is much more important.

        Speaker: Dusan Zigic (Institute of Physics Belgrade)
      • 17:40
        Dynamical initialization at RHIC-BES energies 20m

        The quark gluon plasma (QGP) produced in high-energy nuclear collisions is known to behave like a perfect fluid. In hydrodynamic simulations at RHIC and the LHC energies, space-time evolution of the QGP is usually described in expanding coordinates. On the other hand, in SPS and RHIC-BES energies, Cartesian coordinates are used for effective description of hydrodynamic expansion. However, the difference of the coordinates makes it difficult to describe the reactions in broad range of collision energy in a unified manner.
        In this study, we propose to use the Milne coordinates even at lower collision energies by introducing a dynamic initialization model [1] towards unified description of the reactions at various collision energies. We first generate the initially produced particles by using an event generator, JAM [2]. Instead of putting initial conditions at fixed (proper-)time, fluids are gradually created during the colliding nuclei overlap with each other: We put energy, momentum, and baryon number of the particles into fluids through source terms in hydrodynamic equations at which these are produced. By solving hydrodynamic equations in one-dimensionally expanding coordinates, we describe space-time evolution of thermodynamic variables at RHIC-BES energies. By employing the first-order phase transition model as an equation of state, we describe the trajectories of the system in the energy density-baryon density plane and show the maximum baryon density gradually decreases with increasing collision energy.

        [1] M. Okai et al., Phys. Rev. C95, 054914 (2017).
        [2] Y. Nara et al., Phys. Rev. C61, 024901 (2000).

        Speaker: RURI OTSUKA (Sophia Univ.)
      • 17:40
        Early-Stage Shear Viscosity far from Equilibrium via Holography 20m

        We study the far-from equilibrium shear viscosity as present in the early stage of a heavy-ion collision. Our investigation is based on applying the AdS/CFT correspondence to a time-dependent Vaidya spacetime. A generalization of the entropy density to the non-equilibrium regime is necessary for a consistent description. Throughout the evolution, we observe significant deviations in the shear viscosity over entropy density ratio, $\eta/s$, from the holographic bound in equilibrium, i.e. $1/4\pi$. This value is obtained asymptotically.

        Speaker: Michael Florian Wondrak (Frankfurt Institute for Advanced Studies (FIAS))
      • 17:40
        Effect of longitudinal asymmetry on pseudorapidity distributions in Pb-Pb collisions at 5.02 TeV with ALICE 20m

        In a collision of two identical heavy-ions, the participant zone formed from the overlapping region of the two colliding nuclei contains unequal number of nucleons from each nucleus due to fluctuations. Consequently, the participant zone has a non-zero momentum in the centre of mass frame of the colliding nuclei, causing a longitudinal asymmetry. Using data in Pb-Pb collisions at centre of mass energy 2.76 TeV, the ALICE experiment had demonstrated that the longitudinal asymmetry manifests itself in the measured pseudorapidity distributions. In the present work, the results on the pseudorapidity distributions and the estimated shift in the rapidity will be presented using data from Pb-Pb collisions at centre of mass energy 5.02 TeV. The shift in rapidity of the participant zone due to the longitudinal asymmetry is estimated using the unequal energy deposited in the forward zero- degree calorimeters on either side of the interaction vertex. The results show the relation between the shift in rapidity and the centre of mass energy. In addition, results will be presented for pseudorapidity distributions for charged particles in different transverse momentum intervals.

        Speaker: Dr Rashmi Raniwala (University of Rajasthan, Jaipur, India)
      • 17:40
        Effect of Magnetic field on Electrical Conductivity of QCD Plasma 20m

        Electrical properties of QCD plasma is an important tool to understand the behaviour of strongly interacting matter in different physical conditions. It will help us to understand the effect of electromagnetic interaction with strongly interacting QCD plasma. Recently, it has been shown that a strong magnetic field is created during heavy ion collisions. Thus it is interesting to study the effect of this magnetic field on the transport and thermodynamical properties of matter created in these heavy ion collisions. In this poster, we will show the variation of electrical conductivity of an isotropic quark gluon plasma with respect to temperature. Further we will demonstrate the effect of magnetic field on electrical conductivity and discuss its physical importance.

        Speaker: Dr P. K. Srivastava (Indian Institute of Technology Roapar)
      • 17:40
        Effect of simulating parity-odd observables in high energy heavy ion collisions on balance functions of charged particles and elliptic flow of pions 20m

        At the early stage of heavy ion collisions, non-trivial topologies of the gauge fields can be created resulting in an imbalance of axial charge density and eventually separation of electric charges along the direction of the magnetic field produced in such collisions. This process is called the chiral magnetic effect (CME). In this work we implement such a charge separation at the partonic level in AMPT for Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV to study its consequence on experimental observables. We present the effects on the pion elliptic flow ($v_2$) and the charged particle balance function (BF) for varying strengths of initial charge separation. We find that the shape of the balance function is sensitive to the increasing charge separation. $v_2$ of pion shows a strong decreasing trend at higher transverse momenta ($p_T$) with increasing charge separation. Charge balance functions show a peak at $\Delta\phi \sim 180 $ with charge separation implemented in the partonic level as expected for the parity violation. We have also calculated parity observable $\gamma$ in the form of BF's moments. $\gamma$ shows a decreasing trend with charge separation. It has a negative value for charge separation produced by flipping more than 30 $\%$ of quarks in the parton level. We also notice that $<\gamma>$ for the same charge correlation and the opposite charge correlation shows negative and positive values, respectively.

        Speaker: Dr SK NOOR ALAM (Indian Institute Of Science Education and Research, Tirupati)
      • 17:40
        Effects of hydrodynamic fluctuations on azimuthal flow in ultra-central heavy-ion collisions 20m

        It is reported recently that an intriguing behavior of the anisotropic flow coefficients in ultra-central Pb-Pb collisions at the LHC. Elliptic flow in ultra-central collisions is driven mainly by fluctuations rather than collision geometry. Therefore, magnitudes of elliptic flow and triangular flow coefficients are almost identical. Some hydrodynamic models, which have been successful in describing non-central data, fail to reproduce elliptic flow and triangular flow coefficients simultaneously in ultra-central collisions. We try to resolve the issue by investigating effects of hydrodynamic fluctuations on anisotropic flow coefficients in ultra-central collisions.
        We employ an integrated dynamical model [1] to describe the dynamics of heavy-ion collisions at the LHC energy. Here, we introduce hydrodynamic fluctuations into relativistic hydrodynamic model through the fluctuation-dissipation theorem [2]. Hydrodynamic fluctuations are thermal fluctuations during hydrodynamic evolution. Since anisotropic flow is driven mainly by fluctuations in ultra-central collisions, hydrodynamic fluctuations play an important role in understanding their coefficients. The gap between magnitudes of elliptic flow and triangular flow is expected to decrease because hydrodynamic fluctuations enhance higher order flow coefficients more effectively. Setting impact parameter to be vanished to remove geometric effects, we first compare the results with hydrodynamic fluctuations and without them. Next, we analyze the effect of hydrodynamic fluctuations on azimuthal flow in ultra-central collisions. We also analyze the correlation between initial transverse eccentricity $\varepsilon_n$ and final anisotropic flow $v_n$ in ultra-central collisions.

        [1] T. Hirano et al., Prog. Part. Nucl. Phys. 70 (2013) 108.
        [2] K. Murase, Ph. D thesis, The University of Tokyo (2015)

        Speaker: KENSHI KUROKI (Sophia University)
      • 17:40
        Electromagnetic field from asymmetric to symmetric heavy-ion collisions at 200 GeV/c 20m

        Electromagnetic fields produced in relativistic heavy-ion collisions are affected by the asymmetry of the projectile-target combination as well as the different initial configurations of the nucleus.
        In this study, the results of the electric and magnetic fields produced for different combinations of ions, namely $^{12}$C + $^{197}$Au, $^{24}$Mg + $^{197}$Au, $^{64}$Cu + $^{197}$Au, and $^{197}$Au + $^{197}$Au at $\sqrt{s_{NN}} = 200$ GeV are demonstrated with a multi-phase transport model (AMPT). The configuration of the distribution of nucleons of $^{12}$C is initialized by a Woods-Saxon spherical structure, a three-$\alpha$-clustering triangular structure or a three-$\alpha$-clustering chain structure. It was observed that the electric and magnetic fields display different behavioral patterns for asymmetric combinations of the projectile and target nuclei as well as for different initial configurations of the carbon nucleus. The major features of the process are discussed.

        Speaker: yilin cheng
      • 17:40
        Electroweak boson and forward jet probes of the initial state in Pb+Pb and p+Pb collisions with ATLAS 20m

        Measurements of electroweak bosons produced in Pb+Pb collisions as well as photon and jet production in p+Pb collisions are of great interest to understanding initial state effects. These channels are sensitive to a broad set of physics effects such as high-precision test of the binary collision scaling expected in Pb+Pb, the modification of the parton densities in nuclei, the onset of non-linear QCD or saturation effects at low-$x$, and the energy loss of partons in the nucleus before the hard scattering.

        This poster presents the ATLAS final results on W and Z boson production in lead-lead collisions and photon and dijet production in $p$+Pb collision. W and Z boson yields are reported in 5.02 TeV Pb+Pb data, and the corresponding high-statistics $pp$ data at the same collision energy are used as a baseline. The resulting W and Z nuclear modification factors are shown differentially in pT, rapidity and centrality. Prompt photon yields are reported in 8.16 TeV $p$+Pb data, and an extrapolated $pp$ reference from 8 TeV collision data is used as a baseline. The measured photon nuclear modification factors and forward/backward ratios in $p$+Pb are presented differentially in pT and pseudorapidity. Forward-forward and forward-central di-jet production are reported in 5.02 TeV $p$+Pb, and $pp$ data at the same collision energy are used as a baseline. The measured azimuthal angular correlations and conditional yields are presented.

        The reported results are compared to various theoretical calculations to shed light on initial state energy loss, the modifications of parton distribution functions in nuclei, binary collision scaling, and decorrelation and suppression expected from saturation effects.

        Speaker: ATLAS Collaboration
      • 17:40
        Elliptic flow of electrons from heavy-flavor decays in 54.4 and 27 GeV Au+Au collisions from the STAR experiment at RHIC 20m

        Measurements of heavy-flavor hadron production and elliptic flow ($v_{2}$) provide unique and indispensable information for understanding the properties of the QGP. Recent STAR measurements indicate that in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=$ 200 GeV $D^{0}$ mesons develop large $v_{2}$ similarly as light-favor hadrons, implying that charm quarks interact strongly with the thermalized medium at the top RHIC energy. Interestingly, at lower collision energies the electrons from heavy-flavor decays seem to exhibit much lower $v_{2}$, unlike the light-flavor hadrons. However, the precision of the previous results from STAR at $\sqrt{s_{\mathrm{NN}}}$ = 62.4 and 39 GeV did not allow for firm conclusions.

        Thanks to the large data samples recorded by STAR in 2017 and 2018, we are now able to perform more precise measurements of the elliptic flow of electrons from heavy-flavor decays in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}= 54.4$ and $27$ GeV, respectively. The data sample size for each energy is more than 10 times higher than that of $\sqrt{s_{\mathrm{NN}}}= 62.4$ GeV taken in 2010. In this poster, we will present these new results from the STAR experiment on the $v_{2}$ of electrons from heavy-flavor decays, at $\sqrt{s_{\mathrm{NN}}}$ = 54.4 and 27 GeV, as a function of collision centrality and electron transverse momentum. We will also discuss physics implications of these results by comparing to theoretical model calculations.

        Speaker: Yuanjing Ji (University of Science and Technology of China)
      • 17:40
        Elliptic flow of electrons from heavy-flavour hadron decays in Pb-Pb collisions at $\sqrt{s_{NN}} = $ 5.02 TeV with ALICE 20m

        Charm and beauty quarks (heavy flavours) are produced in hard scattering processes in the early stages of heavy-ion collisions, and propagate through the hot and dense QCD matter (QGP) produced as a consequence of the collision. Therefore, they are sensitive probes to characterize the QGP properties.
        The measurement of the elliptic flow (${v_{2}}$) of open heavy-flavour particles at low ${p_{T}}$ can give insight into the participation of the heavy quarks in the collective expansion of the system and their thermalization in the medium. While at high ${p_{T}}$, it allows us to investigate the path-length dependence of parton energy loss.
        In this poster, we will present the measurement of ${v_{2}}$ for electrons from open heavy-flavour hadron decays in Pb-Pb collisions at $\sqrt{s_{NN}} = $5.02 TeV with ALICE. The electrons are identified by means of Time Projection Chamber (TPC) and the ElectroMagnetic Calorimeters (EMCal).

        Speaker: Mr Kenichi Tadokoro (University of Tsukuba)
      • 17:40
        Energy calibration and signal waveform analysis of the CBM Projectile Spectator Detector 20m

        Forward hadron lead/scintillator sampling calorimeter (Projectile Spectator Detector, PSD) consisting of 44 longitudinally segmented modules is developed and already constructed for the future Compressed Baryonic Matter (CBM) experiment at FAIR. The original approaches in the energy calibration with cosmic muons and in the signal analysis are proposed. The longitudinal segmentation of individual modules allows for the reconstruction of the cosmic muon tracks in the PSD. It makes possible to estimate the muon pass length in each longitudinal section with the subsequent correction of energy depositions in the scintillators. The developed method takes into account more accurately the muon energy deposition and improves the precision of the energy calibration.
        The short (about 40 nsec) PSD analog signals from photodetectors in each longitudinal section will be digitized by 125 MS/s sampling ADCs. To improve the precision of the PSD energy calibration, the procedure of signal waveform fitting based on the Prony least squares method was developed. This method represents the waveform as a linear combination of exponential functions and allows the measurement of signal amplitude with high accuracy. The fit of the signals with a predefined function permits to discriminate the small muon signals from the electronic noises of comparable amplitudes. The speed of the applied fitting procedure is a few orders faster than the standard iteration methods. It allows the signal analysis on the fly. The developed method makes also possible the selection of pileup signals at a high counting rate.

        Speaker: Nikolay Karpushkin (Russian Academy of Sciences (RU))
      • 17:40
        Enhancement of $\bar\Lambda$ / $\bar{p}$ in central heavy-ion collisions and it's implication for strangeness enhancement at RHIC and SPS energies. 20m

        Strangeness enhancement in central heavy-ion collisions (A+A) relative to proton-proton interactions (pp) has long been a well-recognized signature for QCD deconfinement or the formation of Quark Gluon Plasma (QGP). The energy scan program at the Relativistic Heavy Ion Collider (RHIC) in BNL or at CERNs' Super Proton Synchrotron (SPS) have presented evidence that are typical of the enhanced strangeness production via their measurements of kaon to pion ratios which exhibit a non-monotonic energy dependence. Similar indication was also observed in the baryon sector based on the measurements of anti-lambda to anti-proton ratio as a function of beam energy. Later it was thought to be a cleaner probe because their quark compositions have only anti-quarks, which are produced in the reaction and not transported. More-over their high mass resonance contributions are less. However, the final yields of both anti-lambda and anti-proton are sensitive to the baryon-antibaryon (B$\bar{B}$) annihilation in hadronic rescatterings phase. In this work, we present an investigation of the beam energy dependence of $\bar\Lambda$ over $\bar{p}$ ratio within a hadronic transport model, UrQMD and observe that the final state yields of $\bar\Lambda$ and $\bar{p}$ are strongly influenced by B$\bar{B}$ annihilation channel and has a significant impact of on the $\bar\Lambda$ to $\bar{p}$ ratio. In fact, the trend of $\bar\Lambda$ to $\bar{p}$ ratio enhancement in data can be qualitatively described within the UrQMD model because the spectral shapes of $\bar\Lambda$ and $\bar{p}$ are modified differently due to different annihilation cross sections of these two species. This suggests that the observed features of beam energy dependence of $\bar\Lambda$ to $\bar{p}$ ratio enhancement may not relate to the strangeness enhancement unambiguously.

        Speaker: Ms Ekata Nandy (Variable Energy Cyclotron Centre,VECC,Kolkata)
      • 17:40
        Equation of State for BES with EPOS model 20m

        Studies of collisions of highly accelerated ions are the key to understand the creation of quark matter. Experimental physicists put considerable effort in collecting information characterizing the various processes occurring during such collisions. In order to describe such scenarios, complex models have been constructed, one of them being the EPOS approach. It applies Parton-based Gribov-Regge theory as an initial condition, introduces the core-corona approach, hydrodynamical evolution and hadronic cascades as well. The model is used by an experimental physicist at the LHC or in cosmic ray physics. However, the proper theoretical description of the collisions occurring in the region of higher baryon densities (i. e. studied in the frame of Beam Energy Scan program) requires the introduction of the first order phase transition and possible Critical Point (CP).

        The new Equation of State (EoS) proposed by BEST collaboration [1] is introduced in the model. It contains all corssover, first and second order (CP) transitions of the matter. Furthermore, the location of the CP can be changed. Studies of the impact of the new EoS on final observables will be discussed and compared with the published experimental data.


        [1] P. Parotto et al.: 'Lattice-QCD-based equation of state with a critical point', arXiv:1805.05249

        Speaker: Maria Stefaniak (Warsaw University of Technology)
      • 17:40
        Event activity dependence of $\Upsilon$ production in p+p collisions at the STAR experiment 20m

        An interesting strong dependence on charged-particle multiplicity ($n_{ch}$) of $J/\psi$ and $\Upsilon$ production at the LHC and $J/\psi$ at RHIC has been observed. These measurements provide basic information about particle production mechanisms, especially on an interplay between hard and soft processes (multiple parton interactions, string percolations, color reconnection). In order to better understand this behavior a study of $\Upsilon$ production as a function of $n_{ch}$ for different $p_{T}$ ranges and collision energies has to be performed also at RHIC. Furthermore, by measuring the yield ratios between the excited to ground $\Upsilon$ states, $\Upsilon(nS)/\Upsilon(1S)$, as a function of $n_{ch}$, the $\Upsilon(nS)$-hadron interactions can be studied.

        This poster will present STAR results on the self-normalized inclusive $\Upsilon$ production yield ($\Upsilon/\left\langle \Upsilon \right\rangle$) measured as a function of self-normalized $n_{ch}$ in p+p collisions at $\sqrt{s}=500$ GeV. They will be compared to results from other experiments and model calculations. The measured dependence of $\Upsilon(nS)/\Upsilon(1S)$ ratios on $n_{ch}$ will also be presented. Finally, prospects of future measurements at STAR will be discussed.

        Speaker: Dr Leszek Kosarzewski (Czech Technical University in Prague)
      • 17:40
        Event activity, direct photons and photon/hadron ratios in asymmetric collisions 20m

        Collision centrality for large heavy ion systems is well defined
        both theoretically and experimentally, but the same is not necessarily
        true when very asymmetric systems, like p/d+A, collide. In light of
        some surprising result on the centrality dependence of high transverse
        momentum observables in p/d+A collisions at RHIC and LHC,
        the very concept of the geometrically inspired centrality gave way to
        "event activity". Convincing experimental tests of the various
        phenomenological models are so far missing. After a critical review of the
        relevant results from SPS, RHIC and LHC we will discuss whether and how
        the measurement of the ``centrality'' dependence of high and low
        transverse momentum direct photons (pQCD and "thermal") in p/d+A
        collisions, along with the photon/hadron ratios, can break the impass.
        We will also explore whether there are any lessons to be learned with
        respect to the possible formation of QGP droplets in small systems,
        and extreme event classes in p+p and A+A collisions.

        Speaker: Gabor David (Brookhaven National Laboratory)
      • 17:40
        Event anisotropy $v_{2}$ in Au+Au collisions at $\sqrt{s_{NN}}$ = 27 and 54.4 GeV with STAR 20m

        Elliptic flow is one of the most important observables in the relativistic heavy ion collisions. It can provide us opportunities to study the early evolution of the expanding system. In this poster, we will present elliptic flow of identified particles ($\pi^{\pm}$, $K^{\pm}$, $p$($\bar{p}$), $K_{S}^{0}$, $\Lambda$($\bar{\Lambda}$), $\phi$, $\Xi^{-}$($\bar{\Xi}^{+}$), $\Omega^{-}$($\bar{\Omega}^{+}$)) at midrapidity ($\eta <$ 1) as a function of transverse momentum for three centrality classes in Au+Au collisions at $\sqrt{s_{NN}}$ = 27 and 54.4 GeV. The systematic study of $\phi$ mesons and multistrange hadrons ($\Xi^{-}$($\bar{\Xi}^{+}$), $\Omega^{-}$($\bar{\Omega}^{+}$)) will be mainly discussed. These particles have small hadronic re-scattering cross sections and supposed to be sensitive to partonic phase. It is argued that the additional radial flow gained in the hadronic phase modifies the $v_{2}(p_{T})$ shape. Due to the different sensitivity to hadronic interactions of protons and $\phi$ mesons, the mass ordering of $v_{2}$ could be broken between protons and $\phi$ mesons in the low $p_{T}$ range ($p_{T} < $1.5 GeV/c) . The energy dependence of mass ordering between proton and $\phi$ meson $v_{2}$ in the low $p_{T}$ region will be discussed. These results provide us an opportunity to study hadronic contributions on $v_{2}$ measurements as a function of collision energy.

        Speaker: Shaowei Lan (Central China Normal University)
      • 17:40
        Event shape and multiplicity dependence of $\rm{K}^{*\pm}$(892) and $\phi$(1020) production in pp collisions at $\sqrt{s}=5.02$ TeV with ALICE at the LHC 20m

        The study of hadronic resonances such as $\rm{K}^{*}$ and $\phi$ provides a unique tool to investigate the interplay of re-scattering and regeneration effects in the hadronic phase of heavy-ion collisions. As the $\rm{K}^{*}$ has a lifetime comparable to the lifetime of the hadronic phase, one would expect to observe the effects of re-scattering and regeneration processes in the measured $\rm{K}^{*}$ production yield. In contrast, the $\phi$ meson has a longer lifetime compared to other resonances. Thus, it is expected that its yields will not be affected by regeneration and re-scattering. So far, most of the measurements of hadronic resonances in pp collisions have been used as baselines for heavy-ion collisions. However, recent indications of the possible formation of QGP droplets and the presence of a hadronic phase in small systems makes the study of hadronic resonance production in small systems more important. Event shape observables like transverse spherocity, along with charged-particle multiplicity, can serve as an important tool to separate isotropic and jetty events, which can help in understanding the recently observed phenomena in small systems in a more differential manner.

        We report measurements of $\rm{K}^{*\pm}$ and $\phi$ meson production in pp collisions at $\sqrt{s}=5.02$ TeV as a function of charged particle multiplicity and transverse spherocity, reconstructed in their hadronic decay channels of $\rm{K}_{\rm S}^{0}\pi^{\pm}$ and $\rm{K}^{+}\rm{K}^{-}$, respectively. These results include the transverse momentum, $p_{\rm T}$, distributions, integrated yield and mean-$p_{\rm T}$ of $\rm{K}^{*\pm}$ and $\phi$ in different spherocity and multiplicity classes. The results will be compared to pQCD inspired models such as PYTHIA and EPOS-LHC.

        Speaker: Mr Sushanta Tripathy (Indian Institute of Technology Indore (IN))
      • 17:40
        Event shape and multiplicity dependence of identified particle production and freeze-out scenario in pp collisions at $\sqrt{s}$ = 13 TeV using PYTHIA8 15m

        Recent observations of Quark-Gluon Plasma (QGP)-like conditions in high-multiplicity pp collisions from ALICE experiment at the LHC warrants an introspection whether to use pp collisions as a baseline measurement to characterize heavy-ion collisions for possible formation of QGP droplets. A double differential study of the identified particle production and freeze-out scenario of the produced system as a function of charged-particle multiplicity and transverse spherocity in pp collisions would shed light into the underlying event dynamics. The light flavored particle production would help to understand the bulk of the system while the heavy flavored hadrons would retain the entire interaction history in QGP. We report a double differential study of both light and heavy-flavored hadron production in pp collisions at $\sqrt{s}$ = 13 TeV as a function of charged-particle multiplicity and transverse spherocity using PYTHIA8 event generator. We also report the possible chemical freeze-out and kinetic freeze-out parameters using Thermal model, Boltzmann-Gibbs blast wave model and Tsallis non-extensive statistics. We observe that, while studying the QGP-like conditions in small systems, one should separate the isotropic events from the spherocity-integrated events, as the production dynamics are different. The present study, while exploring the particle production mechanism in different class of high-multiplicity pp events, paves a way for making proper experimental investigations.

        Speaker: Raghunath Sahoo (Indian Institute of Technology Indore (IN))
      • 17:40
        Event-by-Event measurement of charge separation in Pb-Pb collisions at √sNN = 5.02 TeV in ALICE 20m

        The interplay between the magnetic and electric field in heavy-ion collisions at high energy results in the charge separation, the phenomenon is known as Chiral Magnetic Effect (CME). Event-by-event charge separation measurements in Pb-Pb collisions at √sNN = 5.02 TeV will be presented. The sum of positive charge fraction on left side and negative charge fraction on right side of the dumbbell on the azimuthal plane is calculated for each event. This sum is then maximized in each event by sliding the dumbbell of size $60^{\circ}$ in steps of one degree over the whole azimuthal plane. We further divide maxima into 10 bins to get CME type enriched sample for each centrality. The charge dependent three-particle gamma correlators, calculated using q-cumulant method, will be presented for different collision centralities as well as for different categories of charge separation. We obtained background estimation using two methods, which are: i) reshuffling the charges of particles in an event and ii) randomising the azimuthal angles of particles in an event. Also, the results will be compared with Pb-Pb collisions at 2.76 TeV using same method.

        Speaker: Ms Anjali Sharma (Panjab University (IN))
      • 17:40
        Evolution of jet shapes in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV with the STAR experiment at RHIC 20m

        In relativistic heavy-ion collisions, a strongly interacting medium known as the Quark Gluon Plasma (QGP) is produced. Quarks and gluons from incoming nuclei collide to produce partons at high momenta early in the collisions. By fragmenting into collimated sprays of hadrons, these partons form `jets'. The resulting jets, which in vacuum are well understood within the framework of perturbative QCD, are attenuated by medium interactions, a process known as jet quenching. The jet shape variable, $\rho(\Delta r)$, reveals the radial profile of transverse momentum distribution inside the jet. By measuring the modifications of the jet shape, properties of the QGP at different length scales can be studied.

        In this poster, the differential jet shape for full (charged + neutral) jets in mid-peripheral Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV with the STAR experiment at RHIC will be presented and compared to a baseline p+p measurement. As the first measurement of its kind at RHIC energies, this work will extend the kinematic range offered at the LHC to lower $\it{p}_{T}$ and demonstrate whether there is a modification and a broadening of the jet profile at RHIC energies. The jet shape measurement is extended to include an event plane (defined by the beam direction and the vector of the impact parameter) dependence to study the path length dependence of medium modifications to the jets and their associated hadrons. To further explore how the substructure of jets are modified in Au+Au relative to p+p collisions, the dependence on centrality and jet size ($R$) will be investigated.

        Speaker: Joel Anthony Mazer (University of Tennessee (US))
      • 17:40
        Evolving Charge Correlations and the Diffusivity of Light Quarks 20m

        We present a full simulation of evolving charge correlations in heavy-ion collisions using a combination of hydrodynamics and a hadronic Boltzmann cascade to model the underlying system evolution. We compute the charge balance functions (CBFs) in both rapidity and azimuthal angle and observe their dependence on several phenomenological parameters in our model. In particular, we observe significant sensitivity in the $K^+K^-$ and $p\bar{p}$ CBFs to the value of the diffusivity of light quarks, suggesting that a comprehensive analysis of heavy-ion observables which includes the CBFs could be sensitive to this previously unmeasured transport coefficient of QCD matter.

        Speaker: Christopher Plumberg
      • 17:40
        Exploring the QCD phase diagram via collision energy dependence of multi-particle Bose-Einstein correlations in Au+Au collisions with PHENIX 20m

        Exploration of the rich structure of the QCD phase diagram is an important topic in the RHIC beam energy scan program whose ultimate goal is to discover the critical endpoint. Investigation of the space-time structure of hadron emissions at various phase transition points using Bose-Einstein correlation of identical bosons will provide insight on the location of the critical endpoint. PHENIX has performed comprehensive measurements of the Bose-Einstein correlation in Au+Au collisions at $\sqrt{s_{NN}}$ = 15, 19, 27, 39, 62.4, and 200 GeV, where we incorporated Levy-type source function to describe the measured correlation functions. We also extended our analysis from two particles to three particle correlations to characterize the nature of the hadron emission source. We put particular focus on one of the parameters in the Levy-type source function, the index of stability $\alpha$, which is related to one of the critical exponents (the so-called correlation exponent $\eta$). We have measured its collision energy and centrality dependence. In addition, we have discovered a product of Levy parameters which has a dimension of length which is linear in $m_T$ whose interpretation is still under debate. The three particle correlations confirmed the findings of the two-particle correlations, and also provided insight on pion production mechanism beyond Core-Halo models. We will present the latest PHENIX results on the multi-particle Bose-Einstein correlation, and discuss its physics interpretation.

        Speaker: Brett Fadem
      • 17:40
        Extracting fluctuation of thermal parameters at freezeout 20m

        The extraction of thermal freezeout parameters from measured hadron yields
        and their higher moments have met with considerable success within the frame-
        work of hadron resonance gas models. The standard assumption in such studies
        is to consider a constant freezeout parameter set which is extracted by chi-square
        fit to data. However, in reality, thermal conditions at freezeout need not be con-
        stant. They can fluctuate event by event as well as in the same event, there
        could be a distribution of temperatures and chemical potentials over freezeout
        spacetime points instead of a constant value. In this study we set up the frame-
        work to study such possible fluctuations in thermal freezeout conditions and
        extract them by comparing the model predictions to mean hadron multiplicities
        and their higher moments. We utilise all available data across beam energies
        and centralities. The extracted thermal parameters and their higher moments
        and the goodness of fits are compared to the standard scenario of constant ther-
        mal parameters. Understanding the nature of fluctuation of freezeout thermal
        parameters has significant implications on the ongoing searches for the QCD
        critical point.

        Speaker: Mr Tribhuban Parida (Indian Institute of Science Education and Research, Berhampur)
      • 17:40
        Extracting jet transport coefficient via single hadron and dihadron productions in high-energy heavy-ion collisions 20m

        We study [1] the suppressions of high transverse momentum single hadron and dihadron productions in high-energy heavy-ion collisions based on the framework of a next-to-leading-order perturbative QCD parton model combined with the higher-twist energy loss formalism [2,3]. Our model can provide a consistent description for the nuclear modification factors of single hadron $R_{AA}$ and dihadron $I_{AA}$ in central and non-central nucleus-nucleus collisions at RHIC and the LHC energies.

        We quantitatively extract the value of jet quenching parameter $\hat{q}$ via a global $\chi^2$ analysis, and obtain the scaled jet quenching parameter ${\hat{q}}/{T^3} = 4.1 \sim 4.4$ at $T = 378$ MeV for 0.2 TeV Au+Au collisions and ${\hat{q}}/{T^3} = 2.6 \sim 3.3$ at $T = 486$ MeV for 2.76 TeV Pb+Pb collisions, which are consistent with the results from JET Collaboration [4]. We also get the ${\hat{q}}/{T^3} = 2.5 $ at $T=516$ MeV for 5.02 TeV Pb+Pb collisions, ${\hat{q}}/{T^3} = 3.5$ at $T= 469$ MeV for 5.44 TeV Xe+Xe collisions only via single hadron productions and provide the predictions for the dihadron $I_{AA}$ of these two collisions. The above numerical analysis shows that ${\hat{q}}/{T^3}$ has some temperature dependence: it decreases as one increases the temperature, which can be understood as decreasing jet-medium interaction strength with increasing temperature.

        Here are some other interesting results that the dihadron $I_{AA}$ are typically larger than single hadron $R_{AA}$ given the same nucleus-nucleus collision conditions and the values of $I_{AA}$ also increase as one increases the trigger hadron $p_T$. These results can be explained by that high $p_T$ single hadrons mainly come from surface bias emission jets, while high $p_T$ dihadrons come from a combination of surfacial and tangential jets as well as punching-through jets [5,6]. And with increasing trigger hadron $p_T$, the contribution from punching-through jets increases [7]. On average in a A + A event, the total energy loss for jets in the surface bias case is larger than in the case with punching-through jets.

        References
        [1] M. Xie, S. Y. Wei, G. Y. Qin and H. Z. Zhang, arXiv:1901.04155 [hep-ph].
        [2] H. Zhang, J. F. Owens, E. Wang and X. N. Wang, Phys. Rev. Lett. 103, 032302 (2009).
        [3] X. f. Guo and X. N. Wang, Phys. Rev. Lett. 85, 3591 (2000).
        [4] K. M. Burke et al. [JET Collaboration], Phys. Rev. C 90, no. 1, 014909 (2014).
        [5] H. Zhang, J. F. Owens, E. Wang and X. N. Wang, Phys. Rev. Lett. 98, 212301 (2007).
        [6] J. G. Milhano and K. C. Zapp, Eur. Phys. J. C 76, no. 5, 288 (2016).
        [7] H. z. Zhang, J. F. Owens, E. Wang and X.-N. Wang, J. Phys. G 35, 104067 (2008).

        Speaker: man xie (Central China Normal University)
      • 17:40
        Extracting jet transport parameter $\hat{q}$ from a multiphase transport model} 20m

        Within a multi-phase transport model with string melting scenario, jet transport parameter $\hat{q}$ is calculated in Au+Au collisions at $\sqrt{s_{NN} } $= 200 GeV and Pb+Pb collisions at $\sqrt{s_{NN} } $= 2.76 TeV. The $\hat{q}$ increases with the increasing of jet energy for both partonic phase and hadronic phase. The energy and path length dependences of $\hat{q}$ in full heavy-ion evolution are consistent with the expectations of jet quenching. The correlation between jet transport parameter $\hat{q}$ and dijet transverse momentum asymmetry $A_{J}$ is mainly investigated, which discloses that a larger $\hat{q}$ corresponds to a larger $A_{J}$. It supports a consistent jet energy loss picture from the two viewpoints of single jet and dijet. It is proposed to measure dijet asymmetry distributions with different jet transport parameter ranges as a new potential method to study jet quenching physics in high energy heavy-ion collisions.

        Speaker: Fengchu ZHOU (Guizhou normal university)
      • 17:40
        Factorization breaking in transverse momentum from hydrodynamic fluctuations 20m

        In recent years, factorization breaking of flow coefficients in transverse momentum has been measured by CMS Collaboration [1] to understand the transport properties of QGP. The factorization ratio $r_n$ measured in Pb + Pb collisions at LHC represents the decorrelation of the event plane angle in different transverse momentum regions. When $r_n = 1$, which implies the coincidence of the event-plane angles along transverse momentum direction, $r_n$ can be factorized into the anisotropic flow coefficients $v_n$ in the individual transverse momentum regions. However, $r_n < 1$ means the event-plane angles differ from each other and consequently this factorization is broken. Hydrodynamic fluctuations are expected to break the factorization because they disturb the event plane.

        In this study, we analyze the factorization ratio $r_n$ in the direction of transverse momentum by using an integrated dynamical model [2] that incorporates thermal fluctuations into the relativistic hydrodynamic model. The QGP produced in high-energy heavy-ion collisions expands rapidly, cools down and becomes a hadron gas in a short time period. Thus, the QGP cannot be measured directly. Therefore, the transport properties of QGP are explored through analysis of the hadron momentum distribution measured by the detector. Since the final state hadron observables carry the information on the whole history of the space-time evolution of the system, it is important to construct an integrated dynamical model that describes the whole reaction. Using this integrated dynamic model incorporating hydrodynamic fluctuations, we compare the analysis results of the factorization ratio in the transverse momentum direction with the experimental results and discuss the influence of the hydrodynamic fluctuations on the factorization ratio in the transverse momentum direction.

        [1] CMS Collaboration, Phys. Rev. C 92, 034911 (2015)
        [2] K. Murase, Ph. D thesis, The University of Tokyo (2015)

        Speaker: Yuki Gogun (Sophia University)
      • 17:40
        First results from hybrid hadronization in small and large systems 20m

        “Hybrid Hadronization” is a new Monte Carlo package to hadronize systems of partons. It smoothly combines quark recombination applicable when distances between partons in phase space are small, and string fragmentation appropriate for dilute parton systems, following the picture outlined by Han et al. [PRC 93, 045207 (2016)]. Hybrid Hadronization integrates with PYTHIA 8 and can be applied to a variety of systems from $e^++e^-$ to A+A collisions. It takes systems of partons and their color flow information, for example from a Monte Carlo parton shower genera-tor, as input. In addition, if for A+A collisions a thermal background me-dium is provided, the package allows to sample thermal partons that con-tribute to hadronization. Hybrid Hadronization is available for use as a standalone code and is also part of the JETSCAPE 2.0 release.
        In this presentation we review the physics concepts underlying Hybrid Hadronization and how users can use the code with parton shower Monte Carlos. We demonstrate how Hybrid Hadronization affects multiplicities, hadron chemistry, fragmentation functions and jet shapes in $e^++e^-$, p+p and A+A collisions when combined with different parton shower Monte Carlos using PYTHIA 6, PYTHIA 8 and JETSCAPE/MATTER. We compare to calculations using pure Lund string fragmentation as well as to data from LEP, RHIC and LHC. In particular we demonstrate observable effects of the recombination of shower partons with thermal partons. As a benchmark we compare to pure PYTHIA 8 string fragmentation and to data.

        Speaker: Rainer Fries for JETSCAPE Collaboration (Texas A&M University)
      • 17:40
        First, second, third and fourth flow harmonics of deuterons and protons in Au+Au reactions at 1.23 A GeV 20m

        We explore the directed, elliptic, triangular and quadrangular flow of deuterons in Au+Au reactions at a beam energy of 1.23 AGeV within the UrQMD approach. These investigations are of direct relevance for the HADES experiment at GSI that has recently presented first data on the flow of light clusters in Au+Au collisions at 1.23 AGeV. To address the deuteron flow, UrQMD has been extended to include deuteron formation by coalescence. We find that this ansatz provides a very good description of the measured deuteron flow data, if a hard equation of state is used for the simulation. In addition we show that light cluster formation has a sizable impact on the proton flow and has to be taken into account to obtain reliable results in the forward/backward region. Based on the observed scaling of the flow, which is a natural result of coalescence, we conclude that deuteron production at GSI energies is a final state recombination effect. Finally, we also discuss the scaling relations of the higher order flow components up to $v_4$. We show that $v_3 \sim v_1v_2$ and $v_4 \sim v_2^2$ as function of transverse momentum and that the integrated $v_2^2 \sim v_4$ over the investigated energy range from $E_{lab}$=0.1 AGeV to 40 AGeV.

        Speaker: Paula Hillmann
      • 17:40
        Fixed-target collisions at LHCb 20m

        LHCb has the unique capability to study collisions of the LHC beams on fixed targets. Internal gas targets of helium, neon and argon have been used so far to collect samples of proton- and Pb-gas collisions corresponding to integrated luminosities up to 0.1 pb$^{-1}$. Results on open and hidden charm productions will be presented, which can provide crucial constraints on cold nuclear matter effects and nPDF at large x.

        Speaker: Felipe Andres Garcia Rosales (Centre National de la Recherche Scientifique (FR))
      • 17:40
        Flow harmonic power spectrum with ALICE at LHC 20m

        for the ALICE Collaboration

        Anisotropic flow provides important constraints on the initial conditions and the transport properties of the medium created in heavy-ion collisions. The flow coefficients of higher order harmonics are sensitive to viscous damping [1] and might hinder so-called "acoustic peaks" in flow harmonic power spectrum in analogy to Cosmic Microwave Background in cosmology experiments [2].
        We present flow harmonic power spectra in various centrality ranges in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV. The results will be compared to viscous hydrodynamic model calculations.

        [1] Nucl.Phys. A904-905 (2013) 377c-380c, [2] arXiv:1710.03776

        Speaker: Dong Jo Kim (University of Jyvaskyla (FI))
      • 17:40
        Fluctuation dynamics near the QCD critical point 20m

        Near the QCD critical point (CP), critically slow processes can invalidate the conventional (dissipative) hydrodynamic description, which simply integrates out all non-hydrodynamic modes. We explore the critical dynamics near the QCD CP with the novel Hydro+ framework [1] which extends the conventional hydrodynamic description by coupling it to additional explicitly evolving slow modes. Their slow relaxation is controlled by the correlation length in the critical region, which is independent from the density inhomogeneities of the QCD matter that control the evolution of the hydrodynamic quantities. In this presentation we study the evolution of a single critical slow mode on top of a simplified matter background with non-zero net baryon density undergoing Gubser flow [2], as a function of the slow mode's wave number and the correlation length. We also discuss how the non-equilibrium slow mode affects the bulk properties of the matter, such as the pressure and entropy density. We find that over a wide range of wave numbers the non-equilibrium effects of the slow mode are dominatingly driven by the fluid expansion rather than by critical slowing-down. Last but not least we explore the critical fluctuation dynamics in systems of various sizes and at different collision energies. As one of the first studies based on Hydro+, this work provides guidance to future more realistic, fully (3+1)-dimensional simulations aiming at locating the QCD CP.

        [1] Hydrodynamics with parametric slowing down and fluctuations near the critical point, M. Stephanov and Y. Yin, Phys. Rev. D98 (2018) 036006.

        [2] Symmetry constraints on generalizations of Bjorken flow, S. Gubser, Phys. Rev. D82 (2010) 085027.

        Speaker: Lipei Du (The Ohio State University)
      • 17:40
        Fluctuation-dissipation relation and fluctuation theorem for causal hydrodynamic fluctuations 20m

        Recently physics of thermal fluctuations of hydrodynamic fields, namely the hydrodynamic fluctuations, in high-energy nuclear collisions are actively discussed. In this talk I will discuss new modification terms [1] in fluctuation-dissipation relation (FDR), which determines the power of hydrodynamic noise fields, and also discuss its importance in the point of view the fluctuation theorem [2], which is a relation of the entropy production probability known in non-equilibrium statistical mechanics.

        The effects of hydrodynamic fluctuations on heavy-ion observables such as flow coefficients and longitudinal decorrelation $r_n(\eta_a, \eta_b)$ are recently analyzed in event-by-event simulations by dynamical models [3-6]. Also the thermal fluctuations near the critical point also play an important role in the critical dynamics. In this sense the hydrodynamic fluctuations in dynamical models are becoming more and more important. The FDR used in dynamical models is normally obtained in the global equilibrium. However, in expanding systems such as matter created in the nuclear collisions, the FDR is non-trivial. I obtain new modification terms to the FDR in the second-order causal dissipative hydrodynamics by considering the linear-response in non-static and inhomogeneous backgrounds. I discuss its relation to the steady-state fluctuation theorem. Also, by performing the numerical simulations of non-linear relativistic fluctuating hydrodynamics assuming the Bjorken flow, I investigate the non-linear fluctuation effects to the fluctuation theorem.

        • [1] K. Murase, arXiv:1904.11217 [nucl-th] (2019).
        • [2] T. Hirano, R. Kurita, K. Murase, Nucl. Phys. A 984, 44-67 (2019).
        • [3] K. Murase, T. Hirano, Nucl. Phys. A 956, 276-279 (2016).
        • [4] A. Sakai, K. Murase, T. Hirano, Nucl. Phys. A 967, 445-448 (2017).
        • [5] M. Singh, C. Shen, S. McDonald, S. Jeon, C. Gale, Nucl. Phys. A 982, 319-322 (2019)
        • [6] A. Sakai, K. Murase, T. Hirano, Nucl. Phys. A 982, 339-342 (2019).
        Speaker: Koichi Murase (Sophia University)
      • 17:40
        Fluctuations of anisotropic flow in transport 20m

        It is well established that the spatial asymmetries of the overlap region in the initial state of a heavy ion collision, together with their fluctuations, are quite faithfully translated into final-state momentum anisotropies by a fluid-dynamical evolution. We investigate the relationship between initial-state eccentricities and final-state anisotropic flow harmonics for a simplified two-dimensional gas of massless particles. We show how geometrical fluctuations from a Monte Carlo Glauber picture are mapped onto flow fluctuations, in particular the dependence on the mean number of rescatterings per particle in the expanding system.

        Speaker: Hendrik Roch (University Bielefeld)
      • 17:40
        Forward-backward centrality fluctuation and its influence on experimental observables in heavy-ion collisions 20m

        In heavy ion collisions, the transverse size or centrality of the QGP is not a boost-invariant concept. Due to forward-backward multiplicity fluctuations, the centrality of the system, defined as $N_{\mathrm{ch}}$ in a given $\eta$ range, also fluctuates in the longitudinal direction. This longitudinal fluctuation leads to decorrelation of centrality along $\eta$, analogous to the decorrelation of harmonic flow $v_n$ along $\eta$. In this work, we quantify the strength of centrality decorrelation using multi-particle cumulants (mean, variance, skewness and kurtosis) using a sub-nucleon Glauber model as well as dynamical event generators HIJING and AMPT. We found the behaviors of multiplicity cumulants in ultra-central collisions (UCC) are extremely sensitive to the particle production implemented in the models, and therefore can be used to quantify the centrality resolution and constrain the particle production mechanism. We further studied the influence of centrality fluctuation and decorrelations on $v_n$ and mean transverse momentum $\langle p_{\mathrm {T}}\rangle$ in each event. We show that the event-by-event probability distribution of these quantities such as $p(v_n)$, $p(v_n, v_m)$, $p(\langle p_{\mathrm {T}}\rangle)$ and $p(v_n,\langle p_{\mathrm {T}}\rangle)$, accessible via mixed-observable multi-particle cumulants, are sensitive to the strength of the fluctuation and longitudinal decorrelations of centrality. We laid out an experimental strategy on how to constrain the centrality dependence of particle production, based on measurements of these mixed-observable cumulants in UCC for systems of different sizes.

        Speaker: Chunjian Zhang (Shanghai Institute of Applied Physics)
      • 17:40
        Future opportunities of small system scan at RHIC 20m

        The observation of multi-particle azimuthal correlations in high-energy small-system collisions has led to intense debate on its physical origin between two competing theoretical scenarios: one based on initial-state intrinsic momentum anisotropy (ISM), the other based on final-state collective response to the collision geometry (FSM). To complement the previous scan of asymmetric collision systems ($p$+Au, $d$+Au and He+Au), we propose a scan of small symmetric collision systems at RHIC, such as C+C, O+O, Al+Al and Ar+Ar at $\mbox{$\sqrt{s_{\mathrm{NN}}}$}=0.2$ TeV, to further disentangle contributions from these two scenarios. These symmetric small systems have the advantage of providing access to geometries driven by the average shape of the nuclear overlap, compared to fluctuation-dominant geometries in asymmetric systems. A transport model is employed to investigate the expected geometry response in the FSM scenario. Different trends of elliptic flow with increasing charge particle multiplicity are observed between symmetric and asymmetric systems, while triangular flow appears to show a similar behavior.

        The enhanced pseudo-rapidity coverage of STAR with iTPC, EPD, and forward upgrade, together with sPHENIX's capabilities of state-of-art hard-probe measurments, make RHIC the ideal place for the proposed scan. Furthermore, a comparison of O+O collisions at $\mbox{$\sqrt{s_{\mathrm{NN}}}$}=0.2$ TeV and at $\mbox{$\sqrt{s_{\mathrm{NN}}}$}=2.76-7$ TeV, as proposed at the LHC, provides a unique opportunity to disentangle the collision geometry effects at nucleon level from those arising from subnucleon fluctuations. Such a proposal of O+O collisions at RHIC in year 2020-2021 has been included in STAR Beam Use Request[1]. Uncertainty projections of key measurements will be presented.

        [1] STAR Collaboration Beam Use Request for Run-20 and Run-21, https://drupal.star.bnl.gov/STAR/starnotes/public/sn0721

        Speakers: Prof. Jiangyong Jia (Stony Brook University), Dr Shengli Huang (Stony Brook University), Prof. Wei Li (Rice University), Prof. Zhenyu Chen (Shandong University)
      • 17:40
        Generalized High Twist Approach to Parton Energy Loss 20m

        The Generalized High Twist approach has been established to investigate the radiative parton energy loss in deeply inelastic scattering off a large nucleus. The parton undergoes multiple medium parton scatterings and medium-induced radiation after scattering with the virtual photon. In the calculation of radiative energy loss, we relax the approximation in High Twist approach that the radiated gluon transverse momentum is much larger than transverse momentum transfer of parton-medium scattering, and do not perform the collinear expansion in the Generalized High Twist approach. In this new approach, the gluon radiation spectrum is expressed in terms of the convolution of hard partonic part and transverse momentum dependent (TMD) quark-gluon correlation function. The TMD quark-gluon correlation can be factorized approximately as a product of initial quark distribution and TMD gluon distribution. The TMD gluon distribution can be used to define the TMD jet transport coefficient. Under static medium and soft radiative gluon approximation, we recover the Gylassy-Levai-Vitev (GLV) approach result in the first order of the opacity expansion. We also compare numerically the difference between our result and that of GLV and High-Twist result.

        Speakers: Mr Yuanyuan Zhang (LBL, CCNU), Prof. Guangyou. Qin (CCNU), Prof. Xin-Nian Wang (LBL, CCNU)
      • 17:40
        GLISSANDO 3: the known software tool with new possibilities 20m

        Fluctuations in physics observables and flow effects in heavy-ion collisions have been topics of particularly interest in recent years as they may provide important signals regarding the formation of quark-gluon plasma, the existence of a critical point and the evolution of the system. Moreover, the fluctuations and correlations measured in the final stage have their sources at least partly in the initial fluctuations and the initial-state geometry provided the initial effects are not largely altered by the intermediate evolution of the system. GLISSANDO is a versatile Monte-Carlo generator for Glauber-like models of the initial stages of ultra-relativistic heavy-ion collisions. The current version incorporates the wounded parton model and, within this model, one can study nucleon substructure fluctuation effects. The code also includes the possibility of investigating collisions of light nuclei as 3He and 3H, or the alpha-clustered 7Be,9Be,12C,16O, where the deformation of the intrisic wave function influences the transverse shape of the initial state. The code can provide output in the format containing the event-by-event source location, which may be further used in modeling the intermediate evolution phase with hydrodynamics or transport models.

        The distributions which illustrate the new features implemented in GLISSANDO 3 will be presented. The potential use of the software tool for the sophisticated analysis and the interpretation of data on relativistic heavy-ion collisions will be discussed.

        Speaker: Grzegorz Stefanek (Jan Kochanowski University (PL))
      • 17:40
        Gluon emission from heavy quarks in dense nuclear medium 20m

        We study the medium-induced gluon emission process experienced by a hard jet parton propagating through the dense nuclear matter in the framework of deep inelastic scattering off a large nucleus. We work beyond the collinear rescattering expansion and the soft gluon emission limit, and derive a closed formula for the medium-induced single gluon emission spectrum from a heavy or light quark jet interacting with the dense nuclear medium via transverse and longitudinal scatterings. Without performing the collinear rescattering expansion, the medium-induced gluon emission spectrum is controlled by the full distribution of the differential elastic scattering rates between the propagating partons and the medium constituents. We then use two different models, heavy static scattering centers and the effective HTL dynamical medium, to characterize the traversed nuclear matter. If one utilizes heavy static scattering centers and takes the soft gluon emission limit, our result can reduce to the first order in opacity Djordjevic-Gyulassy-Levai-Vitev formula (with zero mass for radiated gluon). If we take the effective HTL spectral functions for the exchanged gluon field correlation, our result with similar approximations can reduce to Djordjevic-Heinz formula for medium-induced gluon emission in dynamical QCD medium (with zero thermal mass for radiated gluon).

        [1] Le Zhang, De-Fu Hou, Guang-You Qin, arXiv:1812.11048 [hep-ph].
        [2] Le Zhang, De-Fu Hou, Guang-You Qin, Phys.Rev. C98 (2018) no.3, 034913,
        arXiv:1804.00470 [nucl-th].

        Speaker: Le Zhang (Hubei Normal University)
      • 17:40
        Gluon propagator in two-color dense QCD: Massive Yang-Mills approach at one-loop 20m

        Motivated by the recent lattice result, we study the Landau gauge gluon propagators in dense two-color QCD at quark chemical potential. In order to take into account the non-perturbative effects in the infrared regime, we use the massive Yang-Mills theory which has successfully described the gluon and ghost propagators in the Landau gauge within the one-loop approximation. We couple quarks to this theory and compute the one-loop polarization effects. Dense matter in two-color QCD should possess the diquark condensate which is color-singlet, and hence neither electric nor magnetic screening effects appear at the scale less than the diquark gap. This infrared behavior explains the lattice results which show the insensitivity of screening masses to the quark density.

        Speaker: Dr Daiki Suenaga (Central China Normal University)
      • 17:40
        Hadronic resonance production in asymmetric collisions with ALICE at the LHC 20m

        Hadronic resonances are interesting probes of the hot and dense matter created in heavy-ion collisions. Due to their short lifetimes, resonances
        are useful tools to understand the particle production mechanisms and the properties of the hadronic phase. Resonance yields are expected to be modified due to the interaction of their decay daughters within the hadronic medium via the re-scattering and re-generation processes.
        The study of resonance production in p--Pb collisions fills the gap between pp and heavy-ion (Pb--Pb, Xe--Xe) collisions and also helps us
        to understand the initial state effects due to cold nuclear matter. In asymmetric collisions, the produced particle yields are different at the forward and backward rapidities. The rapidity asymmetry (${Y}_\mathrm{Asym}$) studies are sensitive to nuclear modification effects, like shadowing, the Cronin enhancement, multiple scattering and energy loss.
        We will report on the measurement of the production of K$^{*0}$ and $\phi$ resonances in p--Pb collisions at $\sqrt{\it{s}_{NN }}$ = 8.16 TeV. Results include transverse momentum spectra, mean transverse momenta, yields and particle ratios as a function of charged particle multiplicity in the rapidity range (- 0.5 $<$ $y_\mathrm{CM}$ $<$ 0). The parton energy loss is also studied by measuring the nuclear modification factors of K$^{*0}$ and $\phi$ with other available results in p--Pb collisions at $\sqrt{\it{s}_{NN }}$ = 5.02 and 8.16 TeV. In addition, the first measurements of the rapidity dependence of K$^{*0}$ and $\phi$ production at $\sqrt{\it{s}_{NN }}$ = 5.02 will be presented. These results will also be compared with different model predictions.

        Speaker: Dukhishyam Mallick (National Institute of Science Education and Research (IN))
      • 17:40
        Hanbury-Brown-Twiss radii at 200 GeV using anisotropic hydrodynamics 20m

        In this talk, we will review the basics of 3+1d quasiparticle anisotropic hydrodynamics (aHydroQP) and highlight some phenomenological comparisons with experimental data at both 2.76 TeV and 200 GeV. We will then present preliminary comparisons of the femtoscopic Hanbury-Brown-Twiss (HBT) radii using aHydroQP. We will show comparisons of the HBT radii and their ratios between aHydroQP and the experimental results from both the STAR and PHENIX experiments. Our preliminary results for pion interferometry based HBT radii are in quite good agreement with the experimental results from both collaborations particularly at low pair mean transverse momentum.

        Speaker: Mubarak Alqahtani (Kent State University)
      • 17:40
        Hard symmetry breaking effects in effective theories of the QCD phase diagram 20m

        Effective Field Theories (EFTs) provide a systematic framework in which all terms consistent with the symmetries up to a specific mass dimension are written down in the lagrangian. We explore the consequence of the assumption that a fermionic EFT describes the QCD crossover.

        This EFT was analyzed for zero quark number chemical potential ($\mu=0$) in Ref. [1] considering all chirally symmetric terms up to dimension $6$. Following previous literature [3,4] the only explicit chiral symmetry breaking term considered was the quark mass $m_q\bar{\psi}\psi$. The independent coupling constants of the theory were fit to Euclidean $\pi$ velocity and the $\pi$ screening mass measured on the lattice [2] at $T=0.84T_{co}$ ($T_{co}$ is the crossover temperature) and yielded an independent prediction: $\pi$ decay constant $f$ which agreed with the lattice data. The theory describes the variations of these $\pi$ properties near the crossover temperature at $\mu=0$.

        In this work we analyze the implications of the effective theory for finite $\mu$. From the symmetry point of view a finite quark mass $m_q\bar{\psi}\psi$ breaks chiral symmetry, $\mu\bar{\psi}\gamma^4\psi$ breaks CP symmetry. Usually, analysis is simplified by assuming that only soft symmetry breaking terms (dimension less than $4$) appear which means that these two are the only explicit symmetry breaking terms in the lagrangian. In an effective theory with a cutoff however, a softly broken symmetry will inevitably lead to terms of dimension greater than $4$, which break the symmetry under consideration -- also known as hard symmetry breaking.

        We study the consequences of adding hard breaking of symmetries in fermionic effective theory models for QCD. We focus on the behaviour of two mean fields, the chiral condensate $\langle\bar{\psi}\psi\rangle$ and the number density $\langle\bar{\psi}\gamma^4\psi\rangle$ in the QCD phase diagram. In the absence of hard breaking terms, the two condensates are connected by mean field definitions of the mass and the chemical potential.

        At $\mu=0$ the impact of hard chiral symmetry breaking is simply a redefinition of the four Fermi coupling constant and is inconsequential. For finite chemical potential in the chiral limit no new terms appear but we show using an analysis with two mean fields that the curvature of the critical line changes. This depends on a new linear combination of the coupling constants of the dimension $6$ operators and this combination can be chosen to match the value of the curvature calculated on the lattice [5]. This resolves the discrepancy of our previous calculation [1] of the curvature of the critical line and the lattice.

        Finally, when $m_q$ and $\mu$ are both finite, hard breaking induces a direct coupling between the two condensates. This additional coupling affects the location of the crossover temperature (defined as the maximum of chiral susceptibility) as a function of the chemical potential. The curvature of the crossover line can be used to match this additional constant and this fixes the phase diagram in this framework. This constrains the location of the QCD critical point.

        [1] S.~Gupta and R.~Sharma, An effective field theory for warm QCD, arXiv:1710.05345 [hep-ph].

        [2] B.~B.~Brandt, A.~Francis, H.~B.~Meyer and D.~Robaina, Chiral dynamics in the low-temperature phase of QCD, Phys.\ Rev.\ D {\bf 90} (2014) no.5, 054509 [arXiv:1406.5602 [hep-lat]].

        [3] Y.~Nambu and G.~Jona-Lasinio, Dynamical Model Of Elementary Particles Based On An Analogy With Superconductivity. 1, Phys.\ Rev.\ {\bf 122} (1961) 345;
        Y.~Nambu and G.~Jona-Lasinio, Dynamical Model Of Elementary Particles Based On An Analogy With Superconductivity. Ii, Phys.\ Rev.\ {\bf 124} (1961) 246.

        [4] S.~P.~Klevansky, The Nambu-Jona-Lasinio model of quantum chromodynamics, Rev.\ Mod.\ Phys.\ {\bf 64} (1992) 649.

        [5] O.~Kaczmarek, F.~Karsch, E.~Laermann, C.~Miao, S.~Mukherjee, P.~Petreczky, C.~Schmidt and W.~Soeldner {\it et al.}, Phys.\ Rev.\ D {\bf 83} (2011) 014504 [arXiv:1011.3130 [hep-lat]];
        R.~Falcone, E.~Laermann and M.~P.~Lombardo, PoS LATTICE {\bf 2010} (2010) 183 [arXiv:1012.4694 [hep-lat]];
        G.~Endrodi, Z.~Fodor, S.~D.~Katz and K.~K.~Szabo, JHEP {\bf 1104} (2011) 001 [arXiv:1102.1356 [hep-lat]];
        C.~Bonati, M.~D'Elia, M.~Mariti, M.~Mesiti, F.~Negro and F.~Sanfilippo, Phys.\ Rev.\ D {\bf 90} (2014) 11, 114025 [arXiv:1410.5758 [hep-lat]];
        L.~Cosmai, P.~Cea and A.~Papa, arXiv:1410.2471 [hep-lat].

        Speaker: Rishi Sharma (TIFR)
      • 17:40
        Hawking radiation from acoustic black hole in relativistic heavy-ion collisions 20m

        In relativistic heavy-ion collisions, quark-gluon plasma can have a supersonic motion in the longitudinal direction. The quark-gluon plasma also has barotropic equation of state, negligibly small $\eta/s$ ratio, and irrotational velocity profile (specially in the central collisions, where there is no net initial angular momentum). Thus it can be used to construct an analog model of gravity, and there is possibility to have analog (acoustic) black hole Hawking radiation in the fluid. The plasma in relativistic heavy-ion collisions has a large velocity gradient in the longitudinal direction. Therefore, analog Hawking temperature, produced in the fluid, can not be neglected in comparison to the background temperature of the fluid. Using ultra-relativistic quantum molecular dynamics model (UrQMD), we show that it is possible to have temporarily static sonic horizon in relativistic heavy-ion collisions allowing the applicability of conventional ideas of Hawking radiation. We also study the time evolution of conformal factor (energy density/baryon density where fluid velocity is zero) arising in the acoustic metric and discuss its possible implications (as well as the implications of moving acoustic horizon). We propose possible observational signal for this Hawking radiation in the experiment.

        Speaker: Dr Shreyansh Shankar Dave (The Institute of Mathematical Sciences, Chennai, Tamil Nadu, India)
      • 17:40
        High transverse momentum direct photons in p+Au collisions in PHENIX at RHIC 20m

        The primary source of high transverse momentum (>4-5GeV/c) direct photons is the initial hard scattering of partons, specifically the quark-gluon Compton scattering process. This has been validated not only in hadron-hadron, but also in heavy ion collisions (see for instance PRL 109 (2012) 152302), where the observed yields were proportional, as expected, to the number of binary nucleon-nucleon collisions as calculated from the Glauber model for various collision centralities. This observation supports that the collision geometry is well defined by the centrality measure we have been using, at least in the case when the colliding ions are large. The definition, however, is not obvious in very asymmetric collisions,
        like p+Au. We assume that high transverse momentum direct photons are a "standard candle" for initial hard scattering, and, per extension, for collision geometry not only for p+p and A+A, but also for small-on-large collisions. If true, comparing the centrality dependence of direct photon and hadron production in p+Au is a robust test of the applicability of the Glauber model in such systems. In this poster we will report on the status of the analysis of high transverse momentum direct photons in p+Au collisions at various centralities as well as of the direct photon / hadron ratios and its comparison with hadron production.

        Speaker: Mr Zhandong Sun (University of Debrecen)
      • 17:40
        Hydrodynamic Attractor in Viscous Hubble Flow 20m

        The gradient expansion solutions to hydrodynamic equations are found to be divergent in many cases. The application of resurgence theory rescues the divergent series solutions and reproduces hydrodynamic attractors in Bjorken flow[1,2] and Gubser flow[3,4]. In this talk, I will first present my result of Borel-resummed hydrodynamics in a different situation, a viscous fluid system that undergoes Hubble flow at a controlled rate. Then the topic of effective viscosity will also be discussed.
        [1] M. P. Heller and M. Spalínski, Phys. Rev. Lett. 115, 072501(2015).
        [2] P. Romatschke, Phys. Rev. Lett. 120, 012301 (2018).
        [3] G. S. Denicol and J. Noronha, Phys. Rev. D 99, 116004 (2019).
        [4] A. Behtash et al., Phys. Rev. D 97, 044041 (2018)

        Speaker: Mr Zhiwei Du (Fudan University)
      • 17:40
        Hypernuclei Production in CBM at FAIR - A Feasibility Study 20m

        The main goal of the CBM experiment at FAIR is to study the behavior of nuclear matter at very high baryonic density. This includes the exploration of the high density equation of state, search for the transition to a deconfined and chirally restored phase, critical endpoint. One of the promising diagnostic probes for these new states is the enhanced production of multi-strange (anti-)particles. The CBM detector is designed to measure such rare diagnostic probes multi-differentially with unprecedented precision and statistics. Important key observables are the production of hypernuclei and dibaryons. Theoretical models predict that single and even doubly-strange hypernuclei are produced in heavy-ion collisions with the maximum yield in the region of SIS100 energies. The discovery and investigation of new (doubly strange-)hypernuclei and of hyper-matter will shed light on the hyperon-nucleon and hyperon-hyperon interactions. In this talk, we will report the results of feasibility study on the production of single- and double-strange hypernuclei in CBM experiment. Implications on the high baryon density nuclear matter will be discussed.

        Speaker: Dr Anton Lymanets (GSI, Darmstadt)
      • 17:40
        Identified light flavor particle production in "jetty" and "isotropic" pp collisions at √s = 13 TeV with ALICE at the LHC 20m

        Identified light flavour particles, such as the $\pi$, K, $\phi$ mesons and the p, $\Lambda$, $\Xi$ baryons, constitute interesting probes to investigate the collective behaviour recently observed in small collision systems. The underlying mechanisms of light flavour production are currently not well understood, and the mechanisms are explained in the framework of different models. pQCD models based on hard scatterings, such as PYTHIA, describe light flavour production via string-breakings and rope hadronization. Other thermal and statistical models, mainly dominated by soft processes, predict a mechanism for the production of light flavour particles based on mass hierarchies in (grand) canonical ensembles.

        This analysis is aimed to disentangle and isolate events that are dominated by soft processes ("isotropic") and hard processes ("jetty") by using the transverse spherocity observable. The light flavour production is then studied in both events with jet-like topologies and isotropic topologies, which are assumed to be dominated by hard and soft processes, respectively. This is done in an effort to pin-point the underlying mechanisms of the collective behaviour observed in small systems, such as radial flow and long-range angular correlations.

        In this contribution we report about the measurement of transverse momentum spectra of strange and non-strange mesons and baryons in transverse spherocity selected events. The results are obtained by exploiting the data collected with ALICE in pp collisions at a center-of-mass energy, $\sqrt{s}$, of 13 TeV.

        Speaker: Adrian Fereydon Nassirpour (Lund University (SE))
      • 17:40
        Inclusive b-jet production with the ALICE detector at the LHC 20m

        Heavy-flavor quarks created in ultra-relativistic heavy-ion collisions are mostly produced in hard QCD processes during the early stages of the reaction and their production is largely unaffected in the later
        stages. They interact with the hot nuclear matter throughout the whole evolution of the systems via semi-hard and soft processes such as energy loss via gluon radiations and collisions. Nuclear modification of heavy flavor quarks in pA systems provides insight into
        cold nuclear matter effects such as (anti-)shadowing and $k_{T}$-broadening, and also serves as a baseline for studies in AA collisions. On this regard, fully reconstructed heavy-flavor jets
        provide additional information on the flavor (or mass) dependence of fragmentation, color charge effects as well as insight into the contribution of gluon splitting on heavy-flavor production.

        The ALICE detector at the LHC has excellent tracking capabilities which allow to identify displaced secondary vertices of B-hadron decays and hence enable the reconstruction of b-jets.

        In this contribution, we will present $p_{\rm T}$-differential b-jet production cross section in ${\rm p-Pb}$ collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV measured by the ALICE experiment. The NLO pQCD (POWHEG) predictions will be compared to the data.

        Speaker: Zubayer Ahammed (Department of Atomic Energy (IN))
      • 17:40
        Inclusive diffractive heavy quarkonium photoproduction in pp, pA and AA collisions 20m

        The inclusive $J/\Psi$ production by direct and resolved photoproduction in the $\gamma p$ scattering is calculated based on the nonrelativistic quantum chromodynamics (NRQCD) factorization formalism, which is in good agreement with the experimental data of total cross section distribution of heavy quarkonium production at HERA. Then we extend the formalism including the direct and resolved photoproduction processes to resolved pomeron model to study the heavy quarkonium photoproduction at the LHC energies. We present the predictions of rapidity and transverse momentum distributions of the inclusive diffractive $J/\Psi$, $\Psi(2S)$ and $\Upsilon$ photoproduction in $pp$, $pPb$ and $PbPb$ collisions at the LHC energies. Our numerical results indicate that the resolved photoproduction processes play an important role in the heavy quarkonium production. Especially for $pp$ collisions, the contribution of resolved photoproduction processes is the largest, which can reach to $28\%$, $13\%$ and $44\%$ for the rapidity distributions of $J/\Psi$, $\Psi(2S)$ and $\Upsilon$ inclusive diffractive photoproduction, respectively.

        Speaker: Yanbing Cai
      • 17:40
        Inclusive jet measurements in p+Au collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV in STAR 20m

        The Quark Gluon Plasma (QGP) is a state of matter at extremely high energy density, where the quark and gluon constituents of nucleons become deconfined. Although there is strong evidence at RHIC and the LHC that the QGP is created in A+A collisions, it was initially assumed to be absent in smaller systems, such as p+p and p+A collisions. However, the observation of flow-like correlations in such collisions at the LHC and RHIC has made the existence of the QGP in small systems an open question. High momentum partons produced at early stages of heavy ion collisions generate collimated sprays of hadrons called \textit{jets}. These partons lose energy when passing through the medium. This effect, usually referred to as \textit{jet quenching}, is well established as a probe of the existence and properties of the QGP.

        In this analysis, we aim to investigate p+Au collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV at STAR for possible evidence of jet quenching by studying the binary-scaled inclusive jet yield. Measurements for both full (charged + neutral) and charged jets will be presented. We will present preliminary results on jet spectra along with our analysis process, and compare the jet yields in different backward (Au-going direction) event activity bins. Progress on our simulation procedures will be shown, including the Glauber model calculation and detector response simulations. Progress towards the resultant nuclear modification factor $R_{\mathrm{pAu}}$, after we scale with the average number of binary nucleon collisions from the Glauber model calculation, will also be discussed.

        Speaker: Tong Liu (Yale University)
      • 17:40
        Influence of Initial-state shape deformations in Ultra Central collisions 20m

        We study the fluctuation of shape-deformation as currently implemented in MC-Glauber-like models and their consequences on the magnitude of initial-state eccentricities. We show that for both deformed and spherical colliding species, there are large fluctuations in the deformation that emerge event by event. We characterize these deformations with the ratio of the largest and smallest eigenvalues ($\lambda_1$ and $\lambda_3$) of the covariance matrix for the coordinates of the colliding nucleons. The second order initial-state eccentricity $\varepsilon_2$, shows a strong correlation with fluctuations of the ratio $\lambda_1/\lambda_3$ for ultra central collisions; the conditional mean $E(\varepsilon_2|(\lambda_1/\lambda_3)_1+(\lambda_1/\lambda_3)_2)$ varies by O(100\%) for 0-1\% Pb+Pb collisions. However, the number of participants, as well as the higher-order eccentricities, are unmodified. We further show, via acoustic scaling, that for constrained values of $\lambda_1/\lambda_3$, $v_n/\varepsilon_n$ for ultra-central collisions, scale in the same way as for mid-central and peripheral collisions for the wealth of differential $v_n$ measurements in ultra-central collisions.

        Speaker: Peifeng Liu (Stony Brook University)
      • 17:40
        Influence of the neutron skin effect on nuclear isobar collisions at RHIC 20m

        The unambiguous observation of a Chiral Magnetic Effect (CME)-driven charge separation is the core aim of the isobar program at RHIC consisting of ${^{96}_{40}}$Zr+${^{96}_{40}}$Zr and ${^{96}_{44}}$Ru+${^{96}_{44}}$Ru collisions at $\sqrt {s_{\rm NN}}\!=\!200$ GeV.We quantify the role of the isobars spatial distributions on both the eccentricity and the magnetic field strength within a relativistic hadronic transport approach (SMASH).In particular, we introduce isospin-dependent nucleon-nucleon spatial correlations in the geometric description of both nuclei, deformation for ${^{96}_{44}}$Ru and the so-called neutron skin effect for the neutron-rich isobar i.e. ${^{96}_{40}}$Zr.The main result of this study is a reduction of the magnetic field strength difference between ${^{96}_{44}}$Ru+${^{96}_{44}}$Ru and ${^{96}_{40}}$Zr+${^{96}_{40}}$Zr from $10\%$ to $5\%$ in peripheral collisions when the neutron-skin effect is included.Further, we find an increase up to 10\% of the eccentricity when deformation is taken into account while neither the neutron skin effect nor the nucleon-nucleon correlations result into a significant modification of this observable with respect to the traditional Woods-Saxon modeling.Our results suggest a smaller CME signal to background ratio for the experimental charge separation measurement in peripheral collisions with the isobar systems than previously expected.

        Speaker: Jan Hammelmann
      • 17:40
        Influences of electromagnetic field characteristics on the CME and CMW measurements 20m

        Many great efforts have been made to investigate the Chiral Magnetic Effect (CME) and Chiral Magnetic Wave (CMW), which reply on the existence of extremely large electromagnetic fields in relativistic heavy-ion collisions.

        However, the current main difficulty of measuring the CME signal is some backgrounds which we do not understand clearly. To isolate the influence of those backgrounds, the isobar program at RHIC has been proposed and it collides $_{44}^{96}\textrm{Ru}+_{44}^{96}\textrm{Ru}$ and $_{40}^{96}\textrm{Zr}+_{40}^{96}\textrm{Zr}$ elements, since they have a same nucleon number but the 10$\%$ difference of proton number. The CME signal is expected to be different between the two isobaric collisions. By investigating the the properties of electromagnetic fields in two isobaric collisions with special emphasis on the correlation between magnetic field direction and participant plane angle $\Psi_{2}$ (or spectator plane angle $\Psi_{2}^{SP}$), i.e. $\langle$cos2$(\Psi_B - \Psi_{2})\rangle$ [or $\langle$cos2$(\Psi_B - \Psi_{2}^{SP})\rangle$], we confirm that the magnetic fields of $_{44}^{96}\textrm{Ru}+_{44}^{96}\textrm{Ru}$ collisions are stronger than those of $_{40}^{96}\textrm{Zr}+_{40}^{96}\textrm{Zr}$ collisions. Moreover, we find that the $\textbf{deformation of nuclei has a non-negligible effect on}$ $\langle$cos2$(\Psi_B - \Psi_{2})\rangle$, especially in peripheral events. Because the magnetic field direction is more strongly correlated with $\Psi_{2}^{SP}$ than with $\Psi_{2}$, $\textbf{the relative difference of the chiral magnetic effect observable with respect to}$ $\Psi_{2}^{SP}$ $\textbf{is expected to}$ $\\$ $\textbf{be able to reflect much cleaner information about the CME with less influences of deformation}$[1].

        What is more, with the presence of magnetic field, the coupling of the vector and axial currents induced by the chiral anomaly can motivate a collective gapless excitation in QGP, i.e. CMW. The CMW can lead to an electric quadrupole moment in relativistic heavy-ion collision, which explains the observed charge-dependent elliptic flow of pions. In our study, a dipolar distribution of $\bf E \cdot B$ is observed at the non-central collisions in Au+Au collisions at the RHIC energy $\sqrt{s}$=200 GeV. More importantly, we find that the coupling of the dipole QED anomaly and magnetic field $\bf B$ can also induce an electric quadrupole moment which can further lead to the difference in elliptic flows between positive charged particles and negative charged particles through final interactions. The centrality dependence of the density of $\bf E \cdot B$ is similar to the trend of the slope parameter $r$ measured from the difference in elliptic flows between positive pions and negative pions by the STAR collaboration. Therefore, $\textbf{the novel mechanism for electric quadrupole moment generation can offer a new}$ $\textbf{interpretation of the observed charge-dependent elliptic flow of pions, but without the}$ $\textbf{formation}$ $\\$ $\textbf{of CMW}$[2].

        [1] X. L. Zhao, G. L. Ma and Y. G. Ma, Phys. Rev. C 99, no. 3, 034903 (2019) [arXiv:1901.04151 [hep-ph]].
        [2] X. L. Zhao, G. L. Ma and Y. G. Ma, Phys. Lett. B 792, 413 (2019) [arXiv:1901.04156 [hep-ph]].

        Speaker: Prof. Guo-Liang Ma (Fudan University)
      • 17:40
        Initial Conditions of Conserved Charges in Heavy-Ion Collisions 20m

        In this talk, I will present a new procedure for dynamically generating conserved charges (baryon number, strangeness, and electric charge) to supplement an arbitrary initial condition for ultrarelativistic heavy ion collisions. This algorithm, which we denote ICCING (Initial Conserved Charges in Nuclear Geometries), treats an initial distribution of energy density as if it were composed entirely of gluons. It then samples the probabilities for a gluon to split into a quark-antiquark pair, which we have calculated in the color-glass condensate framework, to redistribute this energy density in space along with the conserved charges carried only by quarks. In this way, we provide a new tool to the community which can be incorporated into any initial-condition framework to initialize the conserved charges. Interestingly, we find that the quark flavors couple differently to the collision geometry: up and down quarks are produced by the bulk event geometry, while strange and charm quarks are preferentially produced from hot spots. As such, different quark flavors can possess significantly different eccentricities which drive the ensuing flavor-dependent flow response.

        Speaker: Matthew Sievert (Rutgers University)
      • 17:40
        Insight into $K^*(892)^{0}$ production in pp collisions as a function of collision energy, event-shape and multiplicity with ALICE at the LHC 20m

        The lifetimes of short-lived hadronic resonances are comparable to the hadronic phase of the medium produced in high-energy collisions. Thus, these resonances are sensitive to the re-scattering and regeneration processes in the time interval between the chemical and kinetic freeze-out, which might affect the resonance yields. In addition, event shape observables like transverse spherocity are sensitive to the hard and soft processes and they represent a useful tool to separate the isotropic and jetty events in pp collisions. Furthermore the measurements in small systems are used as a reference for ion-ion collisions and are helpful for the tuning of Quantum Chromodynamics (QCD) inspired event generators. In this contribution, we present recent results on $K^*(892)^{0}$ obtained by the ALICE experiment in pp collisions at several collision energies, event multiplicities and as a function of transverse spherocity. The results include the transverse momentum spectra, yields and their ratio to long-lived particles. The measurements will be compared with model predictions and measurements at lower energies.

        Speaker: Rutuparna Rath (Indian Institute of Technology Indore (IN))
      • 17:40
        Insight into Multiplicity Dependence of Strangeness and Resonance Production from Small to Large System with ALICE at the LHC 20m

        One of the important results of the LHC Run 1 was the observation of an enhanced production of strange particles in high multiplicity pp and p-Pb collisions at 7 and 5.02 TeV, respectively. A smooth evolution of yields of strange particles relative to the non-strange ones with event multiplicity has been observed in those systems. Results from Run 2 at the top LHC energy allows us to improve previous measurements by exploiting a dedicated high multiplicity trigger. This offers the unique opportunity to study, in elementary collisions, the multiplicity range covered by semi-peripheral Pb-Pb collisions. We present the latest results obtained with ALICE on the multiplicity-dependent strangeness production. The strangeness enhancement is investigated by measuring the evolution with multiplicity of single-strange and multi-strange baryon production relative to non-strange particles. In addition recent measurements of mesonic and baryonic resonances in small collision systems are shown. We investigate the system size dependence in different collision systems as well as lower collision energies to study how the hadronic scattering processes affect measured resonance yields, as well as the interplay between canonical suppression and strangeness enhancement. The measurement of the $\phi$(1020) meson as a function of multiplicity provides crucial constraints in this context. Energy and system-type invariance are discussed and an extensive comparison with statistical hadronization and QCD-inspired models are presented.

        Speaker: Arvind Khuntia (Indian Institute of Technology Indore (IN))
      • 17:40
        Investigating the non-flow effect in proton+proton collisions from two-particle correlation using PYTHIA8 20m

        To explain the underlying mechanisms involved in particle production and the properties of the strongly interacting nuclear matter produced in high multiplicity p+p collisions, one can use two particle azimuthal correlation method as an important tool. We present here measurements of two particle azimuthal correlation with neutral pion$(\pi^0)$, neutral kaon$(k^0)$ and proton as trigger particles having the highest transverse momentum ($p_{T}$) and associated charged hadrons of transverse momentum $(p_{T}) >$ 0.5 in an event on the basis of the difference in azimuthal angle ($\Delta \phi$) and pseudorapidity ($\Delta \eta$) at midrapidity in p+p collisions at $\sqrt{s}$ = 13 TeV using the pQCD inspired model PYTHIA8. Multiplicity dependent study of these measurements can explain the production and hadronization of particles at different multiplicities. In order to explain the collective behavior of the medium formed, we can use this analysis. Mixed event technique is used to obtain the pure correlation distribution and afterward, the per-trigger yields are extracted on the near side ($ |\Delta \phi| < 0.7$) as well as on the away side ($ |\Delta \phi - \pi|<1.1$). The modification in the per-trigger yields is given by a factor $I_{AA}$ which is the ratio of near-side to away-side yields. The collectivity of the medium is explained by the Fourier coefficient ($v_{2}$) extracted from the two particles angular correlation function. This explains the collective motion of the particles. The mass dependency of particles and the behavior of mean transverse momentum ($\langle p_{T} \rangle$) as a function of charged-particle multiplicity is presented.

        Speaker: Dhananjaya Thakur (Indian Institute of Technology Indore (IN))
      • 17:40
        Ion Backflow Studies for the sPHENIX TPC 20m

        A Time Projection Chamber is the main tracking system for the proposed sPHENIX experiment at RHIC. It will measure space points of charged tracks, which provide the needed momentum resolution to separate the Upsilon states in decays to electrons and positrons.
        The strong magnetic field of the solenoid previously used in the BaBAR experiment, a Neon-based fast gas mixture, and an electric field providing a high drift velocity will mostly compensate for E-field distortions due to ion backflow in the current sPHENIX TPC design. A quadruple GEM stack with special hole patterns or a MicroMegas based amplification is expected to further reduce the ion backflow.
        A series of simulations and measurements have been performed to find an optimal configuration and working point for the sPHENIX TPC. In this presentation, we discuss the outcome of this study.

        Speaker: sPHENIX Collaboration
      • 17:40
        Isolated photon production in pp collisions at $\sqrt{s}=13$ TeV measured with ALICE 20m

        Direct photons from Compton and annihilation hard processes, produced in hard scatterings of partons from incoming nucleons, are unique colourless probes of QCD processes. The measurement provides a handle for testing perturbative QCD predictions and constrain the parton distribution functions.
        In this contribution, we present the measurements of isolated photon cross section in pp collisions at $\sqrt{s}=13$ TeV using the data collected by the ALICE with a trigger based on electromagnetic calorimeters. Isolation criterion is applied to select direct photons and reduce contamination from decay and fragmentation photons. The result will be compared to theoretical calculations.

        Speaker: Ran Xu (Central China Normal University CCNU (CN))
      • 17:40
        Isolated Photon-Hadron Correlations in pp and p--Pb Collisions at $\sqrt s_{\rm NN}$ = 5 TeV in ALICE 20m

        Isolated Photon-Hadron Correlations in pp and p--Pb Collisions at $\sqrt s_{\rm NN}$ = 5 TeV in ALICE.
        Fernando Torales Acosta on behalf of ALICE collaboration.

        The measurement of isolated photon-tagged correlations of jets and jet fragments is a promising channel for the study of partonic energy loss in heavy-ion collisions. We use a combination of isolation and electromagnetic shower-shape information obtained from the ALICE electromagnetic calorimeter and ALICE Inner Tracking System to reduce the large background from meson decays and fragmentation photons. We present isolated photon-hadron correlations and yields of charged hadrons in the unexplored kinematic range given by 10-40 GeV/$c$ $p_{\rm T}$ photons and 0.5-15 GeV/$c$ $p_{\rm T}$ charged tracks in $\sqrt{s_{\rm NN}} = $ 5.02 TeV pp and p--Pb collisions. We report the first measurement of photon-tagged fragmentation in p--Pb at the LHC. We show the ratio of fragmentation measurements in pp and p--Pb is consistent with unity, constraining cold nuclear matter effects on parton fragmentation.

        Speaker: Fernando Torales Acosta (Lawrence Berkeley National Lab. (US))
      • 17:40
        J/$\psi$ elliptic flow at mid-rapidity in Pb--Pb collsions at $\sqrt{s_{NN}}$= 5.02 TeV with ALICE 20m

        In the early and hottest phase of nucleus-nucleus collisions the formation of a Quark-Gluon Plasma (QGP) is expected. Several QGP induced effects, such as the melting of charmonium states due to color screening or the recombination of uncorrelated charm and anti-charm quarks, can influence charmonium yields. Recent ALICE measurements of charmonium nuclear modification factor in Pb--Pb collisions at $\sqrt{s_{NN}}$= 2.76 TeV and $\sqrt{s_{NN}}$= 5.02 TeV showed that the (re)combination mechanism plays a dominant role in the production of charmonia at low $p_{\mathrm{T}}$. In addition, the positive elliptic flow, $v_{2} $, measured for low-$p_{\mathrm{T}}$ J/$\psi$ and D-mesons in Pb--Pb collisions suggests that the charm quarks thermalize in the QGP.

        We report on the new measurement of the low and intermediate $p_{\mathrm{T}}$ J/$\psi$ elliptic flow at mid-rapidity ($|y|<$ 0.9) in Pb--Pb collisions at $\sqrt{s_{NN}}$= 5.02 TeV. The J/$\psi$ mesons are reconstructed in the di-electron decay channel using the ALICE central barrel. We employ the Pb--Pb data sets recorded by ALICE during LHC Run 2 in 2015 and 2018. These results are complementary to the existing ALICE measurements at forward rapidity and to ATLAS and CMS high $p_{\mathrm{T}}$ results at mid-rapidity and will be discussed in the context of recent model calculations.

        Speaker: Ms Alexandra Neagu (University of Oslo (NO))
      • 17:40
        J/$\psi$ production at mid-rapidity in p-Pb collisions with the ALICE detector 20m

        The understanding of cold nuclear matter (CNM) effects are essential to study the properties of a state of deconfined quarks and gluons, the quark-gluon plasma, created in relativistic heavy-ion collisions. CNM effects can be studied in p-Pb collisions.
        Furthermore, some results in high-multiplicity p-Pb collisions suggest collectivity similar to that in Pb-Pb collisions. For J/$\psi$ production, a positive second-order flow coefficient ($v_{2}$) was observed at forward and backward rapidity and the origin of this J/$\psi$ $\it{v}_{2}$ remains an open question.
        The centrality dependent nuclear modification factor ($\it{Q}_{\rm{pPb}}$) as a function of transverse momentum ($\it{p}_{\rm{T}}$) was also measured at backward and forward rapidity. At backward rapidity an enhancement of the J/$\psi$ yield was observed around intermediate $\it{p}_{\rm{T}}$ in central p-Pb collisions, while the J/$\psi$ yield is strongly suppressed at low $\it{p}_{\rm{T}}$ at forward rapidity.

        A multi-differential analysis with respect to collision centrality and $\it{p}_{T}$ is performed for inclusive J/$\psi$ production at mid-rapidity via the dielectron decay channel with the ALICE detector. In this poster, the centrality dependence of the inclusive J/$\psi$ production will be presented as well as the inclusive J/$\psi$ nuclear modification factor in minimum bias events. We will discuss CNM effects and other collective effects on J/$\psi$ production in p-Pb collisions by comparing the results to the J/$\psi$ measurement at backward and forward rapidity.

        Speaker: Shinichi Hayashi (University of Tokyo (JP))
      • 17:40
        J/psi polarization measurement in Pb-Pb collisions 20m

        Polarization is a key observable to determine the quarkonium production mechanism in hadronic elementary collisions. Its very small value measured at the LHC has been challenging the commonly-used theoretical models and it still represents a major standing issue in the field.
        On the other hand, phenomenological studies have shown that primordial quarkonium in heavy-ion collisions can be polarized by the strong magnetic field generated by the two colliding nuclei, while re-combined quarkonium is expected to be completely unpolarized.
        We present the preliminary $p_{\mathrm{T}}$-differential measurement of $\mathrm{J}/\psi$ polarization in $\sqrt{s_{\mathrm{NN}}} = $ 5.02 TeV Pb-Pb collisions at the LHC, discussing the analysis strategy and technique. The status of polarization measurements as a function of centrality as well as relative to the event plane will also be presented.

        Speaker: Luca Micheletti (Universita e INFN Torino (IT))
      • 17:40
        J/Psi production at forward rapidities in ultra-peripheral collisions in ALICE 20m

        The cross section for coherent J/$\psi$ photonuclear production in ultra-peripheral collisions (UPC) at the LHC is sensitive to the low x behaviour of the gluon distribution function of the interacting lead nuclei and provides important constraints on the initial stages in heavy ion collisions.

        The measurement of this process by ALICE in Pb-Pb UPC at forward rapidity using Run 2 data at $\sqrt{s_{NN}} = 5.02$ TeV is reported. The measurement samples the gluon distribution of lead down to x~$10^{-5}$. The increased statistics of the LHC Run 2 data sample resulted in a significant improvement in the precision of the measurement. When compared to theoretical predictions the results demonstrate the presence of moderate nuclear gluon shadowing. Details of the analysis procedure are discussed in this poster.

        Speaker: Tomas Herman (Czech Technical University (CZ))
      • 17:40
        J/ψ production as a function of charged-particle multiplicity in pp collisions at √s = 13 TeV at forward rapidity with ALICE at the LHC 20m

        In high-energy (proton-proton) pp collisions, there can be a substantial contribution from Multi-Parton Interactions (MPI) in particle production mechanisms. In this case, several interactions at the partonic level occur in a single pp collision and this implies a correlation between the particle production and the total event multiplicity. At LHC energies, MPI might occur at hard momentum scales, thus affecting the heavy-quark production. Such an effect can be investigated by studying the correlations between heavy-flavour production and the total charged-particle multiplicity. In this poster, we will present the preliminary results of $\rm{J}/\psi$ production (yield and mean transverse momentum) as a function of charged-particle multiplicity in pp collisions at $\sqrt{s}$ = 13 TeV at forward rapidity (2.5 $< y <$ 4) using the data collected by ALICE. $\rm{J}/\psi$ are reconstructed via $\rm{J}/\psi \rightarrow \mu^{+} + \mu^{-}$ decay channel using the Forward Muon Spectrometer, while the charged-particle multiplicity is obtained from the Silicon Pixel Detector. The results will be compared with several perturbative Quantum Chromodynamics inspired models. A comparison study will be presented with similar measurements for $\Upsilon$ and measurements performed for p$-$Pb collisions as well.

        Speaker: Dhananjaya Thakur (Indian Institute of Technology Indore (IN))
      • 17:40
        Jet Shapes in pp at $\sqrt s$ = 5 TeV LHC energy in ALICE 20m

        The measurement of jet shapes such as the angularity, the momentum dispersion and the difference between the leading and subleading jet constituents track momentum will be presented. The measurements were done in pp collisions at $\sqrt s$ = 5 TeV and will be compared to previous measurements by ALICE at $\sqrt s$ = 7 TeV. These jet structure observables probe the radiation pattern of jets. Jets are reconstructed using anti-$k_{\rm T}$ algorithm and for different jet resolution $R=0.2,0.4$ and 0.7. Detector effects are corrected via two dimensional unfolding and the final results are presented in the $p_{T}$ range 20-40 and 40-60 GeV/$c$. The results are also compared to different Montecarlo calculations. As an outlook, the same measurements will be performed in Pb--Pb collisions at $\sqrt{s_{NN}}=$ 5.02 TeV to study medium-induced modification of the jet shape.

        Speaker: Mr Sumit Kumar Saha (Variable Energy Cyclotron Centre, HBNI, India)
      • 17:40
        JETSCAPE 2.0: Towards a complete event generator for heavy ion collisions 20m

        In this talk the second major software release of the JETSCAPE collaboration will be described. The Jet Energy-loss Tomography with a Statistically and Computationally Advanced Program Envelope (JETSCAPE) Collaboration is developing a complete event generator for heavy ion collisions to be used by the wider community. In this talk we highlight the performance of the year-2 release of the JETSCAPE software, which consists of an overall framework program, coupled with individually exchangeable modules describing every aspect of high energy heavy ion collisions.

        We demonstrate step-by-step how a complete set of experimental data from heavy ion collisions is described by the JETSCAPE event generator equipped with state-of-the-art physical components. These components are classified into three categories: (i) the production, propagation and fragmentation of hard partons; (ii) the pre-hydrodynamic evolution, viscous hydrodynamic expansion and hadronic cascade describing the dynamics of the soft degrees of freedom defining the fireball medium; and (iii) the correlations and interactions between hard and soft particles, during the initial production stage, via in-medium energy loss, and through the medium’s response to it.

        Speaker: LongGang Pang for JETSCAPE Collaboration (Lawrence Berkeley National Laboratory)
      • 17:40
        K0Short and Λ production in p-Pb collision system at 8.16 TeV 20m

        Several experimental observables, sensitive to the evolution of the system after nuclear collisions, reveal important information about the properties of the QGP. Among such observables is the production rate of strange quarks, which were originally predicted to be produced with higher probability in a QGP scenario with respect to a pure hadron gas scenario. Studies of strangeness production at LHC energies, compared with the lower energy measurements, can help to determine the properties of the hot system created in ultra-relativistic collisions of heavy ions. In this work, we present results on strangeness production in p-Pb collisions measured with the ALICE detector at the LHC.
        The excellent tracking and particle identification capabilities of ALICE can be used to reconstruct strange hadrons via invariant-mass analysis of their weak decay products. The analysis status of strange ($\rm K^{0}_{s}$ and $\rm \Lambda$ ) hadrons in p-Pb collisions at 8.16 TeV at mid-rapidity as a function of $\rm p_{T}$ and centrality will be presented and the recent results on strange particle productions in different systems and energies will be summarized and discussed.

        Speaker: Vit Kucera (Inha University (KR))
      • 17:40
        Kibble-Zurek scaling near the QCD critical point 20m

        The dynamical models near the critical point are important tools to study the critical phenomena for RHIC BES program. However, the related model calculations depends on various parameters and inputs. In this talk, I will focus on the universal behavior of the dynamical evolving systems near the critical point, which is insensitive to various parameters and input in the model calculations.

        In [1,2], we have investigated the Kibble-Zurek scaling within the framework Langevin dynamics of the order parameter field and net-protons, and within the framework of stochastic diffusion dynamics of conserved charges. We constructed universal functions which are insensitive to various parameters through rescaling the traditional correlation function and cumulant with the properly determined characteristic scales $\tau_{kz}$ ,$\theta_{kz}$ and $l_{kz}$.

        In more details, for the dynamic of non-conserved order parameter, the constructed universal functions are insensitive to the magnitude of relaxation time and the evolving trajectory on phase diagram. And coupling with the net-proton, the oscillating behavior is suppressed for the constructed universal function, comparing with the original cumulants which strongly oscillate in terms of relaxation time and trajectory. For the dynamics of conserved charge, we also construct the universal functions, which are insensitive to the different initial temperature and a parameter in the equation of state.

        [1] S. Wu, Z. Wu and H. Song, Universal scaling of the sigma field and net-protons from

        Langevin dynamics of model A, Phys. Rev. C 99, 064902(2019)

        [2]S. Wu and H.Song,Universal scaling of conserved charge in the stochastic diffusion

        dynamics, arXiv:1903.06075 [nucl-th]

        Speaker: shanjin wu (Peking University)
      • 17:40
        Kinetics and hydrodynamics close to the chiral limit 20m

        First, we recall that close to the chiral limit, and below the critical temperature, the long wavelength effective theory of QCD is not ordinary hydrodynamics, but SU(2)xSU(2) superfluid hydrodynamics (Son 2000). In this theory the usual hydrodynamic variables such as energy are momentum are augmented by long wavelength pions. When the pion is massive, the effective theory reduces to normal hydrodynamics at large distances, but is described by the superfluid theory at short distances. Using techniques developed by Akamatsu et al (Akamatsu 2017), we integrate out the superfluid modes to determine how the transport coefficients of QCD such as the bulk viscosity depend on the pion mass below the critical temperature. These expressions are given by the dissipative parameters in the superfluid theory. We show how to compute these parameters in chiral perturbation theory using the associated chiral kinetic theory.

        References:

        D. Son, ``Hydrodynamics of nuclear matter in the chiral limit,'' Phys. Rev. Lett. 84, 3771 (2000).

        Y. Akamatsu, A. Mazeliauskas and D. Teaney, ``A kinetic regime of hydrodynamic fluctuations and long time tails for a Bjorken expansion,'' Phys.\ Rev. C95, no. 1, 014909 (2017).

        Speaker: Derek Teaney (Stony Brook University)
      • 17:40
        Lambda and antilambda hyperons polarization in heavy-ion collisions within transport model 20m

        $\Lambda$ and $\bar{\Lambda}$ polarization in heavy-ion collisions at BES RHIC energies is studied within the microscopic transport model UrQMD. Two approaches, (1) thermal and (2) axial anomaly approach, are considered. We trace the formation and space-time evolution of vorticiity and helicity patterns in details. This study demands a complex analysis of the fireball conditions including time slices, extraction of temperature and baryo- and strangeness chemical potentials, as well as freeze-out conditions of both hyperons. Rapidity and transverse momentum dependence of the polarization are obtained. We show that difference in global polarization of Lambda and antilambda at c.m. energies below 10 GeV can be explained by different space-time freeze-out conditions of two hyperons. Comparison with the STAR results shows a fair agreement between the model and the data.

        Speaker: Mr Oleksandr Vitiuk (Taras Shevchenko National University of Kyiv)
      • 17:40
        Light Nuclei (d, t) Production in Au+Au Collisions at $\sqrt{s_{\mathrm{NN}}}$ = 27 and 54.4 GeV from the STAR experiment 20m

        In high energy nuclear collisions, light nuclei production is sensitive to the baryon density fluctuations and thus can be used to study the QCD phase transition. For example, the neutron density fluctuation can be extracted from the yield ratio of proton, deuteron and triton, $N_{\mathrm{p}} N_{\mathrm{t}} / N_{\mathrm{d}}^{2}$, which may provide a method to study critical phenomena in relativistic heavy-ion collisions.

        In this poster, we will present measurements of (anti-)deuteron and triton production in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 27 and 54.4 GeV. These results are obtained from the large data samples collected by the STAR experiment in the years 2018 and 2017, respectively. We will show the centrality dependence for the coalescence parameters $B_2(d)$ and $B_3(t)$, particle ratios ($d/p$, $t/p$, and $t/d$), and the yield ratio of $N(t)$$\cdot$$N(p)$/$N^2(d)$. Their physics implications will be discussed.

        Speaker: Hui Liu (CCNU)
      • 17:40
        Limitations of Principal Component Analysis in Heavy-Ion Collisions 20m

        Principal Component Analysis (PCA) is a mathematical tool that can capture the most important information (variance) in data. Recently, CMS collaboration applied the PCA technique to analyze the data in Pb+Pb collisions, and a non-zero subleading mode has been extracted and interpreted as arising from subleading eccentricity [1][2]. In this talk, we study the performance of PCA method in the study of the factorization breaking effects of harmonic flow in two-particle correlation analysis [3]. We show that the choice of weighting factor in the orthogonality criteria, and $p_T$ range of the analysis, and even the statistical uncertainty of the input data could lead to significantly different results in the extracted single-particle flow modes. Therefore, it is necessary to understand the sensitivity of PCA procedure to these issues before one could attach any physics interpretation of the subleading flow modes obtained.

        [1] CMS Collaboration, Phys.Rev. C.96.064902
        [2] A. Mazeliauskas and D. Teaney, Phys.Rev. C91 (2015) no.4, 044902
        [3] Z. Liu, A. Behera, H. Song and J. Jia, in preparation.

        Speaker: Ziming Liu (Peking University)
      • 17:40
        Local Lambda polarization and feed-down effect in heavy-ion collisions 20m

        Spin polarization of $\Lambda$ hyperon has been observed by STAR in non-central heavy-ion collisions [1,2,3]. Among these measurements, the global polarization reflects the bulk-averaged value of the vorticity, while the local polarization probes more detailed structure of the vorticity field.

        We have studied the $\Lambda$ polarization in heavy-ion collisions using a multi-phase transport (AMPT) model. The results show that:

        1. The value of global polarization decreases with increasing collision energy [4]. This is in agreement with the measurement [1,2].
        2. Because of the non-uniform transverse expansion of the fireball, it can produce transverse vorticity circling the beam direction and further generate transverse local polarization [5].
        3. The result for the longitudinal local polarization [5] is consistent with the hydrodynamic calculation. However, these calculations have an opposite sign comparing to the experiment measurement [3].

        To resolve this sign puzzle, we further study the effect of feed-down decay on local $\Lambda$ polarization [6]. We develop a theoretical framework to study how spin polarization is transferred from parent to daughter particle in two-body decay. After Monte-Carlo simulation, we find that the feed-down effect suppresses the primordial $\Lambda$ polarization, but can not flip the sign.

        [1] STAR collaboration, Nature 548 (2017) 62-65.
        [2] STAR collaboration, Phys.Rev. C98 (2018) 014910.
        [3] STAR collaboration, arXiv:1905.11917.
        [4] Hui Li, Long-Gang Pang, Qun Wang, and Xiao-Liang Xia, Phys.Rev. C96 (2017) no.5, 054908.
        [5] Xiao-Liang Xia, Hui Li, Zebo Tang, and Qun Wang, Phys.Rev. C98 (2018) 024905.
        [6] Xiao-Liang Xia, Hui Li, Xu-Guang Huang, and Huan Zhong Huang, arXiv:1905.03120, submitted to Phys.Rev.C.

        Speaker: Dr Xiao-Liang Xia (Fudan University)
      • 17:40
        Locating the critical point in QCD phase diagram using heat capacity 20m

        One of the main aims of beam energy scan (BES) program at relativistic heavy ion collider (RHIC) is to locate the position of critical point in the ($T-\mu_B$) plane of QCD where the first order transition ends and cross over transition begins. Here $T$ denotes temperature and $\mu_B$ stands for baryonic chemical potential.At the critical point, quantities like specific heat and susceptibility
        are expected to diverge due to long range correlation.

        In this work, we have studied variation of specific heat, speed of sound with center-of-mass energies for Au+Au collision at $\sqrt{s_{NN}}$= 7.7, 11.5,19.6, 27.0, 39.0, 62.4, 200 GeV with the help of Hadronic Resonance Gas (HRG) model by using temperature and chemical potential which are extracted from the freeze-out surface at these energies. It is observed that trend of variation of these quantities drastically change at a particular $\sqrt(s_{NN}$)} lying between 39 to 62.4 GeV, thereby hinting toward the possible location of the QCD critical point.

        Speakers: Suman Deb (Indian Institute of Technology Indore (IN)), Raghunath Sahoo (Indian Institute of Technology Indore (IN))
      • 17:40
        Long-range azimuthal correlations arising with HBT suppressions in partially coherent pion emissions in AA and pp collisions 20m

        The presence of coherence in pion emission will suppress the strength of the final-state pion HBT correlations. The recently observed significant pion HBT suppressions in both Pb-Pb and pp collisions at the LHC indicate the pion emissions may be partially coherent in such violent collisions. In this talk we will show that the coherence in particle emission can give rise to a remarkable long-range azimuthal correlation.

        In Ref [1], we study the pion transverse-momentum spectrum and elliptic anisotropy of an expanding coherent source with a classical current radiation model. It is found that the elliptic anisotropy of coherent emission is connected to the source initial geometry through an interference effect but is not sensitive to the source expansion (flow effect). We further construct a partially coherent source by adding an incoherent emission component described by a viscous hydrodynamic model. The partially coherent source model can successfully reproduce the experimental data on the pion $p_T$ spectrum, $v_2(p_T)$ as well as 4-pion HBT correlations in Pb-Pb collisions at the LHC.

        Furthermore, we focus on the coherence phenomena in pp collisions in Ref [2]. We extend the coherent pion source by incorporating a Bjorken longitudinal expansion and study the long-range two-particle angular correlations. A “ridge” structure is found to arise from the interferences in coherent emission and to be largely related to the source transverse shape and size at the initial time. From the 2-pion HBT measurement at the LHC, we extract a coherent fraction increasing with the charged-particle multiplicity, as an input of a partially coherent pion emission model, and the calculations suggest a more pronounced ridge effect from the coherent pion emission in high-multiplicity pp collisions.

        Reference:
        [1] Peng Ru, G. Bary and Wei-Ning Zhang, Pion transverse-momentum spectrum and elliptic anisotropy of partially coherent source, Physics Letters B, 777 (2018) 79-85.
        [2] Peng Ru and Wei-Ning Zhang, Long-range azimuthal correlations arising with HBT correlation suppressions in partially coherent pion emissions in high-multiplicity pp collisions, in preparation.

        Speaker: Dr Peng Ru (South China Normal University / Dalian University of Technology / Central China Normal University)
      • 17:40
        Low mass dielectron studies with the HADES and CBM experiments at GSI/FAIR* 20m

        The High Acceptance DiElectron Spectrometer (HADES) and the Compressed Baryonic Matter experiment (CBM) are dedicated to study strongly interacting matter at high baryon densities and moderate temperatures. Being penetrating probes, dielectrons are a key observable to get direct access to the fireball.
        Currently the HADES experiment is located at SIS 18 at GSI, Darmstadt and will be moved in future to the CBM pit and continue its physics program at SIS100. Both experiments are complementary to each other in terms of detector setup and measureable energy range making it interesting to study one system at both experiments for comparison and verification of the CBM results. Currently Ag+Ag collisions at 4.5A GeV is favored. A major component for electron identification in both experiments is a RICH detector. The HADES RICH detector has been successfully upgraded within FAIR Phase-0 and showed an excellent performance in the recent Ag+Ag beamtime at 1.58A GeV at SIS 18 in March 2019.
        In this poster we present dielectron spectra based on the data collected in this beamtime, clearly showing the potential of dielectrons at HADES. Furthermore simulation results regarding dielectron spectra at HADES and CBM in Ag+Ag collisions at 4.5A GeV are shown as those are planned to be measured at SIS 100.
        *supported by BMBF 05P15RGFCA, 05P19R6FCA and GSI

        Speaker: Mr Jan-Hendrik Otto (JLU Giessen)
      • 17:40
        Low-$p_{T}$ $\mu^{+}\mu^{-}$ pair production in Au+Au collisions at $\sqrt{s_{_{\rm NN}}}$ = 200 GeV at STAR 20m

        In high energy heavy-ion collisions, the strong electromagnetic (EM) fields of the nuclei can produce energetic, high-density photon fluxes, leading to photon-induced interactions. Recently, significant enhancements of $e^{+}e^{-}$ pair and J/$\psi$ production at very low transverse momentum ($p_{T}$) were observed by the STAR [1, 2] and ALICE [3] collaborations in peripheral hadronic A+A collisions. The excess yields exhibit a much weaker centrality dependence compared to the expectation for hadronic production, and are consistent with coherent photon-photon and photon-nucleus interactions. The measured $p_{T}$ broadening for $e^{+}e^{-}$ pairs may indicate the existence of a strong magnetic field in the medium. Measurements with $\mu^{+}\mu^{-}$ pairs provide a complementary channel to investigate these phenomena.

        In 2014 and 2016, the STAR experiment at RHIC recorded large samples of Au+Au collisions at $\sqrt{s_{_{\rm NN}}}$ = 200 GeV with di-muon triggers utilizing the Muon Telescope Detector. In this poster, we will present invariant mass and yield distributions as a function of centrality for inclusive $\mu^{+}\mu^{-}$ pair production at $p_{T} < 0.15$ GeV/$c$ in the mass range large than 2.6 GeV/$c^{2}$. The $p_{T}^{2}$ distribution of the excess yields for these very low $p_{T}$ $\mu^{+}\mu^{-}$ pairs will also be shown. Physics implications will be discussed together with model comparisons.

        [1] J. Adam et al. (STAR Collaboration), Phys. Rev. Lett. 121 (2018) 132301.
        [2] J. Adam et al. (STAR Collaboration), arXiv: 1904.11658v1.
        [3] J. Adam et al. (ALICE Collaboration), Phys. Rev. Lett. 116 (2016) 222301.

        Speaker: Ms Zhen Liu (University of Science and Technology of China and Brookhaven National Laboratory)
      • 17:40
        Low-mass dielectron measurements in minimum-bias pp collisions at 5.02 TeV with ALICE 20m

        Low-mass dielectrons play a key role in the understanding of the chiral-symmetry restoration and in the study of the Quark-Gluon Plasma (QGP) created in relativistic heavy-ion collisions. In the intermediate-mass region, the measurement of thermal dielectrons from the QGP is nevertheless very challenging at the LHC due to the dominant contribution of e$^{+}$e$^{-}$ pairs from open-charm and -beauty hadron decays. To single out the interesting signal characteristics of the QGP, the primordial e$^{+}$e$^{-}$ pair production in vacuum needs to be first understood. It can be studied in minimum-bias proton-proton collisions. Dielectron measurements in elementary collision systems serve not only as a reference for the heavy-ion analysis but provide also a test for Monte-Carlo event generators, aiming to reproduce the heavy-flavour production mechanisms.

        In this poster, we will present the status of the dielectron analysis in pp collisions at $\sqrt{s}$ = 5.02 TeV with ALICE. The dielectron yield is studied as a function of invariant mass, pair transverse momentum, and pair transverse impact parameter (DCA$_{\rm ee}$). The latter helps to disentangle prompt and non-prompt dielectron sources. The results can be compared to the expectated dielectron cross section from known hadronic sources.

        Speaker: Leonhardt Heinrich Viebach (Johann-Wolfgang-Goethe Univ. (DE))
      • 17:40
        Machine learning approach for studying of dielectrons from open charm and beauty decays in p-Pb collisions with ALICE at the LHC 20m

        The measurement of low-mass $e^+e^-$ pairs is a powerful tool to study the properties of the Quark-Gluon Plasma (QGP) created in ultra-relativistic heavy-ion collisions. Since such pairs do not interact strongly and are emitted during all stages of the collisions, they provide information about the full time evolution and dynamics of the medium created.
        Measurements in pp collisions are the necessary reference for heavy-ion studies. Dielectron production in p-Pb collisions can be used to investigate initial state effects, due to the presence of cold nuclear matter in the collision.
        The main contribution to the dielectron continuum in the intermediate mass region 1.1 $<$ $\rm M_{\rm ee}$ $<$ 2.7 GeV/$c^2$ is coming from semi-leptonic decays of correlated beauty and charm hadrons.
        In this poster, one possible way to study dielectrons from heavy-flavour hadron decays and to separate them from from other dielectron sources with the ALICE detector at LHC will be presented.
        More explicitly, a machine learning approach based on Boosted Decision Tree (BDT) to isolate and study the contribution from heavy flavours will be explained.
        The study will be reported based on the p-Pb collision data at $\sqrt{s_{\rm NN}} = 5.02$ TeV.

        Speaker: Dr Elisa Meninno (Stefan Meyer Institute for Subatomic Physics, Vienna)
      • 17:40
        Machine Learning Based Jet $p_{\rm T}$ Reconstruction with Full Jets in ALICE 20m

        Reconstructing the jet transverse momentum is a challenging task, particularly in heavy-ion collisions due to the large fluctuating background from the underlying event. While the standard area-based method effectively corrects for the average background, it does not account for region-to-region fluctuations. These residual fluctuations are handled in an unfolding procedure following the background subtraction.

        A novel method to correct the jet transverse momentum on a jet-by-jet basis to reduce these fluctuations by introducing a dependence on the jet fragmentation will be presented. We utilize machine learning techniques to reconstruct the full jet transverse momentum from jet parameters, including the constituents of the jet. The performance of this approach is evaluated using jets from PYTHIA simulations embedded into ALICE Pb--Pb data. In comparison to the standard area-based method, these machine learning based estimators show a significantly improved performance, which could allow for measurements of jets to lower transverse momenta and larger jet radii.

        Speaker: Laura Brittany Havener (Yale University (US))
      • 17:40
        Magnetic Field Induced Polarization Difference between Hyperons and Anti-hyperons 20m

        Recent STAR measurements of global hyperon polarization in AuAu Collisions at the Relativistic Heavy Ion Collider (RHIC) have attracted significant interest and generated wide enthusiasm. The data present an intriguing puzzle, showing a difference in the global spin polarization between hyperons and anti-hyperons, especially at relatively low collision beam energy. One possible cause of this difference is the potential presence of in-medium magnetic field. In this talk, we report our study on the phenomenological viability of this interpretation. Using the AMPT model framework, we quantify the influence of different magnetic field evolution scenarios on the size of the polarization difference in a wide span of collision beam energies. We find that such difference is very sensitive to the lifetime of the magnetic field and also mildly dependent on the precise form of magnetic field time dependence. Assuming magnetic polarization as the mechanism to enhance anti-hyperon signal while suppress hyperon signal, we phenomenologically extract an upper limit on the needed magnetic field lifetime in order to account for the experimental data. The so-obtained lifetime values are in a quite plausible ballpark and follow approximately the scaling relation of being inversely proportional to the beam energy. The time-integrated magnetic field shows an interesting non-monotonic dependence on the collision beam energy. Possible implications on other magnetic field related effects are discussed. Finally, we also report predictions for polarization effect in the CuCu and CuAu colliding systems, demonstrating an interesting hierarchy CuCu > CuAu > AuAu due to interplay between hyperon production timing and the evolution of vorticity. These predictions can be readily tested by future experimental analysis. [Refs: (1) arXiv:1905.12613; (2) Phys. Lett. B788(2019)409.]

        Speaker: Yu Guo (College of Science, China Three Gorges University)
      • 17:40
        MC study of the reconstruction of $\pi^0$ in MPD/ECal 20m

        The main goal of NICA/MPD is to investigate the hot and dense baryonic matter in heavy-ion collisions over a wide range of atomic masses, from $Au+Au$ collisions at a center-of-mass energy of $\sqrt{s_{NN}} = 11GeV$ (for $Au^{79+}$) to proton-proton collisions with $\sqrt{s_{pp}}= 20GeV$.
        Electromagnetic calorimeter (ECal) is an important detector of the MPD to identify electrons, photons and measure their energy with high precision. The performance of the ECal is simulated and analyzed of a function of many parameters such as the multiplicity, energy spectrum, kinematic. $\pi^0$ signal can be reconstructed from two photons and it is a very important probe to give information of the chiral symmetry restoration and flow signal. The shape of reconstructed $\pi^0$ mass spectra is analyzed. Dependence of the $\pi^0$ reconstruction efficiency from the decay parameters is studied.
        Theta angle reconstructed in the ECal has a clear deviation from real angle as a function of Z position of the interacting point. This theta angle bias is caused by the small deviation from projective geometry for the Z position which is not equal to zero. This bias is corrected and applied to the reconstruction of $\pi^0$, which improved the results of the reconstruction of $\pi^0$.

        Speaker: Dr Yan Huang (Tsinghua University)
      • 17:40
        Measurement of $\text{D}^{0}$ production in d+Au collisions at $\sqrt{s_{\text{NN}}}=200$ GeV by the STAR experiment 20m

        Owing to their large mass, charm quarks are predominantly produced through initial hard scatterings in heavy-ion collisions. Therefore, they can serve as penetrating probes to study the intrinsic properties of the hot medium created in heavy-ion collisions. However, Cold Nuclear Matter (CNM) effects can also affect the charm quark production in nuclear collisions with respect to p+p collisions. These effects can be measured in small systems such as d+Au collisions.

        In this poster, we will report the first measurement of $\text{D}^{0}$ production in d+Au collisions at $\sqrt{s_{\text{NN}}}=200$ GeV by the STAR experiment taking advantage of its high-precision Heavy Flavor Tracker detector. $\text{D}^{0}$ ($\overline{\text{D}^{0}}$) mesons were topologically reconstructed from their hadronic decay channel $\text{D}^{0} (\overline{\text{D}^{0}})\rightarrow K^- \pi^+ (K^+ \pi^-)$. In order to further improve the signal significance, a supervised machine learning algorithm (Boosted Decision Trees) was used. The nuclear modification factor of the $\text{D}^{0}$ meson was extracted to quantify the CNM effects and compared to model calculations.

        Speaker: Lukas Kramarik (Czech Technical University (CZ))
      • 17:40
        Measurement of $\Xi^{0}_{c}$ baryon in pp collisions with ALICE at the LHC 20m

        The ALICE detector at the Large Hadron Collider (LHC) is optimised for the inverstigation of the Quark-Gluon Plasma (QGP) created in heavy-ion collisions. Charm quarks are effective probes to elucidate the properties of the QGP. They are dominantly produced at the initial stage of the collisions via hard partonic scattering processes and experience the whole evolution of the system.Charm-baryon measurements provide unique insight into hadronisation processes. In particular, the baryon-to-meson ratio is expected to be enhanced if charm quarks hadronise via recombination with the surrounding light quarks in the QGP. Moreover, in such a recombination picture, the baryon-to-meson ratio could further be enhanced in the presence of diquark bound states in the hot and dense QCD medium.
        Measurements of charm-baryon production in pp collisions are essential to establish a baseline for Pb--Pb collisions studies.In addition, the measurements in pp collisions provide critical tests of pQCD calculations and for models of charm hadronisation in vacuum.In this poster the $p_{T}$ differential cross section times branching ratio of the $\Xi^{0}_{c}$ baryon measured in the decay channel $\Xi^{0}_{c} \rightarrow e\Xi\nu$ in pp collisions will be reported.

        Speaker: Tiantian Cheng (Central China Normal University CCNU (CN))
      • 17:40
        Measurement of $D^{0}$ and $\overline{D^{0}}$ directed flow using KFParticle in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV from STAR 20m

        Charm quarks, owing to their large mass, are predominantly created through initial hard scatterings in relativistic heavy-ion collisions and thus are ideal probes to study early time dynamics of these collisions. Recent results from STAR show that the slope of $D^{0}$ mesons directed flow ($v_{1}$) versus rapidity is about 25 times larger than that of charged kaons, providing important constraints on the initial geometry and charm quark transport in the QGP. It has also been predicted that the transient electromagnetic field generated at early time can induce a difference between the $v_{1}$ of charm and anti-charm quarks, and the magnitude of this difference can be much larger than those of light-flavor hadrons due to the early formation of charm quarks.

        In this poster, we will present a new measurement of the directed flow for $D^{0}$ and $\overline{D^{0}}$ mesons in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV using data collected with the HeavyFlavor Tracker during the 2014 RHIC run. The $D^{0}$ ($\overline{D^{0}}$) mesons are reconstructed by an algorithm based on the Kalman Filter (KF Particle Finder package), which provides estimation of not only the tracking parameters themselves but also the corresponding covariance matrix as well. By using such additional information in the $D^{0}$ reconstruction, the signal significance is improved considerably. The $D^{0}$ and $\overline{D^{0}}$ meson $v_{1}$ and their difference will be presented as a function of rapidity and $p_{T}$, and compared with the results for light-flavor hadrons. These results will also be compared to model predictions and physics implications will be discussed.

        Speaker: Xinyue Ju (University of Science and Technology of China)
      • 17:40
        Measurement of directed and elliptic flow of $\phi$ meson in $\sqrt{s_{NN}}$ = 3.0, 4.5 GeV Au+Au collisions at the STAR detector 20m

        The $\phi$ vector mesons have much smaller hadronic cross section which makes them less influenced at late-stage interactions than other hadrons [1-4]. Thus their anisotropies like the elliptic flow should be small if the system is always in a hadronic phase. This, in turn, makes $\phi$ meson $v_2$ especially sensitive to the energy where quark-gluon plasma turns off. Measurements from STAR at 7.7 and 11.5 GeV have seen $\phi$ $v_2$ at highest transverse momentum close to zero [5] and $\phi$ directed flow, $v_1$, is consistent with zero [6] with conclusions limited by statistics. On the other hand, the closeness of $\phi$ mass to the nucleon and its $s$ $\bar{s}$ constituent quarks makes them suitable to test the deviation of net-nucleon and net-meson $v_1$ at energies below 7.7 GeV where could be a breakdown of the assumption that $s$ and $\bar{s}$ quarks have the same flow [6]. Measurements of directed and elliptic flow of $\phi$ vector meson at 3.0 and 4.5 GeV Au+Au collisions at STAR will be presented and compared with RHIC Beam Energy Scan results from 7.7-39 GeV. Measurements will have better precision with increased particle acceptance and 100 more statistics at 3.0 GeV compared to 4.5 GeV from the STAR fixed-target run. Physics implication related to the search for quark-gluon plasma turn-off will also be discussed.

        [1] Y. Cheng et al., Phys. Rev. C, 68 (2003) 034910.
        [2] A. Shor, Phys. Rev. Lett. 54 (1985) 1122.
        [3] A. Sibirtsev et al., Eur. Phys. J. A, 29 (2006) 209.
        [4] H. van Hecke, H. Sorge, and N. Xu, Phys. Rev. Lett. 81 (1998) 5764.
        [5] L. Adamczyk et al., Phys. Rev. C 88 (2013) 014902.
        [6] L. Adamczyk et al., Phys. Rev. Lett. 120 (2018) 062301.

        Speaker: DING CHEN (UNIVERSITY OF CALIFORNIA, RIVERSIDE)
      • 17:40
        Measurement of electrons from heavy- flavour hadron decays in proton-proton collisions with ALICE at the LHC 20m

        Due to their large masses, heavy quarks are produced in the early stages of relativistic heavy-ion collisions via initial hard scatterings. Therefore, they are considered as effective probes of the hot and dense Quark-Gluon Plasma (QGP) formed in such collisions and witness the full evolution of the QGP. In pp collisions, the measurement of charm and beauty hadron production cross-sections can be used to test our understanding of the Quantum ChromoDynamics (QCD) in the perturbative regime. In addition, pp collisions provide the required reference for measurements in nuclear collisions such as the measurement of the nuclear modification factor ($R_{\rm AA}$) of electrons from heavy-flavour hadron decays.

        In this contribution, the $p_{\rm T}$-differential production cross-section of electrons from heavy-flavour and beauty-hadron decays in pp collisions at different center of mass energies from $\sqrt{s}$ = 2.76 to 13 TeV measured by ALICE at mid-rapidity are reported. The analysis procedures employed will be discussed. Comparisons of these results with the FONLL (Fixed-Order and Next-to-Leading Logarithms) model calculations will be shown.

        Speaker: Mr Sudhir Pandurang Rode (Indian Institute of Technology Indore (IN))
      • 17:40
        Measurement of heavy flavour jets with electrons from heavy-flavour hadron decays in pp and p-Pb collisions at $\sqrt{s_{\rm{NN}}}=$5.02 TeV with ALICE 20m

        In heavy-ion collisions, charm and beauty quarks are produced in the initial hard partonic scattering and interact with the hot and dense QCD matter (QGP).
        Therefore, measurements of heavy-flavour production provide relevant information on the properties of the QGP. The QCD predicts that partons lose energy via collisions with the plasma constituents and via gluon radiation, and the magnitude of the energy loss depends on the mass and the color charge of the parton. In Pb--Pb collisions, a strong suppression of heavy-flavour yields has been observed at high $p_{T}$ with respect to pp collisions scaled by the number of binary collisions which is attributed to energy loss of heavy quarks in the QCD medium. Further information about the heavy-quark energy loss mechanism can be obtained by measuring the production of jets containing open charm and beauty particles.

        Recently, a positive elliptic flow of open heavy-flavour particles has been observed in pA collisions and the possible formation of the QGP is under scrutiny.
        In this poster, we show the measurements of jets with electrons from open heavy-flavour hadron decays in pp and p--Pb collisions at $\sqrt{s_{\rm{NN}}}=$5.02 TeV.
        Jet measurements are performed with different resolution parameters ($R=$0.2, 0.3 and 0.4). The nuclear modification factors for the different resolution parameters are calculated. Finally the results are compared with model calculations.

        Speaker: Shingo Sakai (University of Tsukuba (JP))
      • 17:40
        Measurement of Intermittency for Charged Particles in Au+Au Collisions at $\sqrt{s_{NN}}=7.7-200$ GeV from STAR 20m

        One of the main goals of RHIC beam energy scan program is to search for the signature of the QCD critical point in heavy-ion collisions. It is predicted that the local density fluctuations near critical point exhibit power-law scaling, which can be probed with a intermittency analysis of the scaled factorial moments ($F_{q}$) for charged particles. The power-law behavior of $q^{th}$ order scaled factorial moments can be expressed as: $F_{q}\sim (M^{2})^{\phi_{q}}$, where $M^{2}$ is the number of equally sized cells in momentum space, and $\phi_{q}$ is the intermittency index. The scaling exponent, $\nu$, related to the critical component can be derived from the ratio, $\phi_{q}/\phi_{2}$. The energy dependence of $\nu$ could be used to search for the signature of the QCD critical point. Such measurement is actively being pursued by the NA49 and NA61 Collaborations in large and small collisions at $\sqrt{s_{NN}}=17.3$ GeV. The BES-I data allow STAR to carry out such measurement over a much broader energy range of$\sqrt{s_{NN}}=7.7-200$ GeV. This poster present the collision-energy and centrality dependence of $\phi_{q}$ and $\nu$ of charged particles in Au+Au collisions measured by the STAR experiment. The physical implications of these results are discussed.

        Speaker: Jin Wu (Central China Normal University)
      • 17:40
        Measurement of jet shape observables and their multiplicity dependence in pp collisions at LHC energies with ALICE 20m

        The measurement of jet shapes and their multiplicity dependence in pp collisions at LHC energies can provide insight on the production of jets and the interplay between jet fragmentation and event multiplicity in small colliding systems (pp,pA). In this contribution, we report the results on jet-shape measurements using the ALICE experiment in minimum bias pp collisions at $\sqrt{s}=$ 5, 7 and 13 TeV and its multiplicity dependence at $\sqrt{s}=$ 13 TeV.

        The observables to be presented include jet transverse profile, first radial moment, momentum dispersion and the difference of the leading and subleading track in the jet. The jet transverse profile describes the energy distribution inside the jet cone while the other observables provide complementary information on the jet fragmentation properties. Jets are reconstructed using anti-$k_{\rm T}$ algorithm with varying resolution parameter and jet $p_{\rm T}$.

        Speaker: Sumit Kumar Saha (VECC)
      • 17:40
        Measurement of non-flow influence on the CMW-sensitive slope parameter from STAR 20m

        The charge asymmetry ($A_{\rm ch}$) dependence of the $\pi^{+}$ and $\pi^{-}$ elliptic flow difference, $\Delta v_{2}(A_{\rm ch})\equiv v_{2}^{\pi^{-}}(A_{\rm ch}) - v_{2}^{\pi^{+}}(A_{\rm ch})$, is sensitive to the Chiral Magnetic Wave (CMW). Previous measurements in 200 GeV Au+Au collisions by STAR indicated a positive $\Delta v_{2}(A_{\rm ch})$ slope and, in central and peripheral collisions, a negative triangular flow $\Delta v_{3}(A_{\rm ch})$ slope. Since only backgrounds contribute to the latter, the results disfavor a pure background scenario for the $\Delta v_{2}(A_{\rm ch})$ slope.

        We show in this poster, however, that including all charged particles as reference in the Q-cumulant flow method automatically introduces a trivial linear term in $v_{n}(A_{\rm ch})$ if non-flow correlations differ between same-sign and opposite-sign particle pairs. This contributed artificial slopes to the previous $\Delta v_{n} (A_{\rm ch})$ measurements. After eliminating this non-flow artifact, the $\Delta v_{2}(A_{\rm ch})$ and $\Delta v_{3}(A_{\rm ch})$ slopes, normalized by the respective $v_{2}$ and $v_{3}$ magnitudes, are consistent with each other within errors. The present error on the $\Delta v_{3}(A_{\rm ch})$ slope is relatively large: the average normalized $\Delta v_{3}(A_{\rm ch})$ slope in $0-80\%$ centrality is about 2.2$\sigma$ above zero, and that in $20-60\%$ is about 1.5$\sigma$ above zero. The implications of our results in terms of the possible CMW signal and local charge conservation backgrounds are discussed.

        Speaker: Fuqiang Wang (Purdue University (US))
      • 17:40
        Measurement of path length-dependent $v_1$ of high-$p_{\mathrm{T}}$ charged hadrons in Au+Au collisions by the STAR experiment 20m

        In heavy-ion collisions, the thermalized matter is tilted in the reaction plane as a function of rapidity, while the production profile of partons from hard scatterings is symmetric in rapidity [1]. This leads to a rapidity-odd asymmetry in the medium path length traversed by the hard partons and results in a rapidity-odd directed flow ($v_1$). Measurements of high-$p_{\mathrm{T}}$ hadron $v_1$ can provide valuable constraints on the initial longitudinal distribution of the fireball as well as the path length-dependent momentum loss of the partons. A similar effect, producing significantly large directed flow for heavy flavor mesons, was predicted [2] and has been observed for $D^0$ mesons (at 3$\sigma$ significance) by STAR recently.

        In this poster, we will present the first measurement of pseudorapidity and centrality dependence of the $v_1$ of high-$p_{\mathrm{T}}$ ($>$ 5 GeV/c) charged hadrons in Au+Au collisions at $\sqrt{s_{NN}}$ = 54.4 and 200 GeV. The $v_1$ of charged hadrons is found to change sign twice as a function of $p_{\mathrm{T}}$ and show large negative slope at high-$p_{\mathrm{T}}$, similarly to $D^0$ mesons. The measurements will be compared to different model calculations and the sensitivity to different initial density distributions will be discussed.

        [1] P. Bozek, I. Wyskiel, Phys. Rev. C. 81 (2010) 054902; A. Adil, M. Gyulassy, Phys. Rev. C. 72 (2005) 034907.
        [2] S. Chatterjee, P.Bozek, Phys. Rev. Lett. 120 (2018) 192301.

        Speaker: Sooraj Krishnan Radhakrishnan (Lawrence Berkeley National Laboratory)
      • 17:40
        Measurement of proton-pion mixed cumulants in Au+Au collisions at $\sqrt{s_{NN}}$ = 19.6, 27 and 200 GeV in STAR 20m

        Fluctuations in conserved charges such as net charge (Q), net strangeness (S) and net baryon (B) are good probes of the QCD phase transition and the critical point [1]. The QCD-based models suggest that the moments of the conserved charge distributions are related to the correlation length of the system as: $\langle (\delta N)^{2} \rangle$ $\sim$ $\xi^{2}$, $\langle (\delta N)^{3} \rangle$ $\sim$ $\xi^{4.5}$ and $\langle (\delta N)^{4} \rangle$ $\sim$ $\xi^{7}$, which are expected to take large values near the critical point [2]. As discussed in Ref [3], one can, however, remove the model dependence, by carefully constructing mixed cumulants and their ratios using the protons and pions produced in heavy-ion collisions. Five constructed ratios such as: $\kappa_{3p}\kappa_{2\pi}^{3/2}$/$\kappa_{3\pi}\kappa_{2p}^{3/2}$, $\kappa_{4p}\kappa_{2\pi}^{2}$/$\kappa_{4\pi}\kappa_{2p}^{2}$, $\kappa_{4p}^{3}\kappa_{3\pi}^{4}$/$\kappa_{4\pi}^{3}\kappa_{3p}^{4}$, $\kappa_{2p2\pi}^{2}$/$\kappa_{4\pi}\kappa_{4p}$ and $\kappa_{2p1\pi}^{3}$/$\kappa_{3p}^{2}\kappa_{3\pi}$ (where $\kappa_{ipj\pi}$ is mixed cumulant of $i^{th}$ order in proton and $j^{th}$ order in pion) are expected to become unity near the presence of the QCD critical point [3]. In this poster, we present the first results on the centrality dependence of proton-pion mixed cumulants and their ratios measured at the midrapidity region and for transverse momentum range of 0.4 $<$ $p_{T}$ $<$ 2.0 GeV/c in Au+Au collisions at $\sqrt{s_{NN}}$ = 19.6, 27 and 200 GeV. Protons and pions are identified using the Time Projection Chamber and Time of Flight detectors in the STAR experiment. The collision energy, centrality and rapidity dependence of the mixed cumulants and their ratios will be shown. Physics implications of these results, as well as comparison with transport (UrQMD) model calculations, will also be presented.

        [1] M. A. Stephanov, K. Rajagopal and E. Shuryak, Phys. Rev. D 60 (1999) 114028.
        [2] M.A. Stephanov, Phys. Rev. Lett. 102 (2009) 032301.
        [3] C. Athanasiou, K. Rajagopal and M. Stephanov, Phys. Rev. D 82, 074008 (2010).

        Speakers: Debasish Mallick, Debasish Mallick (National Institute of Science Education and Research, India)
      • 17:40
        Measurement of semi-inclusive direct photon+jet and $\pi^0$+jet distributions in central Au+Au collisions at $\sqrt{s_\mathrm{NN}}=200$ GeV by the STAR experiment 20m

        We present the semi-inclusive measurement of charged jets recoiling from direct-photon and $\pi^0$ triggers in central Au+Au collisions at $\sqrt{s_\mathrm{NN}}=200$ GeV, using a dataset with integrated luminosity 13 nb$^{-1}$ recorded by the STAR experiment in 2014. The photon and $\pi^0$ triggers have $9<\rm E_{T}^{trig}<20$ GeV. Charged jets are reconstructed with the anti-$\rm{k_{T}}$ algorithm with resolution parameters R=0.2 and 0.5. A Mixed Event technique developed previously by STAR is used to correct the recoil jet yield for uncorrelated background, enabling recoil jet measurements over a broad $\rm p_{T,jet}$ range with large jet radius. We report the corrected semi-inclusive recoil jet yields for both triggers and compare them to those for p+p collisions. These measurements have different trigger bias, in terms of both the path-length distribution and quark/gluon mix of the recoil jet population, and their corrected recoil spectra are compared. We also report the recoil jet azimuthal distribution relative to the $\pi^0$ trigger axis, and search for medium-induced modifications. Such modifications may probe the quasi-particle nature of the Quark-Gluon Plasma and help discriminate different models of it.

        Speaker: Dr NIHAR RANJAN Sahoo for STAR Collaboration (Shandong University)
      • 17:40
        Measurement of the Azimuthal Anisotropy of Charged Particle Production in Xe+Xe Collisions at $\sqrt{s_{NN}}$=5.44 TeV with the ATLAS Detector 20m

        ATLAS measurements of flow harmonics ($v_{n}$) in Xe+Xe collisions are presented. The measurements are performed using two-particle correlations, multi-particle cumulants and scalar product methods. The measurements are also performed using non-flow subtraction techniques -- recently developed for measurements in proton-nucleus and proton-proton collisions -- to improve the understanding of flow in peripheral collisions. The non-flow removal is shown to have a significant impact on the $v_n$ measurements in peripheral events. By comparing to flow measurements in Pb+Pb collisions, the effects of geometric fluctuations and of viscous effects, both of which are stronger in the smaller Xe+Xe system, are demonstrated.

        Speaker: ATLAS Collaboration
      • 17:40
        Measurement of the nuclear modification factor $R_{\rm AA}$ of inclusive J/$\psi$ at midrapidity in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV with ALICE 20m

        Heavy quarks are an excellent probe to study the strongly interacting quark-gluon plasma (QGP) created in high-energy heavy-ion collisions. They are mainly produced via initial hard partonic scattering processes and thus experience the entire evolution of the QGP medium. For J/$\psi$, a bound state of ${c}\bar{c}$ quarks, a strong suppression was seen in central collisions at the SPS and RHIC energies whereas at LHC energies (re-)generation is found to be the dominant production mechanism at low transverse momentum ($p_{\rm T}$) and in central collisions at midrapidity. As both suppression and (re-)generation are caused by the presence of a colored medium, J/$\psi$ yields are indeed a sensitive probe of deconfinement of the charm quarks in the QGP.

        In this poster, the nuclear modification factor of inclusive J/$\psi$ will be shown as a function of centrality and $p_{\rm T}$ at midrapidity ($|y|<0.9$) in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV. The status of the new analysis performed on data which were taken in 2018 by ALICE will be presented. This sample provides significantly increased statistics with the central and semi-central triggers compared to the previous runs, in a kinematic region down to $p_{\rm T}$=0 at midrapidity. The measurement will be compared with the previous ALICE results and model calculations. The status of the analysis aiming at disentangling prompt and non-prompt J/$\psi$ will also be discussed.

        Speaker: Dr Xiaozhi Bai (GSI)
      • 17:40
        Measurement of the sixth-order cumulant of net-proton multiplicity distributions from the STAR experiment 20m

        Cumulants of conserved quantities are the powerful tools to study the QCD phase structure. According to the Lattice Gauge Theory calculations, at vanishing baryon chemical potential ($\mu_{B}$) a "smooth crossover" for the transition from quark-gluon plasma to hadronic system occurs in heavy-ion collisions [1]. One of the possible experimental ways to search for the evidence is to analyze the higher-order cumulant ratios of net-baryon distributions from high-energy nuclear collisions. The sixth-order ($C_{6}$) to second-order ($C_{2}$) cumulant ratio of baryon number fluctuations is predicted to be negative at the freeze-out temperature if it is close to the chiral transition temperature [2]. Net-proton multiplicity distributions can be studied as a reasonable proxy for net-baryon distributions [3,4]. In this poster, we present the centrality dependence of net-proton $C_{6}/C_{2}$ at $\sqrt{s_{\rm NN}}=$ 54.4 and 200 GeV from a high statistics Au+Au collisions data set in the STAR experiment. The transverse momentum and rapidity dependence of $C_{6}/C_{2}$ for net-proton distributions will be also discussed.

        [1] Y. Aoki et al., Nature, 443 (2006) 675.
        [2] B. Friman et al., Eur. Phys. J. C, 71 (2011) 1694.
        [3] Y. Hatta, M. A. Stephanov, Phys. Rev. Lett. 91 (2003) 129901.
        [4] M. Kitazawa, M. Asakawa, Phys. Rev. C 86 (2012) 024904.

        Speaker: Toshihiro Nonaka (Univ. Tsukuba)
      • 17:40
        Measurements of $v_{2}$ and $v_{3}$ in p+Au, d+Au and $^{3}$He+Au collisions at $\sqrt{s_{NN}}=200$ GeV from STAR 20m

        Large uncertainty for initial geometry eccentricity has been found in small systems. Calculations which include subnucleon structure have been found substantially different with standard Glauber model calculations. This will make it difficult to address the physics origin of long-range angular correlations in small systems, which may come from the initial-state momentum correlations or final-state hydrodynamic flow, or both.

        In this poster, we will present the STAR measurement of azimuthal harmonics, $v_2$ and $v_3$, in the p+Au, d+Au and $^3$He+Au data collected at 200 GeV. The non-flow contributions are studied with several different subtracted methods using p+p collision as a reference. A closure testing with the HIJING and AMPT models are also presented. The $v_2$ signals are also extracted using four-particle azimuthal correlations and compared with that from two-particle correlation after non-flow subtraction. These results will be compared to calculations from different models and provide new information to address the physics origin of long-range angular correlations. It will also be helpful for model calculation of the initial geometry, as well as to expose possible limitations to the fluid dynamical description of the matter created in these collisions.

        Speaker: Shengli Huang (Stony Brook University)
      • 17:40
        Measurements of charge-dependent correlations in Xe-Xe collisions with ALICE 20m

        The main goal of heavy-ion collisions is to study the deconfined phase predicted by quantum chromodynamics, the Quark Gluon Plasma.In the presence of the QGP, theories predict the existence of field configurations that could violate parity symmetry locally at a level that could be experimentally measured. In heavy-ion collisions, local parity violation manifests as charge separation along the direction of the strong magnetic field, a phenomenon called the Chiral Magnetic Effect (CME). We present results on the centrality, particle separation in pseudorapidity, and transverse momentum dependence of the charge-dependent two- and three-particle correlators in Xe-Xe collisions at $\sqrt{s_{\rm_{NN}}} = 5.44$ TeV recorded by the ALICE detector. For the charge dependence of the three-particle correlator, often employed as evidence for the CME, we find similar values to those measured in Pb-Pb collisions and we discuss the implications of this observation.

        Speaker: Andrea Danu (Institute of Space Science (RO))
      • 17:40
        Measurements of charm and bottom productions via semi-leptonic decays in Au+Au collisions at $\sqrt{s_{\rm NN}}=200$ GeV at STAR 20m

        Systematic investigation of charm and bottom productions and their modifications in heavy-ion collisions is crucial for understanding the parton energy loss mechanism inside the hot and dense medium. Electrons from semi-leptonic decays of open heavy-flavor hadrons can serve as a proxy for heavy quarks with the possibility of triggering on them during data taking to gain statistics.

        The STAR Heavy Flavor Tracker (HFT) provides excellent track pointing resolution which allows to separate electrons originating from open charm and bottom hadron decays based on their measured Distance of Closest Approach (DCA) to the primary vertex. In this poster, we will present the nuclear modification factor $R_{AA}$ as well as $R_{CP}$ of the charm- and bottom-decayed electrons as a function of transverse momentum (2.5 < ${p}_\mathrm{T}$ < 8.5 GeV/$c$) at mid-rapidity in $\sqrt{s_{\rm NN}}=200$ GeV Au+Au collisions for various centrality classes. The measurements will be compared to theoretical model calculations and physics implications on the parton energy loss will be discussed.

        Speaker: Yingjie Zhou (Central China Normal University CCNU (CN))
      • 17:40
        Measurements of HBT correlations and Levy source parameters in Au+Au collisions at the STAR experiment 20m

        To study the nature of the quark-hadron phase transition, it is important to investigate the space-time structure of the hadron emission source in heavy-ion collisions. Measurements of HBT correlations have proven to be a powerful tool to gain information about the particle emission region. In this study, Levy fits were performed to the measured one-dimensional two-pion correlation functions in Au+Au collisions at $\sqrt{s_{NN}}$=200 GeV. The three extracted parameters are: the Levy scale parameter, $R$, which is in connection with the physical size of the source, the correlation strength parameter, $\lambda$, and the Levy exponent, $\alpha$, which is related to one of the critical exponents (the correlation exponent $\eta$). It is important to investigate the dependence of these parameters on the average transverse mass, $m_T$, as well as on centrality and $\sqrt{s_{NN}}$. In this poster, we report the current status of the analysis of the extracted Levy source parameters.

        Speaker: Dániel Kincses (Eötvös Loránd University Budapest)
      • 17:40
        Measurements of longitudinal flow decorrelations in Xe+Xe collisions with the ATLAS detector 20m

        Measurement of longitudinal flow decorrelations in Xe+Xe collisions involving two- and four-particle correlations for elliptic, triangular and quadrangular flow are presented. The strength of the decorrelation are found to be different from that in Pb+Pb for either the same centrality or Npart. The four-particle decorrelation is found to not factorize as product of two-particle decorrelations. The ability of such measurement to distinguish between different models of initial geometry and in reducing the uncertainty in determining the effective shear-viscosity to entropy density of the QGP are demonstrated.

        Speaker: ATLAS Collaboration
      • 17:40
        Measurements of prompt D-meson production in p–Pb collisions with ALICE at the LHC 20m

        Heavy quarks (i.e charm and beauty quarks) are effective probes to investigate the properties of the hot, dense and strongly-interacting medium, known as the Quark-Gluon Plasma (QGP), formed in ultra-relativistic heavy-ion collisions. Due to their large masses, they are produced in the initial stages of the collision via hard partonic scatterings and hence, they experience the full evolution of the medium. The measurements of prompt $\rm D$-meson production in small systems like p--Pb collisions allow us to decode the Cold Nuclear Matter (CNM) effects such as the modification of parton densities in nuclei and $k_{\rm T}$-broadening or parton energy loss. Recent studies show that the high-multiplicity events of p--Pb collisions at the LHC exhibit unforeseen collective behaviour and the origin remains unclear. For a deeper understanding on the collective-like effects in high-multiplicity p--Pb events, the study of D-meson production as a function of charged-particle multiplicity can give further insight into the interplay between hard and soft mechanisms of particle production. Furthermore, to understand the role of initial-state geometry on the final-state observables in p--Pb collisions, a more differential study can be attempted based on the technique of Event-Shape Engineering (ESE) by selecting events of different initial geometry at similar multiplicity. The modification of production cross sections of D mesons in different shape-engineered events would strengthen our understanding of influence of initial geometry on the final state particle production mechanisms.

        In this contribution, the production cross sections of D mesons (${\rm D}^{0}$, ${\rm D}^{+}$, ${\rm D}^{*+}$ and ${\rm D}_{\rm s}^{+}$) measured at mid-rapidity in p--Pb collisions at $\sqrt{s_{\rm NN}}= 5.02$ TeV with ALICE detector will be presented. The nuclear modification factor ($R_{\rm pPb}$) for minimum bias p--Pb collisions will be shown. The results will be compared with model predictions including CNM effects. The prompt D-meson transverse momentum distributions in p--Pb collisions relative to pp collisions ($Q_{\rm pPb}$), measured in several multiplicity/centrality classes, will also be discussed.

        Speaker: Mr Somnath Kar (Central China Normal University CCNU (CN))
      • 17:40
        Mechanical design of the sPHENIX MAPS-based vertex detector 20m

        The sPHENIX experiment will study the QGP properties with heavy bottom quark jets (b-jets) produced in high-energy heavy ion collisions, in the challenging low-pT regime, where the expected mass-dependence effects are large but the underlying backgrounds are also high. Key to identifying such jets is the 3-layer Monolithic-Active-Pixel-Sensor(MAPS) based vertex detector, originally developed for the ALICE ITS upgrade. The MVTX will serve as the innermost component of the sPHENIX tracking system, covering 2 cm to 4 cm radially and a pseudorapidity range of |η| < 1.1. Although it uses the same sensor elements and basic geometry, many aspects of the mechanical systems had to be adapted from the original ALICE versions. We present the current status of the detector design, highlighting the changes made to integrate the MVTX into the sPHENIX detector.

        Speaker: sPHENIX Collaboration
      • 17:40
        Medium modifications of event shape in high-energy nuclear collisions 20m

        Event shape observables, such as transverse sphericity $S_{\perp}$, have long been proposed to study geometrical properties and patterns of the energy flow, and provide a probe of multi-jet topologies in an interaction. For example, the event is pencile-like when transverse sphericity $S_{\perp}\rightarrow 0$, whereas the event is sphere-like when $S_{\perp}\rightarrow 1$. It is well-known that jet quenching in the QGP may lead to the suppression of hadron and jet spectra in heavy-ion collisions, but how jet quenching effect modifies the global geometrical proporties of jet productions in high-energy nuclear collisions is still an unexplored problem. In this talk, we show the first theoretical results of the medium modification of transverse sphericity distribution due to jet quenching effect in heavy-ion collisions. In our investigation, POWHEG+PYTHIA is employed to provide the p+p baseline up to the next-to-leading order (NLO) accuracy with rusummation by the matched parton shower. The Linear Boltzmann Transport (LBT) model of the parton energy loss is implemented to simulate the in-medium evolution of jets. We calculate the event normalized medium modification factor as a function of transverse sphericity distributions in the overall region. An enhancement at small transverse sphericity region and a suppression at large transverse sphericity region are observed in A+A collisions compared to their p+p references, which implies that the event in heavy-ion collisions becomes more pencile-like relative to that in p+p.

        We further explore the underlying reasons of the medium alteration of transverse sphericity distribution $S_{\perp}$. Our numerical results show that the parton energy loss effect on multiple jet events ($n_{jet}\geq 3$) may cause the event more pencil-like, because in this kind of process jets usually have relatively smaller energies and may fall off the jet selection kinematic cut after their energy loss in the medium. Furthermore, we plot the event normalized azimuth angle correlation factor ($\Delta \phi_{j1,j2}$) between the two leading jets for the full events both in p+p and A+A collisions. We demonstrate that jet quenching effect will enhance the fraction of events in back-to-back region ($\Delta \phi_{j1,j2}\sim \pi$) and naturally lead the full events to be more "jetty". Therefore, even though medium-induced gluon radiation may lead to a more isotropic event, the disappearing of less energetic jets and the enhanced fraction of back-to-back ($\Delta \phi_{j1,j2}\sim \pi$) reaction are more pronounced and thus give rise to an overall more pencil-like event in high-energy nuclear collisions with respect to that in p+p.

        Speaker: Dr Shi-Yong Chen (CCNU)
      • 17:40
        Meson masses in external magnetic fields from Lattice QCD 20m

        We will present the first study in full QCD on meson temporal correlation functions in the presence of external magnetic fields at zero temperature. The simulations of (2+1)-flavor QCD were performed on 32$^3$x96 lattices using the Highly Improved Staggered Quarks (HISQ) action with $m_{\pi}$ around 230 MeV. The strength of magnetic fields is up to 3 GeV$^2$.

        We found that the masses of neutral pseudo-scalars monotonically decrease as the magnetic field grows and then saturate at a nonzero value. It is observed that heavier neutral pseudo-scalars are less affected by magnetic fields. While the masses of charged pion and kaon show a non-monotonic behavior in magnetic field, which is different from all the previous studies from quenched QCD. In the case of small magnetic field (0 $\leq~|eB|\le$ 0.3 GeV$^2$ ) the mass of charged pseudo-scalar grows with magnetic field and can be well described by the Lowest Landau Level approximation, while for eB larger than 0.3 GeV$^2$ the mass starts to decrease.

        We will discuss the possible connection between eB dependences of mesons in pseudo-scalar channels and the decreasing behavior of pseudo-critical temperature in magnetic field. We will also discuss the possibility of superconductivity of QCD induced by strong magnetic field through the study on eB dependence of meson masses in the vector channel.

        Speaker: Xiao-Dan Wang (CCNU)
      • 17:40
        Module and ladder assembly techniques for the Silicon Tracking System of the CBM experiment at FAIR 20m

        The Compressed Baryonic Matter (CBM) experiment is one of the scientific pillars of the Facility
        for Anti-proton and Ion Research (FAIR), which is presently under construction adjacent to GSI,
        Darmstadt. The Silicon Tracking System (STS) is the core detector of the CBM experiment, located
        inside the superconducting dipole magnet. The main task of STS is to reconstruct the tracks and
        measure the momentum of charged particles. The STS detector comprises of 896 low-mass detector
        modules, based on double-sided silicon microstrip sensors, distributed on 8 tracking stations. The
        stations are made from mechanical half units onto which 106 carbon fibre support structures, or
        ladders, are mounted which hold the modules.
        We discuss the steps of module assembly, combining a silicon sensor, ultra-thin micro cables and
        self-triggering front-end electronics into the basic functional unit of the STS. A concept tool has
        been designed to study the feasibility of the ladder assembly with mechanical precision of better
        than 100 μm. The size of the tool has been chosen to mount five modules onto ladders, fitting the
        mSTS demonstrator of the mCBM test experiment at SIS18.

        Speaker: Shaifali Mehta (University of Tübingen)
      • 17:40
        MPD detector for study heavy-ion collisions at NICA: design, performance and construction status 20m

        The NICA heavy-ion program is aimed in studying the properties of nuclear matter under extreme conditions. A detailed energy and system size scan will be performed in the center-of-mass energy range from 4 to 11 GeV with an emphasis on the study of yields, spectra, azimuthal anisotropy, fluctuations and correlations of multiple probes from electrons and gammas to light (hyper)nuclei.In order to fulfill the NICA physics goals, the MPD detector is designed as a large acceptance spectrometer providing high-efficiency tracking, precise vertex reconstruction, and powerful particle ID.
        We are going to present the overall MPD detector design and expected performance for heavy-ion collisions at NICA. The progress in the construction and test of various MPD components will be illustrated.

        Speaker: Vadim Babkin (Joint Institute for Nuclear Research (RU))
      • 17:40
        Multi-harmonic correlations in ALICE 20m

        Genuine multiparticle azimuthal correlations have been used in anisotropic flow analyses to study the properties of the Quark-Gluon Plasma (QGP) produced in ultrarelativistic nuclear collisions. A recently introduced set of observables, based on the measurements of the correlated fluctuations of two different flow harmonics, has allowed the application of new constraints on the properties of the QGP. These two-harmonic observables have been named the Symmetric Cumulants.

        The generalisation of Symmetric Cumulants has been proposed very recently. The new set of observables is sensitive only to the genuine correlations between three or more flow harmonics and has been dubbed higher order Symmetric Cumulants. They provide information which is inaccessible through individual flow harmonics or correlated fluctuations of only two flow harmonics, and in turn yields additional and independent constraints on the properties of the system produced in heavy-ion collisions.

        In this poster, we present the first experimental results for these multi-harmonic correlations in the Pb-Pb collisions collected by ALICE. In particular, the centrality dependence of higher order Symmetric Cumulants involving three or more different flow harmonics is presented. The comparison with predictions from state-of-the-art hydrodynamic models is shown as well.

        Speaker: Cindy Mordasini (Technische Universitaet Muenchen (DE))
      • 17:40
        Multiparticle correlations from the direct calculation of cumulants using particle azimuthal angles 20m

        Instead of using the generating function or Q-cumulant methods for multiparticle correlation studies in heavy ion collisions, we calculate the cumulants directly looping over particle azimuthal angles. It is shown that this method is not possible for central and mid-central AA collisions due to the required computing resource, but possible for smaller collision systems and peripheral AA collisions. With this method we are able to study the correlations as a function of particle pseudorapidity gap between each particle in the multiparticle correlations. The method is tested with PYTHIA and HIJING models and it provides better statistical precision than the three subevent method with a pseudorapidity gap using the same amount of data.

        Speaker: Shengquan Tuo (Vanderbilt University (US))
      • 17:40
        Multiplicity and $\sqrt{s}$ dependent study of jet properties in pp collisions at LHC energies 20m

        Jets are collimated bunches of hadrons produced from fragmentation and hadronization of hard scattered partons (quarks and gluons) in high energy collisions. Due to the different color charges of quarks and gluons, differences in the fragmentation of the two types of partons are expected. Therefore jets originated from primary quarks and gluons, are predicted to have different properties. Experimental measurements of inclusive jets have contributions from both types of partons. The partonic fraction in the inclusive jets is expected to be reflected in their properties. The gluonic contribution increases with increasing $\sqrt{s}$ due to an increase in gluon density inside the hadron. The gluonic contribution is argued to vary with event multiplicity as well. Jet properties are therefore expected to depend on $\sqrt{s}$ and event multiplicity. In this work, we will present a detailed study to estimate the change in the inclusive jet properties as a function of $\sqrt{s}$ and event multiplicity for pp collisions using Monte Carlo simulations at LHC energies.

        Speaker: Prottoy Das (Bose Institute (IN))
      • 17:40
        Multiplicity and rapidity dependence of v2 in small system by using two-particle correlations 20m

        Recent PHENIX measurements indicate that the initial geometry is the cause of the observed positive $v_2$ and $v_3$ in high-multiplicity p+Au, d+Au, and $^3$He+Au collisions at $\sqrt{s_{\rm NN}} = 200$~GeV. These results were obtained using the event-plane method, with the event plane determined in the backward rapidity range and correlated with particles in other sub-events at mid- and forward-rapidity. In this poster, we present the latest PHENIX measurements, in which we employ the two-particle correlation method and investigate the effects of the size of the rapidity gap between particles as well as different non-flow subtraction methods in order to understand possible non-flow contributions to the observed $v_2$. We also extend the measurements of $v_2$ from most-central to peripheral collisions to understand the centrality evolution of $v_2$ in small systems. In this poster, we will present the current analysis status of $v_2$ measurement via the two particle correlation analysis with various subtraction methods in a wide centrality range of p+Au collisions at $\sqrt{s_{\rm NN}} = 200$~GeV.

        Speaker: Qiao Xu (Vanderbilt University (US))
      • 17:40
        Multiplicity dependent charged jet production in pp collisions at $\sqrt{s}=$ 13 TeV 20m

        A jet is a spray of collimated hadrons originated in the fragmentation of an energetic parton. The cross section measurement provides a good test for pQCD calculations. Jet $p_{\rm T}$ spectrum measurement in pp collisions sets a reference for jet quenching study in nucleus-nucleus collisions. In addition, high multiplicity pp collisions show similar collective behavior as found in heavy-ion collisions with comparable event activities, such as long-range correlations or the $v_{n}$ coefficients. In pp collisions, these effects may be caused by multiple-parton interactions or other QCD effects, therefore, the measurements in different multiplicity intervals will provide insights to understand the properties of small interacting system.

        In this contribution, we will present charged jet cross section measurement in pp collisions at $\sqrt{s}=$ 13 TeV with the high statistics collected by ALICE. The jet cross section ratio for various jet resolution parameters will be also shown. Such kind of cross section ratio is sensitive to the transverse energy profile of the jets. In particular, we will present the charged particle jet production in different multiplicity intervals, which will provide important input for understanding the correlations between the hard process and event activities in small colliding systems.

        Speaker: Yongzhen Hou (Central China Normal University CCNU (CN))
      • 17:40
        Multiplicity scaling in the small system within the non-extensive statistical approach 20m

        The non-extensive statistical description of the identified final state particles measured in high energy collisions is well-known by it's wide range of applicability. However, there are many open questions that need to be answered, including but not limited to the question of the observed mass scaling of massive hadrons or the size and multiplicity dependence of the model parameters. This latter is especially relevant, since currently the amount of the available experimental data with high multiplicity at small systems is very limited.

        In this contribution the role of the size of the colliding system and multiplicity dependence of the parameters in the non-extensive hadronization model is investigated with HIJING++ calculations. We present cross-check comparisons of HIJING++ with existing experimental data to verify it's validity in our range-of-interest, as well as calculations at high-multiplicity regions where we have insufficient experimental data.

        Speaker: Dr Gergely Gabor Barnafoldi (Wigner RCP Hungarian Academy of Sciences (HU))
      • 17:40
        Multiplicity-dependent jet shape analysis in pp collisions at $\sqrt{\textit{s}}$ = 13 TeV with ALICE 20m

        High-multiplicity pp collisions show similar collective behavior as found in heavy-ion collisions with comparable event multiplicity, such as long-range near-side correlations and the $v_n$ coefficients. In pp collisions, these effects may be caused by multiple-parton interactions or other vacuum QCD effects. Investigating the modification of the jet shape in terms of the event multiplicity can provide us with deeper insights on the nature of these effects.

        In this contribution, we report on the latest results concerning the jet-shape measurements of the jet radial profile and first radial moment (or girth) and their multiplicity dependence in pp collisions at $\sqrt{\textit{s}}$ = 13 TeV with ALICE. The jet radial profile describes the energy distribution inside the jet cone while the first radial moment provides complementary information on the jet fragmentation properties. Multiplicity-differential measurements provide important input to understand the interplay between jet fragmentation and event multiplicity in small colliding systems.

        Speaker: Zoltan Varga (Hungarian Academy of Sciences (HU), ALICE)
      • 17:40
        Muon Forward Tracker: adding vertexing capability to the ALICE MUON Spectrometer 20m

        For Runs 3 and 4, an ambitious upgrade program is ongoing within the ALICE experiment to further explore the properties of the Quark Gluon Plasma.The Muon Forward Tracker(MFT), one of the major ALICE upgrades, aims to add vertexing capability for muon detection at forward rapidity by providing vital track information in front of the absorber of the Muon Spectrometer. MFT will allow to separate charm and beauty contributions by measuring displaced vertices of heavy flavor hadron decays and allow for high precision low mass vector meson measurements by improving the Muon spectrometer mass resolution.

        MFT consists of 5 double-sided layers of the ALPIDE silicon pixel detector with CMOS technology covering a rapidity range of $-3.6< y <-2.5$. Intensive efforts of the MFT detector assembly are ongoing as well as the development of the detector control system. The commissioning of the MFT has started. In this poster, we will report on the latest status of the MFT assembly, and its commissioning.

        Speaker: Yorito Yamaguchi (Hiroshima University (JP))
      • 17:40
        Net-charge fluctuations in pp, p-Pb, Pb-Pb and Xe-Xe collisions with ALICE Detector 20m

        Net-charge fluctuations in ultrarelativistic heavy-ion collisions are studied, in terms of the variable $\nu_{[+-,dyn]}$, analysing data from pp, p-Pb and Pb-Pb collisions at $\sqrt{s}_{NN}$ = 5.02 TeV and Xe-Xe collisions at $\sqrt{s}_{NN}$ = 5.44 TeV from the ALICE experiment at LHC. Data from various collision systems provide an opportunity to study the dependence of $\nu_{[+-,dyn]}$ on the system size. The effect of the kinematic acceptance has also been looked into by plotting the $\nu_{[+-,dyn]}$ against the collision centrality in various p$_{T}$ windows. In order to check whether the net charge fluctuations are influenced by the decay of hadronic resonances, experimental findings are compared with the Monte Carlo model HIJING. Moreover, the presence of collectivity has also been examined by analysing the AMPT data sets from the two modes of the model$-$with string melting and rescattering, as well as the EPOS model tuned for the LHC physics.

        Speaker: Anar Rustamov (National Nuclear Research Center (AZ))
      • 17:40
        Net-lambda fluctuations in Pb-Pb collisions at 5.02 TeV in ALICE at the LHC 20m

        One of the fundamental goals of heavy-ion collision experiment is to map out the temperature $(T_{f})$ and baryon chemical potential $(\mu_{B}^f)$ of the Quantum Chromodynamics (QCD) phase diagram at which chemical freeze-out occurs - a point on the phase diagram when the chemical composition of the system is fixed. The cumulants of conserved quantities (net-charge, net-baryon number, net-strangeness) are directly related to the quark number susceptibilities calculated with lattice QCD. In a fluctuation analysis, net-pion, net-proton, and net-kaon are typically used as proxies for net-charge, net-baryon, and net-strangeness respectively. The $\Lambda$-particle consists of a strange quark and it is as well a baryon. Hence, measuring the cumulants of net-$\Lambda$ distributions provides insight into the fluctuations of net-strangeness and net-baryon number.
        In addition, the ratios of net-$\Lambda$ cumulants that are used to estimate freeze-out parameters can be compared to the ones extracted using net-proton to identify the signature of a flavor hierarchy, that is, if heavier quarks may freezeout at a different $(T_{f})$ and $(\mu_{B}^f)$ from lighter quarks.
        In this poster, we will present the measurement of the first and second order cumulants of net-$\Lambda$ distributions in Pb-Pb collisions at $\sqrt{s_{NN}}$= 5.02 TeV using the ALICE detector.

        Speaker: Ejiro Naomi Umaka (University of Houston (US))
      • 17:40
        Net-proton number fluctuations in partial chemical equilibrium 20m

        We calculate the first four cumulants of the net-proton number distribution in partial chemical equilibrium (PCE). Such results serve as a necessary baseline for the identification of any critical phenomena in the collision energy dependence of the cumulants. The PCE scenario is relevant for scenarios of the nuclear collisions where chemical freeze-out coincides with hadronisation, but the fireball cools down further until kinetic freeze-out is reached. As a consequence, each stable hadronic species acquires its own chemical potential which depends on the temperature. Since proton number is not a conserved quantity, it may additionally fluctuate due to random nature of the resonance decays. We calculate the first four cumulants of the net-proton number distribution as functions of temperature for different chemical freeze-outs, which correspond to different collision energies. Interestingly, their temperature dependence is rather flat. Hence, this proves that the results obtained for the cumulants at the chemical freeze-out can still be regarded as relevant.

        Speaker: Paula Hillmann
      • 17:40
        Neutral kaon femtoscopy in Au+Au collisions measured at the STAR experiment 20m

        The Solenoidal Tracker at RHIC (STAR) enables the possibility of exploring the properties of strongly interacting nuclear matter using the method of femtoscopy. By studying the quantum statistical effects and final state interactions between two particles, one can extract emission source parameters, which is used to describe geometrical and dynamical properties of the homogeneity region. We use the high statistics data of Au+Au collisions recorded by the STAR experiment to study the correlations between strange particles. The lightest strange particles are kaons. Kaons are less affected by resonances decays and provide a cleaner signal of two-particle correlations. Neutral kaons, $K_S^0$, can be measured through their decay products to the pair of charged pions.

        In this poster, femtoscopic results of system of two neutral kaons produced in Au+Au collisions at the STAR experiment will be presented.

        Speaker: Diana Pawłowska (Warsaw University of Technology)
      • 17:40
        New Probes for Cold QCD physics with sPHENIX and potential forward upgrades 20m

        The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) will enable a spectrum of new or improved cold QCD measurements, enhancing our understanding of the initial state for nuclear collisions. With its excellent tracking and full calorimetry (hadronic and electromagnetic) in the central pseudo-rapidity region, sPHENIX provides excellent opportunities for the studies of the partonic structure and dynamics in nucleons and nuclei. This includes the studies of the polarized structure of the proton utilizing RHIC's polarized proton collisions. With enhanced RHIC luminosity anticipated in 2020+, and sPHENIX high rate capabilities, the expected precisions will far exceed that achieved at RHIC by now. Among such measurements are high precision polarized gluon distribution in the proton utilizing jet, hadron and direct photon probes, gluon dynamics studies in protons and nuclei through twist-3 correlation functions with heavy flavor measurements, and studies beyond the collinear distributions involving intrinsic transverse momentum kT and fragmentation transverse momentum jT through the correlation measurements. A potential upgrade to sPHENIX with forward instrumentation could significantly enhance these physics capabilities, expanding the probed kinematic range to lower and higher parton momentum fraction x. Nuclear parton distributions will be constrained from direct photon and Drell-Yan electron-positron pair measurements. A unique opportunity to study nuclear effects with polarized probes will be utilized through the high precision measurements of transverse spin asymmetry in hadron production in p+p versus p+A collisions over a wide kinematic range. These and other Cold QCD physics measurements for the proposed sPHENIX midrapidity detector as well as the enhanced program enabled with forward upgrades will be presented.

        Speaker: sPHENIX Collaboration
      • 17:40
        Non-Gaussian sources and the shape of the correlation function 20m

        Correlation femtoscopy is a standard technique for the experimental analysis of ultrarelativistic nuclear collisions. The measured two-particle correlation function is clearly non-Gaussian, and so it is often better reproduced by Levy stable distribution than a Gaussian one. It has been suggested that a particular shape of a Levy-stable distribution may help to identify the QCD critical endpoint. In order to set up a baseline for this statement, we show that there are non-critical effects that may influence its shape as well. By making use of two independent models (hydrodynamical simulation and a blast wave parametrisation) we estimate how much the individual effects modify the shape. We show that the Levy index may deviate considerably from 2 due to effects such as non-spherical shape, resonance decays, event-by-event fluctuations and functional dependence on $q_{inv}$ and/or $q_{lcms}$.

        Speaker: Jakub Cimerman (Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University)
      • 17:40
        Non-prompt $\rm D^{0}$-meson production in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV with ALICE 20m

        Heavy-flavor quarks (charm and beauty) play an important role in probing the Quark-Gluon Plasma (QGP) formed in the heavy-ion collisions. Due to their heavy masses, charm and beauty quarks are formed in hard scattering processes on a timescale shorter than the QGP formation time. Therefore, they experience all the phases of the medium evolution interacting with the medium constituents and losing energy via collisional and radiative processes. In particular, the mass difference between beauty and charm quarks provides an ideal tool to investigate the predicted mass dependence of parton in-medium energy loss. On this regard, the study of non-prompt $\rm D^0$-meson production in Pb-Pb collisions provides an indirect measurement of beauty quark production, while the same study in pp collisions, beside providing the needed reference for Pb-Pb studies, is an excellent tool to investigate perturbative Quantum ChromoDynamics (pQCD) calculations.

        This poster will show the production cross section of non-prompt $\rm D^0$ mesons (b→c→$\rm D^0$) at mid-rapidity in pp collisions at $\sqrt{s}$ = 5.02 TeV. In addition, the latest updates on non-prompt D0 meson production in Pb-Pb at $\sqrt{s_{\rm NN}}$ = 5.02 TeV will be discussed.

        Speaker: Mengke Cai (Central China Normal University CCNU (CN))
      • 17:40
        Non-static properties of the chiral magnetic conductivity 20m

        In this talk we investigate the response of the medium of chiral fermions to time and space dependent external electromagnetic fields and chiral imbalance. The axial-vector--vector--vector (AVV) three-point function is studied in a real-time approach at finite temperature in the linear response approximation.
        The different orders of limits lead to different results as the external fields reach to the constant configuration in both space and time. We classify these different scenarios, involving the well-known case dictated by the chiral anomaly and even the case of vanishing chiral magnetic conductivity. The physical interpretation of these different scenarios is discussed through the anomalous conservation of the chiral charge. The result emphasizes the importance of whether or not the assumption of thermal equilibrium is justified for a system with chiral imbalance.
        Two non-static examples are discussed in details: we analyze the AVV response function for i.) arbitrary space-time dependent chiral chemical potential when the magnetic field is constant and ii.) for arbitrary magnetic field with constant chiral imbalance. In the non-interacting limit the response function can be given even analytically, revealing a relatively simple form in both cases.
        We also discuss the phenomenological implications on the electric charge polarization in a high-energy nuclear collision scenario. The effects of quenches and inhomogeneities of the chiral charge are especially explored, assuming the majority of the chiral charge is of QCD origin and that its generation can be described by a stochastic process.

        Speaker: Mr Miklós Horváth
      • 17:40
        Non-zero chiral and isospin imbalance in QCD phase diagram: dualities in effective models and lattice QCD 20m

        in this talk there will be discussed the phase structure of the dense quark matter with isospin and chiral imbalances has been investigated in the framework of effective models and lattice QCD. It has been shown that in the large-N$_c$ limit (N$_c$ is the number of colours of quarks) there exist duality correspondences, which are the symmetries of the thermodynamic potential and the phase structure itself. The first one is a duality between the chiral symmetry breaking (CSB) and the charged pion condensation (PC) phenomena. The dualities were shown to exist in the matter with chiral imbalance that can be produced in compact stars or heavy ion collisions. One of the key conclusions of these studies is the fact that chiral imbalance generates charged PC in dense baryonic/quark matter even in the case of charge neutral matter, which is interesting in the context of neutron stars. It was also shown that the duality can be observed in lattice QCD. Moreover, they were used for prediction of catalysis of chiral symmetry breaking by chiral imbalance. It is known that chiral imbalance can occur due to temperature and sphaleron transitions. Our studies show that chiral imbalance can occur in the cores of neutron stars or in heavy ion collisions at NICA, FAIR, where large baryon densities can be reached, due to other phenomena the so-called chiral separation and chiral vortical effects. Even if the phase diagram contains phases with inhomogeneous condensates, it still possesses the duality. Just by the duality we obtained, in the inhomogeneous case, without any calculations, a full phase diagram of chirally asymmetric dense quark matter. This shows that the duality is an instrument of high predictivity power. The obtained phase diagram is quite rich and contains various spatially inhomogeneous phases.

        Based on:
        Phys.Rev. D95 (2017) no.10, 105010,
        Phys.Rev. D97 (2018) no.5, 054036,
        Phys.Rev. D98 (2018) no.5, 054030,
        Eur.Phys.J. C79 (2019) no.2, 151,
        JHEP 1906 (2019) 006

        Speaker: Roman Zhokhov (IHEP)
      • 17:40
        Nuclear dependence of transverse single-spin asymmetry of charged hadrons in polarized p+p, p+Al and p+Au collisions in PHENIX 20m

        Transverse Single Spin Asymmetries (TSSAs) manifest themselves through
        an azimuthal-angle dependence of particle production relative to the
        transverse spin direction of the polarized proton in the reaction
        p↑ + p → h + X. In recent years, attention has been given to the interplay
        with small-x physics by studying TSSAs in transversely-polarized proton-ion
        collisions (p↑+A). Recent calculations of TSSAs in p↑+A collisions predict
        that they can be sensitive to the nuclear size (or mass number A) and the
        saturation scale (Q_s). The PHENIX experiment at RHIC performed such a
        measurement at forward rapidity (1.4 < η < 2.4) over the range of transverse
        momentum 1.8 < pT < 7.0 GeV/c in polarized p+p, p+Al, and p+Au collisions.
        We observed a positive asymmetry for positively-charged hadrons in p↑+p
        collisions and a significantly reduced asymmetry in p↑+A collisions. The
        measured TSSAs favor an A-dependence consistent with A^-1/3. These results
        provide new insights for the study of small-system collisions.

        Speaker: Jeongsu Bok (New Mexico State University)
      • 17:40
        Nuclear modification factor of isolated photon production in pp and PbPb collisions at 5.02 TeV with the CMS detector 20m

        High-transverse-momentum prompt photons, as colorless objects, do not interact strongly with the medium and provide a direct way to test pQCD and the nuclear PDF. The transverse energy spectra and the nuclear modification factors of isolated photons are measured in pp and PbPb collisions at 5.02 TeV using the CMS detector. The data are compared to JETPHOX NLO calculations and found to be consistent with the prediction of the nuclear modification factor. The measurements significantly improve the accuracy compared to the previous CMS results at 2.76 TeV. No significant modification of isolated photon cross-sections in PbPb collisions with respect to pp collisions is observed in the pseudorapidity range $|\eta| < 1.44$ and $E_{T}$ between 25 to 200 GeV at various collision centralities.

        Speaker: Yeonju Go for CMS Collaboration (Korea University (KR))
      • 17:40
        Nuclear modification of jet shape for inclusive jets and γ-jets at the LHC energies 20m

        With our coupled jet-fluid model, we study the nuclear modifications of full jets and jet structures for single inclusive jets and $\gamma$-jets in Pb+Pb collisions at $5.02$ ATeV and $2.76$ ATeV. The in-medium evolution of full jet shower is described by a set of coupled transport equations including the effects of collisional energy loss, transverse momentum broadening and medium-induced splitting process. The dynamical evolution of bulk medium is simulated by solving relativistic hydrodynamic equation with source term which accounts for the energy and momentum deposited by hard jet shower to soft medium. Our study demonstrates that the hydrodynamic medium response to jet propagation significantly enhances the broadening of jet shape at large angles and is essential for the cone-size dependence of jet energy loss and nuclear modification factor of inclusive jet production. It is also found that the nuclear modification pattern of jet shape is sensitive to jet energy but has weak dependence on the flavor of the parton that initiates the jet.

        Reference:
        [1] Ning-Bo Chang, Guang-You Qin, Phys.Rev,C94,024902 (2016)
        [2] Yasuki Tachibana, Ning-Bo Chang and Guang-You Qin, Phys.Rev,C95,044909 (2017)
        [3] Ning-Bo Chang, Yasuki Tachibana and Guang-You Qin, arXiv:1906.09562 (2019)

        Speaker: Dr NingBo Chang (Xinyang Normal University)
      • 17:40
        On the strength of the QCD crossover at small chemical potentials 20m

        We investigate whether the QCD crossover gets stronger as the chemical potential is increased. To this end, we study the chiral condensate and susceptibility in a finite volume scaling study at zero and small chemical potentials. We achieve this by extrapolating these quantities from imaginary $\mu_B$ maintaining strangeness neutrality. We also extrapolate low order fluctuations of conserved charges in various volumes and explore the range of validity of the ideal hadron resonance gas model at finite density.

        Speaker: Mr Ruben Kara (University of Wuppertal)
      • 17:40
        Open Heavy-Flavour and J/psi production in peripheral PbPb collisions at LHCb 20m

        In 2018, LHCb recorded ~210 microbarn$^{-1}$ integrated luminosity of PbPb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV. In this talk, we present the first LHCb measurements of open heavy-flavour and J/$\psi$ productions from this new sample. The momentum resolution of the detector allows to probe the boundary of peripheral and ultra-peripheral collisions by comparing hadro-produced and photo-produced J/$\psi$, but also to measure mesonic and baryonic open-charm productions in peripheral collisions, down to $p_T$=0, where the performance of the detector is optimal.

        Speaker: Samuel Belin (Universita e INFN, Cagliari (IT))
      • 17:40
        Open heavy-flavour hadron decay muon $v_{2}$ in p--Pb collisions at $\sqrt{s_{\rm NN}}=8.16$ TeV with ALICE at the LHC 20m

        The positive elliptic flow ($v_{2}$) of open heavy-flavour particles observed in semi-central Pb--Pb collisions at LHC energies indicates that heavy quarks suffered strong interactions in the deconfined QCD medium and participated in the collective motion of the medium. Recent observations in high-multiplicity pp and p--Pb collisions show remarkable similarities with Pb-Pb collisions and suggest the presence of collectivity, whose origin is still debated.
        In this contribution, the elliptic flow of open heavy-flavour hadron decay muons at forward rapidity ($2.5 < y < 4$) in p--Pb collisions at $8.16$ TeV with the ALICE detector will be presented. The results are obtained using Q-cumulants and two-particle correlation methods. The measurements will set constraints on the initial-state fluctuations on heavy-quark production. Moreover, the results will be compared with measurements obtained in p-Pb collisions at $5.02$ TeV and with those performed at mid-rapidity for electrons from heavy-flavour hadron decays. Comparisons with model predictions will be presented as well.

        Speaker: Zuman Zhang (Central China Normal University CCNU (CN))
      • 17:40
        Parametrized equation of state with critical point and first-order phase transition 20m

        At low temperature and low density, the chiral symmetry is broken dynamically to form hadronic phase. While, at high temperature and/or high density, this symmetry is restored and consequently the quark gluon plasma (QGP) appears. In the QCD phase diagram with temperature $T$ and baryon chemical potential $\mu_B$, it is established from first-principle calculations that the transition from hadronic matter to the QGP is crossover at $\mu_B = 0$. On the other hand, in the finite density region ($\mu_B > 0$), the equation of state is still unknown due to the difficulty in the first-principle calculations, namely, the sign problem. Nevertheless, some effective models predict the existence of a critical point connected with a first-order phase transition line [1]. The precise position of the point is still unknown.
        In this study, we construct a model of the equation of state in the entire phase space with a critical point which is connected with a first-order phase transition line by smoothly connecting several equations of state. By making use of the fact that the critical phenomena of QCD and the 3D Ising model belong to the same universality class [2], we construct an equation of state near the critical point [3]. The bag model is used in the high temperature and high density region, the lattice QCD calculation in the high temperature and low density region, the hadron resonance gas model with mean field potential in the low temperature and low density region, and the three-dimensional Ising model near the critical point. The model is designed to place the critical point at any position in the QCD phase diagram so that one can utilize it in the hydrodynamic model of nuclear collisions for critical point search. We discuss the relationship between the position of the critical point and the collision energy using the constructed equation of state.

        [1] M. Asakawa and K. Yazaki, Nucl. Phys. A 504, 668 (1989).
        [2] F. Wilczek. Int. J. Mod. Phys. A 7, 3911 (1992).
        [3] C. Nonaka and M. Asakawa, Phys. Rev. C 71, 044904 (2005).

        Speaker: Yuto Yoshida (Sophia University)
      • 17:40
        Passive Gating Grid Studies for a Time Projection Chamber 20m

        A Time Projection Chamber (TPC) is a good candidate as the main tracking device for many experiments.
        A TPC measures space points of charged tracks, which provide momentum resolution and particle identification for a variety of measurements.
        In high multiplicity environments a TPC has to cope with the build-up of space charge in the drift volume which is created by two major effects; primary ionization and Ion Back Flow (IBF) from an amplification device.
        Primary ionization is inevitable and one concentrates on combating IBF. Traditionally, this is accomplished with a temporarily powered gating grid which absorbs all charge carriers. However, this limits the operation of a TPC to very limited readout rates. To overcome this limit micropattern gas detectors (MPGD) will be implemented in future TPCs. MPGDs are inherently capable to reduce IBF yet not at an optimum level. A passive or statically powered gating grid might optimize the IBF reduction.
        We have simulated woven wire meshes, different patterns of etched meshes, hexagonal micropattern meshes and static bi-polar wire gating grids. We have studied several options to achieve good electron transparency for the primary electrons and high blocking for the ions coming from the amplification stage. In this presentation, we will discuss the results and provide conclusions for overcoming IBF.

        Speaker: Prakhar Garg (Stony Brook University)
      • 17:40
        Performance evaluation of a Forward Calorimeter for the ALICE upgrade 20m

        The measurement of direct photons at forward rapidity in high-energy proton-nucleus collisions is a key to investigate the high-density parton distribution functions and to understand the initial state of nuclear collisions. Gluon distributions at very small x (below 10$^{-4}$) may reach saturation of the phase space. The Color Glass Condensate is a theoretical framework that describes the coherent dynamics of this saturated regime of QCD.

        In order to enable the separation of direct photons from the decay photons, a high-granularity-readout electromagnetic calorimeter (FoCal-E) in the forward rapidity region (3.5 $<$ $\eta$ $<$ 5.3) has been proposed in the ALICE experiment at LHC. FoCal-E consists of 20 layers of tungsten absorber plates, interleaved with two types of active silicon layers, low granularity readout layers (LGL) with silicon pads and high-granularity readout layers (HGL) with Monolithic Active Pixel Sensors.
        We have constructed a prototype calorimeter consisting of 20 alternating layers of tungsten and LGL pads. The performance of this prototype was evaluated with positron and hadron beams at CERN PS and SPS in 2018. The results of these testbeam measurements will be reported. This performance evaluation is crucial to determine the final design of FoCal-E.

        Speaker: Yoko Minato (Nara Women's University (JP))
      • 17:40
        Performance evaluation of sensor module for INTT at sPHENIX 20m

        sPHENIX is a new heavy ion experiment at RHIC and aims to study the microscopic structure of quark-gluon plasma by measuring the Jet modification with different flavors and the possible different suppressions of Upsilons.
        Intermediate silicon strip tracker (INTT) is one of the tracking detectors sandwiched between the inner silicon pixel tracker (MVTX) and the outer TPC. INTT consists of two layers of the barrel detector and covers $|y| < 1.1$ and full azimuth. INTT provides hits information for each beam crossing. This enables to separate the event from multiply overlapped events, and to confirm tracks measured by MVTX and TPC.
        INTT ladder is composed of a silicon strip sensor, read-out chips (FPHX), high-density interconnect (HDI) and a carbon fiber (high thermal conductive) stave. The second prototype of ladder was produced to check their performance. We first checked the functionality and ADC response by measuring the test pulse and cosmic ray using the test bench at Nara Women's University. Secondary, the test beam experiment was performed with 120 GeV proton at FNAL during the summer 2019 to measure the detection efficiency and charge distribution of MIP. At the test beam, three ladders were arranged side by side to form a telescope, and the efficiency was evaluated by counting the number of tracks passing through all three ladders.
        In this presentation, we report the current status of the ladder development, and the on-going data analysis for the detection efficiency and charge distribution of MIP.

        Speaker: Ayaka Suzuki (Nara Women's University)
      • 17:40
        Performance of the MPD detector for the study of multi-strange baryon production in heavy-ion collisions at NICA 20m

        Heavy-ion collisions at NICA are well suitable to investigate fundamental problem of strongly interacting matter such as its EOS, bulk properties, state of QCD vacuum, and criticality.
        The production of (anti)hyperons is sensitive to the early stage of the collision, thus the degree of partonic collectivity can be tested by means of multi-strange baryon yields, spectra, and anisotropic flow coefficients. Moreover, the difference in production rates as well as in azimuthal anisotropy between hyperons and antihyperons could depend on the baryon density and EOS in the hadronic stage of the medium. Hence, multi-strange baryons can be a valuable probe to test multiple stages of the evolution of a heavy-ion collision.
        The MPD detector is a spectrometer with a large uniform acceptance capable of detecting and identifying hadrons, electrons and gammas at the very high event rate achieved at NICA. Event reconstruction in MPD is expected to provide a high accuracy in collision centrality and event plane determination, as well as a good performance in secondary vertex finding.
        We present the performance of the MPD detector for reconstruction of strange and multi-strange baryons (Lambda, Xi, Omega and their antiparticles) in heavy-ion collisions. The results, which are obtained from the full MPD simulation and reconstruction chain, include the yields, spectra, and anisotropy coefficients for (anti)hyperons from centrality selected Au+Au collisions. The estimates for the particle rates during first period of data taking at NICA and the accuracy, which can be achieved in multi-strange baryon measurements, will be given.

        Speakers: Nikolay Geraksiev (JINR), Vadim Kolesnikov (Joint Institute for Nuclear Research (RU))
      • 17:40
        Performance studies of scintillator tiles for the sPHENIX hadronic calorimeter 20m

        The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) will begin taking data in 2023, providing detailed measurements of jets and Upsilons in 200 GeV Au+Au collisions. To make precision jet energy measurements, sPHENIX will be equipped with a Hadronic Calorimeter (HCal) located outside a 1.4T superconducting solenoidal magnet. The HCal is composed of 7,680 plastic scintillating tiles sandwiched between layers of steel absorber plates. Light produced by particles striking the tile is captured by a wavelength shifting fiber that routes the light to Silicon Photomultipliers (SiPM) at one end of the tile. The geometry of the mid-rapidity calorimeter is novel, tilted in azimuth such that particles coming from the interaction region traverse a number of scintillating tiles. The scintillator tiles come in different shapes based on their location in pseudorapidity. Tiles of the same shape are grouped together azimuthally in sets of five forming a “tower,” and the readout from a tower is the aggregate of the signals of each tile within a tower. Results of beam tests carried out at Fermilab have shown that the detector has the required energy resolution to accomplish sPHENIX’s physics goals; additionally, in order to optimize the performance of the calorimeter, towers will be constructed out of tiles with similar behavior. Testing has begun at Georgia State University to characterize the performance of each individual tile relative to a baseline reference by analyzing their response to cosmic rays. This poster will detail the design of the test setup, the analysis procedure, and the current results of the performance characterization studies of the sPHENIX HCal tiles.

        Speaker: sPHENIX Collaboration
      • 17:40
        Phase transitions and transport in dense nuclear matter from relativistic density functional theory 20m

        The equation of state of dense nuclear matter, while central in simulations of QCD systems under extreme conditions, is currently inaccessible to first principles calculations. Using relativistic density functional theory, we model the thermodynamics and single-particle equations of motion of nuclear matter over a broad range of temperatures and densities encompassing nuclei, neutron stars, neutron star mergers, and relativistic heavy ion collisions. We obtain a flexible and thermodynamically consistent framework to parameterize the known properties of ordinary nuclear matter and postulate a family of equations of state compatible with the QCD phase transition. Eventually, these equations of state will be constrained by comparison with experimental data. As a first step, we implement the corresponding relativistically covariant single-particle equations of motion within a hadronic transport model and investigate the behavior of dense nuclear matter close to the phase transition.

        Speaker: Agnieszka Wergieluk (University of California, Los Angeles)
      • 17:40
        PHENIX measurements of Bottom and Charm in A+A collisions 20m

        The study of energy loss of quarks in the hot and dense medium has been performed for decades. Both the experimental and theoretical efforts hinted that the energy loss is quark mass dependent (the yield of heavier quarks will be less suppressed). It was found that the electrons from heavy quarks (charm, and bottom) are less or similarly suppressed compared to that of light hadrons. However, the mass ordering of the suppression between charm and bottom was not clear by now due to a large uncertainty in the measurement. We have fully exploited the events recorded at PHENIX from Au+Au collisions in the 2014 RHIC run. Combined with the new charm and bottom $p_{T}$ spectra from p+p collisions from the 2015 RHIC run, we can obtain the new $R_{AA}$ for charm and bottom quarks with smaller uncertainties. We will show the latest results on $p_{T}$ spectra and $R_{AA}$ of charm and bottom quarks separately, and discuss the quark mass dependence of the energy loss

        Speaker: Takashi Hachiya (RIKEN)
      • 17:40
        PHENIX probing forward/small-x dynamics from hadron production 20m

        A better understanding of parton dynamics in the nucleus, in particular in the small-x region, is extremely important as it is needed to understand the nature of recently observed and unexpected phenomena like particle anisotropies in small collision systems. PHENIX can explore the small and large-x regions in the nucleus through measurements in the muon arms and forward vertex trackers. These detectors cover the forward ($1.2<\eta<2.2$) and backward ($-2.2<\eta<-1.2$) rapidity range, which in p+Au collisions at 200 GeV gives access to an average x$\sim$0.005 and x$\sim$0.1, respectively. In this talk PHENIX present new results, including on charged hadrons, muon pairs from bottom decays, and Drell-Yan muon pairs. The ratio of p+Au to p+p data reveals interesting patterns of suppression and enhancement in the p+Au data. When comparing the results to pQCD calculations using nuclear parton distribution functions, reasonable agreement is found only over part of the accessible kinematic range, indicating the possible presence of other nuclear effects.

        Speaker: Sanghoon Lim (University of Colorado Boulder)
      • 17:40
        PHENIX results on $J/\psi$ polarization in p+p collisions 20m

        One of the big puzzles in quarkonia production is how heavy-quark pairs, produced in the initial hard process, hadronize into final quarkonia states. This uncertainty affects the estimation of quarkonia breakup cross sections and color screening in heavy ion collisions. According to Non-Relativistic Quantum Chromodynamics, quarkonia are formed from several intermediate singlet and color octet states. The relative fraction of each contribution can only be determined by experimental data, including yields and angular decay (polarization) measurements in a broad kinematic region. The PHENIX experiment has measured inclusive J/psi polar and azimuthal angular decay coefficients in the mid ($|y|<0.35$) and forward ($1.2<|y|<2.2$) rapidity regions in $p$+$p$ collisions at 200 GeV and 510 GeV. We find that the polarization coefficients are consistent with zero at mid-rapidity and negative at large rapidity. This talk will present the analysis strategy as well as the results in different angles/frames. We will discuss how the results can be explained in terms of singlet and color octet states.

        Speaker: Alexandre Lebedev (Iowa State University)
      • 17:40
        Phenomenological formulation of relativistic spin hydrodynamics 20m

        Recently, there have been significant experimental progresses in observing and/or controlling spin-dependent bulk quantities in broad areas in physics, e.g., relativistic heavy-ion collisions, spintronics. Although hydrodynamics is one of the most powerful theoretical frameworks to describe bulk quantities, its extension to a spinful fluid has not been developed well, especially for relativistic systems.

        In this presentation, we formulate relativistic spin hydrodynamics with first-order dissipative corrections for the first time [1]. Our formulation is based on the phenomenological entropy-current analysis, in which the first and second laws of thermodynamics are utilized to constrain constitutive relations. We also clarify that spin should be a non-hydrodynamic (diffusive) mode by explicitly solving the obtained hydrodynamic equations within the linear-mode analysis on top of a global thermal equilibrium configuration. This diffusive behavior is a consequence of the mutual convertibility between spin and orbital angular momentum.

        [1] K. Hattori, M. Hongo, X.-G. Huang, M. Matsuo, H. Taya, "Fate of spin polarization in a relativistic fluid: An entropy-current analysis," Phys. Lett. B 795, 100 (2019)

        Speaker: Dr Hidetoshi Taya (Fudan University)
      • 17:40
        Photon identification in the ALICE EMCal using a neural network and template fit 20m

        Photon identification in the ALICE EMCal using a neural network and template fit
        Alwina Liu for the ALICE collaboration

        The measurement of isolated photon-tagged correlations of jets and jet fragments is a promising channel for the study of partonic energy loss in heavy-ion collisions. Isolated photons are an excellent probe because they constrain the parton kinematics of the initial hard scattering. For prompt photon measurements, the main background are photons from the decays of neutral mesons. Photons are measured in the ALICE electromagnetic calorimeter (EMCal) and reconstructed as EMCal clusters. Higher-$p_{\mathrm{T}}$ neutral mesons decay into photons with a small opening angle, which can produce a single cluster with both photons when the photon showers overlap; this starts to happen for neutral pions at around 6 GeV/$c$, for example. A deep neural network is trained to distinguish between clusters containing one or two photons. Thus the energy distribution in the cluster (the ``shower shape'') can be encoded with the output of this deep neural network as well as with a geometric variable. The shower shape distribution of isolated clusters in the data can then be fit to two templates. The purity can then be extracted from the result of the template fit and is used in the isolated photon correlation measurements. This poster will present the details and results of calculating the photon purity with a template fit procedure using both the deep neural network and the geometric variable in multiple collision systems. The photons are measured in a $p_{\mathrm{T}}$ range (12--60 GeV/$c$) that provides access to a regime in which the largest modifications due to the QGP are expected and which is thus far unexplored. However, this $p_{\mathrm{T}}$ range is technically challenging due to the large number of neutral mesons produced relative to prompt photons.

        Speaker: Alwina Liu (University of California Berkeley (US))
      • 17:40
        Photons associated with jets in p-p and A-A collisions 20m

        Jet modification is now understood to be a multistage effect: a parton produced in a high virtuality initial state, radiates a multitude of partons, giving way to a variety of lower virtuality stages. In the lower virtuality stage, higher energy partons are weakly coupled with the medium and continue to scatter and radiate whereas lower energy partons are strongly coupled with the medium and will eventually thermalize. Hadrons produced in the fragmentation from these partons are clustered within jets. Modeling of these multistage effects involves several parameters: The coupling in the medium, the scales where the shower transitions from one stage to the next, and the parameters of hadronization.

        We consider a set of these parameters which have been tuned to successfully describe a variety of jet based data, such as the nuclear modification factors of leading hadrons and jets, the intra-jet fragmentation function and the jet shape, and subject this model to a parameter free validation by calculating the photon production from these in-medium jets. Quarks inside jets can radiate photons along with gluons. Photons are also produced in the hard scattering, via the quark-gluon Compton scattering process. In this work, we study the correlation of photons with jets in p-p and A-A collisions. Photon radiation from the hard scattering, from both the large and small virtuality phases, along with radiation from a PYTHIA based hadronization model are included in this analysis. We focus on the photon jet transverse momentum and angular balance. The calculations of photon production from each stage are calculated in close analogy to gluon radiation, with the exact same approximations, i.e., no new parameters are introduced or tuned either in the p-p or A-A collisions. The level of agreement with experimental data provides an independent verification of the multi-stage theory of jet modification.

        Speaker: Chathuranga Sirimanna for JETSCAPE Collaboration (Wayne State University)
      • 17:40
        Physics performance studies for anisotropic flow measurements with the CBM experiment at FAIR 20m

        The Compressed Baryonic Matter experiment (CBM) at FAIR aims to study the area of the QCD phase diagram at high net baryon densities and moderate temperatures using collisions of heavy ions at center-of-mass energies of a few GeV per nucleon. Anisotropic transverse flow is among the key observables to study the properties of matter created in such collisions.

        The CBM performance for anisotropic flow measurements is studied with Monte-Carlo simulations using gold ions at SIS-100 energies with lab momentum up to 12A GeV/c employing different heavy-ion event generators. Various combinations of CBM detector subsystems are used to investigate the possible systematic biases in flow measurement and to study the effects of detector azimuthal non-uniformity. The resulting performance of CBM for flow measurements is demonstrated for different harmonics of identified charged hadron anisotropic flow as a function of rapidity and transverse momentum in different centrality classes.

        Speaker: Oleg Golosov (MEPhI)
      • 17:40
        Pion, kaon and (anti-)proton production in pp, p-Pb and Pb-Pb collisions at the highest LHC energies with ALICE 20m

        In ultra-relativistic nucleus-nucleus collisions a new state of matter where quarks and gluons are not confined into hadrons, the Quark-Gloun Plasma (QGP), is created. The ALICE experiment at the LHC is dedicated to the study of the properties of the QGP. In addition, proton-proton collisions are used as the high energy QCD reference while the study of proton-nucleus collisions provides a fundamental benchmark for the initial state and cold nuclear matter effects. In recent years the multiplicity-dependent results on particle production in pp and p--Pb collisions allowed the discovery of collective–like behavior in small systems at LHC energies. Exploiting its optimal particle identification capabilities, the ALICE experiment is able to measure pion, kaon and (anti-)proton transverse momentum spectra from hundreds of MeV/$c$ up to 20 GeV/$c$. Measurements of the production of pions, kaons and (anti-)protons in pp, p--Pb and Pb--Pb collisions at the highest center of mass energies provided during the LHC Run 2 data taking period, are reported. Results are presented as a function of the collision centrality or multiplicity and include transverse momentum spectra, particle ratios, integrated yields and nuclear modification factors. In addition, particle abundances are discussed in the context of underlying event. Finally, an extensive comparison to statistical hadronization and hydrodynamic model predictions is presented.

        Speaker: Ejiro Naomi Umaka (University of Houston (US))
      • 17:40
        Polarization transfer in hyperon decays and its effect in relativistic nuclear collisions 20m

        We study the contribution to the polarization of $\Lambda$ hyperons in relativistic nuclear collisions at high energy from the decays of $\Sigma^*(1385)$ and $\Sigma^0$, which are the predominant sources of $\Lambda$ production besides the primary component, as a function of the $\Lambda$ momentum. Particularly, we determine the longitudinal component of the mean spin vector as a function of the azimuthal angle and show that it has a very similar pattern to the primary one, if primary $\Sigma^*$ and $\Sigma^0$ polarization follow the predictions of local thermodynamic equilibrium in a relativistic fluid. Therefore, we conclude that the secondary decays cannot account for the discrepancy between experimental data and hydrodynamic model predictions of the longitudinal polarization of $\Lambda$ hyperons recently measured by the STAR experiment at RHIC.

        Speaker: Gaoqing Cao (Sun Yat-sen University)
      • 17:40
        Possible observation of parton energy loss in pp collisions with Pythia 20m

        We study the evolution of jetty and underlying parts of the transverse momentum spectra as a function of multiplicity in pp 13 TeV collisions at midrapidity (|eta|<0.8) using pythia8 event generator. We observe that beyond a multiplicity of dN/deta ~ 40 the maximum reachable leading transverse momentum gets smaller and at the same time the slope of the spectra both in the jetty and underlying parts show a continuous rise. At high multiplicity (>70) a rise in pT spectra at very low momenta (~ 1GeV/c) is also observed. We interpret this as a possible loss of the momentum at a certain particle/energy density in pp collisions.

        The similarity in the behavior of transverse momentum spectra in Pb-Pb and pp collisions (shown in arXiv:1805.04572v2) indicate that the same mechanism could be responsible for the parton energy loss in heavy ions collisions. Although the behaviour of the spectra at low momenta are usually explained by hydro flow mechanisms, we demonstrate that with the present mechanism the low momentum features are perfectly explained by the overall hardening of the spectra. The saturation of the sum of the transverse momenta with multiplicity gives strong base to our observations.

        We will present the results obtained with Pythia8 using different multiplicity estimators (central multiplicity estimator and the one based on the multiplicity in the transverse side) for different pseudorapidity ranges.

        Speaker: Dr Guy Paic (CERN)
      • 17:40
        Pre-hydrodynamic evolution and its signatures in final-state observables 20m

        The system created in high-energy heavy-ion collisions quickly reaches local equilibrium and its evolution is usually modeled with relativistic hydrodynamics. However, the effects of the early, pre-equilibrium stages of system evolution on final-state observables are largely unknown. In this work, we study the effects of pre-hydrodynamic evolution on final-state observables in various heavy-ion collision systems. We employ state-of-the art hydrodynamic simulations coupled to different pre-hydrodynamical scenarios, including Kompost, a recently-developed effective kinetic transport theory evolution model. We find that the addition of a pre-equilibrium stage can have a significant effect on the development of transverse momentum, but only a small effect on flow and fluctuations, even differentially in transverse momentum. These results impose constraints on the way in which the initial particle production immediately after the initial hard scattering is connected to the subsequent hydrodynamic evolution of the system.

        Speaker: Mauricio Hippert Teixeira (Universidade de São Paulo)
      • 17:40
        Precision, radiation hard ZDCs, for high luminosity LHC running 20m

        The Joint Zero Degree Calorimeter Project, JZCap, seeks to deploy new high resolution ZDCs for ATLAS, CMS and possibly other experiments for Run 3 of the LHC. These ZDCs will be radiation hard enough to measure forward neutrons and bremsstrahlung photons during PbPb, pPb and dedicated pp running. The ZDCs are tungsten Cerenkov calorimeters where the active medium consists of fused silica developed for luminosity measurements at the LHC. Segmentation of the ZDCs in depth provides excellent separation of photons and neutrons. The angular distribution of the spectator neutrons will be measured arrays of square silica cells. This talk will present data on radiation hardness, activation and the test beam performance of the detectors as well as detailed simulations. Finally the projected physics performance of the detectors will be discussed and potential for similar detectors in the EIC will be discussed.

        Speaker: Joint Zero Degree Calorimeter Collaboration, JZCAP
      • 17:40
        Presenting the HIJING++ Monte Carlo event generator 20m

        We present the first public release of the HIJING++ Monte Carlo event generator for high energy heavy ion collisions. Along with the summary plots and experimental validity checks the download and technical instructions will be presented for the first time. The code is developed in modern C++ and is a complete revision of the original FORTRAN HIJING [1,2]. The state-of-the-art framework comprise new features such as modularity, CPU multithreading and an analysis interface, while the underlying physics model is extended with modules such as the medium interaction model based on CUJET3.1 [3].

        [1] Wei-Tian Deng, Xin-Nian Wang, Rong Xu, Phys. Rev. C 83, (2010) 014915
        [2] Miklos Gyulassy, Xin-Nian Wang, Comput.Phys.Commun. 83 (1994) 307
        [3] G. Papp, this conference

        Speaker: Gábor Bíró (Wigner RCP)
      • 17:40
        Probe Chiral Magnetic Effect with Signed Balance Function 20m

        In this talk a pair of observables are proposed as alternative ways to study the charge separation induced by Chiral Magnetic Effect (CME) in relativistic heavy ion collisions. They are, the out-of-plane to in-plane ratio of fluctuation of the difference between signed balance functions measured in pairs rest frame, and the ratio of it to similar measurement made in the laboratory frame. Both observables have been studied with simulations including flow-related backgrounds, and for the first time, backgrounds that are related to resonance’s global spin alignment. The two observables have similar positive responses to signal, and opposite, limited responses to identifiable backgrounds arising from resonance flow and spin alignment. Both observables have also been tested with two realistic models, namely, a multi-phase transport (AMPT) model and anomalous-viscous fluid dynamics (AVFD) model. These two observables, when cross examined, will provide useful insights in the study of CME-induced charge separation.
        ( https://arxiv.org/abs/1903.04622)

        Speaker: Dr Aihong Tang (Brookhaven National Laboratory)
      • 17:40
        Probing small-x gluons with gamma+hadron correlations in the forward rapidity with the LHCb detector 20m

        Gluon nuclear PDFs still have large uncertainties in the small-x ($x$<10^{-3}) and small virtuality $Q^2<$50 (GeV/c)$^{2}$ region. Yields from particles coming from these gluons obtained in nuclear collisions are suppressed relative to $p$+$p$ collisions because of initial-state effects such as shadowing, energy loss and gluon saturation. Precise measurement of yields coming from small-x, small-$Q^2$ gluons are essential to understand these effects which have a significant contribution to the suppressions observed in A+A collisions at RHIC and LHC. The inverse Compton process $q+q\rightarrow \gamma+q \rightarrow \gamma+h$ is one of the few which can access and provide information on the gluon $x$ and $Q^2$ in the region where nPDFs are not well constrained. The LHCb detector can measure photons through the Electromagnetic Calorimeter or photon conversion to dielectrons in the pseudorapidity range 2$<\eta<$5, covering $x>5\times 10^{-6}$ and $Q^2>2$GeV$^2$ in the case of inverse Compton processes. This unique coverage allow us to search for the gluon saturation scale, the transition between dilute and saturated gluons, predicted by the Color-Glass Condensate effective theory. This presentation will show the status of the isolated $\gamma+$hadron correlation analysis using data collected in $p$+Pb and Pb+$p$ collisions at 8.16 TeV and $p$+$p$ collisions at 8 TeV. New techniques will also be presented to identify isolated photons and subtract the large background from neutral meson decays.

        Speaker: Maitreyee Mukherjee (Central China Normal University CCNU (CN))
      • 17:40
        Production of $D_{s}^{\pm}$ mesons in Au+Au collision at $\sqrt{s_{NN}}$ = 200 GeV by STAR 20m

        Charm quarks are excellent probes to study properties of the Quark-Gluon Plasma (QGP) created in ultra-relativistic heavy-ion collisions. In particular, measurements of the $D_{s}^{\pm}$ meson production can provide valuable information on the strangeness enhancement in the QGP as well as the charm quark hadronization mechanisms in heavy-ion collisions. In this poster, we will present results from the STAR experiment on invariant yields of $D_{s}^{\pm}$ mesons as a function of transverse momentum for different centrality classes of Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. The measurements utilize the data with the Heavy Flavor Tracker from 2014 and 2016. The ratio between strange ($D_{s}^{\pm}$) and non-strange ($D^{0}$) open charm mesons will also be shown, and compared to PYTHIA and model calculations. A clear enhancement relative to the PYTHIA calculation is seen in the ratio, while model calculations incorporating strangeness enhancement and charm quark coalescence hadronization are closer to data. These results suggest that recombination of charm quarks with equilibrated strange quarks in the QGP plays an important role in charm quark hadronization.

        Speaker: Chuan Fu (Central China Normal University)
      • 17:40
        Production of $J/\psi$ meson in jets at mid-rapidity in pp collisions at $\sqrt{s}$ = 13 TeV with ALICE 20m

        The production of quarkonia in hadron-hadron collisions occurs at the transition between the perturbative and nonperturbative regimes of QCD, resulting in a rich phenomenology that remains far from being fully understood. $J/\psi$ hadronization dynamics can be studied by measuring the $p_{T}$ fraction, $z \equiv p_{T,J/\psi} / p_{T,jet}$, carried by the $J/\psi$ meson detected inside a jet. The distribution of this quantity, also called fragmentation function, gives us an opportunity to investigate the dominant subprocesses responsible for $J/\psi$ production. In addition, the production of non-prompt $J/\psi$, coming from b hadron decays, inside a jet should be sensitive to the fragmentation functions of quarks and gluons into b hadrons. The fragmentation of high $p_{T}$ jets containing a $J/\psi$ meson was measured in pp collisions by LHCb and CMS Collaborations, respectively. The results surprisingly show that non-prompt $J/\psi$ in jets are well described by models, but that prompt $J/\psi$ tend to be produced at much lower $z$ than the model predicted.

        In this contribution, we present the measurements of the fragmentation of jets into $J/\psi$ in pp collisions at $\sqrt{s}$ = 13 TeV using the data collected by ALICE,with the $J/\psi$ being measured at mid-rapidity in the di-electron decay channel by the central barrel detectors. Prompt and non-prompt components will be separated using the pseudo-proper decay length.

        Speaker: Mr Yitao Wu (University of Science and Technology of China (CN))
      • 17:40
        Production of D$^{\pm}$ mesons in Au+Au collisions at $\sqrt{s_\mathrm{NN}}$ = 200 GeV at the STAR experiment 20m

        Charm quarks are an ideal probe of the QGP created in heavy-ion collisions as they are produced at very early stages of such collisions and subsequently experience the whole evolution of the system. At STAR experiment, charm quark production can be accessed by direct topological reconstruction of open-charm hadrons thanks to an exceptional spatial resolution of the Heavy-Flavor Tracker detector.

        In this poster, we will present a measurement of D$^\pm$ meson production in Au+Au collisions at $\sqrt{s_\mathrm{NN}}$ = 200 GeV by the STAR using data collected in 2014 and 2016. Supervised machine-learning techniques were used to optimize the yield extraction from the three body hadronic decay channel $\textrm{D}^\pm \rightarrow \textrm{K}^\mp \pi^\pm \pi^\pm$. The D$^\pm$ invariant spectrum was then obtained in 0-10\%, 10-40\%, 40-80\%, and 0-80\% central Au+Au collisions. The measured nuclear modification factor $R_\mathrm{AA}(p_\mathrm{T})$ reveals a significant suppression of high-$p_\mathrm{T}$ D$^\pm$ mesons in central and mid-central Au+Au collisions with respect to p+p collisions. The $(\textrm{D}^++\textrm{D}^-)/(\textrm{D}^0+\overline{\textrm{D}^0})$ yield ratio has also been extracted and compared to that from PYTHIA calculations.

        Speaker: Jan Vaněk (Nuclear Physics Institute, Czech Academy of Sciences)
      • 17:40
        Production of identified light flavour hadrons as a function of underlying event activity in pp collisions using the ALICE detector 20m

        Various recent measurements of high-multiplicity pp and p-A collisions at the LHC center-of-mass energies have revealed, surprisingly, that these small collision systems exhibit some of the quark-gluon plasma features, e.g. collective behaviour and strangeness enhancement, formerly thought to be achievable only in heavy-ion collisions. A promising method to narrow down the origin of this behaviour is to study the effect of Multi-Parton Interactions (MPIs). The underlying event (UE), which is the collection of particles not originating from the primary hard parton-parton scattering or the related fragmentation, is thought to be highly sensitive to the MPIs. To access the mean number of MPIs experimentally, it has been proposed to use the self-normalised charged particle density in the region transverse to a jet, $R_\mathrm{T} = N_\mathrm{ch}^\mathrm{trans} / \langle N_\mathrm{ch}^\mathrm{trans} \rangle$, as it effectively disentangles the soft processes of interest from the hard component.

        In this contribution, we report on the $\pi$, $p$, $K$, $\phi$, $\Lambda$, and $\Xi$ transverse momentum spectra—covering both mesons and baryons, as well as non-strange and strange hadrons—as a function of $R_\mathrm{T}$ in pp collisions at $\sqrt{s}=13$TeV measured with the ALICE detector at the LHC. Thus, we probe collective behaviour and strangeness enhancement in both the low-UE and the high-UE extremes and provide results with a good discriminatory potential for theoretical models.

        Speaker: Oliver Matonoha (Lund University (SE))
      • 17:40
        Production of J/$\psi$ and $\psi$(2S) in p+p collisions at $\sqrt{s}$ = 510 GeV from the STAR experiment 20m

        Measurements of the production cross sections of heavy quarkonia, namely J/$\psi$ and $\psi$(2S), in hadron-hadron collisions provide valuable information about yet unsolved questions of Quantum Chromodynamics. The Solenoid Tracker At RHIC (STAR) is a major high-energy nuclear physics experiment at the Relativistic Heavy Ion Collider. Its Muon Telescope Detector, which provides trigger and identification capability for muons, enables to study quarkonia in the $\mu^{+}$$\mu^{-}$ decay channel which is less affected by bremsstrahlung energy losses in detector materials.

        In this poster, we will present the measurements of the production cross sections of the J/$\psi$ and $\psi$(2S) mesons, as well as the $\psi$(2S) to J/$\psi$ yield ratio as a function of $p_{T}$ via the $\mu^{+}$$\mu^{-}$ decay channel in p+p collisions at $\sqrt{s}$ = 510 GeV from data recorded in 2017 by the STAR experiment. It is the first measurement of $\psi$(2S) as a function of $p_{T}$ from STAR experiment. The results will be compared with various theoretical models including Next-to-Leading Order NRQCD, Improved Color Evaporation Model, and Color Glass Condensate effective theory with the NRQCD formalism.

        Speaker: ChanJui Feng (National Cheng Kung University)
      • 17:40
        Production of pions, kaons and protons in p--Pb collisions at $\mathrm{\sqrt{s_{NN}}}$=8.16 TeV with ALICE at LHC 20m

        At the end of 2016 the ALICE experiment at the LHC collected data from p--Pb collisions at $\mathrm{\sqrt{s_{NN}}}$=8.16 TeV.
        These data represent an important chance to test the emergence of possible initial state effects, by comparing the transverse momentum distributions of identified light hadrons extracted in this dataset to those previously measured in pp and Pb--Pb collisions, in a wide transverse momentum range.
        In this poster, we present the results of non single diffractive as well as multiplicity-dependent transverse momentum spectra, $p_{\rm{T}}$-integrated yield ratios and $\langle p_{\rm{T}} \rangle$ for identified $\mathrm{\pi}$, K and p, in p--Pb collisions at $\mathrm{\sqrt{s_{NN}}}$=8.16 TeV. The measurement is performed thanks to the excellent particle-identification capabilities of the ALICE ITS (Inner Tracking System), TPC (Time Projection Chamber) and TOF (Time Of Flight) detectors.
        These results will be compared to those obtained with colliding systems of various sizes and at different energies as well as to the predictions of the available Monte Carlo event generators and hydrodynamic models.

        Speaker: Dr Pavel Larionov (INFN - LNF)
      • 17:40
        Production of the higher mass K* (1430) resonance in pp collisions at √ s = 13 TeV 20m

        Short lived hadronic resonances are very useful tools to probe the evolution of high energy heavy-ion collisions. Owing to the short lifetime of resonances $(\sim 10^{-23}$s), their characteristic properties such as mass, width and yield are very sensitive to the collision dynamics and in-medium effects. Multiple resonances have been studied in ALICE, including $\rho(770)$, $K^{*}(892)$, $\phi(1020)$, $\Lambda(1520)$ . However there are higher excited state resonances like $K^{*}(1430)$ and $K_2(1770)$ which have not yet been studied in the experiment because of their low production rate and difficulties in separating them cleanly from the underlying correlated background. Recent high statistics data in pp collisions collected by ALICE allow us to study the higher excited kaon state $K^{*}(1430)$. The lifetime of the $K^{*}(1430)$ ($\sim$1.5 fm$\thinspace /c$) is smaller than that of $K^{*}(892)$ ($\sim$4 fm$\thinspace /c$), it is expected that $K^{*}(1430)$ will be affected more by re-scattering in the late hadronic phase and hence measuring $K^{*}(1430)$ production in pp collisions will provide a baseline for similar measurements in Pb--Pb collisions.

        We will present the first measurement of the $K^{*}(1430)$ meson reconstruced through its hadronic decay channel, $K^{*}(1430)\rightarrow K\pi$ at mid-rapidity ($|y| < 0.5$) in pp collisions at $\sqrt{s} = 13$ TeV using the ALICE detector. Measurements of its mass, width and yields will be presented and discussed.

        Speaker: Prottay Das (National Institute of Science Education and Research (IN))
      • 17:40
        Prospects for measuring $\Xi_{\rm c}^{+}$ and $\Sigma_{\rm c}^{++,0}$ baryons with ALICE 20m

        Recent measurements of charm baryon production in pp and p-Pb collisions at LHC energies show a baryon-over-meson ratio significantly higher than expectations from Monte Carlo generators tuned to reproduce the lower values measured in ${\rm e}^{+}{\rm e}^{-}$ and ${\rm e}^{\pm}{\rm p}$ collisions. In Pb--Pb collisions at LHC and Au--Au collisions at RHIC, even higher values of $\Lambda_{\rm c}^{+}/{\rm D^{0}}$ ratios were observed, described within large uncertainties by models that foresee that $\Lambda_{\rm c}^{+}$ can form via coalescence of charm quarks with light quarks from the medium. These results indicate that charm baryon production in hadronic collisions is not fully understood and suggest that heavy-quark hadronisation can be sensitive to the presence of a surrounding hadronic environment.

        Models that better reproduce the $\Lambda_{\rm c}^{+}/{\rm D^{0}}$ ratio in pp collisions expect a significant contribution to $\Lambda_{\rm c}^{+}$ yield from decays of heavier charm-baryon states, among which $\Sigma_{\rm c}$ states. The same models also predict an enhancement of $\Xi_{\rm c}/{\rm D^{0}}$ ratios with respect to ${\rm e}^{+}{\rm e}^{-}$ data. Therefore, the measurement of the production of $\Sigma_{\rm c}$ and $\Xi_{\rm c}$ states can provide fundamental insight into charm hadronisation.

        In this contribution the prospects for measuring $\Xi_{\rm c}^{+}$ and $\Sigma_{\rm c}^{++,0}$ production at mid-rapidity with the ALICE detector via the reconstruction of the $\Xi_{\rm c}^{+}\rightarrow {\rm pK^{-}}\pi^{+}$ and $\Sigma_{\rm c}^{++,0}\rightarrow \Lambda_{\rm c}^{+}\pi^{+,-}, \Lambda_{\rm c}^{+}\rightarrow{\rm pK^{-}}\pi^{+}$ decay channels will be presented.

        Speaker: Mattia Faggin (Universita e INFN, Padova (IT))
      • 17:40
        Proton Yields, Multiplicities, and Event-by-event Fluctuations for Au+Au Collisions at $\sqrt{s_{NN}}$ from 3 GeV at STAR 20m

        The first RHIC Beam Energy Scan (BES-I) was run from 2010-2014 to search for the turn-off of signatures of the quark-gluon plasma (QGP), evidence of the first-order phase transition, and the possible QCD critical point. The QGP signatures studied in BES-I became insensitive or disappeared at energies below $\sqrt{s_{NN}}$ = 19.6 GeV. The fluctuations in the event-by-event net-proton multiplicities exhibited a dip at $\sqrt{s_{NN}}$ ≈ 19.6 GeV and a rise at 7.7 GeV. Motivated by the findings of BES-I, STAR has initiated a phase II of the BES program (BES-II). The BES-II program improves upon the earlier BES-I program with detector upgrades to extend the acceptance, higher luminosity to provide $10-20$ times better statistics at each energy, and a Fixed-Target program to extend the range of BES-II below the expected critical point. In this poster, results from the first dedicated fixed-target physics run at $\sqrt{s_{NN}}$ = 3 GeV will be presented. The run used a 250 $\mu$m thick gold target and accumulated 335 million Au+Au events. We present proton (and anti-proton) yields and multiplicities. These measurements will be compared with results from AGS experiments E866 and E895. We will discuss the implications of the observed multiplicities and efficiency corrections to the study of cumulants of event-by-event net-proton multiplicities up to the fourth order as a function of rapidity. It is expected that this collision energy of $\sqrt{s_{NN}}$ = 3 GeV should fall below the transition to QGP, therefore measurements at this energy will test for the return of the critical fluctuations to the expected baseline. Results at this energy will help understand the trends observed in the previous results from the BES program and preliminary results from HADES. Additionally, we will discuss the future of BES-II fixed-target measurements at RHIC.

        Speaker: Daniel Cebra (University of California, Davis)
      • 17:40
        QLBT: The Linear Boltzmann Transport model for heavy quarks with a medium of quasi-particles 20m

        Heavy quarks are ideal probes of the QGP matter. To consistently describe the medium evolution and heavy-quark-medium interaction, we improve the linear Boltzmann Transport (LBT) model [Phys. Lett. B777 (2018) 255-259] by modeling QGP as a collection of quasi-particles with equation of state (EOS) fitted to the lattice QCD data. We call this QLBT model, in which the in-medium scatterings of heavy quarks are described using the linear Boltzmann transport that includes both elastic and inelastic energy loss of heavy quarks within the perturbative QCD framework. The temperature dependences of the quasi-particle masses, as well as the strong coupling parameter among them, are systematically extracted from two different sets of lattice EOS (Hot QCD and Wuppertal­-Budapest) with a Bayesian statistical analysis method. With all model parameters fixed by the lattice QCD calculations, QLBT naturally provides a good description of the nuclear modification factors and elliptic flow coefficients of heavy mesons at high transverse momenta. Systematical uncertainties arising from applying two different lattice equations of states are evaluated and turn out to be small for heavy flavor observables.

        Speaker: Feng-Lei Liu (CCNU)
      • 17:40
        Quantitative evaluation of muon track matching efficiency with Muon Forward Tracker and Muon Spectrometer at ALICE 20m

        \documentclass{article}
        \usepackage[utf8]{inputenc}

        \title{Quantitative evaluation of muon track matching efficiency with Muon Forward Tracker and Muon Spectrometer at ALICE}
        \author{Kaede Kamano for the ALICE collaboration}
        \date{June 2019}

        \begin{document}

        \maketitle

        ALICE has been designed to study the quark-gluon plasma in heavy-ion collisions at LHC. Extensive efforts in the ALICE upgrade projects are currently being made toward LHC-Run3 (2021-2024). The Muon Forward Tracker (MFT), one of the new detectors, will be installed upstream of the hadron absorber in front of the Muon Spectrometer (MUON). The vertex information is smeared out with the present MUON setup due to multiple scattering occurring in this absorber. This prevents us from precisely measuring the track direction which plays a crucial role in determining the mass resolution especially in the low transverse momentum region. The chiral nature of the phase transition can be investigated via low mass vector meson measurements with superior mass resolution provided by MFT. The present uncertainty in the vertex region prevents us from distinguishing between charm and beauty, and between prompt and displaced J/$\psi$.\par
        The matching performance between MFT and MUON is therefore crucial to improve the dimuon mass resolution and reject muons from hadron decays in the hadron absorber. The matching efficiency is calculated including multiple scatterings in the hadron absorber simulated by Geant4. The measured charged particle multiplicity and a quality of muon tracks are carefully taken into account in the calculation. In this poster, we present the results of the evaluation of the muon track matching efficiency.

        \end{document}

        Speaker: Kaede Kamano (Nara Women's University (JP))
      • 17:40
        Quantum dissipation in the quarkonium evolution by Lindblad master equation 20m

        In heavy ion collisions, physical properties of quark-gluon plasma(QGP) have been long studied. In these experiments, survival probability of quarkonia, which are bound states of the heavy quark and antiquark pair, is expected to be a good probe to the formation of the QGP. Their dynamics has been studied to interpret the experimental data.

        A quarkonium can be theoretically described by master equation for the density matrix in the framework of open quantum system. It allows us to describe the Langevin dynamics of quarkonia in a quantum mechanical manner. In particular, quantum dissipation as well as decoherence of quarkonia attract much attention recently.

        In this study, we consider the relative motion of a heavy quark pair in the QGP. We derive and numerically simulate the master equation in the Lindblad form in one spatial dimension. We analyze the effects of the quantum dissipation to its equilibration. We also discuss whether or not the dissipative process of quarkonium is significant in heavy-ion collisions by simulating in a short-lived Bjorken expanding QGP.

        Speaker: Takahiro Miura
      • 17:40
        Quantum kinetic theory for Dirac fermions in curved spacetime 20m

        Many-body systems with chiral fermions exhibit anomalous transport phenomena originated from quantum anomalies. Based on quantum field theory, we derive the quantum kinetic theory for Dirac fermions interacting with an external electromagnetic field in a background curved geometry. The resultant framework is U(1) gauge invariant and local Lorentz and diffeomorphism covariant. In this talk, I will illustrate the gravitational or noninertial effects for Dirac fermions. We study the chiral dynamics in a rotating coordinate and clarify the roles of the Coriolis force and spin-vorticity coupling in generating the chiral vortical effect. We also show that the chiral vortical effect is an intrinsic phenomenon of a rotating chiral fluid, and thus independent of the observer's frame. The framework is also available for massive fermions. We derive the kinetic equation and spin evolution equation for massive fermions, and calculate the spin polarization induced by vorticity and magnetic field via kinetic theory.

        Speaker: Yu-Chen Liu (Fudan University)
      • 17:40
        Quark-hadron continuity beyond Ginzburg-Landau paradigm 20m

        Quark-hadron continuity [1] is a scenario that the hadronic matter is continuously connected to a color superconducting phase without phase transitions as the baryon chemical potential increases. This scenario is based on the fact that the two phases have the same symmetry breaking pattern, in the spirit of Landau's classification of phases. When we consider quantum phases of matter, it is known that the classification based on symmetry is insufficient: it fails to detect so-called topological orders. We address the question whether this continuity is true as quantum phases of matter, which requires the treatment beyond Ginzburg-Landau description [2,3].
        To examine the topological nature of color superconductor, we study the low-energy theory describing U(1) Nambu-Goldstone (NG) bosons and vortices of the color-flavor locked phase, and discuss the fate of emergent higher-form symmetries. The theory has the form of a topological BF theory coupled to NG bosons, and fractional statistics of test quarks and vortices arises as a result of an emergent Z3 two-form symmetry. We find that the two-form symmetry is not spontaneously broken, indicating that quark-hadron continuity is still a consistent scenario.

        [1] T. Schafer and F. Wilczek, Phys. Rev. Lett. 82, 3956(1999).
        [2] Y. Hirono, Y. Tanizaki, Phys. Rev. Lett. 122, 212001(2019).
        [3] Y. Hirono, Y. Tanizaki, [arXiv:1904.08570]

        Speaker: Yuji Hirono (Asia Pacific Center for Theoretical Physics)
      • 17:40
        Quarkonia as an Open-Quantum-System 20m

        Quarkonia suppression has been long predicted \cite{satz19861} and explored as a defining signature of formation of quark-gluon-plasma (QGP). Various physical processes \cite{satz19861,laine20071,brambilla20081} have been understood to contribute to the dynamics of a Q-$\bar{Q}$ traversing through the QGP. The proper framework to implement a Schr\"{o}dinger equation, which takes into account the dynamical nature of the above problem, is treating the system as an open quantum system \cite{akamatsu20121,akamatsu20151}.

        In our calculation, we implement a stochastic Schr\"{o}dinger equation which describes the evolution of the Q-$\bar{Q}$ pair starting from a pure state.
        In the first part, we start with an extension of the results obtained in \cite{akamatsu20181} by extending the calculation to three-dimensional case and including the full-color structure of a Q-$\bar{Q}$ pair (including color-octet states as well). We do so by expanding the equations obtained in \cite{akamatsu20151} in small $\vec{r}$ limit. This is not an ad hoc approximation but is rather motivated by the idea of effective-field-theory (EFT) methods, such as pNRQCD \cite{brambilla20081}. Further, in a simple calculation, we check how much of an error small `$\vec{r}$' expansion brings. This is an example of a Markovian process as shown in \cite{akamatsu20151}. This formalism does not include on-shell gluon emission or absorption.

        The second part of the calculation is a dynamical implementation of the physical process called gluo-dissociation \cite{brambilla20081} by the means of stochastic evolution. This necessarily involves kernels which remember correlation in time as the process occurs at a finite frequency. This is an example of a non-Markovian process. If one wants to use results from lattice (since the QGP formed at RHIC and LHC is an example of a strongly coupled system), one would like to understand the relative importance of these physical processes. We suggest that this can be done by comparing correlation functions of color electric-fields at zero and non-zero frequencies. It appears that non-Markovian dynamics will play an important role when higher-excited states are considered.

        \bibitem{satz19861}
        T. Matsui, H. Satz, (1986),
        \emph{Phys.Lett.B178,(1986),416-422}

        \bibitem{laine20071}
        M. Laine, O. Philipsen, (2006), \emph{JHEP 0703,(2007), 054}

        \bibitem{brambilla20081}
        N. Brambilla, J. Ghiglieri, A. Vairo, P. Petreczky, (2008), \emph{Phys.Rev.D 78,(2008),014017}

        \bibitem{akamatsu20121}
        Y. Akamatsu, A. Rothkopf, (2012), \emph{Phys.Rev.D 85,(2012),105011}

        \bibitem{akamatsu20151}
        Y. Akamatsu (2015), \emph{Phys.Rev.D 91 (2015),056002}

        \bibitem{akamatsu20181}
        Y. Akamatsu, A. Rothkopf, S. Kajimoto and M. Asakawa (2018), \emph{Phys.Rev.D 97 (2018),014003}

        Speaker: Mr Anurag Tiwari (Tata Institute of Fundamental Research)
      • 17:40
        Quarkonium dynamics with colorful stochastic potential 20m

        In heavy ion collision experiments at RHIC and LHC, quarkonium yields have been measured at various collision energies. The experimental findings reveal different characteristic behavior: sequential suppression dominates for bottomonium and recombination for charmonium. A comprehensive understanding of this phenomenology requires a genuine quantum mechanical treatment, in particular to capture the phenomenon of decoherence central to a unified description of suppression and recombination.

        Recently progress has been made in understanding the in-medium dynamics of a quarkonium based on the framework of open quantum system. It allows us to derive the dynamics of quarkonium in the quark-gluon-plasma systematically from QCD and already has helped improve our understanding of the complex in-medium potential. In a previous study, based on the stochastic potential approximation [1], we have elucidated the role of decoherence on the stability of in-medium heavy quarkonium, identifying it as a novel mechanism for quarkonium dissociation via scattering with the medium [2], in addition to the well-known Debye screening.

        In this talk we present results [3], where for the first time color degrees of freedom are taken into account in fully quantum mechanical fashion without invoking a semi-classical approximation. I.e. we simulate a genuine color SU(3) stochastic Schrödinger equation. We discuss how SU(3) color degrees of freedom affect the real-time evolution of quarkonium color singlet and octet states. We find the preservation of quarkonium parity in the colorful stochastic potential. We also show how the decoherence proceeds in the color octet states and discuss the availability of classical description for the gluo-dissociation process.

        [1] Y. Akamatsu and A. Rothkopf, Phys. Rev D 85 (2012) 105011;
        [2] S.Kajimoto, Y. Akamatsu, M. Asakawa, and A. Rothkopf, Phys. Rev. D
        97 (2018) 014003.
        [3] S.Kajimoto, Y. Akamatsu, M. Asakawa, and A. Rothkopf (in progress)

        Speaker: Ms Shiori Kajimoto (Osaka University)
      • 17:40
        Readout electronics for the sPHENIX Time Projection Chamber 20m

        One of the major physics goals of the sPHENIX experiment at RHIC
        is to major the Upsilon states with 100MeV mass resolution. In order to
        achieve this resolution, a Time Projection Chamber (TPC) was proposed
        for momentum measurements of electrons and hadrons. The TPC does
        not have a gating grid similarly to the ALICE TPC case and therefore
        capable for handing the collision rate of up to a few hundreds KHz.
        In turn, the charge has to be readout continuously. The readout
        electronics was newly designed to meet this requirement. The signal is
        readout by 624 Frontend cards that have 8 SAMPA v5 chips, the new
        version of the one employed for ALICE TPC, and sent to a backend
        electronics, FELIX PCI card, designed for ATLAS experiment. The data
        rate from the whole TPC may reach as much as 1.4Tbps. We will show
        the readout scheme for the TPC and the performance from the prototype
        boards as well as the data reduction scheme.

        Speaker: sPHENIX Collaboration
      • 17:40
        Recent measurements of hadronic resonances in small systems at ALICE 20m

        Hadronic resonances are unique and useful probes of ion-ion collision systems. They can be used to study the evolution of the hadrochemistry with system size, including resonance suppression and strangeness enhancement. Resonances can also be used to explore the various mechanisms that influence the shapes of hadron $p_{\mathrm{T}}$ spectra and to search for the possible onset of collective effects in small systems. The ALICE Collaboration has measured a wide variety of mesonic and baryonic resonances in pp and p-Pb collision systems at different energies from low to high charged-particle multiplicities. New results will be reported as functions of the multiplicity, including measurements of the $\mathrm{f}_{0}(980)$ meson in pp collisions at $\sqrt{s}=5.02$~TeV; the $\mathrm{f}_{0}(980)$, $\Sigma(1385)^{\pm}$, $\Lambda(1520)$, $\Xi(1530)^{0}$, and $\Xi(1820)$ resonances in pp collisions at $\sqrt{s}=13$~TeV; and the $\mathrm{K}^{*}(892)$ and $\phi(1020)$ mesons in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ and 8.16 TeV. The results will be compared to measurements from lower energies and discussed in the context of theoretical models.

        Speaker: Jihye Song (University of Houston (US))
      • 17:40
        Reconstruction of neutral mesons in heavy ion collisions using the conversion method with HADES and CBM* 20m

        The Compressed Baryonic Matter experiment (CBM) and the High Acceptance Di-Electron Spectrometer (HADES) are part of a worldwide research program devoted to study the phase diagram of strongly interacting matter at high baryon densities $\rho_{B}$ and moderate temperatures $T$ in p+A and A+A collisions. One of the major observables addressed by both experiments is dilepton production.

        A central goal is to establish the excitation function of dilepton emission for heavy collision systems. While HADES is studying the lowest collision energies up to 1.5$A$ GeV, CBM, in a first campaign, will continue the excitation function to 12$A$ GeV. Central component of both detector setups is Ring Imaging Cherenkov Detectors (RICH), which are intended to identify and select leptons among all other particles.

        Dalitz decays of long-lived neutral mesons ($\pi^0$, $\eta$) constitute an important source of dielectrons in the LMR (hadronic cocktail). The presented analysis aims to reconstruct neutral mesons using conversion ($\pi^0/\eta \rightarrow \gamma\gamma \rightarrow (e^+e^-)+(e^+e^-)$ or $\pi^0/\eta \rightarrow e^+e^-\gamma \rightarrow e^+e^-+(e^+e^-)$) inside the target or in first detector layers in order to provide an independent measurement of the respective multiplicities needed to constrain the hadronic cocktail with sufficient precision. Proper counting of these mesons requires an exact description of the combinatorial background below $\pi^0/\eta$ invariant mass peaks, which is achieved using the event mixing technique.

        The poster will present first results from the conversion based analysis of $\pi^0$ and $\eta$ multiplicities using the new HADES data set obtained for Ag+Ag at 1.58$A$ GeV collisions in spring this year. For this run, the photon detector of HADES RICH was replaced by a newly developed MAPMT based system also foreseen for CBM. The performance obtained in the HADES run was studied in details and consistently introduced in the CBM experiment simulation framework.
        Respective results of performance studies of the CBM experiment will also be shown.

        $\text{*supported by BMBF 05P15PXFCA and GSI}$

        Speaker: Dr Ievgenii Kres (University of Wuppertal)
      • 17:40
        Relaxation to CKW state in a transport calculation 20m

        Using a transport model based on BAMPS, we investigate the evolution of magnetic field in a system of charged particles, which is embedded in a cylinder with the periodic boundary condition. We find that when the ratio of the helicity to the magnetic energy goes to a maximum, the system relaxes towards the CKW state with ∇×B∥B and we test the result both in classical plasma and QGP.

        Speaker: Mr Zeyan Wang (Tsinghua University)
      • 17:40
        Results from open charm production at LHCb in pPb 20m

        Within proton-lead collisions collected by the LHCb detector at nucleon-nucleon center-of-mass energy of 5 and 8.16 TeV, a rich set of open charm hadrons is observed with abundant statistics. Thanks to the LHCb forward acceptance that is complementary to general purpose detectors and excellent performance in particle reconstruction and identification, these charm states are studied down to zero $p_T$ with overwhelming precision in heavy ion data. Presented in this talk is the measurements of production of charm mesons and baryons reconstructed in exclusive hadronic final states. Nuclear effects are studied, quantified by the nuclear modification factors, forward-to-backward production ratios and baryon-to-meson ratios. The impact of the results, in particularly, on the improvement of nuclear PDF and parton saturation are discussed.

        Speaker: Jianqiao Wang (Tsinghua University (CN))
      • 17:40
        Rotation Induced Novel Condensation in a Magnetic Field 20m

        We mainly focus on the effect of rotation on the QCD phase structure in a background magnetic field. We analyze the energy spectra of Dirac fermions in the presence of rotation and magnetic field. We find that the Landau degeneracy is resolved by rotation. A drastic change in the energy dispersion relation leads to the “rotational magnetic inhibition” that is a novel phenomenon analogous to the inverse magnetic catalysis in a magnetic system at finite chemical potential. Then we take in to account the boundary condition to perserve the casuality find that mode accumulation at the boundary occurs for large angular momenta and that the magnetic effect is enhanced on the boundary surface. Using a simple fermionic model, we confirm that the magnetic catalysis is strongly amplified at the boundary due to the mode accumulation. Besides, we also find that there is a competition between the rotational inhibition of the spin zero pairing and the enhancement of the pion BEC.

        Speaker: Mr Hao-Lei Chen (Fudan University)
      • 17:40
        Search for axion-like particles at Electron-ion collider: higher luminosity, brighter perspective 20m

        We study the promising perspective of search for axion-like particles (ALP) at the future electron-ion collider experiments. ALP could be the candidate for the dark matter of the universe. We calculate the production rate for those ALPs which are coupled to photons at electron-ion collider. Because of the large gamma factor for the electron but more prominently due to the achievable high luminosity at EIC, the number of such ALPs produced per year through light-by-light scattering at EIC can be sizable if their masses are within the range between 10 GeV and 100 GeV. This is in turn would provide unprecedented constraint on ALP in this mass range. Furthermore, we also show the possibility of constraining Axion-gluon coupling if gluon saturation scenario is achieved at EIC.

        Speaker: Dr Yi Yin (MIT)
      • 17:40
        Search for the QCD Critical Point by Transverse Velocity Dependence of Anti-deuteron to Deuteron Ratio 20m

        The QCD critical point can attract the system evolution trajectory in the QCD phase diagram, which is recognized as the QCP focusing effect[1,2]. To quantify this effect, we employ thermal model and hadronic transport model to simulate the dynamical particle emission along a hypothetical focusing trajectory near the critical point. It is found that the focusing effect can lead to anomalous $\beta_T$ dependence of anti-pariticle to particle ratio. Heavier light anti-nuclei to light nuclei ratios are more sensitive to the focusing effect in the vicinity of critical point.

        In this talk, We will present the $\beta_T$ dependence of $\bar{d}/d$ ratio in Au+Au collisions at $\sqrt{s_{NN}} = $ 11.5-200 GeV measured by the STAR experiment at RHIC. We observed a negative slope of the $\beta_T$ dependence of $\bar{d}/d$ ratio at 19.6 GeV, although the statistical and systematical errors are large. It might indicate the trajectory evolution has passed through the critical region. Further constraint of the location of the critical point and/or width of the critical region can be studied by making precise measurements in the RHIC BES-II.

        [1] M. Asakawa, S. A. Bass, B. Muller, and C. Nonaka, Phys. Rev. Lett. 101, 122302 (2008)
        [2] C. Nonaka and M. Asakawa, Phys. Rev. C 71, 044904 (2005)

        Speaker: Ning Yu (Xinyang Normal University)
      • 17:40
        Semi-inclusive hadron-jet productions in pp collisions at $\sqrt{s}=$ 5.02 TeV with ALICE 20m

        The measurement of reconstructed jets over a wide range in jet energy and jet resolution parameter $R$ is required for comprehensive understanding of jet quenching in heavy-ion collisions. Such measurements are challenging, however, due to the presence of complex, uncorrelated background to the jet signal, and the need to minimize biases in the selected jet population imposed by background suppression techniques.

        In this contribution, we present an approach to measure jets using the semi-inclusive distribution of charged jets recoiling from a high-$p_{\rm T}$ charged hadron trigger in pp collisions at $\sqrt{s}=$ 5.02 TeV, with emphasis on the region of low recoil jet $p_{\rm T}$ by taking the advantages of the high statistics collected with ALICE. The semi-inclusive recoil jet measurement provides precise, data-driven suppression of the large uncorrelated background and uniquely enables the exploration of medium-induced modification of jet production over wide phase space, including low $p_{\rm T}$ for large jet resolution parameter $R$. Such measurement provides a good test for pQCD calculations, and sets as a reference for jet quenching study in nucleus-nucleus collisions.

        Speaker: Yuxing Dang (Central China Normal University CCNU (CN))
      • 17:40
        Sensitivity analysis of the chiral magnetic effect observables using a multiphase transport model 20m

        The chiral magnetic effect is a good observable to investigate the topological and electromagnetic properties of the QGP. But the $\gamma$ correlator, a common observable used to detect the CME, contains both contribution from the CME and its background. This observable can not identify the CME from its background. Recently, a new observable of $R_{\Psi_{m}}$ has been proposed[1-4], which is expected to distinguish the CME from the background. We apply mixing particles method and shuffling particles method to calculate $R_{\Psi_{m}}$ using a multiphase transport model without or with a percentage of CME-induced charge separation[5,6]. From the results, we found that the shape of final $R_{\Psi_{2}}$ distribution is flat for the case without CME[7], but concave for that with some amount of the CME. By comparing the responses of $R_{\Psi_{2}}$ and $\gamma$ to the strength of the CME, we found that the CME signal can survive only when the initial charge separation percentage is large enough (more than $5\%$), which indicates a nonlinear sensitivity of these observables to the CME due to strong final state interactions.

        [1]N. N. Ajitanand, R. A. Lacey, A. Taranenko, J. M. Alexander, Phys. Rev. C 83. 011901 (2011), [arXiv:1009.5624].

        [2]N. Magdy, S. Z. Shi, J. F. Liao, N. Ajitanand, R. A. Lacey, Phys. Rev. C 97. 061901 (2018), [arXiv:1710.01717].

        [3]Y. C. Feng, J. Zhao, F. Q. Wang, Phys. Rev. C 98. 034904 (2018), [arXiv:1803.02860].

        [4]P. Bo$\mathrm{\dot{z}}$ek, Phys. Rev. C 97. 034907 (2018), [arXiv:1711.02563].

        [5]G. L. Ma, B. Zhang, Phys. Lett. B 700. 39 (2011), [arXiv:1101.1701 [nucl-th]].

        [6]L. Huang, C. W. Ma, G. L. Ma, Phys. Rev. C 97. 034909 (2018), [arXiv:1711.00637].

        [7]L. Huang, M. W. Nie, G. L. Ma, [arXiv:1906.11631].

        Speaker: Ling Huang (Shanghai Institute of Applied Physics)
      • 17:40
        Sensitivity to detect ultra-intense magnetic field in Pb-Pb collisions via dimuon polarization measurement at the ALICE experiment 20m

        In non-central nucleus-nucleus collisions, an ultra-intense magnetic field reaching 10^15 [Tesla] is generated. Many interesting phenomena such as non-linear QED and Chiral Magnetic Effect are expected to be induced under the field. Nucleus-nucleus collisions are the only one way to generate such a field and to study the field-induced phenomena experimentally.
        Di-leptons from virtual photons are a unique tool for probing such an ultra-intense magnetic field because virtual photons should decay into di-leptons with nonuniform decay planes with respect to the field due to the field-induced birefringence in vacuum.
        To get more precise data, ALICE will install a new detector “Muon Forward Tracker (MFT)” in front of hadron absorber of Muon Spectrometer. MFT allows us to approach more accurate information about vertex of dimuons. This is expected to reduce background muons mainly from charged pions or kaons.
        In this poster, the sensitivity for detecting the field by polarization of di-muons from virtual photons will be discussed.

        Speaker: Takumi Osako (Hiroshima University (JP))
      • 17:40
        Separating quark and gluon jet distributions in heavy ions 20m

        Current measurements of the modification of jets in the quark–gluon plasma necessarily average over the quark–gluon composition of the jets in the sample. This introduces substantial complications in measuring differences of energy loss and modification between quark-initiated and gluon-initiated jets. Additionally, even in the absence of jet modification, a modified quark–gluon fraction of jets in heavy-ion collisions could give rise to a substantial apparent modification arising just from differences between the production properties of quark- and gluon-initiated jets. We demonstrate a fully data-driven method for separating contributions to jet observables coming from quark- and gluon-initiated jets using a statistical technique called topic modeling. Assuming that jet observable distributions are a mixture of underlying quark and gluon distributions enables us to extract those distributions and their relative fractions from dijet and photon+jet samples. As a proof of concept, we extract the fractions of quark- and gluon-initiated jets as a function of $p_T$ and separately compute $R_{A A}$ for quark and gluon jets. We furthermore use this method to distinguish between modification of an observable that arises from modification of the quark–gluon fraction versus modification of that observable individually for either quark or gluon jets. We show that this distinction is of central importance to even qualitative interpretations of jet modification observables in heavy-ion collisions.

        Speaker: Andrew Turner (Massachusetts Institute of Technology)
      • 17:40
        Shear viscosity of ultrarelativistic Boson systems in the presence of Bose-Einstein condensate 20m

        We calculate the shear viscosity of ultrarelativistic Boson systems in the presence of Bose-Einstein condensate (BEC). Two different methods are used. One is the Grad’s method of moments and another is the Green-Kubo relation within a kinetic transport approach. In this work we consider a Boson system with isotropic elastic collisions and a gluon system with elastic scatterings described by perturbation QCD (pQCD). The results show that the presence of BEC lowers the shear viscosity. This effect becomes stronger for the increasing proportion of the BEC in the Boson system and is insensitive to the detail of interactions.

        Speaker: Mr Zhengyu Chen
      • 17:40
        Shedding new light on the photon and dilepton spectral functions 20m

        Photons and dileptons offer themselves as 'clean' probes of the quark-gluon plasma because they are unlikely to reinteract once produced. Their emission rates are given via the vector spectral function $\rho_{\mu\nu}$, an object that can ultimately be reconstructed by analytic continuation of lattice data. To help scrutinise ensuing systematic uncertainties, we determine the NLO corrections to $\rho_{\mu\nu}$ in all domains that affect the associated imaginary-time correlator, namely for energies above, below and in the vicinity of the light cone.

        Speaker: Greg Jackson (University of Bern)
      • 17:40
        Signatures of Chiral Magnetic Effect in Isobaric Collisions 20m

        Chiral Magnetic Effect (CME) is the macroscopic manifestation of the fundamental chiral anomaly, and emerges as an anomalous transport current in a many-body system of chiral fermions such as the hot quark-gluon plasma created in heavy ion collisions. Experimental observation of CME would provide a tantalizing evidence for the chiral symmetry restoration as well as QCD topological fluctuations. Measurements at RHIC and LHC so far show intriguing hints but remain inconclusive, due to strong background contamination and relatively small CME signal. To address these challenges and to understand sensitivity of various proposed observables, it is crucial to have a sophisticated modeling framework that realistically quantify both the CME signal and background correlations. In this talk, we present such a new tool, the Event-By-Event Anomalous Viscous Fluid Dynamics (EBE-AVFD) framework. The EBE-AVFD starts with event-wise fluctuating initial conditions for the bulk+axial charge+magnetic fields, simulates the evolution of fermion currents in QGP on top of the data-validated bulk fluid evolution from either VISHNU or MUSIC, samples freeze-out particles with local charge conservation implemented, to be followed by URQMD hadron scattering stage that includes resonance decay contributions. We use this tool to characterize the various features of CME signal and related backgrounds, to validate the simulation parameters with existing experimental data, and to investigate the sensitivity of several different observables with respect to signal and backgrounds. Finally, we present the state-of-the-art quantitative predictions for the CME signatures in isobaric collisions (RuRu v.s. ZrZr), which will provide the unique opportunity for potential discovery of CME in heavy ion collisions.

        Refs: CPC42(2018)011001; AnnalsPhys.394(2018)50; NPA967(2017)748; NPA982(2019)539; in preparation

        Speaker: Hui Zhang
      • 17:40
        Simulating chiral anomalies in a box system 20m

        We have investigated the chiral anomalies with transport simulations in a box system. In the box system with the periodic boundary condition under a uniform magnetic field, the chiral magnetic effect and the chiral magnetic wave were simulated based on the spin kinetic equations of motion (SEOM) and the chiral kinetic equations of motion (CEOM), with the latter derived from the SEOM for massless particles with approximations. We found that the chiral magnetic effect is weaker while the damping of the chiral magnetic wave is stronger from the SEOM compared with that from the CEOM, and they are both weaker than the analytic results. In addition, effects induced by chiral anomalies from the SEOM are less sensitive to the decay of the magnetic field than from the CEOM due to the spin relaxation process. Furthermore, effects of the temperature, the magnetic field, and the specific shear viscosity on the key properties of the chiral magnetic wave with different scenarios are discussed.

        Speaker: Mr WenHao Zhou (Shanghai Institute of Applied Physics, CAS)
      • 17:40
        Simulations of thermal dielectrons for the CBM experiment 20m

        The Compressed Baryonic Matter (CBM) experiment will access a wide range of physics observables for heavy-ion collisions in the region of highest net-baryon densities. One of the core topics of its physics program are the measurement of rare thermal dilepton channels. These EM probes have a very low cross section and therefore need very high statistics and a powerful particle identification. The combination of the Ring-Imaging Cherenkov Detector (RICH) and the Transition Radiation Detector (TRD) provide a good electron identification over the whole momentum range and especially for the study of thermal radiation into dielectrons at intermediate masses the electron identification capabilities of the TRD are crucial. The measurement of thermal dileptons in the intermediate mass range and at different energies of the CBM energy range would provide a better understanding of the excitation function and therefore could give insights about potential phase transitions in CBM’s region of the QCD phase diagram. This contribution will present the newest simulations at different collision energies of spectra of dielectrons and the extraction of the fireball parameters from dielectrons at intermediate masses.

        Speaker: Christoph Blume (Johann-Wolfgang-Goethe Univ. (DE))
      • 17:40
        SiPM testing for the sPHENIX electromagnetic and hadronic calorimeters 20m

        The electromagnetic (EMCal) and hadronic (HCal) calorimeters for the sPHENIX
        experiment will use about 100,000 silicon photomultipliers (SiPMs) as optical sensors (Hamamatsu S12572-33-015P). The effects of radiation damage in SiPMs from gamma rays has been measured and compared with the damage produced by neutrons. We have designed and constructed an automated SiPM testing device that measures the breakdown voltage and gain curve with the IV scan and SPS (single photon spectrum) method. It is being used to characterize SiPMs for the sPHENIX calorimeters and to prepare a database for SiPM sorting. We will report on the first months of operational experience, including precision, stability and reproducibility of the measurements, consistency with the available factory data, and the projected effect of the SiPMs on the overall calorimeter performance in sPHENIX.

        Speaker: sPHENIX Collaboration
      • 17:40
        Smallest QCD Droplet for Hydrodynamic Response via Gubser Flow 20m

        Over the past years, the observed features in the collisions of small systems which resemble collective flow patterns, are under intense debates. A relevant question is to what extent these observations are related to the real collective evolution of the medium, and if this is the case, the related question is what is the smallest system size which can still accommodate collective behaviour. The present talk attempts to shed new light on these non-trivial questions. Specifically, we address the following problem: what is the smallest system consistent with hydrodynamic equations and with hydrodynamization time $\tau_\text{hyd} \, T \sim 1$? In order to solve, we employ the Gubser solution as a toy model to perceive the consistency between the hydrodynamization time and the system size. We show that, up to a factor of the order of unity, the rms radius of the system, $\sigma_\text{rms}$, cannot be smaller than the inverse of the square root of the total energy in the transverse plane, $\epsilon_\text{tot}^{1/2}$. According to our simple model, we find that hydrodynamic is applicable for the core of the systems with size $\sigma_\text{rms}\sim 0.5\;$ fm corresponds to the multiplicity around two particles per unit rapidity. However, a large fraction of particles are emitted from the corona part (hadron gas at the tail of the fireball) for such system. On the other hand, for a system with the same size, the events with multiplicity per unit rapidity above 20 are dominated with particles from the core with strong flow signal. Using perturbation on top of Gubser flow, we discuss about the hydrodynamic response of an elliptic initial energy density in small systems.

        Speaker: Dr Seyed Farid Taghavi (Technische Universitaet Muenchen (DE))
      • 17:40
        sPHENIX capabilities for jet-based observables 20m

        The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) benefits from the extensive detector advances driven by LHC and Electron-Ion Collider (EIC) detector R&D. The combination of electromagnetic calorimetry, hadronic calorimetry, precision tracking, and the ability to record data at a very high rates enables measurements of jets, jet substructure, and jet
        correlations at RHIC with a kinematic reach that will overlap with similar measurements at the LHC. Jet observables are a particularly useful probe of the Quark Gluon Plasma (QGP) formed in heavy-ion collisions since the hard scatted partons that fragment into final state jets are strongly “quenched”, losing energy to the medium as they traverse it. To answer fundamental questions about the physics of this process, we need to characterize the medium induced modification of the jet fragmentation pattern and the correlation of the lost energy with the jet axis. The measurements require removal of the soft, underlying event (UE), and we will show the performance of different UE subtraction techniques for calorimetric jets in sPHENIX. The performance of the detector for photon-jet and jet fragmentation observables will also be shown.

        Speaker: sPHENIX collaboration
      • 17:40
        sPHENIX capabilities for measuring $\Lambda_c$ production in Au+Au collisions 20m

        A strong enhancement of $\Lambda_c$/D$^0$ ratio compared to the fragmentation baseline is observed in Au+Au collisions at the top energy of the RHIC. This also suggests that $\Lambda_c$ may be an important component for the total charm cross section. Precision measurements of charm baryons over a broad momentum range are needed for a detailed understanding of hadronization and parton energy loss mechanisms as well as to characterize QGP transport properties. sPHENIX is a planned next-generation high-rate jet, Upsilon and open heavy-flavor detector at RHIC. A state-of-the-art MAPS-based silicon detector (MVTX) is proposed to enhance heavy flavor detection capabilities greatly. We will present simulation studies of $\Lambda_c$ baryon measurements in 200 GeV Au+Au collisions utilizing the full sPHENIX tracking capabilities with MVTX. The simulation method for estimating the expected signal and background will be discussed. Statistical projections of the $\Lambda_c$/D$^0$ ratio will be presented.

        Speaker: sPHENIX Collaboration
      • 17:40
        sPHENIX EMCal design, construction and test beam results 20m

        Abstract: The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) is designed to accurately study proton-proton, proton-nucleus, and nucleus-nucleus collision systems. The design of sPHENIX, including full azimuthal calorimeter coverage, will allow it to precisely study properties of the Quark Gluon Plasma through open heavy flavor production, jet modification, and Upsilon measurements. It will also perform a variety of cold QCD studies. Helping to enable the broad measurement capabilities of sPHENIX is the Electromagnetic Calorimeter (EMCal), which is the primary detector for identifying and measuring the energy of photons and electrons. The EMCal is constructed of scintillating fibers embedded in blocks of tungsten powder in an epoxy matrix, with the emitted light collected with acrylic light guides and read out through Silicon Photomultipliers (SiPMs). This poster will discuss the design and construction of the EMCal as well the results from a 2018 Beam Test.

        Speaker: sPHENIX Collaboration
      • 17:40
        sPHENIX EMCal module prototyping and production plan in China 20m

        The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) will probe the strongly interacting Quark-Gluon Plasma (QGP) with jets, heavy flavor tagged jets and Upsilon production. The sPHENIX electromagnetic calorimeter (EMCal) detector is essential for these measurements. The Chinese sPHENIX EMCal Consortium includes groups from Fudan, PKU and CIAE, and the consortium is planning to build sPHENIX EMCal modules covering the pseudorapidity range ±(0.8–1.1), significantly extending the experimental acceptance and greatly enhancing the physics capability for jets and Upsilon measurements. We will show the status of the Chinese prototyping project including investigations on the quality of tungsten powder from Chinese vendors and the quality assurance procedures under development. We will also report on the status of our development of a machine to precisely place scintillating fibers automatically.

        Speaker: sPHENIX Collaboration
      • 17:40
        sPHENIX MAPS prototype test beam results 20m

        The sPHENIX MVTX detector will be a state-of-the-art monolithic active pixel (MAPS) vertex detector, used by the sPHENIX collaboration, which will allow the study of heavy flavor physics within heavy ion collisions at RHIC. The detector is at an advanced stage of testing with several test beam activities having taken place through 2019. Three test beams have been performed since 2018 to evaluate the physics readiness, the integration of the system with other detectors within sPHENIX (both using four staves, two readout boards and one front end link exchange), and the demonstration of the full readout capability of the minimal detector segment (using eight staves, eight readout boards and one front end link exchange) is expected to be complete by the end the summer of 2019. The results of these tests are being used to drive the collaboration to production-readiness in late 2019 while simultaneously evaluating the track reconstruction software that will be used within the heavy flavor environment experienced by the MVTX.

        Speaker: sPHENIX Collaboration
      • 17:40
        Stability of Israel-Stewart theory in the presence of heat flow 20m

        In this contribution we investigate the properties of the complete Israel-Stewart equations when perturbed around a global equilibrium state. Such analyses have been previously performed including only the effects of the shear-stress tensor and/or bulk viscous pressure and only using the simplified Israel-Stewart equations (which do not include any second order terms, except the one related to the time derivative of the dissipative current). In our studies, we include for the first time the effects of heat flow and study the consequences of the (linear) second order terms that couple the shear stress tensor to the heat flow 4-current. We show that such terms can affect the stability of the theory in the linear regime and find certain bounds that the transport coefficients associated with such terms have to satisfy. Consequences to the fluctuation-dissipation theorem will also be discussed.

        Speaker: Caio Brito (Universidade Federal Fluminense)
      • 17:40
        STAR Measurement of Longitudinal Decorrelation of Elliptic Flow from Au+Au Collisions at $\sqrt{s_{NN}}=$ 200 and 27 GeV 20m

        Measurement of pseudorapidity dependence of local event plane correlations may reveal the possible existence of twist in participant matter density distribution, which provides a novel input in initial conditions of heavy-ion collisions. The factorization ratio, $r_2(\eta)=\frac{\langle V_2(-\eta,\eta^{ref}) \rangle }{ \langle V_2(\eta,\eta^{ref})\rangle }$, has been extensively used to quantify this longitudinal decorrelation of elliptic flow. However, non-flow effects could also contribute to the $r_2$ value. In this poster, in order to distinguish these mechanisms, we explore the dependence of $r_2$ on the $\eta$ coverage of the event plane, $p_T$ of particles of interest, and event shape as a function of centrality based on the STAR data of Au+Au collisions at 27 and 200 GeV. Observation on $\eta$, $p_T$ and beam energy dependence implies possible non-flow contribution. An alternative observable, correlating the forward, backward and midrapidity event planes, $\langle\sin(2(\Psi_{f} -\Psi_{mid,1})) \sin(2(\Psi_{b} -\Psi_{mid,2}))\rangle$, will be carried out to further probe the genuine flow decorrelation. We also compare the STAR measurement with simulation from AMPT, where the model results seem to overpredict the magnitude of $r_2$, presumably arising from the difference in the initial geometry.

        Speaker: Gang Wang (UCLA)
      • 17:40
        STAR measurements on charge-dependent correlations at 27 GeV and implications on search for the Chiral Magnetic Effect at lower collision energies 20m

        The observability of the Chiral Magnetic Effect in heavy-ion collisions has been argued to strongly depend on collision energy because of the variations in the lifetime of magnetic field, the domain size of chiral charge and also on the possibility of formation of a medium with deconfinement and chiral symmetry restoration. While isobar analysis at top RHIC energy is ongoing, in this poster we present an analysis of high statistics data of Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 27 GeV taken by STAR in 2018. In this poster, we will present results on different harmonics of charged dependent two- ($V_n$) and three-particle angular correlations ($\gamma_{1,m,n}$) using the newly installed event plane detector (EPD) which has better resolution compared to previously used BBC. These new measurements with improved precision will be compared to Beam Energy Scan I data and provide important insights on the search for CME at lower collision energies.

        Speaker: Subikash Choudhury (Department of Atomic Energy (IN))
      • 17:40
        Status and Performance of the CBM-TOF systems 20m

        The Compressed Baryonic Matter (CBM) experiment aims at exploring the QCD phase diagram at large baryon densities with heavy ion beams in the beam energy range from 2 A GeV to 11 A GeV at the SIS100 accelerator of FAIR/GSI. For charged particle identification that is required by many observables that are sensitive to the phase structure like collective flow, phase space population of rare hyperons, fluctuations of conserved quantities, … a high performance Time-of-Flight (TOF) wall with a granularity of about 100.000 channels and a system timing resolution of better than 80 ps is being built.. The system comprises Multi-gap Resistive Plate Chambers (MRPCs) in multi-strip configuration with free-streaming readout enabling the measurement of charged particles at a flux of up to 30 kHz/cm2 on the detector surface.
        As part of the CBM-FAIR phase 0 program about 8% of the CBM TOF wall has been installed in the forward hemisphere (1.0 < $\eta$ < 1.5) of the STAR experiment at RHIC/BNL (called eTOF) during the beam energy scan (BES II) campaign which started in the beginning of 2019. Another 5 modules (1600 channels) are installed at miniCBM at SIS18/GSI (also part of FAIR phase 0).
        The status, performance and perspectives of both TOF detector systems will be presented.

        Speaker: Ingo-Martin Deppner (Physikalisches Institut der Universität Heidelberg)
      • 17:40
        Strangeness production in Au+Au collisions at $\sqrt{s_{\rm{NN}}}=27$ and 54.4 GeV at STAR 20m

        Strangeness production is a classic tool to study properties of the quark gluon plasma (QGP). The ratios of particle yields involving strange particles are often utilized to study various properties of nuclear matter, such as the strangeness chemical potential and the chemical freeze-out temperature. In particular, the yield ratios $(N_{K}N_{\Xi})/(N_{\phi}N_{\Lambda})$ and $(N_{K}N_{\Omega})/(N_{\phi}N_{\Xi})$ are suggested in [1] to be sensitive to strange quark density fluctuations. Studying this ratio as a function of collision energy may provide a unique probe to explore the vicinity of the critical endpoint in heavy ion collisions via the fluctuation of strange quark densities. In addition, studying the central-to-peripheral nuclear modification factor $R_{CP}$ of strange hadrons may provide insight into strangeness production mechanisms in nuclear collisions.

        In this poster, we will present new measurements of strange baryons $\Lambda(\bar{\Lambda})$, $\Xi(\bar{\Xi})$ and $\Omega(\bar{\Omega})$ at mid-rapidity using $\sqrt{s_{\rm{NN}}}=27$ and 54.4 GeV Au+Au collisions taken in years 2017 and 2018 by STAR, respectively. With the large data samples (a factor of 10 more minimum bias events compared to previous runs at similar collision energies) and supervised machine learning techniques, we can extend the previous measurements to lower and higher $p_{T}$ regions that have never been explored by STAR. Collision centrality and transverse momentum dependence of the yields will be discussed and compared with thermal calculations. The yield ratios $(N_{K}N_{\Xi})/(N_{\phi}N_{\Lambda})$ and $(N_{K}N_{\Omega})/(N_{\phi}N_{\Xi})$ at $\sqrt{s_{\rm{NN}}}=27$ and 54.4 GeV will be presented and compared with those at other collision energies, and the physics implications will be discussed.

        [1] Che Ming Ko, EPJ Web of Conferences 171 (2018) 03002.

        Speaker: Yue-Hang Leung (Lawrence Berkeley National Laboratory)
      • 17:40
        Strangeness production in carbon-nucleus and argon-nucleus interactions at BM@N 20m

        The BM@N (Baryonic Matter at Nuclotron) is the first experiment started at the accelerator complex of NICA-Nuclotron. The aim of the BM@N experiment is to study interactions of relativistic heavy ion beams with fixed targets. The scientific program comprises studies of nuclear matter in the intermediate energy range between experiments at the SIS-18 and NICA/FAIR facilities. The BM@N experiment has recorded first experimental data with the carbon, argon and krypton beams at the kinetic energy from 2.4 to 4.5 AGeV. First physics results on strangeness production are presented including the measurements of the Lambda hyperon yields in carbon-nucleus interactions at the beam kinetic energies of 3.5, 4.0 and 4.5 AGeV. The yields of positive kaons and pions and the ratios of their production rates in interactions of the 3.2 AGeV argon beam with fixed targets are also presented. The configuration of the BM@N detector setup for the future heavy ion program is shown.

        Speaker: Peter Senger (GSI)
      • 17:40
        Streaming readout of the sPHENIX detector 20m

        The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) will enable a comprehensive measurement of jets in relativistic heavy ion collisions. The detector will cover the full azimuth and a pseudorapidity range of |η| < 1.1. The tracking system will consist of a silicon detector (MVTX) based on MAPS (Monolithic Active Pixel Sensors), followed by an Intermediate Tracker (INTT), and then by a TPC. The calorimetry system consists of an electromagnetic calorimeter, and, for the first time at a RHIC experiment, a mid-rapidity hadronic calorimeter.
        The calorimeter signals are sampled with silicon photomultipliers and waveform digitizing electronics. The digitized waveforms are read out with custom PCIe boards in a ``classic'' event-driven scheme. Conversely, the three tracking detectors are read out in streaming mode, where data are pushed from the front-end and captured continuously. Only streaming data overlapping with RHIC beam crossings that were triggered for the calorimeter readout are permanently stored.
        Streaming readout is widely believed to be the readout method best suited for the detectors at a future Electron-Ion Collider. A sPHENIX TPC prototype has successfully been read out with near-final readout electronics at the Fermilab test beam in streaming mode. The analysis of the streaming data is under way. We will give an overview of the streaming readout technology and present the advantages of the technology, and highlight results from the test beam.

        Speaker: sPHENIX Collaboration
      • 17:40
        Studies of heavy flavor collectivity in pp collisions with the CMS detector at the LHC 20m

        Measurements of long-range, collective azimuthal correlations involving heavy-flavor quarks provide a powerful tool for unraveling the origin of the collectivity observed in small collision systems. In particular, these measurements are sensitive to the early stages of the collisions. As compared to those for light flavor hadrons, large azimuthal anisotropy signals have been observed by CMS for charm hadrons, including prompt $D^{0}$ and J/$\Psi$ particles, in high multiplicity pPb collisions. With new pp data collected by the CMS experiment at the LHC in 2018, collectivity of prompt $D^{0}$ meson is studied in the smallest collision system via measurements of elliptic azimuthal anisotropy ($v_2$) as a function of event multiplicity and transverse momentum. Results are compared to light flavor species, and also to larger pPb and PbPb systems, providing new insights to the heavy quark collectivity developed in small systems.

        Speaker: Liuyao Zhang for CMS Collaboration (Rice University (US))
      • 17:40
        Studies of large-$R$ jets and their substructure in Pb+Pb and $pp$ collisions with ATLAS 20m

        Measurements of the jet substructure in Pb+Pb collisions provide information on the jet quenching in the quark-gluon plasma (QGP) created in these collisions, over a wide range of energy scales. This poster presents ATLAS measurement of the suppression of yields of large-radius jets and its dependence on the jet substructure, characterized by the presence of sub-jets and their angular correlations. This measurement is performed using the large Pb+Pb data sample at the center-of-mass energy of 5.02 TeV recorded in 2018 and compared to the result from $pp$ collisions at the same collision energy. Studies of the suppression of inclusive yields of large-$R$ jets probe the angular redistribution of energy in the parton shower and medium response when compared to existing measurements of suppression of smaller jets. Further, this measurement might provide new information about the scales at which jet constituents lose energy coherently or as independent color charges.

        Speaker: ATLAS Collaboration
      • 17:40
        Study of $R_{2}(\Delta\eta, \Delta\varphi)$ and $P_{2}(\Delta\eta, \Delta\varphi)$ correlation functions in pp collisions at $\sqrt{\textit{s}} = 2.76$ TeV with the PYTHIA and HERWIG models 20m

        We study charge-independent (CI) and charge-dependent (CD) two-particle differential number correlation function, $R_{2}( \Delta\eta, \Delta\varphi)$, and transverse momentum correlation function, $P_{2}( \Delta\eta, \Delta\varphi)$, of unidentified ($h^{\pm}$) and identified (i.e. $\pi^{\pm}, K^{\pm}$ and $p\bar{p}$) charged particles produced in pp collisions at $\sqrt{\textit{s}}$ = 2.76 TeV using PYTHIA and HERWIG models. Correlators $R_{2}$ and $P_{2}$ calculated in the low-$\textit{p}_{\rm T}$ ($0.2 < \textit{p}_{\rm T} \leq 2.0~\rm{GeV}/\textit{c}$), intermediate-$\textit{p}_{\rm T}$ ($2.0 < \textit{p}_{\rm T} \leq 5.0 ~\rm{GeV}/\textit{c}$) and high-$\textit{p}_{\rm T}$ ($5.0 < \textit{p}_{\rm T} \leq 30.0 ~\rm{GeV}/\textit{c}$) transverse momentum ranges exhibit qualitatively similar near-side and away-side correlation structures but feature important quantitative differences. A narrower near-side peak is observed for $P_{2}$ as compared to $R_{2}$ along $\Delta \eta$, similar to recently published results from ALICE in the low-$\textit{p}_{\rm T}$ range for both CI and CD at any given centrality in A-A collisions. This difference is largely due to $\textit{p}_{\rm T}$ dependent angular ordering of hadrons produced inside jets. Comparing the two model predictions for the strength, shape and the width of both the correlators provides underlying particle production mechanism in pp collision. We conclude that future measurements of $R_{2}$ and $P_{2}$ correlators, particularly for high $\textit{p}_{\rm T}$ particles, would shed more light on the internal structure of jets and further the understanding the jet fragmentation function at low momentum fraction ($z$).

        Speaker: Baidyanath Sahoo (IIT- Indian Institute of Technology (IN))
      • 17:40
        Study of ${\rm W}^{\pm}$--boson production in p--Pb and Pb--Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV with ALICE at the LHC 20m

        ${\rm W}^{\pm}$ bosons are created in hard scattering processes at the initial stage of heavy-ion collisions and they are insensitive to the presence of the strongly-interacting medium. This makes them clean probes of the initial-state effects in heavy-ion collisions, such as the nuclear modification of the Parton Distribution Functions (nPDFs). Furthermore, their measurement in heavy-ion collisions is a powerful test of the binary scaling of hard processes as well as a reference for hot-matter effects on other probes.

        In this contribution, focus will be given to the ${\rm W}^{\pm}$ production cross-section measurement in p–Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV. In addtion the status of the ongoing ${\rm W}^{\pm}$ analyses in Pb–Pb collisions at the same center of mass energy will be discussed.

        Speaker: Mingrui Zhao (China Institute of Atomic Energy (CN))
      • 17:40
        Study of (multi-)strange particle production in jets and two-particle correlations with high-$p_{\rm T}$ ${\rm V}^{0}$ particles in small collision systems with ALICE at the LHC 20m

        Recent ALICE results on the yield of strange particles in pp and p-Pb collisions reveal the possibility that similar strange quark production mechanisms could be present in all collision systems. The $p_{\rm T}$-dependent baryon-to-meson yield ratio in hadronic and nuclear collisions is sensitive to the collective expansion of the system, the partonic recombination into hadrons, the jet fragmentation and hadronization.

        In this work, we explore the connection between (multi-)strange hadron yields enhancement and jet production via the measurement of the $p_{\rm T}$-differential spectrum of strange and multi-strange particles (${\rm K}_{\rm S}^{0}$, $\Lambda$, $\overline{\Lambda}$ and $\Xi$) within jets and in the underlying event, in pp collisions at $\sqrt{s}=13$ TeV and p-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV, respectively. To gain insight on the fragmentation of jets containing a ${\rm V}^{0}$s, an alternative approach that uses two-particle correlation is considered. Both the near-side and away-side components of the correlation functions between the high-momentum ${\rm K}_{\rm S}^{0}$, $\Lambda$ and $\overline{\Lambda}$ (${\rm V}^{0}$s) and charged hadrons as a function of $p_{\rm T}$ of the trigger and associated particles as well as the event multiplicity in pp collisions at $\sqrt{s} = 13$ TeV will be presented. The comparison of ratios of yields from ${\rm V}^{0}$-hadron correlations to the yields from hadron-hadron correlations will be discussed as well.

        Speaker: Pengyao Cui (Central China Normal University CCNU (CN))
      • 17:40
        Study of dielectron productions in Pb--Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV with ALICE 20m

        Photons and dileptons ($\gamma^{*} \to l^{+}l^{-}$) are unique tools to study the space-time evolution of the quark-gluon plasma (QGP) produced in high-energy heavy-ion collisions.
        The space-time evolution of heavy-ion collisions can be calculated using relativistic hydrodynamics and hadronic transport models.
        Up to the present time, theoretical models fail to describe the large direct photon yields and the large elliptic flow simultaneously.
        One advantage to measure direct photons via dielectrons from virtual direct photons is that the background from $\pi^{0}$ decays can be significantly reduced compared to real photon measurements by selecting invariant mass region at $M_{ee} > M_{\pi^{0}}$.
        The fraction of direct virtual photon to inclusive virtual photon in the kinematic region of $p_{\rm T}^{ee} \gg M_{ee}$ is expected to be identical to that of real photons in the $M_{\gamma^{*}} \to 0$ limit.
        Therefore, measurements of direct virtual photons are independent and complementary to those of real direct photons.
        Finally, thermal virtual photons are expected to contribute to the direct virtual photon yield at $p_{\rm T} < 3$ GeV/$c$, providing information about the thermalization of the system.
        In ALICE, electrons can be identified by TPC, ITS and TOF at mid-rapidity.
        The LHC provided Pb--Pb collisions in 2018 and ALICE accumulated about 90M events in centrality 0-10 \% which is 9 times larger than the 2015 data, and 80M events in 30-50 \% centrality.
        In this poster, the status of the dielectron analyses in Pb--Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV with the ALICE data recorded in 2018 will be presented.

        Speaker: Daiki Sekihata (University of Tokyo (JP))
      • 17:40
        Study of in-medium momentum broadening with photon-jet momentum correlations in PbPb collisions at 5.02 TeV in the CMS experiment 20m

        Studies of jet energy loss and momentum broadening with photon-jet momentum and angular correlations will be presented, with PbPb data at 5.02 TeV collected by the CMS detector. Photon-jet events provide a means of probing in-medium jet energy loss with good constraints on the initial parton kinematics and flavour. Studies of momentum and angular correlations in photon-jet events can enable precision measurements of jet quenching effects, such as energy loss and momentum broadening, which are important towards a full understanding of the underlying mechanisms of jet quenching.

        Speaker: Ran Bi for CMS Collaboration (Massachusetts Inst. of Technology (US))
      • 17:40
        Study of medium-induced modifications of dijet energy balance, jet substructure distributions, and medium response to dijets with 5.02 TeV PbPb and pp collisions at CMS 20m

        Jet quenching is one of the well-established signatures of the quark-gluon plasma produced in heavy ion collisions. Studies of energy balance for back-to-back hard probes, as well as medium-induced modifications to jet shapes and fragmentation functions, provide important experimental constraints for theoretical understanding of QGP properties. Using large sample of dijet events from 5.02 TeV PbPb and pp collisions recorded by CMS, we study quenching effects differentially with respect to dijet momentum asymmetry. We use jet-track correlations to assess medium-induced modifications to jet substructures on each side of the dijet, and correlate the observed effects with medium response to dijet propagation.

        Speaker: Jussi Viinikainen (University of Illinois at Chicago (US))
      • 17:40
        Study of spin polarizations in an angular momentum conserved chiral kinetic transport model 20m

        The anomalous side-jump mechanism is a Lorentz invariant and angular momentum conserved approach to include the spin-orbital interactions in scatterings of chiral fermions [1]. In the present study, we incorporate for the first time this mechanism in a transport model that is based on the chiral kinetic equations. For a system of rotating and unpolarized quarks in a box, we find that the side-jump mechanism can dynamically generate the spin polarization of quarks with its final value consistent with that of massless quarks in thermal equilibrium in a self-consistent nonzero vorticity field. The total angular momentum of the system is also seen to be conserved during the evolution of the system. We further employ this angular momentum conserved chiral transport model to study the spin polarizations of quarks in relativistic heavy ion collisions. Besides the global polarization of massless quarks, results from this model can also help understand the puzzles in the local spin polarizations measured in experiments at the Relativistic Heavy Ion Collider [2].
        [1]J.-Y. Chen, D. T. Son, and M. A. Stephanov, Phys. Rev.Lett. 115, 021601 (2015)
        [2]S. Y. F. Liu, Y. Sun and C. M. Ko, Inpreparation

        Speaker: Shuai Liu (Texas A&M University)
      • 17:40
        Study of the charm quark production mechanisms through angular correlation of dielectrons in pp collisions with ALICE at the LHC 20m

        The aim of relativistic heavy-ion collisions is to investigate the properties of the Quark-Gluon Plasma (QGP) created at high-enough temperatures and/or densities. For this purpose, heavy-quarks, i.e. charm and beauty, are very useful probes for the characterization of the QGP. They are produced at the early stages of the collisions via initial hard scatterings and, therefore, they experience the full evolution of the system. However, to quantify the QGP effects it is first needed to understand the heavy-quark production in proton-proton collisions as a reference system and further in p-Pb collisions to subtract cold nuclear matter effects. In particular, the production mechanisms of heavy flavours can be studied through their angular correlations which is inherited by their decay products, such as electrons.

        At leading order the heavy-flavour pair is created back to back through flavour creation. On the other hand, PYTHIA creates pairs also via higher order processes like flavour excitation and gluon splitting with different angular correlation functions. While gluon splitting produces pairs with small angles, flavour excitation processes produce pairs without preferred angular correlation. In this poster we present the current analysis of angular distribution functions between correlated heavy-flavour electron-positron pairs in proton-proton collisions at a centre of mass energy $\sqrt{s}$ = 13 TeV measured with the ALICE detector and the comparison with simulated mechanisms processes obtained by PYTHIA and POWHEG generators. Angular correlation functions will also be compared to HVQMNR NLO calculations, which show that they are sentistive to $k_{\rm T}$ broadening.

        Speaker: Hermann Franz Degenhardt (Universidade de Sao Paulo (BR))
      • 17:40
        Study of the soft and hard production as a function of the event multiplicity and the Relative Transverse Activity Classifier 20m

        The study of charged-particle production in small systems as a function of event multiplicity has exhibited many of the features of collective behaviour found in heavy-ion collisions. Event multiplicity dependent studies may be subject to significant autocorrelation bias due to jet production. In order avoid these effects, a new multiplicity estimator has been proposed which is based on the self-normalised multiplicity density of the Underlying Event (UE) as measured in the transverse region with respect to the leading jet direction: $R_{\rm T}=N_{ch}^{transv}/\langle N_{ch}^{transv} \rangle$. The study of charged particle production at high-$R_{\rm T}$ gives us the opportunity to test the presence of non-trivial soft-QCD dynamics, such as colour reconnections or other collective phenomena.
        We present a study of unidentified charged-particle production in the leading jet and in the UE for pp collisions at 13 TeV, using both conventional multiplicity estimators and $R_{\rm T}$. All the results are compared with those obtained from QCD-inspired Monte-Carlo event generators.

        Speaker: Aditya Nath Mishra (ICN-UNAM)
      • 17:40
        Study on QGP bulk property in small system 20m

        Utilizing our developed relativistic viscous hydrodynamic code [1] to analysis of proton-lead and lead-lead collisions at the LHC [2], we investigate applicability of hydrodynamics, QGP bulk property and viscosities effects at hadronization process. Here we focus on one-particle distributions such as rapidity distributions and particle identified transverse momentum spectra and elliptic flows.
        We show that relativistic viscous hydrodynamics works for explanation of experimental data of central and mid-central proton-lead collisions. Furthermore, we find that modification of particle distribution due to bulk viscosity at hadronization process affects determination of value of bulk viscosity of QGP. For example, extracted values of bulk viscosities of QGP are much smaller than those of our previous study where bulk viscosity effect at hadronization process is neglected [3].
        According to our results of mean transverse momentum, effect of final state interactions in the small system is smaller than that in the large system. It indicates that produced particles in the small system keep information of the QGP fluid in high-energy heavy-ion collisions. We also discuss thermalizeation of systems from comparison between small and large systems.

        References:
        [1] K. Okamoto and C. Nonaka, Eur. Phys. J. C 77, no. 6, 383 (2017).
        [2] J. Adam et al. [ALICE Collaboration], Nature Phys. 13 (2017) 535.

        [3] K. Okamoto and C. Nonaka, Phys. Rev. C 98 (2018) no.5, 054906.

        Speaker: Mr Kouki Nakamura (Nagoya University)
      • 17:40
        Studying strangeness enhancement in small systems through $\Xi-$hadron correlations using the ALICE detector 20m

        One of the remaining puzzles in heavy-ion physics is that strangeness enhancement - believed to be a signature of the Quark-Gluon Plasma - is not only observed in heavy-ion collisions, but also in high-multiplicity proton-proton and proton-nucleus collisions. Various phenomenological models have been developed to try to understand this, such as rope hadronisation (used in the Angantyr extension of Pythia) and core-corona models (used in EPOS). A prediction of the string/rope model is that strangeness is produced in $s\bar{s}$ pair breakings, so there will be correlations between strange and anti-strange hadrons in the same event, even between different hadronic species. By studying these correlations one can learn more about the strangeness production mechanism and test if it changes with multiplicity.

        In this study, these predictions are tested by comparing angular correlations between in particular $\Xi^--K^+$ ($\overline{\Xi}^+-K^-$) and the reference $\Xi^--\pi^+$ ($\overline{\Xi}^+-\pi^-$) as a function of multiplicity, in $pp$ collisions at $\sqrt{s}=13\,\rm TeV$ using the ALICE detector. The results are compared to theoretical predictions by Angantyr and EPOS. A comparison will also be done between $\Xi-$baryon and $\Xi-$meson correlations. While this probes different physics, it further aids in the understanding of the production of multi-strange hadrons in small systems.

        Speaker: Jonatan Adolfsson (Lund University (SE))
      • 17:40
        Studying the phi meson in nuclear matter by simulating low energy pA reactions 20m

        The behavior of the $\phi$ meson in nuclear matter has attracted renewed interest because of (recent and future) experiments that aim to study its properties in nuclei [1-3]. Theoretically, many works have however been conducted assuming infinite nuclear matter [4-5], which is not realistic from an experimental point of view. To relate theoretical predictions with experimental observables, a thorough understanding of the actual reaction, in which the $\phi$ meson is produced in a nucleus, is required. For the past E325 experiment at KEK [1] and the future E16 experiment at J-PARC [3], this is a pA reaction with initial proton energies between 10 and 30 GeV. To simulate such a reaction, we make use of the PHSD transport approach, which is based on a covariant microscopic transport model [6]. In this framework, the $\phi$ meson spectral function obtained theoretically as a function of density, can be used as an input, while the output of the simulation can be compared with experimentally observed dilepton spectrum.
        In this presentation, I will give an overview of first results obtained in simulations of the p-Cu reactions probed at the E325 experiment at KEK.

        [1] R. Muto et al., Phys. Rev. Lett. 98, 042501 (2007).
        [2] A. Polyanskiy et al., Phys. Lett. B 695, 74 (2011).
        [3] K. Aoki (J-PARC E16 Collaboration), arXiv:1502.00703 [nucl-ex].
        [4] P. Gubler and K. Ohtani, Phys. Rev. D 90, 094002 (2014).
        [5] P. Gubler and W. Weise, Phys. Lett. B 751, 396 (2015).
        [6] W. Cassing and E. Bratkovskaya, Phys. Rev. C 78, 034919 (2008).

        Speaker: Dr Philipp Gubler (JAEA)
      • 17:40
        Substructure-based classification of medium-modified jets 20m

        We study the feasibility of a substructure-based classification of medium-modifed jets employing a metric formulated in terms of the earth mover's distance. We aim at isolating a subset of jets measured in p--Pb or Pb--Pb collisions that is characterized by an enhanced dissimilarity to the vacuum sample. The selected jet ensemble can be then inspected by projecting it on any substructure observable of interest such as (groomed) jet mass. A particular question addressed in this contribution is whether fluctuations of the underlying event background dominate the substructure-based difference between jets measured in proton-proton and heavy-ion collisions. For this exploratory classification analysis we employ samples of pp/p--Pb/Pb--Pb track-based jets measured with ALICE at $\sqrt{s_{\mathrm{NN}}} = $ 5.02 TeV as well as simulated PYTHIA jets embedded in the underlying event background.

        Speaker: Kirill Lapidus (CERN)
      • 17:40
        Suppression of elliptic flow without viscosity 20m

        We investigate fluid-to-particle conversion using the usual Cooper-Frye approach but with more general local equilibrium distributions than the Boltzmann or Bose/Fermi distributions typically used. Even though we study ideal fluids (i.e., shear stress and bulk pressure are zero everywhere), we find a suppression of elliptic flow ($v_2$) at high transverse momenta ($p_T>1.5$ GeV/c), relative to results obtained with the traditional Boltzmann distributions [1]. The non-viscous suppression shows qualitatively similar features to the well-known shear viscous suppression of $v_2$; for example, it increases with $p_T$, and it is smaller for heavier species as seen in self-consistent kinetic theory calculations. Our results question whether all of the $v_2$ suppression seen in the data can be attributed to viscous effects, and indicate that shear viscosities extracted from RHIC and LHC elliptic flow data might be overestimated. For more details, see Ref. [1].

        [1] A. Takacs and D. Molnar, arXiv:1906.12311 [nucl-th]

        Speaker: Denes Molnar (Purdue University)
      • 17:40
        Symmetries in the QGP - the case of the #eta′ 20m

        We study the behaviour of the η′ around above the pseudocritical temperature by use of lattice QCD simulations with two families of dynamical quarks. Due to its anomalous component the η′ carries significant informations on the nature of the phase transition, and the role of the anomaly. We contrast and compare the results for the η′ with the behaviour of chiral observables as well as with predictions of models. Results are obtained from the analysis of the gluonic defined topological charge density correlator after gradient flow. Our results indicate the growth of the η′ mass above the pseudocritical temperature, associated with the chiral symmetry restoration. In the vicinity of the pseudocritical temperature the results are consistent with a small dip in the η′ mass. The magnitude of the dip is compatible with the reduction of the η′ mass obtained by experimental analysis and suggests that η′ mass comes close to zero temperature non-anomalous contribution. We outline the current status of our study and the upcoming steps.

        Speaker: Maria Paola Lombardo (INFN)
      • 17:40
        Symmetry-plane correlations in flow analyses 20m

        Multiparticle correlations built from azimuthal angles whose distributions have been parametrized with the Fourier series expansion, depend generically on two distinct degrees of freedom: flow amplitudes $v_n$ and symmetry-planes $\Psi_n$. While analyses techniques for flow amplitudes $v_n$ have advanced over the past years, robust and unbiased techniques for analysing symmetry-planes $\Psi_n$ still need to be developed. Previous attempts in the measurements of symmetry-plane correlations (SPC) in high-energy nuclear collisions have built-in biases due to neglected correlations between the flow amplitudes $v_n$ themselves. In this poster, we summarize the recent improvements in the direction of newly developed analyses techniques for SPC without these built-in biases. Predictions of these new observables in high-energy nuclear collisions are provided for the initial coordinate space by MC-Glauber and for the momentum space by iEBE-VISHNU.

        Speaker: Marcel Markus Lesch (Technische Universitaet Muenchen (DE))
      • 17:40
        System size and flavor dependence of chemical freeze-out in relativistic particle collisions from RHIC-BES to LHC energies 20m

        The validity of the Statistical Hadronization Model (SHM) has been successfully tested to adequately reproduce hadronic particle abundances over nine orders of magnitude in high energy collisions of heavy ions. Assuming a thermally equilibrated system, experimental particle yields at RHIC and the LHC serve as an anchor for the determination of common freeze-out parameters in the QCD phase diagram -- namely, the baryo-chemical potential ($\mu_B$) and the chemical freeze-out temperature ($T_{ch}$) -- via thermal fits in the SHM framework. A point of interest arises when comparing the extracted freeze-out parameters obtained using different sets of particles in the thermal fit; namely, the $T_{ch}$ differences between the light hadrons and the strange hadrons. In this talk, I will show recent calculations of the freeze-out parameters using STAR and ALICE particle yields measured at collision energies ranging from 7.7 GeV to 7 TeV. Employing the Grand Canonical approach within the framework of the Thermal-FIST HRG model package, I will show evidence for a flavor-dependent freeze-out in the QCD crossover region and compare our findings with lattice calculations. Lastly, I will compare the quality of the extrapolated fits using various treatments of strangeness conservation under different freeze-out conditions. I will focus on system size dependence by applying the same approach to pp and pPb collisions and show that the statistical hadronization approach is applicable to small systems and that flavor dependencies in the freeze-out parameters lead to a natural explanation of strangeness enhancement from small to large systems.

        Speaker: Fernando Antonio Flor (University of Houston (US))
      • 17:40
        System size and multiplicity dependence of thermal parameters in high energy collisions 20m

        We will present a comprehensive study of chemical freeze-out parameters in high energy
        collisions[1-3]. The experimental data of light flavor particles are used to obtain the freeze-out parameters using the statistical thermal model. Three different ensembles are used in this study: the grand canonical ensemble, the canonical ensemble with exact strangeness conservation, and the canonical ensemble with exact baryon number, strangeness, and electric charge conservation. Chemical freeze-out temperature, baryon chemical potential, Radius, and strangeness suppression factor are compared for different collision systems and energies. The multiplicity dependence of these parameters and thermodynamic limit in high multiplicity pp collisions at LHC will be also discussed [1].

        [1] N. Sharma, J. Cleymans, and B. Hippolyte, Advances in High Energy Physics 2019, 5367349 (2019).
        [2] N. Sharma, J. Cleymans, B. Hippolyte, and M. Paradza, Phys. Rev. C 99, 044914 (2019).
        [3] N. Sharma, J. Cleymans, L. Kumar, Eur. Phys. J. C78, no.4, 288 (2018).

        Speaker: Natasha Sharma (Panjab University (IN))
      • 17:40
        System size dependence of direct photon production in large and small system collisions from PHENIX 20m

        The PHENIX experiment recently found a remarkably simple scaling law for the number of photons emitted in relativistic heavy ion collisions. When the direct-photon invariant yields are divided by $(dN_{ch}/d\eta)^{1.25}$, data from large systems falls onto a single curve in the low transverse momentum ("thermal") region. What is remarkable is that this is true if $dN_{ch}/d\eta$ is varied by collision energy from $\sqrt{s_{NN}}$ = 39 to 200 GeV up to 2.76 TeV, by collision centrality, or size of the colliding ions down to about $dN_{ch}/d\eta$ of 20. Data from small systems suggests a rapid turn on of the scaling behavior over a rather narrow range in $dN_{ch}/d\eta$ between 5 to 20. While these findings could have many explanations, perhaps the most intriguing is that the bulk of the thermal photons are produced near the transition from QGP to hadron gas combined with an onset of QGP formation at low $dN_{ch}/d\eta$. In this talk PHENIX complements the published results with new measurements from both small and large collision systems.

        Speaker: Norbert Novitzky (University of Tsukuba (JP))
      • 17:40
        System size scan of D meson $R_{\rm AA}$ and $v_n$ using PbPb, XeXe, ArAr, and OO collisions at LHC 20m

        Recent results at LHC and RHIC involving small collision systems have found evidence of collective flow behavior consistent with relativistic hydrodynamic expectations, which suggests the formation of tiny specks of quark-gluon plasma in these reactions. However, questions still remain about the nature of the matter formed in these minute systems. One of the main signatures of the quark-gluon plasma, i.e. the suppression of hard probes, has not yet been seen in small systems data. In fact, current experimental measurements indicate no suppression (e.g. $R_{\rm pPb} \sim 1$) in small systems. On the other hand, a surprisingly large D meson flow (though still suppressed compared to lighter hadrons) was measured in pPb collisions by the CMS collaboration. In order to reconcile these results we use Trento+v-USPhydro+DAB-MOD [1] to make predictions and propose a system size scan at the LHC involving $^{208}$PbPb, $^{129}$XeXe, $^{40}$ArAr, and $^{16}$OO collisions [2,3]. We find that the nuclear modification factor approaches unity as the system size is decreased, but nonetheless, in the 0--10% most central collisions $v_2\{2\}$ is roughly equivalent regardless of system size. Additionally we find that unlike in PbPb collisions the $v_3\{2\}$ gets a centrality dependence in smaller systems. These results arise from a rather non-trivial interplay between the shrinking path length in small systems and the enhancement of eccentricities in small systems at high multiplicity. Finally we also find a surprising sensitivity of D mesons $ v_2\{2\}$ in 0--10% at $p_T =$ 2--5 GeV to the slight deformation of $^{129}$Xe recently found at LHC.

        [1] R. Katz, C. Prado, J. Noronha-Hostler, J. Noronha and A. Suaide, ''DAB-MOD sensitivity study of heavy flavor $R_{\rm AA}$ and azimuthal anisotropies based on beam energy, initial conditions, hadronization, and suppression mechanisms'' [arXiv:1906.10768 [nucl-th]].
        [2] R. Katz, C. Prado, J. Noronha-Hostler and A. Suaide, ''System size scan of D meson $R_{\rm AA}$ and $v_n$ using PbPb, XeXe, ArAr, and OO collisions at LHC'' [please look for the paper on arXiv or Inspire].
        [3] Z. Citron et al., ''Future physics opportunities for high-density QCD at the LHC with heavy-ion and proton beams,'' [arXiv:1812.06772].

        Speaker: Caio Prado (Central China Normal University (CN))
      • 17:40
        Systematic Searches of CMW from Heavy-Ion Collisions at STAR 20m

        The Chiral Magnetic Wave (CMW) was predicted to arise from the interplay of the chiral magnetic effect and the chiral separation effect, which can lead to the formation of electric quadrupole moment in heavy-ion collisions. This electric quadrupole moment can produce charge asymmetry dependence of the elliptic flow ($v_2$) for charged particles: $v_2(\pm) - v_2(\mp) = \mp r_{2} \times A_{\rm ch}$, where $r_{2}=\frac{q_{e}}{\hat{\rho}_{e}}$.

        In this poster, we will present the STAR measurements of the slope parameter ($r_{2}$) from different colliding systems: Au+Au at 200, 54.4 and 27 GeV, Cu+Cu and Cu+Au at 200 GeV. Two approaches, Q-Cumulant ($v_2 \{2\}$ and $v_2\{4\}$) and event-plane ($v_2(EP)$) methods, are used to measure $v_2$ of $\pi^{\pm}$ at low transverse momenta in order to evaluate the non-flow contributions in the $v_2$ measurement. $v_2\{2\}$ and $v_2(EP)$ with pseudorapidity gaps can reduce the short-range non-flow contributions. $v_2\{4\}$ can suppress non-flow contributions and is believed to be more sensitive to the reaction plane (and hence the magnetic field). Thus $v_2\{4\}$ can be more sensitive to the CMW dynamics. The centrality dependence of $r_{2}$ will be compared across different collision systems and beam energies. Physics implications on the search of the CMW and the background dynamics from our systematic studies will be discussed.

        Speaker: Ms Maria Sergeeva (UCLA)
      • 17:40
        Temperature Fluctuation and the Specific Heat in Au+Au Collisions at $\sqrt{s_{NN}}$ = 7.7 $-$ 200 GeV from STAR 20m

        Specific heat is a thermodynamic quantity that characterizes the equation of state of the system. For a system undergoing phase transition, the specific heat, $C_{V}$, is expected to diverge at the critical point. Temperature fluctuation of the system provides an estimation of $C_{V}$. The specific heat can be extracted from event-by-event temperature fluctuation. Thus the variation of thermal fluctuations with temperature can be effectively used to probe the QCD phase transition and QCD critical point [1].

        In this poster, we will present the energy dependence of specific heat and temperature fluctuations of the QCD matter created in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7, 11.5, 19.6, 39, 62.4 and 200 GeV from STAR and compared with model calculations.

        [1] Sumit Basu, Sandeep Chatterjee, Rupa Chatterjee, Tapan K. Nayak, Basanta K. Nandi, Phys. Rev. C 94 (2016) 044901.

        Speaker: Xiujun Li (University of Science and Technology of China)
      • 17:40
        Testbeam Results for the sPHENIX TPC Prototype 20m

        A Time Projection Chamber (TPC) will be the central tracking detector in the sPHENIX experiment. Its main task is to provide a high tracking efficiency and excellent momentum resolution for precise upsilon spectroscopy and jet measurements. The TPC will cover the full azimuth and a pseudorapidity range of up to $\pm$ 1.1.
        A small scale prototype TPC with a radial extension of 40 cm and a similar drift length has been manufactured which can accommodate a full size amplification module as for the sPHENIX TPC.
        The prototype has been exposed to a 120 GeV proton beam at the Fermilab Test Beam Facility (FTBF). The results of the test-beam campaigns including SAMPA readout electronics will be presented.

        Speaker: sPHENIX Collaboration
      • 17:40
        Testing the SiPMs for the sPHENIX electromagnetic and hadronic calorimeters 20m

        The electromagnetic (EMCal) and hadronic (HCal) calorimeters for the sPHENIX experiment will use about 100,000 Silicon Photo-Multipliers (SiPMs) as optical sensors (Hamamatsu S12572-33-015P). The effects of radiation damage in SiPMs from gamma rays has been measured and compared with the damage produced by neutrons. We designed and constructed an automated SiPM testing device that measures the breakdown voltage and gain curve with the IV scan and SPS (single photon spectrum) method. It is used to characterize the SiPMs for the sPHENIX calorimeters and prepare a database for SiPM sorting. We will report on the first few months of operational experience, including precision, stability and reproducibility of the measurements, consistency with the available factory data, and the projected effect of the SiPMs on the overall calorimeter performance in sPHENIX.

        Speaker: Dr Balazs Ujvari (University of Debrecen)
      • 17:40
        The $J/\psi$ suppressions and chromo-electromagnetic field fluctuations in relativistic heavy-ion collisions 20m

        The charm quarks are mainly produced by primordial hard scatterings in the early stage of the ultra-relativistic heavy-ion collisions. The produced charm quarks propagate through the dense QGP medium formed in such collisions and lose energy during their entire path of travel. The QGP is a statistical system of dynamic colour charges, it can also be characterised by stochastic chromo-electromagnetic field fluctuations. These chromo-electromagnetic field fluctuations in the QGP cause an energy gain of charm quarks of all momentum, significantly at the lower momentum limit. The motion of these charm quarks can be described by Langevin transport equations and the underlying evolving medium can be modeled by the (3 + 1)-D relativistic viscous hydrodynamics.

        In this contribution, we have studied the effect of the chromo-electromagnetic field fluctuations on $J/\psi$ suppression at RHIC and LHC energies. The nuclear modification factors ($R_{AA}$) of $J/\psi$ have been calculated at RHIC and LHC energies by considering the effect of the field fluctuations. The results are compared with the experimentally measured $R_{AA}$ of $J/\psi$ by ALICE and CMS experiments at $\sqrt {s_{NN}} = 2.76 $ TeV and by PHENIX experiment at $\sqrt {s_{NN}} = 200$ GeV. The experimental measurements can be nicely described with the effect of these field fluctuations without invoking the regeneration phenomena.

        Speakers: Zubayer Ahammed (Department of Atomic Energy (IN)), Ashik Ikbal Sheikh (Department of Atomic Energy (IN))
      • 17:40
        The ALICE TPC: Upgrade and Physics Perspectives 20m

        The large Time Projection Chamber (TPC) is the main tracking and PID
        device of the ALICE detector. It is currently being upgraded with a new
        readout system, including new GEM-based Readout Chambers and new
        front-end electronics. This will enable to operate the TPC in continuous mode,
        recording the full minimum-bias interaction rate of 50 kHz in Pb-Pb, as
        anticipated at the LHC in Run3 and beyond.

        In this presentation, we discuss the physics potential of the upgraded TPC
        and show the status of the TPC upgrade activities during the ongoing LHC
        Long Shutdown 2, for which the TPC was lifted into a large clean room at
        ground level. First results of the commisioning tests will be presented.

        Speaker: Borge Nielsen (University of Copenhagen (DK))
      • 17:40
        The elliptic flow of $D^0$ meson in pA collisions from the initial state 20m

        The azimuthal angular correlation between a heavy-flavor meson ($J/\psi$ and $D^0$) and a light hadron has been measured firstly by the CMS experiment. The elliptic flow of $J/\psi$ from the initial state has been successful described recently. We investigate the angular correlation between a $D^0$ meson and a charged light hadron in the Color Glass Condensate framework. Our results show that $D^0$ meson also has a sizable $v_2$, which agrees with the CMS results. In addition, we make the prediction for the elliptic flow of B meson.

        Speaker: Yu Shi (ccnu)
      • 17:40
        The HADES RICH upgrade within the FAIR Phase-0 program* 20m

        The High Acceptance Di-Electron Spectrometer (HADES) is measuring properties of baryonic matter at moderate temperatures in A+A collisions at the SIS18 accelerator at GSI, Darmstadt. After a long shutdown of SIS18 to prepare for the future FAIR facility, beamtimes have been resumed within the FAIR Phase-0 program in March 2019.
        Meanwhile, the HADES experiment has undergone several upgrades. In this presentation the successful upgrade of the Ring Imaging Cherenkov Detector (RICH) with MAPMTs will be reported as well as first performance studies from the beamtime in March 2019. This success is also an important step towards the realization of the CBM-RICH detector in due time for the start of the SIS100 physics program.

        The RICH detector of the HADES experiment measured for nearly two decades with a CsI photocathode based readout which now has been replaced with modern Hamamatsu H12700 MAPMTs that have been purchased already for the CBM-RICH detector. The complete readout chain of the subdetector was replaced by newly developed DiRICH frontend boards. The update to a MAPMT based readout has been a big steps to excellent timing property, high quantum efficiency, fine pixel granularity and low dark noise. As key features the new readout chain can work at higher rates than before and also provided a substantial gain in photoelectrons per ring.

        The updated HADES RICH MAPMT plane is build up with 428 H12700 MAPMTs where the inner part of the plane is coated with a wavelength shifter to increase the number of photons per ring. The readout electronics is based on the TrbNet system and uses FPGA based TDCs for signal measurements. Each of the 856 DiRICH frontend boards measures on 32 channels - half a MAPMT – and provides a prepacked dataflow.
        As a second central improvement the radiator gas of the HADES RICH was exchanged from C4F10 to C4H10 which reduced the amount of scintillation light. As measured in previous tests the old CaF2 window, a separator between the old radiator and the photocathode volume, was unmounted to reduce the scintillation light in the detector by orders of magnitudes.

        The combination of the new TrbNet readout, new MAPMTs, temperature measurements and the change of the radiator gas brought the HADES RICH upgrade to a full success. The HADES RICH detector participated with unprecedented performance in the HADES beamtime in March 2019 recording Ag+Ag collisions at 1.58 AGeV.

        *supported by BMBF 05P15R6FCA and 05P19R6FCA

        Speaker: Adrian Amatus Weber (Justus-Liebig-University Giessen)
      • 17:40
        The neutral meson measurement in jets in Pb--Pb collisions in ALICE 20m

        Neutral mesons and jets are good probes to study particle production mechanisms and jet phenomena in various collision systems, providing comparisons to model calculations and constraining coefficients of hot QCD matter. Recent measurements of ALICE in pp collisions show a modification of the $\eta/\pi^{0}$ ratio for the neutral meson production in jets with respect to the inclusive measurement. The reconstruction of neutral pions inside jets can be extended to Pb--Pb and p-Pb collisions. The comparison of the production inside jets in cold and hot nuclear collisions would shed light on the final state effects of the jet quenching mechanism. The reconstruction of neutral pions is done via the two photon decay channel combining various methods of reconstruction. The decay photons are reconstructed via the Photon Conversion Method (PCM) and in the ALICE calorimeters (EMCal and PHOS). In this poster, the latest advances of the neutral meson production inside charged jets in nuclear collisions will be presented.

        Speaker: Mr Masahiro Takamura (University of Tsukuba)
      • 17:40
        The new hybrid tracking system of the Baryonic Matter at the Nuclotron (BM@N) experiment at JINR 20m

        In order to study the high-density nuclear equation-of-state in collisions between gold nuclei at Nuclotron beam energies (2– 4.5A GeV), the existing BM@N experiment at JINR in Dubna has to be substantially upgraded. The measurement of high-multiplicity events at reaction rates up to 50 kHz requires the installation of four new tracking stations equipped with double-sided micro-strip silicon sensors, which have been developed for the CBM experiment at FAIR. It has been demonstrated by simulations using the UrQMD event generator together with the GEANT transport code, that the hybrid tracking system comprizing four silicon stations and seven (already partly existing) GEM tracking detectors will be able to reconstruct charged particles including hyperons emitted in Au+Au collisions with good efficiency and high signal-to-background ratio. The results of the simulations and the status of the detector development will be presented.

        Speaker: Ms Dmitry Dementiev (JINR Dubna)
      • 17:40
        The Reaction Plane Upgrade to the CMS ZDCs 20m

        In order to measure the orientation of the spectator reaction plane, the CMS Zero-Degree Calorimeters (ZDCs) are augmented with two 4x4 hodoscopes of quartz tiles, called the Spectator Reaction Plane Detectors. To reduce electronic noise the signals are digitized in the tunnel, very close to the detectors, which sit at zero degrees, 140m from the interaction point. The performance of the detectors in the recent PbPb run will be presented and the angular resolution in data will be compared to that found in GEANT simulations.

        Speaker: Matthew Thomas Nickel for CMS Collaboration (The University of Kansas (US))
      • 17:40
        The readout of the sPHENX MAPS vertex detector 20m

        The MVTX detector will serve as the inner tracker of the sPHENIX experiment at RHIC. It is an extremely precise silicon pixel vertex detector, with excellent displaced secondary vertex detecting capabilities. The MVTX will enable key measurements of heavy-flavor-tagged jets and B-mesons in heavy ion collisions. The detector is based on the latest generation of Monolithic Active Pixel Sensors (MAPS) technology, developed for the ALICE collaboration at CERN. The readout chain is composed of three parts: a sensor stave assembly, a RU (Readout Unit) board, and a FELIX (Front End LInk eXchange) board. The stave assembly consists of nine ALPIDE (ALice PIxel DEtector) sensor chips, which will send its data on nine gigabit links over a FireFly cable to an RU board. The RU board consists of two FPGAs, one for reading the stave data and sending data using CERNs rad-hard GBT links over fiber to the FELIX board and a second FPGA which is used for scrubbing (SEU detection). The FELIX board consists of an FPGA that reads out the data over the fiber link and sends its data to a 16 lane PCIe interface, placing the data to disk. We will present the latest R&D efforts and performance achievements of the three parts of the Readout system mentioned above.

        Speaker: sPHENIX Collaboration
      • 17:40
        The sPHENIX heavy flavor jet physics physics program 20m

        Jets initiated by the fragmentation of heavy flavor quarks (HF-jet) are sensitive to collisional energy loss of the high energy parton when traversing through Quark Gluon Plasma. Using the state-of-the-art jet detector at RHIC, sPHENIX, we will perform the first HF-jet measurement at RHIC, which includes the nuclear modification and flow of b-jets, and the momentum balance in di-b-jet pairs. A variety of b-jet tagging algorithms have been developed, which select a HF-jet sample rich in tracks displaced from the primary collision point as measured by the high precision MAPS vertex tracker for sPHENIX. The detection method, physics projection and possible impacts to the field of heavy ion physics will be presented.

        Speaker: sPHENIX Collaboration
      • 17:40
        The sPHENIX MAPS-based vertex detector 20m

        The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) will study QGP properties with heavy bottom quark jets (B-jets) produced in high-energy heavy ion collisions. B-jets are expected to offer a unique set of observables due to the large bottom quark mass, but need to be measured across an unexplored kinematic regime, particularly at low $p_T$ where the expected mass-dependence effects are large but the underlying backgrounds are also high. We will use a three-layer Monolithic-Active-Pixel-Sensor (MAPS) based vertex detector, originally developed for the ALICE ITS upgrade, to identify the signal and suppress the background. The MVTX will serve as the innermost tracking system of sPHENIX, covering 2 cm to 4 cm radially and a pseudorapidity range of |η| < 1.1. The very fine 27 µm x 29 µm pixels allow us to identify B-decay secondary vertices and B-jets in heavy ion collisions with high efficiency and high purity. In this presentation, we show the current status of R&D efforts towards custom readout and mechanical systems to integrate the MVTX detector into the sPHENIX system.

        Speaker: sPHENIX Collaboration
      • 17:40
        The sPHENIX open heavy flavor hadron physics program 20m

        Recent data from RHIC and LHC show that $\mathrm{R}_\mathrm{AA}$ and $\mathrm{v}_2$ of charm hadrons are very similar to that of light and strangeness hadrons. The $\mathrm{R}_\mathrm{AA}$ of bottom decay daughters at low p$_\mathrm{T}$ seems to be less suppressed than that of light and charm hadrons, suggesting a mass suppression hierarchy. Precision open bottom measurements over a broad momentum range are needed for a detailed understanding of parton energy loss mechanisms and to characterize the transport properties of the strongly-coupled QGP medium. The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) will have extensive capabilities for jet and Upsilon measurements. A fast MAPS-based silicon vertex detector (MVTX) is proposed to greatly enhance the heavy flavor detection capabilities of sPHENIX. We will present physics simulation studies on the open bottom measurements within the full sPHENIX tracking environment including the MVTX detector. Open bottom reconstruction has been explored via the inclusive non-prompt $\mathrm{D}^0$ daughters and the full exclusive reconstruction of $\mathrm{B}^+\rightarrow\bar{\mathrm D}^0\pi^+$. Statistical projections on the nuclear modification factor and the elliptic flow measurements will be presented.

        Speaker: sPHENIX Collaboration
      • 17:40
        The STAR measurements on off-diagonal cumulants of net-particle multiplicity distributions in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7-200 GeV 20m

        We present measurements of the second-order off-diagonal cumulants of net-charge, net-proton, and net-kaon multiplicity distributions in Au+Au collisions at $\sqrt{s_{NN}} =$ 7.7-200 GeV. We focus on the pseudorapidity window and centrality dependence of these cumulants. We compare our results with the hadron resonance gas (HRG) and UrQMD calculations. The energy dependence of the second order off-diagonal over diagonal cumulant ratios cannot be fully described by different model calculations [1]. We extend such measurements to the third-order off-diagonal cumulants. These measurements provide important insights on the correlations between different conserved charges from the QGP and hadronic phase, as well as their dependence with temperature and baryon chemical potential. We also study correlations between net-pion with net-proton as well as net-pion and net-kaon that have recently been shown to constrain frameworks of local charge conservation during hadronization [2].

        [1] J. Adam et al., STAR Collaboration, arXiv:1903.05370.
        [2] D. Oliinychenko and V. Koch., arXiv:1902.09775.

        Speaker: Mr Arghya Chatterjee (CCNU/ VECC)
      • 17:40
        Theoretical framework for multi-harmonic correlations in heavy-ion collisions 20m

        Measurements of the correlated fluctuations of the amplitudes of two different flow harmonics have been shown to be more sensitive to the properties of the Quark-Gluon Plasma created in ultrarelativistic heavy-ion collisions than the flow harmonics taken individually. In particular, their computation have given constraints to the details of the temperature dependence of shear viscosity to entropy density ratio, to which the measurements of individual flow harmonics are nearly insensitive. These observations have been made using a set of recently introduced observables called Symmetric Cumulants.

        In this poster, the theoretical framework for the generalisation of Symmetric Cumulants to three and more different harmonics is presented. This new set of observables can provide information previously inaccessible and thus, independent constraints on the system produced in the nuclear collisions. Predictions of their centrality dependence at LHC energies for the coordinate space and for the momentum space obtained with the iEBE-VISHNU model are shown as well.

        Based on C. Mordasini, A. Bilandzic, D. Karakoç and S. F. Taghavi, "Higher
        order Symmetric Cumulants", arXiv:1901.06968 [nucl-ex].

        Speaker: Cindy Mordasini (Technische Universitaet Muenchen (DE))
      • 17:40
        Thermal Field Theory of the Tsallis statistics 20m

        Classical and quantum Tsallis distributions have been widely used in many branches of natural sciences. But, the quantum field theory of the Tsallis distributions is relatively a less explored arena. In the article arXiv:1906.02893v2 [hep-ph], we derived the expressions for the thermal two-point functions for the Tsallis statistics with the help of the corresponding statistical mechanical formulations. In the conference, we will show that the quantum Tsallis distributions used in the literature appear in the thermal part of the propagator much in the same way the Boltzmann-Gibbs distributions appear in the conventional thermal field theory. As an application of our findings, the thermal mass in the $ \phi^4 $ scalar field theory within the realm of the Tsallis statistics will also be discussed. For small system like quark gluon plasma (QGP) where the application of Boltzmann-Gibbsstatistics is uncertain, the thermal field theoretic formulation developed in this work for Tsallis statistics will have crucial importance. The thermal spectral function of quarks and gluons estimated using BG and Tsallis statistics will differ (as the case for $ \phi^4 $ interaction) which may have significant impact on the signals of QGP.

        Speaker: Mr Mahfuzur Rahaman (Variable Energy Cyclotron Centre, 1/AF, Bidhan Nagar, Kolkata - 700064, India and Homi Bhabha National Institute, Anushaktinagar, Mumbai, India.)
      • 17:40
        Thermal production of Sexaquarks in Heavy Ion Collisions 20m

        Sexaquarks are a hypothetical low mass, small radius uuddss dibaryon which has been proposed recently and especially as a candidate for Dark Matter [1]. The low mass region below 2 GeV escapes upper limits set from experiments which have searched for the uuddss dibaryon and did not find it [1].

        Depending on its mass, such state may be absolutely stable or almost stable with decay rate of the order of the lifetime of the Universe therefore making it a possible DarK Matter candidate [1].

        Even though not everyone agrees [2] its possible cosmological implications as DM candidate cannot be excluded and it has been recently searched in the BaBar experiment [3[.

        Its production in heavy ion collisions is expected to have a larger rate as compared to its production via the decay $\Upsilon \rightarrow S \overline{\Lambda} \overline{\Lambda} $ which is assumed in [3], due to new production modes that open up in heavy ion collisions at high energies namely through parton coalescence and/or thermal production, and the avoidance of requiring a low multiplicity exclusive final state.

        We use a model which has very successfully described hadron and nuclei production in nucleus-nucleus collisions at the LHC [4], in order to estimate the thermal production rate of Sexaquarks with characteristics such as discussed previously rendering them DM candidates. The model has been extended by new calculations [5] allowing solid estimates for 6 quark states.

        We show first results on a study of the variation of the Sexaquark production rates with mass, radius and temperature and chemical potentials assumed and their ratio to hadrons and nuclei and discuss the

        interdependences and their consequences.

        These estimates are important for future experimental searches and enrich theoretical estimates in the multiquark sector.

        [1] G. R. Farrar, (2017), arXiv:1708.08951 [hep-ph] and G. R. Farrar, (2018), arXiv:1805.03723 [hep-ph]
        [2] E. Kolb, M. Turner,Phys.Rev. D99 (2019) no.6, 063519
        [3] BABAR Coll. J. P. Lees et al, Phys.Rev.Lett. 122 (2019) no.7, 072002
        [4] K. A. Bugaev et al, Nucl.Phys. A970 (2018) 133-155 and references therein.
        [5] K. A. Bugaev et al, To be published

        Speaker: Sonja Kabana (Centre National de la Recherche Scientifique (FR))
      • 17:40
        Thermomagnetic effects in Heavy Ion Collisions 20m

        Due to the relative motion of the charged heavy-ions in heavy-ion-collision experiments, a high magnetic field is produced. The initial magnitude of this magnetic field can be very high at RHIC and LHC energies at the time of the collision and then it decreases very fast. The presence of an external anisotropic field in the medium subsequently requires modification of the present theoretical tools that can be applied appropriately to investigate various properties of QGP. Recently, we have reformulated Hard Thermal Loop perturbation theory for a magnetized hot and dense nuclear matter by calculating quark and gluon self-energies and also the other N-point functions. We have also applied those results to calculate various quantities such as QCD thermodynamics in one-loop level, hard dilepton production rate from hot and dense deconfined magnetized nuclear matter. In this talk, I will summarized those results and the findings.

        Speaker: Najmul Haque (NISER, India)
      • 17:40
        Tidal deformability with magnetic field for neutron star and quark star 20m

        The recent detection of gravitational wave signal from binary
        compact star merger has set a strong constraint on tidal defomability,
        which motivated a large amount of studies about the equation of state.
        But the tidal deformability of compact star depends not only on the
        equation of state, but also on the spin and magnetic field of the star.
        In this study, we calculated for the first time the contribution of
        tidal deformability from magnetic field. Both the magnetic field and
        tidal field act as a perturbation of a spherical star. We found that
        they are independent with each other at first order because of linearity
        of perturbed equations, and their coupling firstly appears in the second
        order of perturbation. Our results show that the correction of tidal
        deformability is only about 0.1% for magnetic field at surface of star
        is 10^15 gauss. We explored the difference of our results from neutron
        star and quark star. the possibility of detection for this difference
        from magnetic field in the future gravitational wave observations are
        also discussed.

        Speaker: Zhenyu Zhu (Goethe University Frankfurt am Main)
      • 17:40
        Time evolution of chirality imbalance of the massive fermions under parallel electric and magnetic fields 20m

        In the past several years there has been increasing interest in the chirality imbalance $n_5$, which is the difference between right- and left-handed fermions. The chirality imbalance is expected to be produced from the Adler-Bell-Jackiw anomaly(ABJ-anomaly) and plays a key role to understand anomalous transport phenomena in the hot/dense quark matter or the Dirac/Weyl semimetals under the magnetic field. One of interesting transport phenomena in the presence of chirality imbalance is the chiral magnetic effect(CME), appearance of electric current in direction of the external magnetic field.

        The ABJ-anomaly relation implies that the electric field gives a crucial contribution to the emergence of the chirality imbalance in addition to the magnetic field. In the previous work, we have studied the chirality imbalance and the CME using the solution of the Dirac equation in the constant magnetic and general time-dependent electric fields, and found that the time-dependence of the gauge field is essentially important for the production of $n_5$. In particular, we found that $n_5$ and CME at $t \to \infty$ are solely determined by the probability distributions of the fermion created non-perturbatively by the electric field.

        In this talk, we study the emergence of the chirality imbalance and the electric current under spatially-uniform and parallel electromagnetic field in the vacuum of massive fermion. For the time-dependence, we assume the constant magnetic field, but do not impose any specific form for the electric field with boundary conditions $E(t \to \pm \infty) \to 0$. We solve the Dirac equation and calculate vacuum expectation values of the currents with the gauge invariant regularization.

        As a result, asymptotic forms of $n_5$ and CME consists of a constant part and an oscillating part independent of details of intermediate time-dependence of the gauge potential. The non-zero constant term is proportional to a relativistic velocity and the momentum distribution of the created particle, and understood as a classical analogue of the electric current. We discuss how the chirality imbalance arises by the time-dependent electric field.

        Speaker: Mr Hayato Aoi (Department of Physics, Faculty of Science, Tokyo University of Science)
      • 17:40
        Towards improved measurements with the upgrade of the ALICE Inner Tracking System in LS3 20m

        During the second LHC shutdown (LS2) the Inner Tracking System (ITS) of ALICE will be upgraded by replacing the current ITS with seven layers of CMOS Monolithic Active Pixel Sensors (MAPS). However, the latest innovations in the silicon imaging technology allow for the construction of large, ultra thin silicon wafers which can further improve the capabilities of the ALICE tracker. A proposal for a further upgrade of the ALICE ITS, regarding the construction of a novel vertex detector, is under consideration. The installation of the new ITS, ITS3, is planned for the third LHC shutdown (LS3) during which the three innermost layers of ITS2 will be replaced by three cylindrical layers of large curved CMOS wafers. The next ITS upgrade (ITS3) will improve further the impact parameter resolution and the tracking efficiency of low momentum particles. The innermost ITS layer will be positioned closer to the interaction point and the material budget will be reduced down to 0.05$\%$$~$$X_0$ per layer.

        Monte Carlo simulations of a simplified ITS3 geometry within the ITS2 design indicate an improvement in the impact parameter resolution and the tracking efficiency. Based on these MC simulations the significance of measuring the $\Lambda_b$ particle with the ITS3 was calculated and compared to the value obtained for the ITS2. This contribution will focus on the analysis results of the $\Lambda_b$ measurement, which reflect the substantially improved performance of the next ALICE tracker.

        Speaker: Mrs Dimitra Andreou (CERN, Nikhef)
      • 17:40
        Towards understanding the origin of collectivity in small systems: a study of the interplay between initial-state momentum anisotropy and final-state geometry response 20m

        The origin of long-range collective azimuthal correlations in small-system collisions is an area of intense research in the heavy ion community. To disentangle between collectivity associated with initial-state intrinsic momentum anisotropy and the collectivity arising as a final-state response to the collision geometry, we studied the development of collectivity in 5.02 TeV and 0.2 TeV $p$+Pb collisions with both initial-state and final-state effects included in a transport model AMPT. We find that the initial momentum anisotropy may not be fully isotropized through parton interactions, and the final-state partonic harmonic flow $v_n$ in general are correlated with both the initial momentum anisotropy and the shape of the collision geometry. The initial momentum anisotropy also influences the event by event fluctuation of $v_n$. Therefore the mere evidence of geometry response of the collective flow does not rule out the presence of large contributions from the initial state[1].

        We also compared the results between 5.02 TeV and 0.2 TeV[2], which have the same Glauber geometry but different parton densities (each nucleon produces three times more particles at 5.02 TeV than 0.2 TeV). We found that results are NOT the same for the same $N_{part}$ nor for the same $N_{ch}$, suggesting a non-trivial influence of different particle production at the two energies. We discuss the prospect of disentangling the non-equilibrium transport or near-equilibrium hydrodynamics in future small system run ($p$+A and O+O) at RHIC and the LHC.

        [1] M. Nie, L. Yi, J. Jia and G. Ma, arXiv:1906.01422.
        [2] M. Nie, L. Yi, J. Jia and G. Ma, in preparation.

        Speaker: Maowu Nie (Shandong University (SDU))
      • 17:40
        Two-particle correlations with high-p$_{\rm{T}}$ $\Lambda$ baryons and $K^0_S$ mesons in pp collisions at ALICE 20m

        Complementary to jet reconstruction, two-particle correlations in $\Delta\eta$ and $\Delta\varphi$ are used to study jets, in particular their particle composition. While in Pb-Pb collisions this is done as means for the characterization of the Quark-Glon Plasma, pp collisions serve as reference and also allow for a deeper study of particle production mechanisms. Recent ALICE results on the production of strange particles in small systems (pp and p-Pb collisions) reveal the possibility that similar strange quark production mechanisms could be present in all collision systems. Thus in this work, two-particle correlations between a high-momentum $K^{0}_{S}$ meson, $\Lambda$ ($\bar{\Lambda}$) baryon and charged hadrons are used to study strange particle production in jets. The pp collisions at $\sqrt{s} = 13~\rm{TeV}$ collected with the ALICE experiment at the LHC are analyzed.
        The per-trigger yields of the associated hadrons are studied on both the near-side and away-side of the V$^0$-h correlation functions as a function of the transverse momenta of the trigger and associated particles as well as the event multiplicity. The ratios of yields from V$^0$-h correlations to the yields from h-h correlations will be compared.

        Speaker: Lucia Anna Husova (University of Münster (DE))
      • 17:40
        Understanding Baryon Stopping at the Beam Energy Scan within a Hadron-String Approach (SMASH) 20m

        The second phase of the beam energy scan at RHIC is currently ongoing with the goal to identify signals for the first order phase transition or the critical endpoint. One basic observable that needs to be understood before assessing more complex correlations and fluctuations is the rapidity distribution of net protons, that determines the net baryon density of the system.
        The stopping dynamics of baryons is still lacking a quantitative understanding from the theory side. Here, we implement a string model for the description of hadronic interactions within a newly developed transport approach, SMASH (Simulating Many Accelerated Strongly-interacting Hadrons). The free parameters of the string model are determined by comparing to experimental measurements in elementary proton-proton collisions. With the adjusted parameters, we advance to heavy ion collisions, where the experimentally observed change of the shape of the net proton rapidity spectrum from a single peak structure to a double peak structure with increasing beam energy is reproduced.
        By adjusting details of the formation process of string fragments, a good agreement with the measured rapidity spectra of protons and pions is achieved while insights on the fragmentation process are obtained.
        Within the presented framework, dynamic 3-dimensional event-by-event initial conditions for hydrodynamic calculations can be provided.

        Speaker: Justin Mohs
      • 17:40
        Understanding the space-time picture of in-medium jet evolution using a dynamical model 20m

        The LIDO partonic transport model is used to study the evolution of hard partons inside the quark-gluon plasma produced in heavy-ion collisions.
        The energy loss model includes scatterings between hard partons and the medium as well as inelastic (bremsstrahlung) processes.
        Importantly, the model takes into account the finite formation time of parton bremsstrahlung, an essential ingredient for a realistic implementation of the Landau-Pomeranchuk-Migdal (LPM) effect in an evolving medium.
        The model predictions in a static medium agree quantitatively with leading-order theoretical calculations. It also captures the qualitative features of bremsstrahlung in a finite-size and expanding medium.
        The model with these features makes possible a more reliable space-time description of jet propagation in the quark-gluon plasma.

        In a finite brick medium, early time splittings receive larger transverse-momentum broadening than those received by later time splittings.
        To study such relation between momentum broadening and locations of splitting vertices in an event-by-event fluctuating and expanding medium, we look into the transport evolution history after calibrating the model to inclusive jet $R_{AA}$.
        We demonstrate that the early/high-temperature regions of the medium can be probed by large-angle splittings, while small angle splittings are favorably produced at later times of the evolution.
        We discuss how measurable quantities in jet experiments can help probe different space-time regions of the medium evolution.

        Speaker: Mr Wenkai Fan (Duke University)
      • 17:40
        Unfolding as a Solution to the Non-binomial Efficiency Correction for Higher Moments of Multiplicity Distribution 20m

        We apply the iterative Bayesian unfolding method provided by RooUnfold package in the non-binomial efficiency correction problem for higher moments. We study the non-binomial efficiency distribution such as beta-binomial and hypergeometric distributions in this work. We also consider the efficiency with multiplicity dependence and the effect of track merging, which will lead to non-binomial detector response. With comparison to the previous efficiency correction method for cumulants, we find that the unfolding method has improvement in the non-binomial efficiency correction.

        Speaker: Shu HE (Central China Normal University)
      • 17:40
        Uniform readout system for the sPHENIX electromagnetic and hadronic calorimeters 20m

        The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) will provide a detailed understanding of the evolution of the Quark-Gluon Plasma using precision measurements of jets and heavy flavors in heavy ion collisions at RHIC. The sPHENIX detector is based on the former BaBar 1.5T super-conducting solenoid and consists of precision tracking, electromagnetic (EMCal) and hadronic (HCal) calorimetry covering 2π in azimuth and |η| < 1.1. The EMCal is a 2D projective calorimeter consisting of scintillating fibers embedded in a tungsten powder infused epoxy. The HCal is a 2D projective design using tilted plates consisting of steel absorber and scintillating tiles with wave-shifting fibers. Both the EMCal and HCal calorimeters use a common electronics design for readout based on silicon photomultipliers (SiPMs) as the optical sensor. A custom designed analog front-end provides amplification and shaping for the 14-Bit ADC system designed specifically for sPHENIX which digitizes and records the waveforms for all of the 24576 EMCal and 1526 HCal towers. In addition, the digitizer system provides trigger primitives for the sPHENIX trigger system. We will present an overview of the design of the calorimeter electronics, status of the design and prospects for sPHENIX.

        Speaker: sPHENIX Collaboration
      • 17:40
        Universal features of the medium-induced gluon cascade and jet quenching in expanding media 20m

        Comprehensive understanding of medium-induced radiative energy loss is of a paramount importance in describing observed jet quenching in heavy-ion collisions. In this work, we calculate the medium-modified gluon splitting rates for different profiles of the expanding partonic medium, namely profiles for static, exponential, and Bjorken expanding medium. In the presented study, the Baier-Dokshitzer-Mueller-Peigne-Schiff-Zakharov (BDMPSZ) formalism is used for multiple soft scatterings with a time-dependent transport coefficient for characterizing the expanding medium. The medium-evolved gluon spectra are systematically calculated using the kinetic rate equation for all the medium profiles and a study of the distinctive features at low and high momentum fractions of radiated gluons are provided. Finally, we provide a calculation of the jet $R_{AA}$ which quantifies a sensitivity of the inclusive jet suppression on the way how the medium expands. Comparisons of predicted jet $R_{AA}$ with experimental data from the LHC are also provided.

        Speaker: Dr Souvik Priyam Adhya (Institute of Particle and Nuclear Physics Faculty of Mathematics and Physics, Charles University)
      • 17:40
        Using characteristic temperatures of transport coefficients to search for the QCD critical point 20m

        While at at zero baryon chemical potentials one expects a minimum in the shear viscosity over entropy density and a maximum in the bulk viscosity to entropy density ratio, the exact values where these characteristic temperatures occur has not yet been determined from first principle Lattice QCD calculations and may occur anywhere within the cross-over regime of the phase transition. However, if there is a critical point in the QCD phase diagram then all characteristic temperatures should converge and, depending on the universality class, some of the hydrodynamic transport coefficients themselves may diverge. In order to explore out-of-equilibrium effects in the QCD phase diagram we use 1+0D (Bjorken flow) viscous hydrodynamics to study the hydrodynamical lifetime, cavitation, and attractor physics in a simple cross-over phase transition versus one with a critical point (where we expect all characteristic temperatures to converge). Comparisons between results obtained using an equation of state with nonzero baryon, strange, and electric charge chemical potentials and results obtained using the assumption of only a finite baryon chemical potential (i.e. $\mu_S=\mu_Q=0$) are also made.

        Speaker: Mr Travis Dore (University of Illinois Urbana-Champaign)
      • 17:40
        Using Event Shape Engineering to study anisotropic flow of inclusive and identified particles in Pb-Pb collisions with ALICE 20m

        Heavy-ion collisions produce asymmetric pressure gradients which convert via interactions the initial spatial asymmetry into an anisotropy in final state momentum space, a phenomenon referred to as anisotropic flow. Anisotropic flow is characterized using the harmonic coefficients $v_{\rm n}$ in a Fourier decomposition of the azimuthal distribution of produced particles relative to the symmetry plane in a collision. It is found that flow fluctuates event-by-event due to fluctuations in the initial geometry, which allows for an efficient selection of events that correspond to a specific initial geometry. This technique, called Event Shape Engineering, was applied to select events within the same centrality but having very different values of the elliptic ($v_2$) and triangular ($v_3$) flow coefficients. For those events, we present results on centrality, transverse momentum ($p_{\rm T}$) and event-shape dependence of anisotropic flow for inclusive and identified ($\pi^{\pm}$, $K^{\pm}$, ${\rm p}+\overline{\rm p}$, $\Lambda + \overline{\Lambda}$, $\rm K^{0}_{\rm S}$, $\Xi^{-} + \overline{\Xi}^{+}$, and $\Omega^{-} + \overline{\Omega}^{+}$) particles in Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV recorded by the ALICE detector in 2015 and 2018. We also investigate the correlation between $v_2$ of inclusive and identified particles averaged over low and high $p_{\rm T}$ ranges.

        Speaker: Catalin Ristea (Institute of Space Science (RO))
      • 17:40
        Viscous fluid dynamics for binary neutron-star mergers 20m

        The recent detection of a binary neutron star merger using gravitational waves and electromagnetic signals marked the dawn of the multi-messenger astronomy era. Such events are expected to provide key information about the properties of matter at extreme densities and temperatures and, for many years, it was assumed that this system could be reasonably described as an ideal (i.e. inviscid) fluid coupled to Einstein’s equations. This was recently revisited by Alford et al. in [1] using state-of-the-art merger simulations which showed that damping of high-amplitude oscillations due to bulk viscosity is expected to play an important role in gravitational wave emission and, as such, this should be taken into account and thoroughly investigated in realistic merger simulations. However, viscous effects have not yet been included in merger simulations because this requires a formulation of relativistic fluid dynamics, including bulk viscosity, that is causal in the strong nonlinear regime probed by the mergers. This has been an open problem in the field since Israel and Stewart's seminal work in 1979. In this work we solve this problem and prove [2] that the Einstein-Israel-Stewart equations, describing the dynamics of a relativistic fluid with bulk viscosity and nonzero baryon charge dynamically coupled to gravity, are causal in the full nonlinear regime. We use an arbitrary equation of state and do not make any simplifying symmetry or near-equilibrium assumption, requiring only physically natural conditions on the fields. These results pave the way for the inclusion of bulk viscosity effects in simulations of gravitational-wave signals coming from neutron star mergers, which will provide key information about the novel out-of-equilibrium properties of highly dense QCD matter in neutron stars.

        [1] M.G. Alford, L. Bovard, M. Hanauske, L. Rezzolla and K. Schwenzer,
        ``Viscous Dissipation and Heat Conduction in Binary Neutron-Star Mergers,''
        Phys. Rev. Lett. 120, no. 4, 041101 (2018).

        [2] F. S. Bemfica, M. M. Disconzi and J. Noronha,
        ``Causality of the Einstein-Israel-Stewart Theory with Bulk Viscosity,''
        Phys. Rev. Lett. 122, no. 22, 221602 (2019).

        Speaker: Jorge Noronha (University of Sao Paulo)
      • 17:40
        When Jet Quenching meets Machine Learning 20m

        It’s believed that the properties of quark-gluon-plasma (QGP) can be studied through measurements of the jet quenching phenomenon. More specifically, observation of jet substructure variables may reveal the microscopic properties of the QGP.

        Recently the modification of groomed jet observables was studied in heavy-ion collisions [1]. In addition, the Lund radiation plane was introduced to investigate parton shower modifications in the QGP [2].

        In this poster I am going to show how machine learning techniques can help evaluate how quenched a jet is. The first approach is to use a convolution neural network (CNN) which is a technique heavily used in computer vision. The second approach uses a technique based on long and short-term memory (LSTM). The LSTM model is an artificial recursive neural network and is capable of processing sequential data. This design makes it well-suited for making predictions on jets considering that the way of calculating substructure variables implies sequential information of how branchings occur.

        Simulations are made with monte-carlo event generators such as PYTHIA8 and JEWEL which simulates jet showering in vacuum and in medium respectively. Classifiers are trained in order to evaluate how quenched a jet is. In addition, experience from the perspective of hardware will also be shared.

        Reference:
        [1] Measurement of the splitting function in pp and PbPb collisionsat√sNN =5.02TeV
        [2] Novel tools and observables for jet physics in heavy-ion collisions

        Speaker: Lihan Liu (Vanderbilt University (US))
      • 17:40
        Zilch currents and chiral kinetic theory for vector particles 20m

        The chiral vortical effect (CVE) is believed to be intrinsically related to the anomalies of the axial current and the topological properties of the system. It was suggested that the CVE can be generalized to systems of higher-spin particles and, particularly, to photons. However, there is no local gauge invariant definition of photonic helicity current. This problem can be overcome with an appropriate choice of the polarization measure. Recently, it was shown that there is a vortical effect in photonic zilch current (ZVE), which can play the role of a local gauge invariant helicity separation measure. In this work we study the zilch current in terms of chiral kinetic theory and show that the ZVE can be related to the non trivial topological properties of the system in momentum space manifested through the Berry phase. We also show how the ZVE arises in terms of the Wigner-function formalism for vector particles.

        Speaker: Enrico Speranza (Frankfurt University)
    • 18:00 20:00
      Reception 2h
    • 08:40 10:40
      Parallel Session - Small systems I Ball Room 3

      Ball Room 3

      Wanda Reign Wuhan Hotel

      Convener: Federico Antinori (Universita e INFN, Padova (IT))
      • 08:40
        Collectivity of heavy flavor hadrons in pp and pPb collisions with the CMS detector 20m

        Measurements of long-range, collective azimuthal correlations involving heavy-flavor quarks provide a powerful tool for unraveling the origin of the collectivity observed in small collision systems. In particular, these measurements are sensitive to the early stages of the collisions. As compared to those for light flavor hadrons, large azimuthal anisotropy signals have been observed by CMS for charm hadrons, including prompt $D^{0}$ and J/$\Psi$ particles, in high multiplicity pPb collisions. With data collected by the CMS experiment at the LHC in 2016 and 2018, the multiplicity and transverse momentum dependence of the elliptic azimuthal anisotropy ($v_2$) of prompt $D^{0}$ meson in 8.16 TeV pPb and 13 TeV pp collisions are presented over wide rapidity (|y|<2) ranges. The analysis is based on long-range, two-particle correlations. Results for nonprompt $D^{0}$ mesons from B meson decay are also presented to explore the possible collective flow of bottom quarks. These results provide key insights to the heavy quark collectivity developed in high-multiplicity pp and pPb systems.

        Speaker: Austin Alan Baty for the CMS Collaboration (Rice University (US))
      • 09:00
        ATLAS measurements of collective flow of heavy-flavor hadrons in small collision systems 20m

        ATLAS measurements of azimuthal anisotropy of heavy flavor mesons in the small systems is presented. A template fit method is used to subtract non-flow contributions using simultaneous fit to low and high charged-particle multiplicity samples. The heavy flavor flow in $p$+Pb is studied using multiple probes, including prompt $D^{0}$ mesons, J/$\psi$, and muons from semi-leptonic decays of heavy flavor hadrons. In $pp$ collisions, flow coefficient for muons from heavy flavor decays, separated for charm and bottom origins, are also presented. The observed heavy flavor azimuthal anisotropies in $p$+Pb and $pp$ collisions are found to be qualitatively similar to those of light hadrons indicating a similar origin for both types of particles.

        Speaker: Sanghoon Lim for the ATLAS Collaboration (University of Colorado Boulder)
      • 09:20
        Flow in AA and pA as an interplay of fluid-like and non-fluid like excitations 20m

        To study the microscopic structure of quark-gluon plasma, data from hadronic collisions must be confronted with models that go beyond fluid dynamics. Here, I describe a study of a kinetic theory model that encompasses fluid dynamics but contains also particle-like excitations in a boost invariant setting with no symmetries in the transverse plane. The kinetic theory results are compared to data on azimuthal flow coefficients over a wide centrality range in PbPb collisions at the LHC, in AuAu collisions at RHIC, and in pPb collisions at the LHC. By comparing kinetic transport to viscous fluid dynamics we find that non-hydrodynamic excitations make the dominant contribution to collective flow signals in pPb collisions at the LHC and contribute significantly to flow in peripheral nucleus-nucleus collisions, while fluid-like excitations dominate collectivity in central nucleus-nucleus collisions at collider energies.

        Speaker: Eero Aleksi Kurkela (CERN)
      • 09:40
        Measurement of $v_2$ and $v_3$ in p+Au, d+Au and $^3$He+Au collisions at $\sqrt{s_{NN}}=200$ GeV from STAR 20m

        We present a comprehensive measurement of the transversal momentum ($p_T$) and multiplicity ($N_{ch}$) dependence of azimuthal harmonics $v_2$ and $v_3$ in RHIC small system scan at $\sqrt{s_{NN}}=200$ GeV. This measurement contains several new results and important improvements: 1) previous results on $v_2$ in p+Au and d+Au collisions are now expanded to include $^3$He+Au collisions, as well as new $v_3$ results in all three systems; 2) the non-flow systematics are reduced using the actual p+p data at 200 GeV as reference in the peripheral subtraction procedure. This is demonstrated by the reduced sensitivity on the choice of non-flow subtraction methods as well as a closure test of these methods with the HIJING and AMPT models; 3) the $v_2$ signal is also extracted using four-particle subevent cumulant method in d+Au and $^3$He+Au, and compared with that from two-particle correlations to gain insight on the flow fluctuations in small systems. We also compare our results with existing measurements from the RHIC and LHC. The implications of these new results on our understanding of the initial geometry including nucleon substructure and the origin of collectivity in small systems are discussed.

        Speaker: Roy Lacey for the STAR Colllaboration (Stony Brook University)
      • 10:00
        Recent quarkonium measurements in small systems with the ALICE detector at the LHC 20m

        Quarkonium production measurements represent a key probe to investigate the space-time properties of the Quark-Gluon Plasma (QGP) created in heavy-ion collisions. Measurements in small systems, namely pA and proton-proton (pp), are crucial in order to interpret correctly results in heavy-ion collisions. Potential initial-state effects can be constrained through the measurement of the nuclear modification factor in pA collisions ($R_{\rm pA}$), defined as the ratio of quarkonium yields in pA to the reference production in pp collisions, collected at the same center-of-mass energy and scaled by the number of binary nucleon--nucleon collisions. Besides serving as reference, results in pp collisions represent a benchmark test of QCD based models in both perturbative and non-perturbative regimes.

        The ALICE detector has unique capabilities at the LHC for measuring quarkonia down to zero transverse momentum. Measurements are carried out at both central
        and forward rapidity, in the dielectron and dimuon decay channel, respectively.

        In this contribution the latest quarkonium measurements performed by the ALICE collaboration in pp and p-Pb collisions will be presented. Recent nuclear modification factor measurements at mid-rapidity in p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV will be shown for both prompt and non-prompt J/$\psi$ mesons, the latter originated from the decays of long-lived beauty-flavored hadrons. The status of mid-rapidity J/$\psi$ analyses in p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 8.16 TeV, using both minimum bias and high $p_{\rm T}$ triggered (using ALICE TRD detector) events and including the study of non-prompt J/$\psi$ contribution, will be also presented. In addition the centrality, rapidity and transverse momentum dependence of $R_{\rm pPb}$ for $\psi$(2S), $\Upsilon$(1S) and $\Upsilon$(2S), measured at forward rapidity in p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 8.16 TeV, will be shown. Regarding pp collisions, recent J/$\psi$ cross-section measurements at $\sqrt{s}$ = 5 and 13 TeV performed at central and forward rapidity, including the status of the analysis for the separation between prompt and non-prompt J/$\psi$ components at mid-rapidity, will be presented. Results in both pp and p-Pb collisions will be compared with available theoretical model calculations.

        Speaker: Jhuma Ghosh (Saha Institute of Nuclear Physics (IN), HBNI)
      • 10:20
        The elliptic flow of heavy quarkonia in pA collisions from the initial state. 20m

        The particular azimuthal angular correlation between a heavy meson and a light hadron has first been measured at the LHC recently. In this two particle correlation method, the experimental results show that the elliptic flows for heavy-flavor mesons (J/psi and D^0) are almost as large as those for light hadrons. We investigate the angular correlation between a heavy quarkonium and a charged light hadron in the Color Glass Condensate framework, which indicates that the heavy quarkonium v_2 can be naturally interpreted as an initial state effect. We also predict that the heavy quarkonium Upsilon should have a similar elliptic flow as compared to that of the J/psi, which can be tested in future measurements.

        Speaker: Dr Cheng Zhang (Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University & Key Laboratory of Particle Physics and Particle Irradiation (MOE), Institute of frontier and interdisciplinary science, Shandong University)
    • 08:40 10:40
      Parallel Session - Collective dynamics I Ball Room 1

      Ball Room 1

      Wanda Reign Wuhan Hotel

      Convener: Raimond Snellings (Nikhef National institute for subatomic physics (NL))
      • 08:40
        ATLAS measurements of transverse and longitudinal flow decorrelations in Pb+Pb and Xe+Xe collisions 20m

        ATLAS measurements of flow harmonics ($v_{n}$) and their fluctuations in Pb+Pb and Xe+Xe collisions covering a wide range of transverse momenta, pseudorapidity and collision centrality are presented. The $v_{n}$ are measured up to $n=7$ using the two-particle correlations, multi-particle cumulants and scalar product methods.The $v_{n}$ for $n$=2-7 is obtained with various correlation methods, together with a non-flow subtraction technique to improve the understanding of flow in peripheral region.A universal scaling in the $p_{T}$ dependence of the $v_{n}$ is observed for both systems. For the first time, longitudinal flow decorrelations involving two- and four-particle correlations for $v_{2}$ and $v_{3}$ are measured in Xe+Xe collisions and compared with results from Pb+Pb collisions.The four-particle decorrelation is found to not factorize as a product of two-particle decorrelations. The ability of such measurements to distinguish between different models of initial geometry and to reduce the uncertainty in determining the effective shear-viscosity to entropy-density ratio of the QGP are demonstrated.

        Speaker: Soumya Mohapatra for the ATLAS Collaboration (Columbia University (US))
      • 09:00
        Longitudinal De-correlation of Anisotropic Flow in Au+Au Collisions at $\sqrt{s_{NN}}$ = 27 and 54.4 GeV from STAR 20m

        Studies of longitudinal de-correlation of anisotropic flow provide unique constraints on the initial conditions and dynamical evolution of the quark-gluon-plasma in heavy-ion collisions. With data collected by the STAR experiment at RHIC, the factorization ratio for flow harmonics, $r_n(\eta^a, \eta^b) (n = 2, 3)$, are obtained over a wide $\eta$ range for 27 and 54.4 GeV Au+Au collisions as a function of centrality and transverse momentum. Comparing to results from LHC and 200 GeV Au+Au collisions, we observe a clear collision-energy dependence indicating a stronger longitudinal de-correlation at lower collision energies. The results provide new insights into the three-dimensional modeling of the evolution of relativistic heavy-ion collisions and the shear viscosity of the QGP, especially their collision energy dependence. Comparison with the hydrodynamic model calculations will be included.

        Speaker: Maowu Nie for the STAR Collaboration (Shandong University (SDU) & Stony Brook University)
      • 09:20
        Longitudinal hydrodynamic response and pseudo-rapidity dependent harmonic flow in relativistic heavy-ion collisions 20m

        In heavy-ion collisions, it is well-established that geometrical shapes of the initial density distribution in transverse plane are responsible for the observed harmonic flow, through the hydrodynamic response of a set of modes. In particular, elliptic flow $V_2$ is linearly proportional to initial eccentricity $\mathcal{E}_2$.

        In this work, we generalize the framework to study hydrodynamic response along the longitudinal direction. We propose a differential hydrodynamic response relation, $V_2(\eta)=\int d\xi G(\eta-\xi) \mathcal{E}_2(\xi)$, to describe the formation of a pseudo-rapidity dependent elliptic flow, in response to a 3D initial density profile. By analyzing the medium expansion using event-by-event simulations of 3+1D MUSIC, with initial conditions generated via the AMPT model for the Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV, the differential response relation is verified and expansion coefficients to very high orders are identified in the response function $G(\eta-\xi)$.

        Our investigations of the hydrodynamic response function have yielded two important insights: 1. The two-point auto-correlation of elliptic flow in pseudo-rapidity (an observable in heavy-ion experiments), can be separated as medium response and two-point correlation of initial $\mathcal{E}_2$. Especially, shear viscosity of the medium reduces the correlation length systematically. 2. Higher order expansion coefficients increase exponentially, which implies a finite radius of convergence of the gradient expansion in the dispersion relation of hydrodynamics. The radius of convergence in the response function results in a minimal length scale that can be used to estimate the applicability of hydrodynamic modeling of heavy-ion collisions, which provides a possible solution to the question of fluidity in small systems.

        Speaker: Li Yan (Fudan University)
      • 09:40
        Rapidity decorrelation caused by hydrodynamic fluctuations and initial longitudinal fluctuations 20m

        Factorization breaking of flow coefficients is actively studied to understand longitudinal dynamics of the quark-gluon plasma produced in high-energy nuclear collisions, yet no hydrodynamic models have successfully described the centrality dependence of the factorization breaking in various collisions systems. In this study, we reproduce the centrality dependence of rapidity decorrelation in Pb+Pb collision at LHC by constructing an integrated dynamical model with hydrodynamic fluctuations [1,2] and initial longitudinal fluctuations.

        Hydrodynamic fluctuations are thermal fluctuations arising during the hydrodynamic stage of high-energy nuclear collisions. We include hydrodynamic fluctuations obeying the fluctuation-dissipation theorem [1]. For initial longitudinal fluctuations, we employ an initial model discussed in Ref. [3]. In this model, we run PYTHIA for each binary $p+p$ collision, scale it by the number of participants and regard the distribution of produced particles as entropy density distribution. We switch on and off the initial longitudinal fluctuations and hydrodynamic fluctuations to understand the origin of longitudinal rapidity decorrelation.

        [1] Koichi Murase, “Causal hydrodynamic fluctuations and their effects on high-energy nuclear collisions”, Ph. D thesis, the University of Tokyo (2015).
        [2] Koichi Murase, “Causal hydrodynamic fluctuations in non-static and inhomogeneous backgrounds”, arXiv:1904.11217 (2019).
        [3] Michito Okai, Koji Kawaguchi, Yasuki Tachibana, and Tetsufumi Hirano, “New approach to initializing hydrodynamic fields and mini-jet propagation in quark-gluon fluids”, Phys. Rev. C 95, 054914 (2017)

        Speaker: Azumi Sakai (Sophia University, Japan)
      • 10:00
        Anisotropic flow fluctuations of charged and identified hadrons in Pb-Pb collisions with the ALICE detector 20m

        Anisotropic flow fluctuations can be used to probe the properties and evolution of the system created in heavy-ion collisions. In this talk, we present the first $p_{\rm T}$-differential measurements of the first and second order moments of $v_{\rm 2}$ probability density function (PDF), extracted from a comprehensive set of light-flavor hadrons. In addition, we also present higher order moments, skewness and kurtosis, as a function of $p_{\rm T}$ and centrality for unidentified charged hadrons. Finally, we discuss the $p_{\rm T}$-differential measurements of charged hadrons' $v_{\rm 2}$ with 2-, 4-, 6- and 8-particle cumulants in context of the underlying PDF.

        We report the measurements of $\pi^{\pm}$, ${\rm K}^{\pm}$, ${\rm p + \bar{p}}$, $\rm \Lambda + \bar{\Lambda}$, $\rm \Xi^{\pm}$, $\rm \Omega^{\pm}$, $\rm \phi$ and inclusive charged hadrons $v_{\rm n}$ fluctuations, measured in Pb-Pb collisions at $\sqrt{s}_{\rm NN}=5.02{\rm TeV}$ using multi-particle cumulants with the ALICE detector. Measurements are performed in central pseudorapidity region $|\eta|<0.8$ and cover a wide transverse momentum range. The implications of our results for understanding of the properties of the medium will be discussed.

        Speaker: Ya Zhu for the ALICE Collaboration (Central China Normal University )
      • 10:20
        Longitudinal dynamics of multiple conserved charges 20m

        It is the aim of the RHIC BES program and the future FAIR and NICA facilities to produce compressed baryonic matter. In such experiments, strong gradients in baryon density are expected, and therefore the diffusion of baryon number could play a major role in the description of the fireball. The constituents of the produced matter carry a multitude of conserved charges, namely the baryon number, strangeness and electric charge, so that the diffusion currents of conserved charge couple with each other. Therefore, baryon density gradients in the above-mentioned high-density collision experiments will generate equalizing currents in all conserved charges. In common fluid dynamic studies of the evolution of the fireball, this coupling of currents was not accounted for. We provide for the first time a fluid dynamical approach including the complete diffusion coefficient matrix describing the evolution of a dense system with multiple conserved charges. A novel phenomenon arising from the coupled diffusion currents is the generation of positive and negative net-strangeness domains from originally net-strangeness neutral matter. We show how these domains are generated dynamically, and argue that observing the rapidity dependence of net-strangeness can give an experimental access to diffusion.

        Speaker: Jan Fotakis (University of Frankfurt)
    • 08:40 10:40
      Parallel Session - EM probes I HongKong Room

      HongKong Room

      Wanda Reign Wuhan Hotel

      Convener: Ming Shao (Univ. of Sci. and Tech. of China)
      • 08:40
        Measurements of dileptons and photon pairs from two-photon scattering in ultra-peripheral and hadronic Pb+Pb collisions with the ATLAS detector 20m

        In ultra-relativistic heavy-ion collisions, one expects copious rates of $\gamma+\gamma$ processes through the interaction of the large electromagnetic fields of the nuclei, which can produce new particles (e.g. leptons) or even lead to light-by-light scattering via loop diagrams. The latter process is a notable prediction of QED and was only recently observed by ATLAS using the full 2018 dataset. In ultra-peripheral collisions (UPCs), characterized by large impact parameter between the nuclei, the outgoing leptons and photons are produced exclusively, and exhibit a strong back-to-back momentum correlation, with long tails induced by higher-order QED effects. This talk presents measurements of dilepton production and light-by-light scattering performed by the ATLAS collaboration. The angular correlations as well as differential production cross sections in UPCs are measured and compared to theoretical models, including final state QED radiation. The role of forward neutron production in disentangling pure QED and dissociative processes will also be discussed. Finally, limits on axion-like particle production, from the observed light-by-light cross sections, will be discussed. Muon pairs produced the same two-photon scattering process in hadronic Pb+Pb collisions also potentially provide a sensitive probe of the quark gluon plasma. First measurements by ATLAS and STAR of dileptons produced via two-photon scattering in non-ultra-peripheral (non-UPC) nucleus-nucleus collisions showed an unexpected centrality-dependent broadening of the angular correlation between the two leptons and/or of the two-lepton $p_T$ distribution. ATLAS has recently measured dimuons produced via two-photon scattering in non-UPC Pb+Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$~TeV using data collected during the 2018 Pb+Pb run at the LHC corresponding to an integrated luminosity of $1.73~\mathrm{nb}^{-1}$. This data set represents a factor of $\sim4$ increase in statistics over the 2015 data set used for the first ATLAS measurement. The increased statistics allow new features to be observed in the data, as well as differential studies of the dependence of the pair-distribution on the transverse-momentum and pseudorapidity of the two muons. The results of the new measurement and the possible physics implications will be discussed.

        Speaker: Prabhakar Palni for the ALICE Collaboration (AGH University of Science and Technology (PL))
      • 09:00
        Measurements of the $\gamma\gamma\rightarrow e^+e^−$ process and its angular correlations in UPC and peripheral Au+Au collisions with the STAR Detector 20m

        Ultra-relativistic heavy ion collisions are expected to produce some of the strongest magnetic fields ($10^{13}−10^{16}$ Tesla) in the Universe [1]. Recently, there has been intense interest in the magnetic fields produced by heavy ion collisions and their possible observational impacts through phenomena like the Chiral Magnetic Effect. The initial strong electromagnetic fields produced in heavy ion collisions have been proposed as a source of linearly-polarized, quasi-real photons [2] that can interact to produce $e^+e^−$ pairs.

        In this talk we present STAR measurements of $e^+e^−$ pair production in ultra-peripheral and peripheral Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. Multi-differential measurements of the pair kinematics are presented to distinguish the $\gamma\gamma\rightarrow e^+e^−$ process from other possible production mechanisms. These measurements provide an important experimental tool and baseline for the possible measurement of medium effects driven by strong final state magnetic fields or from Coulomb multiple scattering through the QGP.

        Furthermore, we present the first observation of a 4th-order azimuthal modulation of $e^+e^−$ pairs produced in heavy ion collisions. The observed 4th-order angular modulation, a result predicted for the collision of linearly-polarized photons [3], has general implications for fermion, anti-fermion pair production in the collision of polarized fields. Specifically, similar angular measurements of heavy quark pairs have been proposed for the study of gluon transverse momentum dependent (TMD) distributions within nuclei [4,5].

        [1] V. Skokov, A. Illarionov, and V. Toneev, International Journal of Modern Physics A 24 (2009) 5925–5932.
        [2] C. Weizsaecker, Zeitschrift fuer Physik 88 (1934) 612–625.
        [3] L. Cong, J. Zhou, and Y. Zhou, arxiv:1903.10084.
        [4] J. Collins, and D. Soper, Nuclear Physics B 194 (1982) 445–492.
        [5] A. Metz, and J. Zhou, Phys. Rev. D 84 (2011) 051503(R).

        Speaker: Daniel Brandenberg for the STAR Collaboration (Shandong University & Brookhaven National Laboratory)
      • 09:20
        Probing early time dynamics and QGP transport properties with photons in relativistic heavy-ion collisions 20m

        We present the first study quantifying the sensitivity of hadron and photon observables to the early-time evolution in heavy-ion collisions which implements a realistic pre-equilibrium stage with effective QCD kinetic theory [1, 2] and a state-of-the-art hybrid (IP-Glasma + MUSIC + UrQMD) framework [3]. We calculate photon emission from the pre-equilibrium phase by folding the system's energy momentum-tensor with thermal photon emission rates including their viscous corrections. By changing switching time and coupling parameters inherent to the pre-equilibrium evolution, we study how the non-equilibrium phase influences the hadron and photon flow coefficients in Pb+Pb, Xe+Xe, and O+O collisions at 5 TeV. Because the space-time volume scales differently from the number of binary collisions from O+O to Xe+Xe and Pb+Pb collisions, a systematic system size comparison of photon production can further shed light on the relative contributions from thermal and prompt sources and provide further insight into early time QGP dynamics.

        Recent Bayesian extractions of the QGP bulk viscosity using hadronic observables alone [4] cannot disentangle easily a large narrow peak temperature dependence of bulk viscosity from a broader $\zeta/s(T)$ with a lower maximum value. Utilizing the power of photons as clean and penetrating probes, we demonstrate how thermal photon production and its flow coefficients can improve constraints on QGP bulk viscosity owing to its sensitivity to early stages of the QGP evolution.

        [1] A. Kurkela, A. Mazeliauskas, J.F. Paquet, S. Schlichting, and D. Teaney, "Matching the Nonequilibrium Initial Stage of Heavy Ion Collisions to Hydrodynamics with QCD Kinetic Theory," Phys. Rev. Lett. 122, no. 12, 122302 (2019)

        [2] A. Kurkela, A. Mazeliauskas, J.F. Paquet, S. Schlichting, and D. Teaney, "Effective kinetic description of event-by-event pre-equilibrium dynamics in high-energy heavy-ion collisions," Phys. Rev. C 99, no. 3, 034910 (2019)

        [3] S. McDonald, C. Shen, F. Fillion-Gourdeau, S. Jeon and C. Gale, "Hydrodynamic predictions for Pb+Pb collisions at 5.02 TeV", Phys. Rev. C 95, no. 6, 064913 (2017)

        [4] J.F. Paquet, C. Shen, G. Denicol, S. Jeon and C. Gale, "Phenomenological constraints on the bulk viscosity of QCD," Nucl. Phys. A 967, 429 (2017).

        Speaker: Charles Gale (McGill University)
      • 09:40
        Charmonium production in Pb-Pb ultra-peripheral collisions (UPC) and Z production in pPb collisions at LHCb 20m

        Photo-produced vector mesons in ultra-peripheral Pb-Pb collisions at forward rapidity are sensitive to the small-x parton distribution functions (nPDFs) in the target nucleus. In pPb collisions, measurements of the Z production in forward (pPb) and backward (Pbp) configuration are also sensitive to the nPDFs in another kinematic domain, both probes allowing to study in a complementary fashion the structure of the nucleus.

        In this talk, we present the latest results obtained on the charmonium production in PbPb ultra-peripheral collisions and the Z production in pPb and Pbp collisions by LHCb.

        Speaker: Hengne Li for the LHCb Collaboration (South China Normal University (CN))
      • 10:00
        A Non-Equilibrium Approach to Photon Emission from the Late Stages of Relativistic Heavy-Ion Collisions 20m

        Cross sections for photon production in hadronic scattering processes have been calculated according to an effective chiral field theory. For $\pi + \rho \to \pi + \gamma$ and $\pi + \pi \to \rho + \gamma$ processes, these cross sections have been implemented into a novel hadronic transport approach (SMASH), which is suitable for collisions at low and intermediate energies. The implementation is verified by systematically comparing the thermal photon rate to theoretical expectations. The impact of form factors is assessed, and scattering processes mediated by ω mesons are found to contribute significantly to the total photon production. The photon rates we obtain are compared with parametrizations commonly used in hydrodynamic simulations, and also with previous works addressing the production of direct photons from the hadronic stage. Finally, the impact of considering the finite width of the $\rho$ meson is investigated, and a significant enhancement of photon production in the low-energy region is observed. This work is the first step towards a consistent treatment of photon emission in hybrid hydrodynamics+transport approaches, and towards a genuine dynamical description. It will further quantify the importance of the hadronic stage for the resolution of "the direct photon flow puzzle" and can be applied to identify equilibrium and non-equilibrium effects in the hadronic afterburner.

        References:
        A. Schäfer et al. „Benchmarking a Non-Equilibrium Approach to Photon Emission in Relativistic Heavy-Ion Collisions“, Phys. Rev. D 99, 114021 (2019)
        J. Weil et al., „Particle production and equilibrium properties within a new hadron transport approach for heavy-ion collisions“, Phys. Rev C 94, 054905 (2016)

        Speaker: Anna Schäfer (Frankfurt Institute for Advanced Studies (FIAS))
      • 10:20
        Electrical Cross-Conductivity in the Hadron Gas 20m

        Inducing an electric field in the QCD medium generates an electric current which is proportional to the matter’s electric conductivity. Since quarks and hadrons also carry baryon and strange charge, such a field also respectively produces a baryon and strangeness current whose amplitude depends on baryo-electric and strange-electric conductivities. We dub the combination of these 3 properties of matter the cross-conductivity and proceed to calculate it in the hadron gas phase at and below temperatures corresponding to the phase transition between the hadron gas and the quark-gluon plasma. We use the newly-released SMASH transport code to simulate the hadron gas and the Green-Kubo formalism to extract the transport coefficients. After validating the approach for a simple system for which analytical results can be calculated (namely, pions, kaons and protons interacting with constant cross-sections), we gradually increase the number of degrees of freedom, up to reaching a state-of-the-art hadronic resonance gas as described by our current knowledge. Our results show that there are significant differences in the temperature dependence of the different components of the cross-conductivity as a function of the number of degrees of freedom. This new observable can in principle be computed on the lattice, and as such could be used to further constrain the properties of the hadron gas in the low temperature region.

        Speaker: Jean-Bernard Rose
    • 08:40 10:40
      Parallel Session - Jet modifications I Ball Room 2

      Ball Room 2

      Wanda Reign Wuhan Hotel

      Convener: Urs Wiedemann (CERN)
      • 08:40
        In-medium jet modification measured by PHENIX via two particle correlations and high $p_T$ hadrons in A+A collisions 20m

        The first evidence of jet quenching was observed at RHIC via suppression of single high $p_T$ hadron
        $R_{AA}$ and the disappearance of the awayside jet peak in two-particle correlations. Hadron
        $R_{AA}$ and two particle correlations continue to be useful probes of the QGP in heavy ion collisions,
        since the particles involved are fragments of the jets produced in the initial hard scattering. PHENIX recently improved the width measurements extracted from $\pi^{0}$-hadron correlations after removing the higher ordered flow terms in the underlying event. Measurements of the awayside jet correlated with direct photons have shown an increase in low momentum particle production at wide angles consistent with theoretical expectations for energy loss. The use of isolation cuts to select direct photons now allows us to measure this effect as a function of centrality. The system size dependence of energy loss is further investigated at PHENIX by measuring the absolute yield and $R_{AA}$ for various hadron species at high $p_T$ in several collision systems including U+U and Cu+Au. This talk will present the newest PHENIX $R_{AA}$ and two particle correlation measurements and their role in our understanding of jet quenching and medium response in heavy ion collisions.

        Speaker: Anthony Hodges for the PHENIX Collaboration (Georgia State University)
      • 09:00
        Jet shapes and fragmentation functions in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV in STAR 20m

        Jet quenching refers to the energy loss of partons due to interactions with the Quark Gluon Plasma (QGP) in relativistic heavy-ion collisions. It generally modifies measured jet spectra as well as substructure, including the fragmentation pattern and radial distribution of transverse momentum ($\it{p}_{T}$) inside the jet relative to jets in vacuum. In this talk, we report measurements of the differential jet shape and semi-inclusive jet fragmentation functions of quenched jets in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV with the STAR detector at RHIC.

        Based on the semi-inclusive population of jets recoiling from a high-$\it{p}_{T}$ trigger hadron, the fragmentation functions are constructed from the fraction of the transverse momentum of charged particles projected onto the jet axis over that of the jet. The mixed-event technique along with the semi-inclusive approach is further developed for the fragmentation measurement, and applied accordingly to isolate contributions from hard-scattered partons. We attempt to correct for uncorrelated background effects and instrumental effects in the fragmentation functions, and will present preliminary results for central and peripheral collisions. Similarly, the differential jet shapes are constructed by summing the charged particle yields in radial distance from the jet core weighted by $\it{p}_{T}$ of the corresponding charged particles. The presented results will extend the kinematic range offered at the LHC to lower $\it{p}_{T}$ and demonstrate whether there is a modification and a broadening of the jet profile at RHIC energies. We explore the dependence of the jet shape on centrality and jet size ($R$) and further expand the analysis as a function of the event plane angle (defined by the beam direction and the vector of the impact parameter) to investigate the path length dependence of medium modifications to the jets and their associated hadrons.

        Speaker: Saehanseul Oh for the STAR Collaboration (Yale University & Brookhaven National Laboratory)
      • 09:20
        First direct measurement of the dead-cone effect at colliders using iterative declustering techniques in the Lund plane, with D meson jets in pp collisions at $\sqrt{s}$ = 13 TeV with ALICE 20m

        We report the first direct measurement of the dead-cone effect at colliders, using iterative jet declustering techniques in pp collisions at $\sqrt{s}=13$ TeV. The procedure detailed in, exposes the splittings of D mesons in the jet shower, by iteratively declustering the angular ordered C/A tree. The splitting history of the D meson initiated jet is mapped onto the Lund plane, where appropriate cuts can be made to suppress hadronisation effects. The reported variable is the splitting angle with respect to the D meson axis, which is updated after each splitting. Track-based jet finding, along with the low $p_{\rm T}^{\rm ch}$ reach of the ALICE detector, allow for an accurate reconstruction of the splitting angle in the phase-space where the dead-cone effect is expected to be largest. The results are compared to those of inclusive jets and theoretical models.

        Speaker: Nima Zardoshti for the ALICE Collaboration (CERN)
      • 09:40
        Extracting the jet transport coefficient of cold nuclear matter from world data 20m

        Quantifying the differences between nuclear and hadronic collisions, phenomenologically known as medium modification due to multiple scatterings between the hard probe and medium, can provide a solid baseline for unambiguous identification of the medium fundamental property. In this talk, we consider parton propagation in cold nuclear matter within the framework of high-twist expansion, which has been shown to be a successful approach to describe the nuclear effects as observed in heavy ion collisions. Through global analysis of world data on transverse momentum broadening in semi-inclusive eA deep inelastic scattering, Drell-Yan process and heavy quarkonium production in pA collisions, as well as the nuclear modification of the structure functions in DIS related to the coherent dynamical shadowing, we perform the first global extraction of jet transport coefficient for cold nuclear matter. This provide the first evidence that the medium transport property, rather than a constant value as commonly used in heavy ion collisions, depends on the probing scale similar to that in standard parton distribution functions of proton. We expect the extracted scale dependence of qhat for cold nuclear matter can be extended to precisely identify the fundamental property of quark gluon plasma.

        Speaker: Hongxi Xing (South China Normal University)
      • 10:00
        Hydrodynamic response to jets with a source based on causal diffusion 20m

        We present a systematic study of the hydrodynamic medium response to jet shower propagation, based on a strongly-coupled description of the Quark-Gluon Plasma (QGP). A causal formulation for the space-time profile of energy-momentum source terms is incorporated with a multi-stage jet evolution and (3+1)-D viscous hydrodynamics within the JETSCAPE 2.0 framework. In this work, we employ a causal relativistic diffusion equation to model the evolution of the localized energy and momentum depositions by jet partons before injection into the QGP fluid. This formulation provides the source terms with a space-time profile that naturally preserves causality. The diffusion coefficient and the relaxation time used in this model are directly connected to the transport properties of the QGP, such as its specific shear viscosity, and determine the size and shape of the source-term profile.

        Utilizing this new framework, we quantify the effects of the hydrodynamic response of a strongly-coupled medium on jet substructures (e.g. jet shape and jet fragmentation functions), by comparing with results for a weakly-coupled QGP where the medium response is modeled with recoil partons. Furthermore, we explore the dependence on the diffusion coefficient and the relaxation time in the diffusion of the sources to show how the transport properties of the QGP manifest themselves in the medium response to jet propagation.

        Speaker: Yasuki Tachibana for the JETSCAPE Collaboration (Wayne State University)
      • 10:20
        The medium modification of jet fragmentation function and baryon-to-meson ratio in jet 20m

        We use CoLBT-hydro model for simultaneous event-by-event simulations of jet propagation and hydrodynamics evolution of the bulk medium including jet-induced medium excitation. The final reconstructed jet in heavy-ion collision include not only hadrons from medium response for the deposited energy and momentum of hard partons, but also hadrons from the fragmentation and recombination process of in-medium hard partons. We carry out the study with CoLBT-hydro of medium modification of jet fragmentation function and baryon-to-meson ratio in jet. CoLBT-hydro describes both CMS and ALICE data well on the suppression of leading hadrons due to parton energy loss and an enhancement of soft hadrons due to jet-induced medium excitation in different collisional centralities. And it also shows the medium modification of particle ratio (p/π, Λ/k^0_s) in the reconstructed jet in the large p_T range.

        Speaker: WEI CHEN (CCNU)
    • 10:40 11:00
      Coffee Break 20m
    • 11:00 12:40
      Parallel Session - Heavy Flavor I Ball Room 3

      Ball Room 3

      Wanda Reign Wuhan Hotel

      Convener: Roberta Arnaldi (Universita e INFN Torino (IT))
      • 11:00
        Latest results on $\Lambda_c$ and D production in pp and Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV with ALICE at the LHC 20m

        Charm quarks are a powerful probe of the Quark-Gluon Plasma (QGP) formed in
        high- energy heavy-ion collisions. Produced in hard scattering processes on a
        timescale shorter than the QGP formation time, they experience the whole evolution
        of the medium interacting with its constituents. The measurements of charm-hadron
        production allows testing the mechanisms of in-medium parton energy loss. Moreover,
        the study of charm-baryon production in heavy-ion collisions and in particular the
        baryon-to-meson ratio, provides unique information on hadronisation mechanisms,
        constraining the role of coalescence and testing the predicted presence of
        diquark states in the medium. In particular, the $\Lambda_c/\rm D^0$ ratio is
        expected to be enhanced with respect to the proton-proton baseline if charm quarks
        hadronise via recombination with the surrounding light quarks in the QGP. In this
        scenario, the presence of diquark bound states in the QGP could further increase
        the $\Lambda_c$ production. Thus, charm baryons are ideal tools to investigate
        unexplored aspects of the QGP. The ALICE detector is well suited to detect charm
        baryons down to low $p_{\rm T}$ thanks to the excellent tracking capabilities and
        state-of-art particle identification. In pp and Pb-Pb collisions, $\Lambda_c$ baryons
        are reconstructed in the hadronic decay channels $\Lambda_c\rightarrow pK^0_s$ and
        $\Lambda_c\rightarrow pK\pi$ by means of machine-learning methods.

        In this contribution, the new ALICE results on charm-meson and baryon production
        from the 2018 Pb-Pb sample and from the 2017 pp sample will be shown. In the pp system,
        the measurement of $\Lambda_c$ production as a function of charged-particle multiplicity
        will be discussed. In the Pb-Pb system, the measurement of the $\Lambda_c$ production, n
        uclear modification factor and the $\Lambda_c/\rm D^0$ ratio in central and
        semi-central events in a large transverse-momentum interval
        ($2 \le p_{\rm T} \le 24$ GeV/$c$) will be discussed together with the comparison
        with similar results in smaller collision systems. Moreover, the comparison of our
        results to theoretical models will be shown.

        Finally, we will discuss the status and prospects for the $\Xi_c$ and $\Sigma_c$ analyses.

        Speaker: Gian Michele Innocenti for the ALICE Collaboration (CERN)
      • 11:20
        Charm-hadron production in pp and AA collisions 20m

        The enhancements of D_s/D^0 and Lambda_c/D^0 ratios in heavy-ion collisions as recently measured at RHIC and the LHC have posed formidable challenges for
        theoretical models. We address these puzzles by developing a theoretically
        controlled hadronization framework of heavy quarks that conserves 4-momentum and
        recovers thermal and chemical equilibrium limits [1]. In particular, we implement
        space-momentum correlations of charm quarks with flowing partons as a genuine
        consequence of a hydrodynamic background (but elusive in most coalescence models
        to date), and an improved charm hadro-chemistry [2] that incorporates additional
        charm hadrons beyond the current listings by the PDG but predicted by the
        relativistic quark model and lattice QCD. We show that the charm-hadron data at
        RHIC and the LHC can be fairly well accounted for by our strong-coupling
        framework of heavy-flavor transport and hadronization, within current theoretical
        uncertainties.
        [1]. Min He and Ralf Rapp, arXiv: 1906.00035 [nucl-th].
        [2]. Min He and Ralf Rapp, Phys. Lett. B795, 117 (2019).

        Speaker: Min He (Nanjing University of Science & Technology)
      • 11:40
        Sequential Hadronization with Charm Conservation in High Energy Nuclear Collisions 20m

        Heavy quarks are initially produced in nuclear collisions and the number is conserved during the evolution of the system. We establish a sequential coalescence model with charm conservation and apply it to charmed hadron production at RHIC and LHC energies. The charm conservation enhances the earlier formed hadrons and reduces the later formed ones, which leads to a $D_s/D^0$ enhancement and a $\Lambda_c/D^0$ suppression. The mass dependence of the sequential hadron formation provides us a new tool for studying the quark-gluon plasma hadronization in high energy nuclear collisions. In the meantime, we have extend this framework to study the $D_s/D^0$ and $\Lambda_c/D^0$ at high baryon density regions.

        Speaker: Jiaxing zhao
      • 12:00
        Beauty production with ALICE at the LHC 20m

        In hadronic collisions, beauty quarks are produced in hard scattering processes with large momentum transfer.Their production provides a very important test of perturbative QCD calculations in pp collisions. In heavy-ion collisions, the measurement of beauty hadron production is a unique tool to investigate the properties of the Quark-Gluon Plasma. In particular, beauty quarks, being four times heavier than charm quarks, can be utilized to study the in-medium mass dependent energy loss.
        In addition, measurements in p-Pb collisions are crucial to investigate the effects of cold nuclear matter on their production.

        With the ALICE detector, beauty quarks are studied by measuring electrons and non-prompt D mesons coming from beauty hadron decays at mid-rapidity. In addition, more direct access to the initial parton kinematics is obtained by measuring beauty-tagged jets. They can provide further constraints for energy loss models adding information on how the radiated energy is dissipated.

        In this contribution, the latest measurements of beauty production using beauty-decay electrons, non-prompt D-mesons and beauty-tagged jets in pp collisions at $\sqrt{s} = 5.02$ TeV, and their comparison to pQCD calculations will be presented.

        New measurements of beauty-tagged jet production down to low $p_{\rm T }$ in p--Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV will be discussed. The latest results on the centrality dependence of $R_{\rm AA}$, and $v_{2}$ of beauty-decay electrons in Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV compared to different theoretical models will be presented.

        In addition the status of the measurement of the production of non-prompt D-mesons in Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV will also be discussed.

        Speaker: Deepa Thomas for the ALICE Collaboration (University of Texas at Austin (US))
      • 12:20
        Diffusion of charm quarks in jets in high-energy heavy-ion collisions 20m

        Heavy flavor physics in high-energy heavy-ion collisions is a promising and active area to study the `` jet quenching " effects both at the RHIC and the LHC. The recent reported $D^0$ meson radial profiles in jets measured by CMS collaboration provide new experimental constraints on the mechanisms of heavy flavor production in proton-proton collisions and give new insights into the in-medium interaction mechanisms of heavy quarks inside the quark-gluon plasma (QGP). In this talk, we present the first theoretical calculations of the $D^0$ meson radial distributions relative to the jet axis both in p+p and Pb+Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV, which show a nice agreement compared to the experimental data. In our work, the in-medium parton propagations are described by a Monte Carlo transport model which uses the next-to-leading order (NLO) plus parton shower (PS) event generator SHERPA as input and includes elastic (collisional) and inelastic (radiative) interaction for heavy quarks as well as light partons. Our simulated results show that, at low $D^0$ $p_T$, the radial distribution shifts to larger radius indicating a strong diffusion effect of charm quarks due to the in-medium interactions, but no significant modification observed at high $D^0$ $p_T$, which are consistent with the experimental data. In the further study, we estimate the net effect on the charm diffusion from collisional and radiative mechanism, and demonstrate the $p_T$ dependence of this diffusion effect. We find that collisional process has significant effects at low $p_T$, especially dominates at $0-5$ GeV, and the radiative process has a non-zero effect even at high $p_T\sim 50$ GeV. The total diffusion effect decreases with $D^0$ $p_T$ which explains the significant modification at low $D^0$ meson $p_T$ observed in experiment. Besides, for unit energy loss, the collisional interaction shows much stronger angular deviation than radiative interaction indicating an essential difference between these two mechanisms. For completeness, we also present the calculations of $D^0$ meson radial distribution in jets in p+p and $0-10\%$ Au+Au collisions at $200$ GeV, and estimate the nuclear modification factor of charm jet in central Au+Au collisions at $200$ GeV and central Pb+Pb collisions at $5.02$ TeV.

        Speaker: Sa WANG (Central China Normal University)
    • 11:00 12:40
      Parallel Session - QCD at finite temperature I HongKong Room

      HongKong Room

      Wanda Reign Wuhan Hotel

      Convener: Frithjof Karsch (Brookhaven National Laboratory)
      • 11:00
        Mesonic Condensation under a Global Rotation 20m

        Recently there have been rapidly growing interests in understanding the properties and phase structures of matter under extreme fields like magnetic field or global rotation. Examples of such physical systems come from a variety of different areas, such as the hot quark-gluon plasma in peripheral heavy ion collisions, dense nuclear matter in rapidly spinning neutron stars, lattice gauge theory in rotating frame, cold atomic gases as well as certain condensed matter materials. In particular rotation has nontrivial interplay with microscopic spin degrees of freedom through the rotational polarization effect and could often induce novel phenomena. For example, there are highly nontrivial anomalous transport effects such as the chiral vortical effect and chiral vortical wave in rotating fluid with chiral fermions. A generic effect is the rotational suppression of fermion pairing in the zero angular momentum states, which has been demonstrated for e.g. chiral phase transition and color superconductivity in the strong interaction system (Y.~Jiang & J.~Liao, Phys. Rev. Lett. 117, no. 19, 192302 (2016)).

        We investigate the mesonic condensation in isospin matter under rotation and demonstrate two important effects of the rotation on its phase structure: a rotational suppression of the scalar-channel condensates, in particular the pion condensation region; and a rotational enhancement of the rho condensation region with vector-channel condensate. A new phase diagram for isospin matter under rotation is mapped out on the $\omega-\mu_I$ plane where three distinctive phases, corresponding to $\sigma$, $\pi$, $\rho$ dominated regions respectively, are separated by a second-order line at low isospin chemical potential and a first-order line at high rotation which are further connected at a tri-critical point.

        Refs: arXiv: 1812.11787; Phys. Rev. Lett. 117, no. 19, 192302 (2016); in preparation

        Speaker: Defu Hou (Central China Normal University)
      • 11:20
        Regressive and generative neural networks for scalar field theory 20m

        We explore the perspectives of machine learning techniques in the context of quantum field theories. In particular, we discuss two-dimensional complex scalar field theory at nonzero temperature and chemical potential – a theory with a nontrivial phase diagram. A neural network is successfully trained to recognize the different phases of this system and to predict the value of various observables, based on the field configurations. We analyze a broad range of chemical potentials and find that the network is robust and able to recognize patterns far away from the point where it was trained. Aside from the regressive analysis, which belongs to supervised learning, an unsupervised generative network is proposed to produce new quantum field configurations that follow a specific
        distribution. An implicit local constraint fulfilled by the physical configurations was found to be automatically captured by our generative model. We elaborate on potential uses of such a generative approach for sampling outside the training region.

        Speaker: Kai Zhou (FIAS, Goethe-University Frankfurt am Main)
      • 11:40
        The crossover line in the (T, mu)-phase diagram of QCD 20m

        An efficient way to study the QCD phase diagram at small finite density
        is to extrapolate thermodynamical observables from imaginary chemical
        potential. The phase diagram features a crossover line starting from the
        transition temperature already determined at zero chemical potential. In
        this talk we focus on the Taylor expansion of this line up to $\mu^4$
        contributions. We present the continuum extrapolation of the crossover
        temperature based on different observables at several lattice spacings.

        Speaker: Jana N. Guenther (University of Wuppertal)
      • 12:00
        Structure and Signals for a Lifshitz Regime 20m

        In the plane of temperature and chemical potential, QCD may exhibit a Critical End Point (CEP). if a region with spatially inhomogeneous condensates exists, there may also be a Lifshitz Regime, either instead of, or in addition to, a CEP. We study the Lifshitz Regime using both a large N expansion and using numerical simulations at small N. Experimentally, we contrast the fluctuations in net proton number when one injects momenta from a condensate at zero momentum, near a CEP, to that at non-zero momentum, in a Lifshitz Regime. This is done using a hydrodynamic code, including especially the effect of the rapid expansion of the local rest frame of the medium.

        Speaker: Robert Pisarski (Brookhaven National Lab.)
      • 12:20
        Spectral functions for hot pions below Tc 20m

        Long-distance properties of QCD are non-perturbative in nature. Lattice computations provide a reliable tool for extracting such information for correlation functions in the space-like domain of momenta, for example for screening phenomena. However, the approach to equilibrium of QCD matter requires knowledge of correlation functions in the time-like domain.

        Analytic continuation of correlation functions from space-like to time-like momenta require knowledge of a spectral function. There are few known constraints on the nature of spectral functions at finite temperature. Computations in the weak-coupling theory, provide constraints at high momenta. Analytic continuations of lattice data otherwise have used ``zero-knowledge schemes'' such as MEM. However, any further information on the nature of spectral functions would help to guard against unknown theoretical biases.

        Here we apply an effective field theory (EFT) which was developed recently to examine correlators of axial currents. This is a generalization of the Nambu-Jona-Lasinio model applied to finite temperatures. This was parametrized to describe lattice data obtained with two flavours of light dynamical Wilson quarks.

        We use this effective field theory to examine the analytic continuation of correlation functions of composite pion operators below T_c from the space-like to the time-like domain. Several interesting phenomena are observed: the analytic continuation of the pion mass and decay constant are non-trivial. We discuss the complex behaviour of the corresponding spectral function.

        Speaker: Sourendu Gupta (TIFR)
    • 11:00 12:40
      Parallel Session - Search for the CP I Ball Room 1

      Ball Room 1

      Wanda Reign Wuhan Hotel

      Convener: Bedangadas Mohanty (Institute of Physics)
      • 11:00
        Recent results on event-by-event fluctuations in ALICE 20m

        One of the key goals of nuclear collision experiments is to map the phase diagram of strongly interacting matter. At LHC energies there would be, for vanishing light quark masses, a temperature-driven genuine phase transition of second order between the hadron gas and the quark-gluon plasma. For realistic quark masses, however, this transition becomes a smooth cross over. Nevertheless, due to the small masses of current quarks one can still probe critical phenomena at the LHC energy, which can be confronted with the ab-initio LQCD calculations at vanishing baryon chemical potential. In this report recent results on event-by-event fluctuation measurements in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 2.76 and 5.02 TeV will be presented. Together with the measured first four cumulants of net-protons in Pb-Pb collisions, differential studies on the second moments of net-charge distributions and their evolution from pp through p-Pb, Xe-Xe to Pb-Pb interactions will be highlighted. The obtained experimental results will be compared with the corresponding model calculations.

        Speaker: Mesut Arslandok for the ALICE Collaboration (Ruprecht Karls Universitaet Heidelberg (DE))
      • 11:20
        Measurement of the Cumulants of Conserved Charge Multiplicity Distributions in Au+Au Collisions from the STAR experiment 20m

        Higher-order cumulants of conserved quantities (B, Q, S) are sensitive observables to study the QCD phase structures, nature of quark-hadron phase transition and freeze-out dynamics.

        In this talk, we will present new measurements of sixth to second-order cumulant ratios (C6/C2) of net-proton distributions in Au+Au collisions at sNN =54.4 and 200 GeV, as well as cumulants up to the fourth-order of net-proton, net-kaon and net-charge multiplicity distributions in Au+Au collisions at sNN =27 and 54.4 GeV. The C6/C2 results are compared with a recent model calculation which predicts a negative C6/C2 value if the freeze-out occurs 10 near the chiral transition temperature. The dependence of cumulants, measured in Au+Au collisions at sNN =27 GeV, on the centrality definition was tested using the Event Plane Detector (EPD). The physics implications of the results, a detailed discussion of the background contributions and the status and prospects of phase II of the STAR Beam Energy Scan program are discussed.

        Speaker: Ashish Pandav for the STAR Collaboration (National Institute of Science Education and Research (NISER), INDIA)
      • 11:40
        NA61/SHINE results on fluctuations and correlations at CERN SPS energies 20m

        The aim of the NA61/SHINE strong interaction programme is to explore the phase diagram of strongly interacting matter. The main physics goals are the study of the onset of deconfinement and the search for the critical point of strongly interacting matter. These goals are pursued by performing a beam momentum (13A - 158A GeV/c) and system size (p+p, p+Pb, Be+Be, Ar+Sc, Xe+La, Pb+Pb) scan. This contribution presents new results from NA61/SHINE on fluctuations and correlations which includes in particular quantum correlations, as well as multiplicity and net-charge fluctuations, proton density fluctuations and anisotropic collective flow. Obtained results will be compared with other experiments and with model predictions.

        Speaker: Maja Katarzyna Mackowiak-Pawlowska for the NA61/SHINE Collaboration (Warsaw University of Technology (PL))
      • 12:00
        Feasibility studies of conserved charge fluctuations in Au–Au collisions with CBM 20m

        The physics program of the Compressed Baryonic Matter (CBM) experiment at FAIR is focused on the measurement of properties of nuclear matter at high net-baryonic density. This experiment will offer the possibility to find signatures of discontinuous transition from QGP to hadronic phase and the QCD critical point where the first order phase transition ends. In the search of the QCD phase transition and its speculated critical point, the most reliable way is to study the fluctuations of conserved charges such as net-baryon (B), net-charge (Q), and net-strangeness (S) number with collision energy in the event by event basis.

        We will discuss the feasibility studies of conserved charge fluctuations in Au--Au collisions with CBM at SIS100 energies.Au--Au minimum bias events are generated at $E_{lab} = 10$ AGeV using UrQMD model and transported through the CBM detector setup using GEANT3. The CBM detector setup for hadronic physics consists of Micro Vertex Detector (MVD), Silicon Tracking System (STS), Ring Imaging Cherenkov Detector (RICH), Transition Radiation Detector (TRD) and Time-of-Flight Detector (TOF) covering a pseudo-rapidity range, $1.5< \eta< 3.8$. The particle identification is done using TOF detector. The simulations results on higher order cumulants of net-charge, net-proton (proxy for net-baryon) and mixed cumulants of
        proton-kaon (proxy for baryon-strangeness correlation) within the CbmRoot framework at SIS100 energy region will be presented. The cumulants are centrality bin width corrected. The efficiency correction using unfolding techniques will be discussed. The transverse momentum ($p_{T}$), rapidity and centrality dependence of the higher order cumulants of conserved charges will be presented.

        Speaker: Subhasis Samanta for the CBM Collaboration (National Institute of Science Education and Research )
      • 12:20
        Critical fluctuations in a dynamically expanding heavy-ion collision 20m

        For the discovery of the QCD critical point it is crucial to develop dynamical models of the fluctuations of the net-baryon number that can be embedded in simulations of heavy-ion collisions.

        In this talk we present the implementation of net-baryon number fluctuations near the critical point in an expanding system. We include the coupling to the fluctuations of energy density and momentum flow explicitly. We study the dynamical formation of the correlation length and its relation to the critical enhancement of higher-order cumulants for boost-invariant initial conditions. By adding second order fluid dynamical relaxation equations we distinguish between the propagative and the damped critical mode contributions.

        Speaker: Masakiyo Kitazawa (Osaka University)
    • 11:00 12:40
      Parallel Session - Small systems II Ball Room 2

      Ball Room 2

      Wanda Reign Wuhan Hotel

      Convener: Hannah Elfner
      • 11:00
        Search for jet quenching effects in high multiplicity proton-proton collisions at $\sqrt{s}=13$ TeV with ALICE 20m

        The ALICE Collaboration reports a search for jet quenching effects in high multiplicity pp collisions at $\sqrt{s}$ = 13 TeV, utilizing the semi-inclusive distribution of charged-particle jets recoiling from a high transverse momentum charged-hadron trigger. The multiplicity is measured using forward scintillation detectors that are separated in phase-space from the central region where the trigger and jet are measured. A data-driven statistical method is used to correct for uncorrelated jet background, which includes multi-partonic interactions. This trigger-normalized coincidence approach does not require the association of event activity with collision geometry in order to measure jet quenching, in contrast to inclusive observables, and has been used to set a stringent limit on jet quenching effects in high-multiplicity p--Pb collisions at the LHC. The magnitude of jet quenching is quantified by comparing recoil jet distributions for low and high-multiplicity pp collisions.

        Speaker: Peter Martin Jacobs for the ALICE Collaboration (Lawrence Berkeley National Lab. (US))
      • 11:20
        Collective behavior of high-$p_{T}$ particles in 8.16 TeV $p$+Pb collisions with the ATLAS detector 20m

        Charged particles in small collision systems such as $pp$ and $p$+Pb have been observed to have significant azimuthal modulations of their momenta, commonly interpreted as flow, up to a transverse momentum of $p_{T} \approx 10$~GeV. In large collision systems such as Pb+Pb, lower but non-zero flow coefficients at higher $p_{T}$ ($> 10$~GeV) are usually understood to reflect jet quenching, and specifically the path-length differential energy loss in elliptical events. Extending these measurements in small systems to high-$p_{T}$ particles, which are predominantly produced in jets, can thus provide crucial information on the origin of these collective phenomena. This talk presents a new measurement by ATLAS of two-particle angular correlations in 8.16 TeV $p$+Pb events with a jet trigger. An additional restriction on the associated particle positions is used to suppress the large non-flow contributions in the jet events. Measurements of the resulting single-particle second- and third-order flow coefficients are presented for charged-hadrons from $p_{T}$ = 0.5 to 50 GeV, in selections of $p$+Pb event activity. The $p_{T}$-dependent results are compared to those from minimum-bias $p$+Pb events, and the differences between the two event samples are analyzed in terms of the different origin of particles in these events, such as the different fraction of particles that arise from the jet fragmentation process.

        Speaker: Kurt Keys Hill for the ATLAS Collaboration (University of Colorado Boulder (US))
      • 11:40
        Probing the partonic degree of freedom in high multiplicity p-Pb at  $\sqrt{s}$=  5.02 TeV collisions. 20m

        The collective flow and the possible formation of the Quark-Gluon Plasma (QGP) in the small colliding systems are hot research topics in the heavy-ion community. Recently, ALICE, ATLAS and CMS collaborations have measured the elliptic flow and the related number of constituent quark (NCQ) scaling of identified hadrons in p+Pb collisions at $\sqrt{s}$ = 5.02 TeV, which are important observables to probe the partonic degree of freedom in the created small system.

        In this talk, we focus on the coalescence model calculations for the NCQ scaling of at intermediate $p_T$ for the high multiplicity p+Pb collisions, which includes thermal-thermal, thermal-jet and jet-jet partons recombinations, using the thermal partons from hydrodynamics and jet partons after the energy loss of the Linear Boltzmann Transport (LBT) model. Such coalescence model calculations have also been smoothly connected with the low hydrodynamic calculation and with high jet fragmentation. Within such combined framework, we present a nice description of the spectra and elliptic flow over the $p_T$ range from 0 to 6 GeV, and obtain the approximately NCQ scaling at intermediate $p_T$ as measured in experiment. We also switch off the coalescence process of partons and find that without such coalescence, one can not describe the differential elliptic flow and related NCQ scaling at intermediate $p_T$.  Such comparison calculations also demonstrate the importance of the partonic degree of freedom and indicate the possible formation of QGP in the high multiplicity p+Pb collisions.

        Speaker: Wenbin Zhao (Peking University)
      • 12:00
        Ultracentral Collisions of Small and Deformed Systems at RHIC 20m

        We study a range of collision systems involving deformed ions and compare the elliptic and triangular flow harmonics produced in a hydrodynamics scenario versus a color glass condensate (CGC) scenario. For the hydrodynamics scenario, we generate initial conditions using TRENTO and work within a linear response approximation to obtain the final flow harmonics. For the CGC scenario, we use the explicit calculation of two-gluon correlations taken in the high-$p_T$ ``(semi)dilute-(semi)dilute'' regime to express the flow harmonics in terms of the density profile of the collision. We consider ultracentral collisions of deformed ions as a testbed for these comparisons because the difference between tip-on-tip and side-on-side collisions modifies the multiplicity dependence in both scenarios, even at zero impact parameter. We find significant qualitative differences in the multiplicity dependence obtained in the initial conditions+hydrodynamics scenario and the CGC scenario, allowing these collisions of deformed ions to be used as a powerful discriminator between models. We also find that sub-nucleonic fluctuations have a systematic effect on the elliptic and triangular flow harmonics which are most discriminating in $0-1\%$ ultracentral symmetric collisions of small deformed ions and in $0-10\%$ $\mathrm{d} {}^{197}\mathrm{Au}$ collisions. The collision systems we consider are ${}^{238}\mathrm{U} {}^{238}\mathrm{U}$, $\mathrm{d} {}^{197}\mathrm{Au}$, ${}^{9}\mathrm{Be} {}^{197}\mathrm{Au}$, ${}^{9}\mathrm{Be} {}^{9}\mathrm{Be}$, ${}^{3}\mathrm{He} {}^{3}\mathrm{He}$, and ${}^{3}\mathrm{He} {}^{197}\mathrm{Au}$.

        Speaker: Douglas Wertepny (Ben Gurion University of the Negev)
      • 12:20
        Correlation measurements of charged particles and jets at mid-rapidity with event activity at backward-rapidity in $\sqrt{s_\mathrm{NN}}=200$ GeV p+Au collisions at STAR 20m

        Recent measurements of small system collisions, p+p and p+A, show signals which, in A+A collisions, had been attributed to the formation of a strongly interacting medium. These notably include flow-like correlations. However, so far no clear demonstration of jet energy losses in small system collisions have been observed.

        In this talk, we will present correlations of mid-rapidity charged particles to backward-rapidity (Au-going direction) event activity (EA) in 200 GeV p+Au collisions at STAR. They demonstrate an expected positive correlation between high EA at backward-rapidity and the probability of finding a high energy particle at mid-rapidity. Intriguingly, this correlation softens for increasingly energetic triggers. We will also present semi-inclusive jet spectra at mid-rapidity which, due to self normalization, avoid the difficulties of applying the Glauber model in small systems. The measured high-EA spectrum is distinctly suppressed relative to the low-EA spectrum. We will present comparison of these results to those in d+Au and p+Pb collisions at RHIC and the LHC, respectively. EA-dependent modification of the jet spectrum has been observed at the LHC but only for jets at forward-rapidities and appears to scale with Bjorken-$x$. The presented mid-rapidity jet spectra span a similar Bjorken-$x$ range, allowing the Bjorken-$x$ scaling to be tested.

        Speaker: David Stewart for the STAR Collaboration (Yale University)
    • 12:40 14:00
      Lunch Break 1h 20m
    • 14:00 16:00
      Parallel Session - Chirality I Ball Room 2

      Ball Room 2

      Wanda Reign Wuhan Hotel

      Convener: Huanzhong Huang (Fudan University)
      • 14:00
        Search for the chiral magnetic effect and the chiral magnetic wave with the ALICE experiment 20m

        Theoretical considerations suggest the chiral magnetic effect (CME) and chiral magnetic wave (CMW) are reflected in a charge separation with respect to the event plane in heavy-ion collisions. Although considerable experimental efforts have been expended to investigate the existence of such phenomena, in recent years, evidence remains inconclusive because observables sensitive to these effects are challenged by the presence of strong background processes.

        In this talk, we present results of searches for the CME/CMW with charge dependent two- and three-particle correlators based on unidentified and identified hadrons in Pb-Pb, p-Pb and Xe-Xe collisions at the TeV energy scale. A novel data-driven method was used to constrain the CME contribution to multi-particle correlators. This method relies on correlations of particles relative to higher harmonic symmetry planes to quantify the contribution of background effects to the CME sensitive observables. An updated upper bound from ALICE on the CME fractional contribution in Pb-Pb collisions is obtained. The results are compared with various theoretical calculations and results from other experiments.

        Speaker: Sizar Aziz for the ALICE Collaboration (Centre National de la Recherche Scientifique (FR))
      • 14:20
        Search for CME in U+U and Au+Au collisions in STAR with different approaches of handling backgrounds 20m

        We present two approaches to handle the dominant elliptic flow ($v_2$) background in the observable, $\Delta\gamma_{112}$ (charge separation across second-order event plane), sensitive to the chiral magnetic effect (CME).

        In the first approach, we present the $\Delta\gamma_{112}$ and $\Delta\gamma_{123}$ measurements in U+U and Au+Au collisions. While hydrodynamic simulations including resonance decays and local charge conservation predict that $\Delta\gamma_{112}$ scaled by $N_{\rm part}/v_2$ will be similar in U+U and Au+Au collisions, the projected B-field exhibits a distinct difference between the two systems and with varying $N_{ \rm part}$. Therefore, U+U and Au+Au collisions provide a two-system configuration to contrast signal and background expectations for the CME. The charge separation across third-order event plane $\Delta\gamma_{123}$ scaled by $N_{\rm part}/v_3$ provides necessary system dependence only from backgrounds. Although some features of our data appear to hint CME interpretation driven by B-field, the background expectations capture most of the observed trends at 200 GeV. We repeat our measurements with the recent high statistics Au+Au collisions data at 27 GeV to see if such a trend persists at lower collision energies. The newly installed forward event plane detector helps to suppress non-flow correlations.

        In the second approach, we handle the $v_2$ background by measuring $\Delta\gamma_{112}$ with respect to the planes of spectators $\Psi_{ \rm ZDC}$ and elliptic anisotropy $\Psi_2$. These measurements contain different amounts of contributions from CME signal (along B-field, due to spectators) and $v_2$ background (determined by the participant geometry). With the two $\Delta\gamma_{112}$ measurements, the possible CME signal and the background contribution can be determined. Applying this method, we have previously reported the measurements of possible CME signal fraction in 200 GeV Au+Au collisions, revealing dominant background contribution. Here, we report our findings in U+U collisions where the spectator-participant plane correlations are expected to differ from those in Au+Au collisions.

        Speaker: Jie Zhao for the STAR Collaboration (Purdue University)
      • 14:40
        Measurement of the charge separation along the magnetic field with Signed Balance Function in 200 GeV Au + Au collisions at STAR 20m

        Experimental searches for CME in heavy ion collisions have been going on for a decade, and so far there is no conclusive evidence for its existence. Recently, the Signed Balance Function (SBF), based on the idea of examining the momentum ordering of charged pairs along the in- and out-of-plane directions, has been proposed as a probe of Chiral Magnetic Effect (CME) [1]. In this approach a pair of observables are invoked, they are, the out-of-plane to in-plane ratio of fluctuation of the difference between signed balance functions measured in pairs rest frame ($r_{rest}$), and the ratio ($R_{B} = r_{rest}/r_{lab}$) of it to a similar measurement made in the laboratory frame ($r_{lab}$). These two observables give opposite responses to the CME-driven charge separation and background correlations arising from resonance flow and global spin alignment.

        In this talk, we will present $r_{rest}$ and $R_{B}$ measurements in Au+Au collisions at 200GeV. The two observables will be cross examined and compared to model calculations. The procedure-similarity and difference between this approach and previous methods will be compared, and the physics implications of the measurement will be discussed.

        [1] A.H. Tang, arXiv:1903.04622.

        Speaker: Yufu Lin for the STAR Collaboration (Central China Normal University (CCNU) & Brookhaven National Laboratory (BNL))
      • 15:00
        Chirality and spin transport from Wigner function approach 20m

        The covariant Wigner function formalism is a powerful and systematic quantum kinetic approach. In this talk, we will discuss how the chirality and spin transport in relativistic plasma can be described from Wigner function approach. It provides very natural and systematic method to describe the chiral effects and spin effects in heavy ion collisions. We find that the massless fermion systems in a background EM field can be described sufficiently by one distribution function and one equation up to any order of ℏ. For the massive fermions, we need four independent Wigner functions and four independent transport equations. We have demonstrated that various chiral or spin effects such as the chiral anomaly, chiral magnetic effect, chiral vortical effect, chiral separate effect, quantum magnetization effect and global polarization effect can arise successfully and naturally from the Wigner function approach.

        Speaker: Jian-Hua Gao (Shandong University at Weihai)
      • 15:20
        Chiral magnetic effect, chirality production and Schwinger mechanism 20m

        We elucidate chirality production under parity breaking constant electromagnetic fields, with which we clarify qualitative differences in and out of equilibrium. For a strong magnetic field the pair production from the Schwinger mechanism increments the chirality. The pair production rate is exponentially suppressed with mass according to the Schwinger formula, while the mass dependence of chirality production in the axial Ward identity appears in the pesudo-scalar term. We demonstrate that in equilibrium field theory calculus the axial anomaly is canceled by the pseudo-scalar condensate for any mass. In a real-time formulation with in- and out-states, we show that the axial Ward identity leads to the chirality production rate consistent with the Schwinger formula. We illuminate that such an in- and out-states formulation makes clear the chiral magnetic effect in and out of equilibrium, and we discuss further applications to real-time condensates.

        Speaker: Shi Pu (USTC, China)
      • 15:40
        Investigate the possible physics mechanisms of the CMW-like flow signals 20m

        The interplay between the chiral magnetic effect and the chiral separation effect can lead to a collective excitation, a phenomenon called Chiral Magnetic Wave (CMW). Previous measurement of a positive slope for the charge asymmetry ($A_{\rm ch}$) dependence of the $\pi^{+}$ and $\pi^{-}$ flow difference $\Delta v_{2}(A_{\rm ch})\equiv v_{2}^{\pi^{-}}(A_{\rm ch}) - v_{2}^{\pi^{+}}(A_{\rm ch})$, indicated effects that are consistent with the CMW, but firm conclusions have not been established because of possible background contaminations in those measurements. In this work, we study the effects of resonance decays (local charge conservation) and find strong sensitivities of the $\Delta v_{2} (A_{\rm ch})$ slope parameter on kinematics. We then study several main sources of pions in relativistic heavy ion collisions, and find that the competitions among the different $\pi$ sources can yield another linear $A_{\rm ch}$ term due to their multiplicity fluctuations and different $v_{2}$ values. This linear $A_{\rm ch}$ term does not require any $A_{\rm ch}$ dependence in the pion $v_{2}$ from each individual source. We discuss the implications of our findings on the experimental search for the CMW.

        Speaker: Haojie Xu (Huzhou University)
    • 14:00 16:00
      Parallel Session - Collective dynamics II Ball Room 1

      Ball Room 1

      Wanda Reign Wuhan Hotel

      Convener: Tetsufumi Hirano (Sophia Univ)
      • 14:00
        Measurement of Flow Fluctuation and Centrality Fluctuation in Pb+Pb collisions with the ATLAS Detector 20m

        Multi-particle azimuthal cumulants are measured as a function of centrality and transverse momentum in 5.02 TeV Pb+Pb collisions. These cumulants provide information on the event-by-event fluctuations of harmonic flow coefficients $v_{n}$ and correlated fluctuations between two harmonics $v_{n}$ and $v_{m}$.
        For the first time, a non-zero four-particle cumulant is observed for dipolar flow, $v_{1}$. The four-particle cumulants for elliptic flow, $v_{2}$, and triangular flow, $v_{3}$, exhibit a strong centrality dependence and change sign in ultra-central collisions. This sign change is consistent with significant non-Gaussian fluctuations in $v_{2}$ and $v_{3}$. The four-particle cumulant for quadrangular flow, $v_{4}$, is found to change sign in mid-central collisions. Correlations between two harmonics are found to decrease in strength towards central collisions and either approach zero or change sign in ultra-central collisions. To investigate the possible flow fluctuations arising from intrinsic centrality or volume fluctuations, the results are compared between two different event classes used for centrality definitions. In peripheral and mid-central collisions where the cumulant signals are large, only small differences are observed. In ultra-central collisions, the differences are much larger and transverse momentum dependent.
        These results provide new information to disentangle flow fluctuations from the initial and final states, as well as new insights on the influence of flow observables by centrality fluctuations.

        Speaker: Jiangyong Jia for the ATLAS Collaboration (Stony brook Universty (US))
      • 14:20
        Directed and elliptic flow of high-pT charged hadrons, identified hadrons and light nuclei in Au+Au collisions at STAR 20m

        The thermalized QCD matter formed in heavy-ion collisions is tilted in the reaction plane as a function of rapidity, while the production profile of partons from hard scatterings is symmetric in rapidity [1]. This leads to a rapidity-odd directed flow (v1) for high-pT hadrons and can provide valuable constraints on the initial longitudinal distribution of the fireball as well as the path length-dependent energy loss of partons. Hydrodynamic models suggest that the double sign change of v1 slope (dv1/dy) at midrapidity for net baryon as a function of beam energy is a signature of the first-order phase transition [2]. The light nuclei and strange hadrons might be more sensitive to the early EoS because of their heavy masses and smaller hadronic interaction cross section, respectively. Due to the different sensitivity of strange particles to hadronic phases, the mass ordering of elliptic flow (v2) is expected to be violated between proton and φ meson in the low-pT range (pT <1.5 GeV/c) [3].

        In this talk, we will present the new precise v1 measurement of π, K, p and φ in Au+Au collisions at sNN = 27, 54.4 GeV and deuteron at sNN = 7.7 to 39 GeV. The first measurement of pseudorapidity and centrality dependence of the v1 of high-pT (>5 GeV/c) charged hadrons in Au+Au collisions at sNN = 54.4 and 200 GeV will be presented. The v2 of identified hadrons (π, K, p, φ, KS0 , Λ, Ξ, Ω) in Au+Au collisions at √sNN = 54.4 GeV will also be presented. These results will be compared to model calculations and the physics implications will be discussed.

        Referene :
        [1] P. Bozek, I. Wyskiel, Phys. Rev. C. 81, 054902 (2010); A. Adil, M. Gyulassy, Phys. Rev. C. 72, 034907 (2005).
        [2] D. H. Rischke et al, arXiv:nucl-th/9505014 (1995); H. St¨ocker, Nucl. Phys. A 750, 121 (2005).
        [3] T. Hirano et al., Phys. Rev. C 77, 044909 (2008); S. Takeuchi et al., Phys. Rev. C 92, 044907 (2015).

        Speaker: Kishora Nayak for the STAR Collaboration (Central China Normal University, China)
      • 14:40
        Effects of dissipative baryon current in heavy-ion collisions at RHIC-BES energies 20m

        One of the most important objectives of Beam energy scan (BES) program at the Relativistic Heavy ion collider (RHIC) is to search for the critical point in the QCD matter via performing nucleus-nucleus collisions with wide collision energies (7.7 - 200 GeV). At such energies, the produced quark-gluon plasma (QGP) matter has sizable net baryon density at the central rapidity region due to baryon stopping power. Therefore, the dissipation of net-baryon current plays an important role in the dynamical evolution of the hot and dense QCD matter produced in RHIC-BES heavy-ion collisions.

        The (3+1)-dimensional viscous hydrodynamic has been very successful in describing the collective behavior of the QGP fireball at zero chemical potential. In order to study the properties of QGP and the dissipative phenomena of net baryon current at a non-zero baryon environment of the BES energies, we extend the CLVisc [1, 2] hydrodynamic model to include the equation of net baryon charge conservation and Israel-Stewart-like equations about dissipative baryon current with NEOSB [3] equation of state. Assuming instantaneous smooth energy density and net baryon density distribution at the initial proper time, we study the impact of the net-baryon dissipation on particle yields, pT spectra and anisotropic flows in the final state of BES heavy-ion collisions.
        [1] Pang, Long-Gang et al. Phys.Rev. C97 (2018) no.6, 064918 arXiv:1802.04449 [nucl-th]
        [2] Pang, Longgang et al. Phys.Rev. C86 (2012) 024911, arXiv:1205.5019 [nucl-th].
        [3] Monnai, Akihiko et al. arXiv:1902.05095 [nucl-th]

        Speaker: Xiang-Yu Wu (Central China Normal University.)
      • 15:00
        Quark flavor dependence of particle flow in nucleus-nucleus collisions measured by PHENIX 20m

        An outstanding puzzle in the field is the mechanism that generates collective motion of heavy quarks (charm and bottom) in large collision systems. The measured azimuthal anisotropies of electrons from heavy quarks closely resemble those of light quarks, despite the enormous differences in quark mass. In order to further understand the quark mass dependence of the flow, we have separated the flow contributed from charm and bottom quarks. As opposed to the apparent heavy quark flow, the $J/\psi$, a charmonium state, has shown no significant flow at RHIC by now. Consistent understanding of the results will need results with better precision as well as comparisons with models including quark recombination process. We will present $v_2$ vs $p_T$ of $J/\psi$ and of electrons originating from charm and bottom decays measured at mid-rapidity in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. Implications for the origins of collective motion of heavy quarks and quarkonia will be discussed.

        Speaker: Takahito Todoroki for the PHENIX Collaboration (Brookhaven National Laboratory)
      • 15:20
        Search for extreme electromagnetic fields through measurements of charm meson flow harmonics in PbPb collisions at $5.02~\mathrm{TeV}$ with the CMS detector 20m

        In ultrarelativistic heavy-ion collisions, a very strong (on the order of $10^{16}~\mathrm{Tesla}$) and transient (lifetime on the order of $10^{-1}~\mathrm{fm/c}$) electromagnetic (EM) field is expected to be generated inside the medium formed in the collision. This EM field, generated by the collision participants and spectators, is predicted to produce a difference in the $v_n$ harmonics for positive- and negative-charged particles, with the magnetic field mainly responsible for a splitting in rapidity-odd directed flow ($v_1$), and the Coulomb electric field leading to a charge-dependent splitting in the $v_2$ and average $p_T$ values of emitted particles. Because of their large mass, charm quarks are expected to be created very early in the collision, and thus have a better chance of interacting with this strong EM field than light flavor hadrons. In this talk, measurements of $D^0$ ($\bar{u}c$) and $\bar{D^0}$ ($u\bar{c}$) meson flow harmonics ($v_1$ and $v_2$) are presented as functions of rapidity ($y$), transverse momentum ($p_T$), and collision centrality for PbPb collisions at $5.02~\mathrm{TeV}$, using high statistics data samples collected by the CMS detector during the LHC Run 2. The results are compared to model calculations, where they provide important constraints on the electrical conductivity and the drag coefficient assumed for the QGP medium. The wide rapidity coverage ($|y|<2$) of these new charm mesons measurements allow for a better understanding of the 3-dimensional evolution of the medium formed in heavy-ion collisions.

        Speaker: Cesar Bernardes for the CMS Collaboration (UNESP - Universidade Estadual Paulista (BR))
      • 15:40
        New results on light (anti-)(hyper-)nuclei production and hypertriton lifetime in Pb-Pb collisions at the LHC 20m

        New results on the production of light nuclei, including deuterons, tritons,
        $^{3}\rm{He}$, $^{4}\rm{He}$ and the corresponding anti-nuclei, in Pb-Pb collisions
        at $\sqrt{s_{\rm NN}}$ = 2.76 TeV and $\sqrt{s_{\rm NN}}$ = 5.02 TeV will be presented
        and compared with theoretical predictions to provide insight into their production
        mechanisms in heavy-ion collisions. Those results will be complemented by the production
        measurement of nuclei containing one strange baryon, namely the (anti-)hypertriton,
        exploiting both the invariant mass method and a machine learning approach to enhance
        the significance of the measurement with respect to the published results.

        We also present the latest measurement of the hypertriton lifetime aiming at shedding
        light on the hypertriton lifetime puzzle. During the end of LHC Run 2, the ALICE experiment
        recorded Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV that complement the already
        available Pb-Pb datasets. Indeed, most calculations on the hypertriton lifetime give
        similar values, which are close to the lifetime of free $\Lambda$ decays. On the
        experimental side, all results from other heavy-ion experiments show a significantly
        shorter lifetime in comparison with that of the free $\Lambda$ decay.

        Furthermore, new results on the measurement of the elliptic and the triangular flow of
        deuteron and $^{3}$He produced in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV
        will be presented and they will be compared to the lower energy results and to the
        expectations from coalescence and hydrodynamic models. The measurement of the elliptic
        and triangular flow of light nuclei provides a powerful tool to give insight into their
        production mechanism and freeze-out properties at a late stage of the collision evolution.

        Finally, the large variety of measurements performed with the ALICE apparatus at different
        energies allows us to constrain the models of the production mechanisms of light-flavour
        baryon clusters, in particular those based on the coalescence and statistical hadronisation
        approaches.

        Speaker: Esther Bartsch for the ALICE Collaboration (Johann-Wolfgang-Goethe Univ. (DE))
    • 14:00 16:00
      Parallel Session - Heavy flavor II Ball Room 3

      Ball Room 3

      Wanda Reign Wuhan Hotel

      Convener: Boris Hippolyte (IPHC / USIAS (Strasbourg, FR))
      • 14:00
        Quarkonium production in Pb+Pb collisions with ATLAS 20m

        The experimentally observed dissociation and regeneration of bound quarkonium states in heavy-ion collisions provide a powerful tool to probe the dynamics of the hot, dense plasma. These measurements are sensitive to the effects of color screening, color recombination, and possibly to other, new phenomena affecting dynamics of heavy quarks in the QCD medium. In the large-statistics Run 2 lead-lead collision data, these phenomena can be probed with unprecedented precision. In this talk, the new ATLAS results on bottomonium nuclear modification factor and excited-to-ground state ratio using 2018 Pb+Pb data and 2017 pp data both at 5.02 TeV will be presented as a function of transverse momentum and event centrality. Additionally, new measurements on the correlation of the J/$\psi$ and jet production will be presented, which may help understanding the mechanism of the suppression of J/$\psi$ measured at high transverse momenta of few tens of GeV.

        Speaker: Songkyo Lee for the ATLAS Collaboration (Iowa State University (US))
      • 14:20
        Quarkonium production in nucleus-nucleus collisions with ALICE 20m

        Heavy quarks are produced at the first instant of a nucleus-nucleus collision and therefore
        are an important tool to study the subsequent high energy-density medium formed in
        relativistic heavy-ion collisions. Over the last few decades major efforts have been
        undertaken in order to understand the properties of the Quark-Gluon Plasma (QGP) using
        quarkonia. The extent of medium modification for heavy-quark production in heavy-ion
        collisions is measured in terms of a nuclear modification factor $R_{\rm AA}$, defined as
        the quarkonium yield in heavy-ion collisions with respect to the pp cross sections scaled
        by the nuclear overlap function. A possible path-length dependent quarkonium dissociation
        probability as well as a contribution of (re)combined quarkonia from flowing heavy quarks
        would lead to an azimuthal anisotropy of quarkonium production relative to the reaction plane.

        Recent ALICE J/$\psi$ $R_{\rm AA}$ results for Pb-Pb collisions at
        $\sqrt{s_{\rm NN}}$ = 5.02 TeV will be presented for mid and forward rapidity.
        The individual contribution of prompt and non-prompt J/$\psi$ production will be
        discussed for the $R_{\rm AA}$ measurement at mid-rapidity. At forward rapidity,
        the centrality, $p_{\rm T}$ and rapidity dependence of J/$\psi$ and $\psi({\rm 2S})$
        $R_{\rm AA}$ will be discussed. The $\Upsilon$ $R_{\rm AA}$ will also be shown.
        The ${\rm J}/\psi$ elliptic and triangular flow, as well as event-shape-engineering
        studies and the first measurement of the $\Upsilon$ elliptic flow will be reported.
        The ALICE results will be compared with those by other LHC experiments and the current
        theoretical interpretation of the results will be also discussed.

        Speaker: Xiaozhi Bai for ALICE Collaboration (GSI)
      • 14:40
        Heavy quark diffusion coefficients and thermal quarkonium mass shifts from lattice QCD 20m

        We will present recent results on thermal modifications of heavy quark spectral functions and transport properties based on continuum extrapolated charmonium and bottomonium correlation functions in pure SU(3) plasma, extending the previous study in the pseudoscalar channel to the vector channel. Using the gradient flow technique for the color-electric field correlator on large and fine lattices in the quenched approximation as well as in full QCD with physical light quark degrees of freedom, we will discuss the effects of dynamical fermions on the heavy quark momentum diffusion coefficient and provide first estimates on the thermal quarkonium mass shift of heavy quarks in the thermal medium. Furthermore we will extend our previous estimation of the heavy quark momentum diffusion coefficient to a wider temperature range relevant for the phenomenology of heavy quark transport in the QGP medium.

        Speaker: Olaf Kaczmarek (University of Bielefeld)
      • 15:00
        Recent Measurements of Heavy Quarkonium Production in p+Au and p+p Collisions at STAR 20m

        Heavy quarkonia are useful probes of the quark-gluon plasma, where quarkonium dissociation is expected at high enough temperatures. Indeed, such a suppression is clearly present in the latest STAR measurements of $J/\Psi$ production in Au+Au collisions. The suppression is observed to have little dependence on $p_{T}$, although cold nuclear matter effects, such as shadowing, anti-shadowing, nuclear or comover absorption, play a significant role at low $p_{T}$. Measurements of the $J/\Psi$ production in p+A collisions can help us to disentangle the cold nuclear matter effects from the hot medium effects in A+A collisions. In this talk, we will present the measurement of $J/\Psi$ production in p+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV by the STAR experiment. The nuclear modification factor $R_{pA}$ will be presented as a function of the event activity (i.e. "centrality") and compared to theoretical models. In addition, we will present recent STAR measurements of $J/\Psi$ and $\Upsilon$ production in p+p collisions including their dependence on the charged-particle multiplicity at mid-rapidity. These measurements are important for understanding the mechanism of the heavy quarkonium production in elementary nucleon-nucleon collisions and the interplay of soft and hard processes.

        Speaker: Yanfang Liu for the STAR Collaboration (TAMU)
      • 15:20
        PHENIX $J/\psi$ measurements in $p$+Al, $p$+Au, and $^3$He+Au collisions 20m

        Nuclear modification of charmonium in small systems is thought to be caused by a combination of initial-state effects in the charm quark production, such as depletion from gluon shadowing and Cronin enhancement, and final-state breakup through comoving particles. The timescale of a charmonium state to neutralize with respect to the duration of the charmonium crossing the nuclear media may also be relevant. The PHENIX collaboration measured $J/\psi$ yields in $p$+Al, $p$+Au and $^3$He+Au at $\sqrt{s_{NN}}$ = 200 GeV at forward and backward rapidities ($1.2<|y|<2.2$). Along with previous $d$+Au data, these measurements comprise the most extensive study of inclusive $J/\psi$ in small systems including dependence on system size, centrality, transverse momentum, and rapidity, all at the same collision energy. This presentation will show the conclusion of this experimental effort and discuss the implications on the current understanding of charmonia interaction with nuclear media.

        Speaker: Krista Smith for the PHENIX Collaboration (Florida State University)
      • 15:40
        Flavor hierarchy of jet quenching in relativistic heavy-ion collisions 20m

        Relativistic heavy-ion experiments have observed similar quenching effects for (prompt) $D$ mesons compared to charged hadrons for transverse momenta larger than 6-8 GeV, which remains a mystery since heavy quarks typically lose less energies in quark-gluon plasma than light quarks and gluons. Recent measurements of the nuclear modification factors of $B$ mesons and $B$-decayed $D$ mesons by the CMS Collaboration provide a unique opportunity to study the flavor hierarchy of jet quenching. Using a linear Boltzmann transport model combined with hydrodynamics simulation, we study the energy loss and nuclear modification for heavy and light flavor jets in high-energy nuclear collisions. By consistently taking into account both quark and gluon contributions to light and heavy flavor hadron productions within a next-to-leading order perturbative QCD framework, we obtain, for the first time, a satisfactory description of the experimental data on the nuclear modification factors for charged hadrons, $D$ mesons, $B$ mesons and $B$-decayed $D$ mesons simultaneously over a wide range of transverse momenta (8-300 GeV). This presents a solid solution to the flavor puzzle of jet quenching and constitutes a significant step towards the precision study of jet-medium interaction. Our study predicts that at transverse momenta larger than 30-40 GeV, $B$ mesons also exhibit similar suppression effects to charged hadrons and $D$ mesons, which may be tested by future measurements.

        Reference:

        [1] Wen-Jing Xing, Shanshan Cao, Guang-You Qin, and Hongxi Xing, arXiv:1906.00413

        Speaker: Wen-Jing Xing (Central China Normal University)
    • 14:00 16:00
      Parallel Session - New theoretical developments I HongKong Room

      HongKong Room

      Wanda Reign Wuhan Hotel

      Convener: Qun Wang (University of Science and Technology of China)
      • 14:00
        Relativistic Hydrodynamic Fluctuations 20m

        In heavy ion collisions, the typical system size is large enough to be treated hydrodynamically but small enough for hydrodynamic fluctuations to be important and directly observable via event-by-event measurements. We present a general systematic formalism describing dynamics of fluctuations in an arbitrary relativistic hydrodynamic flow. We derive a deterministic evolution equation for the fluctuation modes which nontrivially matches the kinetic equation for phonons propagating on an arbitrary background including relativistic inertial and Coriolis forces due to acceleration and vorticity of the flow. We introduce a concept of confluent connection which takes into account the relativity of "equal time" in the definition of the equal-time correlator of fluctuation. We also describe the procedure of renormalization of short-distance singularities which eliminates cutoff dependence, allowing efficient numerical implementation of these equations.

        Speaker: Misha Stephanov (UIC)
      • 14:20
        From Chiral Kinetic Theory to Spin Hydrodynamics 20m

        As a conserved quantity in the evolution of the quark-gluon plasma (QGP) created in heavy-ion collisions, the total angular momentum consists of two sectors: the orbital angular momentum (OAM) caused by kinetic motion, and the intrinsic spin angular momentum of quarks and gluons. In a heavy-ion collision event, the system starts with finite OAM but un-polarized spin density (unless prepared specifically). Microscopic scattering processes allow a coupling between these two components. Therefore, spin polarization can eventually develop that may have a non-trivial influence on the QGP evolution. In the current hydrodynamic frameworks, the stress tensor $T^{\mu\nu}$ is assumed to be symmetric, hence OAM and spin are conserved independently, and the spin effect is mostly neglected. A hydrodynamic theory, with the aforementioned spin polarization effect properly taken into account, is required, especially for quantitative studies of the polarization rate of observed hadrons, e.g. $\Lambda$-hyperon. The latter has been observed in RHIC experiment, serving as an evidence of the most vortical fluid in the universe.

        In this work, we start with chiral kinetic theory and construct the spin hydrodynamic framework for a chiral spinor system. We obtain the equations of motion of second-order dissipative relativistic fluid dynamics with non-trivial spin polarization density. In a chiral spinor system, the spin alignment effect could be treated in the same framework as for Chiral Vortical Effect (CVE). However, the fluid vorticity induces not only the CVE current but also asymmetric stress tensor as well as spin polarization of final state hadrons, all of which emerge as quantum corrections. The consequences for current measurements related to angular momentum observables will be discussed.

        Speaker: Shuzhe SHI (McGill University)
      • 14:40
        Computing real time correlation functions on a hybrid classical/quantum computer 20m

        Nuclear structure functions and parton Wigner distributions of protons and nuclei are principal components of QCD phenomenology. Their first principle computation is an outstanding problem in QCD, because they involve non-perturbative nucleon/nuclear matrix elements of electromagnetic currents that are light-like separated in Minkowskian spacetime. Real-time correlation functions are a difficult problem for lattice computations, which are only feasible in Euclidean space time. To overcome restrictions of classical computing, we outline a strategy to compute nuclear structure functions in the high energy Regge limit of QCD using a hybrid quantum computer [1]. Our approach takes advantage of the representation of the fermion determinant in the QCD path integral as a quantum mechanical path integral over 0+1-dimensional fermionic and bosonic world-lines in background gauge fields [2]. While extremely challenging in general, the problem simplifies in the Regge limit, where the interaction of the world-lines with gauge fields is strongly localized in proper time and the corresponding quantum circuits can be written down. As a proof principle, we employ the Color Glass Condensate effective theory of high energy QCD to construct the algorithm for a first straightforward application of the framework, specifically, the problem of computing the well-known dipole model result for the structure function $F_2$ [3]. We outline how this computation can be systematically scaled up in complexity and extended in scope to other real-time correlation functions, for example to describe non-equilibrium transport of quarks and gluons in a Quark-Gluon-Plasma, where the restrictions of euclidean lattice computations are evident.

        [1] N. Mueller, A. Tarasov, R. Venugopalan, in preparation
        [2] N. Mueller, R. Venugopalan, Phys.Rev. D99 (2019) no.5, 056003
        [3] A. Tarasov, R. Venugopalan, arXiv:1903.11624 [hep-ph]

        Speaker: Niklas Mueller (Brookhaven National Laboratory)
      • 15:00
        Electromagnetically induced flow in heavy ion collisions 20m

        I will discuss the charge-dependent flow induced by magnetic and electric fields in heavy ion
        collisions. We simulate the evolution of the expanding cooling droplet of strongly coupled plasma
        hydrodynamically, using the iEBE-VISHNU framework, and add the magnetic and electric fields as
        well as the electric currents they generate in a perturbative fashion. We confirm the previously
        reported effect of the electromagnetically induced currents, that is a charge-odd directed flow
        $\Delta v_1$ that is odd in rapidity, noting that it is induced by magnetic fields (a la Faraday and Lorentz)
        and by electric fields (the Coulomb field from the charged spectators). In addition, we find a
        charge-odd $\Delta v_3$ that is also odd in rapidity and that has a similar physical origin. We furthermore
        show that the electric field produced by the net charge density of the plasma drives rapidity-even
        charge-dependent contributions to the radial flow $\langle p_T \rangle$ and the elliptic flow $\Delta v_2$. Although their
        magnitudes are comparable to the charge-odd $\Delta v_1$ and $\Delta v_3$, they have a different physical origin, namely the Coulomb forces within the plasma. Recent ALICE and STAR measurements confirm these effects but exhibit an opposite sign and bigger magnitude. I will discuss possible ingredients missing in the theory that would possibly resolve this apparent mismatch.

        Speaker: Dmitri Kharzeev
      • 15:20
        Hard probes of non-equilibrium quark-gluon plasma 20m

        A primary goal in heavy-ion collisions is to learn about non-equilibrium properties of the quark-gluon plasma (QGP), such as the size of its thermalization timescale and the values of its transport coefficients. Hard experimental probes like jets and heavy quarks, as well as photons [1], give direct access to these non-equilibrium properties. However, theoretical challenges have hindered calculating their dynamics in a non-equilibrium QGP. Some of these challenges stem from gauge field instabilities that arise in non-equilibrium, weakly-coupled plasma, and lead to exponentially growing gauge fields [2].

        In this talk we show how to handle the gauge field instabilities consistently. We first derive the time evolution of gluon correlators analytically. Building on the formalism elaborated in [1] then allows for a microscopic calculation of jet-medium interaction in a non-thermal QGP. Specifically, we evaluate how jets radiate gluons when they traverse a non-equilibrium medium and show that the medium effects can be factorized into transverse kicks on the jet [3] and a new Schwinger-like effect in the exponentially growing gauge fields. We solve the resulting equations numerically and comment on phenomenological implications for jets and photons. Our calculations not only apply to jets, but also to the kinetic theory of quarks and gluons. We compare our results to commonly used simplifications of the collision kernel in numerical kinetic theory calculations. Finally, we discuss how to explore the effect of non-equilibrium physics on other probes of the QGP, such as the heavy-quark potential.

        [1] S. Hauksson et al., Phys. Rev. C97 (2018) 014901.
        [2] S. Mrowczynski et al., Phys.Rept. 682 (2017) 1-97.
        [3] P. Arnold et al., JHEP 0206 (2002) 030

        Speaker: Sigtryggur Hauksson (McGill University)
      • 15:40
        New challenges for the open heavy flavor physics in ultrarelativistic collisions 20m

        The study of the QCD interaction at high temperature in the heavy quark (HQ) sector has attracted a wide interest in the last decade. The theoretical efforts to build realistic phenomenological models able to predict the main observables for D mesons, $R_{AA}$ and $v_2$, has lead to a first estimate of the Ds space diffusion of charm quarks. This has been a successful program that has allowed to have a general consensus that the charm quark interaction is non-perturbative, the estimated Ds is in agreement with current lattice QCD calculations and its thermalization time is of the order of QGP lifetime [1].
        Given the success of this first stage of the study, very recently new important perspectives are emerging. These can lead from one hand to improving the determination of Ds and on the other hand open the way for employing HQ as a novel probe of the initial stage of the ultra-relativistic collisions.
        More directly related to the determination of the HQ diffusion and hadronization are:
        - The surprisingly large $\Lambda_c$ production at both RHIC and LHC energies. We will show that this affects the $R_{AA}(p_T)$ also of the D meson and hence the determination of the HQ interaction [2]. We show also that an hadronization by coalescence plus fragmentation can largely account for this new finding and discuss new prediction for $\Lambda_b$/B ratio.
        - The correlation between the $v_n$ anisotropies of the bulk matter and the one of HQs ($v_n(light), v_n(heavy)$) and, in particular, the normalized variance of $\sigma_n/ < v_n >$ constitute a novel and more powerful tool to constraint the Ds transport coefficient [3].

        HQs have been poorly explored as a probe of the initial vorticity and electromagnetic field. We will show that a large directed flow v1 can be generated by the longitudinal initial tilt along with a splitting between D0 and anti-D0 [3]. The last can be seen also as a probe of the deconfined phase. Predictions in agreement with preliminary STAR data will be presented together with first results compared to ALICE data. A correlation study of the D0 splitting in $v_1$ with the one of muons from Z0 decay can provide a new insight into the determination of the initial magnetic field and its lifetime.
        Furthermore, we will show a novel approach that studies the potential impact of a glasma phase on the HQ dynamics and how this can provide a link between pA and AA collisions [4].

        [1] X.Dong and V. Greco, Prog. Part. Nucl. Phys. 104 (2019) 97.
        [2] S. Plumari et al., Eur. Phys. J. C78 (2018) 348
        [3] S. Plumari et al., “Azimuthal anisotropies correlation between light and heavy hadrons”, in preparation.
        [4] S.K. Das et al., Phys. Lett. B768 (2017) 260
        [5] Y. Sun et al., %``Impact of Glasma on heavy quark observables in nucleus-nucleus collisions at LHC,''  arXiv:1902.06254 [nucl-th].

        Speaker: Dr Yifeng Sun (Texas A&M University)
    • 16:00 16:20
      Coffee Break 20m
    • 16:20 18:40
      Parallel Session - Collective dynamics III Ball Room 1

      Ball Room 1

      Wanda Reign Wuhan Hotel

      Convener: Shinichi Esumi (University of Tsukuba (JP))
      • 16:20
        Signatures of collectivity and flow of light and heavy quarks in small systems observed by PHENIX 20m

        A wide variety of recent measurements from small systems indicate that there are collective flow phenomena in these systems, which are well described by hydrodynamics. However, it is widely understood that all flow measurements are affected by non-flow correlations. In order to disentangle the genuine hydrodynamical flow from other contributions, we have systematically studied the $v_2$ as a function of $p_T$ and $\eta$ in p+Au and d+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV with a mixture of different detector combinations and by comparing several non-flow subtraction methods. We have also measured 4-particle cumulants in p+Au and d+Au at $\sqrt{s_{NN}}$ = 200 GeV with subevents, which kinematically suppress non-flow via removal of short-range correlations. As found in heavy ion collisions, the quark mass dependence of the flow will further provide an evidence of collective effects. PHENIX has measured $v_2$ vs $p_T$ of muons at forward rapidity originating from heavy quark decays in d+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. We will show these results and discuss implications for the underlying mechanism that drives both light and heavy quark collectivity.

        Speaker: Seyoung Han for the PHNEIX Collaboration (EWHA Womens University, South Korea)
      • 16:40
        Latest results on the production of hadronic resonances in ALICE at the LHC 20m

        Short-lived hadronic resonances are used to study different aspects of particle production
        and collision dynamics in pp, p—A and relativistic heavy-ion collisions. The yields of
        resonances are sensitive to the competing processes of hadron rescattering and regeneration,
        thus making these particles unique probes of the properties of the late hadronic phase.
        Measurements of resonances with different masses and quantum numbers also provide insight
        into strangeness production and processes that determine the shapes of particle momentum
        spectra at intermediate transverse momenta, as well as the species dependence of hadron
        suppression at high momentum.

        Thanks to a campaign of precise measurements, the ALICE experiment now has a comprehensive
        set of results with unprecedented precision for $\rho(770)^{0}$, K$^{*}(892)$, $f_{0}(980)$,
        $\phi(1020)$, $\Sigma(1385)^{\pm}$, $\Lambda(1520)$, and $\Xi(1530)^{0}$ production in pp,
        p—Pb, Xe-Xe and Pb-Pb collisions in the energy range $\sqrt{s_{\rm NN}}$ = 2.76-13 TeV,
        including the latest measurements from LHC Run 2. The obtained results are used to study
        the system-size and collision-energy evolution of transverse momentum spectra, particle
        ratios and nuclear modification factors and to search for the onset of collectivity in
        small collision systems. These results are compared to lower energy measurements and
        model calculations where available.

        Speaker: Arvind Khuntia for the ALICE Collaboration (Indian Institute of Technology Indore (IN))
      • 17:00
        pT-Dependent Particle Number Fluctuations From Principal Component Analyses in Hydrodynamic Simulations of Heavy-Ion Collisions 20m

        We carry out a principal component analysis of fluctuations in a hydrodynamic simulation of heavy-ion collisions, and compare with experimental data from the CMS collaboration. The principal components of anisotropic flow reproduce the trends seen in data, but multiplicity fluctuations show an interesting difference in transverse momentum dependence. We checked this is also the case for other hydro models. To investigate this, we construct an analytical toy model and verify that hydrodynamic simulations agree with its predictions. We find that the discrepancy in the momentum trend is likely due to the fact that hydrodynamic models typically have transverse momentum fluctuations that are larger than seen experimentally.

        We conclude that the n=0 principal components open a new window on initial fluctuations, which can be used to rule out initial condition models.

        More details can be found in arXiv:1906.03045

        Speaker: Frederique Grassi (Instituto de F´ısica, Universidade de S˜ao Paulo)
      • 17:20
        Identifying the nature of the QCD transition in relativistic collision of heavy nuclei with deep learning 20m

        Using deep neural network, the nature of the QCD transition can be identified from only the final-state pion spectra from hybrid model simulations of heavy-ion collisions. Within this hybrid model, a viscous hydrodynamic model is coupled to a hadronic cascade “after-burner”. Two different types of equations of state (EoS) of the medium are used in the hydrodynamic evolution. The resulting spectra are used as the input data to train the neural network to distinguish EoS. Different scenarios for the input data are studied and compared in a systematic way. A clear hierarchy is observed in the prediction accuracy when using the event-by-event, cascade-coarse-grained and event-fine-averaged spectra as input for the network, which are about 80\%, 90\% and 99\%, respectively. Thus the high-level correlations of pion spectra learned by a carefully-trained neural network can serve as an effective "EoS-meter" to distinguish the nature of the QCD transition even in a simulation scenario which is close to the experiments.

        Speaker: Yilun Du (University of Bergen, Norway)
      • 17:40
        Multi-system Bayesian constraints on the transport coefficients of QCD 20m

        We present state-of-the-art constraints on the properties of the quark-gluon plasma by performing a comprehensive Bayesian model-to-data comparison of heavy-ion measurements. Soft observables from both RHIC and the LHC are combined into a global Bayesian analysis, enabling us to obtain more reliable constraints on the transport coefficients of QCD, in particular for the temperature dependence of shear and bulk viscosity.

        We study multiple different mappings of the hydrodynamic fields to hadronic momentum distributions (i.e. viscous effects on particlization) and for the first time quantify the resulting theoretical uncertainty on the Bayesian analysis. Uncertainties originating from modeling the late hadronic rescattering stage of the collisions are also investigated by preliminary comparisons of SMASH and UrQMD as afterburners. The newly obtained Bayesian constraints are validated by comparisons with additional measurements, including high-statistics observables that are currently too challenging to include in Bayesian calibrations.

        Speaker: Jean-Francois Paquet (Duke University)
      • 18:00
        Light neutral meson production in heavy ion collisions with ALICE in the era of precision physics at the LHC 20m

        The production of light neutral mesons in AA collisions probes the physics of the Quark-Gluon Plasma (QGP), which is formed in heavy-ion collisions at the LHC. More specifically, the centrality dependent neutral meson production in AA collisions compared to its production in minimum-bias pp collisions, known as nuclear modification factor, provides information on the energy loss of partons traversing the QGP. The measurement allows to test with high precision the predictions of theoretical model calculations. In addition, the decay of the $\pi^{0}$ and $\eta$ mesons are the dominant backgrounds for all direct photon measurements. Therefore, pushing the limits of the precision of neutral meson production is key to learning about the temperature and space-time evolution of the QGP.

        In the ALICE experiment neutral mesons can be detected via their decay to two photons. The latter can be reconstructed using the two calorimeters EMCal and PHOS or via conversions in the detector material. Combining the excellent momentum resolution of the conversion photons down to very low $p_{T}$ and the high reconstruction efficiency and triggering capability of calorimeters at high $p_{T}$, we are able to measure the light neutral mesons over a wide kinematic range.

        Combining state-of-the-art reconstruction techniques with the high statistics delivered by the LHC in Run 2 gives us the opportunity to enhance the precision of our measurements. In this talk, new run 2 results for neutral meson production in Pb-Pb and Xe-Xe collisions at LHC energies, as measured with the ALICE experiment, will be presented and contrasted with theoretical predictions.

        Speaker: Mike Henry Petrus Sas for the ALICE Collaboration (Nikhef National institute for subatomic physics (NL))
      • 18:20
        Two-Pion Intensity-Interferometry in Collisions of Au+Au at 1.23A GeV with HADES 20m

        We present results on azimuthally-integrated and azimuthally-dependent analyses of identical pion intensity interferometry (HBT) studied in collisions of Au+Au at $\sqrt{s_{NN}}=2.4$ GeV. The data are taken with the HADES spectrometer at SIS18/GSI Darmstadt. We study the dependence of the space-time extent of the pion emitting source on the pair transverse momentum and on the collision centrality. We observe a substantial charge sign difference of the source radii, most pronounced at low transverse momenta. The extracted source parameters do well complement the beam-energy dependences at higher energies. Furthermore, we study the evolution (with transverse momentum, centrality, and collision energy) of both, the eccentricity and the tilt angle, of the $\pi\pi$ emission ellipsoid.

        Speaker: Mr Robert Greifenhagen for the HADES Collaboration (HADES)
    • 16:20 18:40
      Parallel Session - Future facilities HongKong Room

      HongKong Room

      Wanda Reign Wuhan Hotel

      Convener: Peter Senger (GSI)
      • 16:20
        The STAR detector upgrades for the BES II and beyond physics program 20m

        The Beam Energy Scan program (BES) at the Relativistic Heavy Ion Collider (RHIC) is dedicated to exploring the Quantum Chromodynamics (QCD) phase diagram and search for the critical point of the QCD phase transition. The results from the BES phase I program show hints of a first-order phase transition in the QCD phase diagram and the turn-off of the characteristic signatures of the quark gluon plasma at low collision energies, $\sqrt{s_{\rm NN}} < $ 20 GeV. Three upgrades of the STAR detector, the Event Plane Detector, the inner Time Projection Chamber, and the endcap Time Of Flight, provide an unique opportunity to further investigate the nature of the QCD phase diagram during the BES phase II program (BES II), which covers the $\sqrt{s_{\rm NN}}$ from 7.7 to 19.6 GeV in collider mode and from 3 to 7.7 GeV in fixed-target mode.

        Beyond the BES II, the STAR Collaboration plans to design, construct, and install a suite of new detectors in the forward rapidity region (2.5 $< \eta <$ 4) over the next two years, enabling a program of novel measurements in pp, pA and AA collisions. This extension of STAR’s kinematic reach will allow detailed study of cold QCD physics at both very high and very low partonic momentum fraction. The new subdetectors to be installed comprise a Forward Calorimeter System, with electromagnetic and hadronic calorimetry. As well as a Forward Tracking System, which consists of 3 layers of silicon mini-strip detectors and 4 layers of small-strip Thin Gap Chambers.

        In this presentation, the detailed description on the detector upgrades of the STAR detector for the BES II and beyond, their performance, as well as the future physics opportunities, will be given.

        Speaker: Yi Yang for the STAR Collaboration (National Cheng Kung University (TW))
      • 16:40
        The MPD experiment at JINR: construction status and physics performance 20m

        The Multi-Purpose Detector is under construction at the Joint Institute for Nuclear Research, as part of the NICA Accelerator Complex. It aims to study the phase diagram of QCD matter at maximum baryonic density, determine the nature of the phase transition between the deconfined and hadronic matter and search for the critical point in the diagram. The current status of the construction of MPD subdetectors will be reported on, as well as progress in preparations of the software and computing infrastructure.

        The designed physics performance of the detector components will be discussed. Spectra of identified hadrons, including hyperons and hypernuclei will be presented, which emphasis on differential measurement and total yield extraction. The quality of directed and elliptic flow determination will be discussed, with comparison to model expectations. The sensitivity of event-by-event fluctuations and femtoscopic measurements to the nature of the phase transition and the
        presence of a critical point will be given. Performance of the electromagnetic calorimeter working in conjunction with the tracking system for the di-lepton measurements and the potential for identification of charmed mesons will be described. The novel method of spectator nucleons energy reconstruction, based on the transverse gradient measurements of the energy deposition in the forward
        calorimeter FHCal is also presented showing its capabilities to resolve the ambiguity in the energy deposition for central/peripheral A-A collisions. In summary, all the main components of the physics program of the MPD Collaboration will be presented.

        Speaker: Adam Kisiel for the NICA/MPD Collaboration (Warsaw University of Technology (PL))
      • 17:00
        The Compressed Baryonic Matter (CBM) Experiment at FAIR 20m

        The Compressed Baryonic Matter experiment (CBM) at FAIR aims to study the area of the QCD phase diagram at high net baryon densities and moderate temperatures using heavy-ion collisions. The FAIR accelerator will provide high-intensity heavy-ion beams up to Au ions in the energy range 2-11 GeV per nucleon. In order to achieve it's physics goals and to perform multi-differential measurements of rare probes such as multi-strange particles or hypernuclei, CBM plans to operate at unprecedented peak interaction rates of up to 10 MHz.

        Following an introduction into the physics program of the CBM experiment, the talk will focus on recent developments related to the preparation of the experiment, physics performance studies, and detector components tests within the so-called FAIR PHASE-0 program. In particular, the status of the mini-CBM project at GSI, which combines various CBM detector subsystems with a common data acquisition and analysis system, and was operated with high-intensity beams for the first time this spring, will be given.

        Speaker: Viktor Klochkov for the CBM Collaboration (Johann-Wolfgang-Goethe Univ. (DE))
      • 17:20
        LHC Run 3 and Run 4 prospects for heavy-ion physics with LHCb 20m

        The largely unknown parton distribution functions of nuclei and the similarities observed between high-multiplicity pp and pPb events compared to PbPb, often described by means of hydrodynamics, are the main motivations for an extended pPb data taking program during LHC Run 3 and Run 4. The future increase in luminosity combined with the LHCb unique detector capabilities will allow to perform new and precise measurements. Moreover, an upgraded internal gas target is going to be installed for the LHCb run 3 fixed target program, allowing a wider choice of target gas species and an increase of the gas density by up to two order of magnitude. Prospects will be presented on both the LHCb collider and fixed target programs.

        Speaker: Pasquale Di Nezza for the LHCb Collaboration (INFN e Laboratori Nazionali di Frascati (IT))
      • 17:40
        New opportunities in heavy ion physics at HL-LHC with a Mip Timing Detector at CMS 20m

        The Compact Muon Solenoid (CMS) detector at the CERN Large Hadron Collider (LHC) is undergoing an extensive Phase II upgrade program to prepare for the challenging conditions of the High-Luminosity LHC (HL-LHC). A new timing layer is designed to measure minimum ionizing particles (MIPs) with a time resolution of ~30 ps and hermetic coverage up to a pseudo-rapidity of $|\eta|$=3. The precision time information from the mip timing detector (MTD) will serve as an excellent time-of-flight detector for particle identification in QCD and heavy ion physics. Together with the wide coverage of tracker and calorimetry, the MTD will enable a broad range of new and unique opportunities in heavy ion physics at CMS. We present the current status and ongoing R&D of the MTD and performance of extending heavy ion physics program at CMS with particle identification, such as heavy flavor hadron reconstruction over wide rapidity down to very low transverse moment.

        Speaker: Andre Govinda Stahl Leiton for the CMS Collaboration (Rice University (US))
      • 18:00
        Heavy flavor physics with the sPHENIX MAPS vertex tracker upgrade 20m

        The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) will measure a suite of unique jet and Upsilon observables with unprecedented statistics and kinematic reach at RHIC energies. A MAPS-based vertex detector upgrade to sPHENIX, the MVTX, will provide a precise determination of the impact parameter of tracks relative to the primary vertex in high multiplicity heavy ion collisions. The MVTX utilizes the latest generation of MAPS technology to provide precision tracking with high tracking efficiency over a broad momentum range in the high luminosity RHIC environment. These new capabilities will enable precision measurements of open heavy flavor observables, covering an unexplored kinematic regime at RHIC. The physics program, its potential impact, and recent detector development of the MVTX will be discussed in this talk.

        Speaker: Yuanjing Ji for the sPHENIX Collaboration (University of Science and Technology of China)
      • 18:20
        Upgrading the Inner Tracking System and the Time Projection Chamber of ALICE 20m

        The ALICE experiment at CERN is undergoing a major upgrade during the Long Shutdown 2 (LS2) of the LHC during 2019-2020. The key elements regarding the central barrel are the installation of a new Inner Tracking System (ITS) and the upgrade of the large Time Projection Chamber (TPC).

        The TPC, the main tracking and PID device of ALICE, is currently being upgraded with a new readout system, including new GEM-based Readout Chambers and new front-end electronics. This will enable to operate the TPC in continuous mode, recording the full minimum-bias interaction rate of 50 kHz in Pb-Pb, as anticipated at the LHC in Run 3 and beyond.

        The new ITS based on CMOS Monolithic Active Pixel Sensors, will significantly improve the impact parameter resolution and the tracking efficiency, especially for particles with low transverse momenta, as well as the readout rate capability. The ITS will cover a total surface area of 10 m$^{2}$ containing 12.5 billion pixels of about $29 \times 27$ $\mu$m$^{2}$ achieving a material budget of $0.35$ $\%$ $X_{0}$ for the three innermost layers.

        This talk will summarize the motivation and concept of these upgrades as well as report on the status of the assembly and commissioning at the surface.

        Furthermore, an outlook
        will be given on plans for the installation and the upgrade of the ITS foreseen for the third long shutdown of the LHC in 2024-2026. For the following upgrade, the three innermost
        layers will be replaced by cylindrical detector layers, made of curved wafer-scale-sized CMOS sensors, to even further lower the material budget and to improve the pointing
        resolution.

        Speaker: Felix Reidt for the ALICE Collaboration (CERN)
    • 16:20 18:40
      Parallel Session - Heavy flavor III Ball Room 3

      Ball Room 3

      Wanda Reign Wuhan Hotel

      Convener: Xin Dong (Lawrence Berkeley National Lab)
      • 16:20
        Azimuthal anisotropy and nuclear modification of Upsilon states in PbPb collisions with the CMS detector 20m

        The production cross-sections are reported for the $\Upsilon(1S)$, $\Upsilon(2S)$, and $\Upsilon(3S)$ mesons in pp and PbPb collisions at 5.02 TeV, as functions of transverse momentum and rapidity. The dependence of the yield on the event activity and collision centrality is also presented for PbPb collisions. A comparison with the 2.76 TeV data in order to assess the energy dependence of the hot nuclear effects. Additionally, a new measurement of the azimuthal anisotropy ($v_{2}$) of the $\Upsilon(1S)$ meson is reported. The results are discussed in the context of the sequential melting scenario in dense partonic matter, considering the effect from recombination of uncorrelated quarks, as well as the impact of the medium and its collective evolution.

        Speaker: Jaebeom Park for the CMS Collaboration (Korea University (KR))
      • 16:40
        Recent results on azimuthal anysotropies of open heavy-flavour particles with ALICE at the LHC 20m

        Heavy quarks are unique tools to investigate the properties of the Quark-Gluon Plasma (QGP) formed in ultra-relativistic heavy-ion collisions. Due to the large masses, heavy quarks
        are produced in hard scattering processes on timescales shorter than the QGP formation time, thus they experience the entire evolution of the medium interacting with its constituents.

        The hot QCD matter is produced within an unprecedented strong magnetic field, which properties and effects can be probed by charm quarks via investigating the charm-particle
        directed flow $v_{1}$, because the charm quark formation time scale is comparable to the time scale when the magnetic field attains its maximum value. The charm interaction with the medium constituents and its degree of thermalisation can be investigated via the measurement of the second coefficient of the D-meson azimuthal anisotropy, the elliptic flow $v_{2}$, that allows one to study whether low-momentum charm quarks participate in the collective expansion of the system.
        Furthermore, the role of the recombination mechanism
        can be studied for charm via the comparison of non-strange D meson $v_{\rm 2}$ with the $\rm D_s$ meson $v_{\rm 2}$. The dynamics of heavy quarks in the QGP can be further
        investigated through the Event Shape Engineering (ESE) analysis. Measuring the D-meson $v_{2}$ in classes of events defined on the basis of the average flow in a given centrality class allows to evaluate the correlation between the elliptic flow of soft hadrons and D mesons.

        The interest in heavy-flavour measurements in small systems, like p-Pb and pp, have been for a long time limited to the possibility of providing tests of perturbative QCD, measurements of cold-matter effects in the nuclear medium, and the baseline for observations of hot-medium effects in heavy-ion collisions. However, such measurements have recently gained additional interest due to the possibility of observing final-state like effects typically attributed, in Pb-Pb collisions, to the presence of QGP. The orgin of such effects
        is still debated. In this contribution, the measurement of the ${\rm D}^{0}$ $v_{1}$ together with strange and non-strange D meson $v_{2}$ and the $v_{2}$ ESE analysis in Pb-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV will be presented. The comparison with predictions from theoretical models will be extensively discussed.New measurements on production cross sections and nuclear modification factors of fully-reconstructed charmed mesons and of leptons from heavy-flavour hadron decays in pp and p-Pb collisions at various
        energies will be presented with focus on their dependence on the charged-particle multiplicity.Finally, recent results on the study of azimuthal anisotropy of open heavy-flavour decay electrons and muons in p-Pb collisions will be discussed.

        Speaker: Siyu Tang for the ALICE Collaboration (Central China Normal University CCNU (CN))
      • 17:00
        Multi-stage evolution of heavy quarks in the Quark Gluon Plasma 20m

        High energy jets, evolving from a single parton, produced with transverse momentum up to a TeV, have a variety of scale dependent interactions with the QGP. The mass of heavy-quarks introduce another scale within this evolution. Modeling both the heavy quark shower and the fluid dynamical medium event by event, we demonstrate that in the high virtuality portion of a jet, where the dead-cone effect can be ignored, light and heavy-flavor evolution are indeed similar. However, in the later lower virtuality part of the shower, when the mass is comparable to the transverse momenta of the parton, heavy quarks radiate differently. Recently, it has been suggested that longitudinal drag and diffusion can stimulate radiation from heavy-quarks. The effect of this new channel is shown to partially compensate for the reduction in radiation from the dead cone effect. All these factors result in a different nuclear modification factor for heavy flavors (and heavy-flavor tagged jets).

        We present an extensive, comparative study that explores the importance of differences between various heavy quark energy-loss mechanisms with a realistically expanding quark-gluon plasma (QGP) in a multi-stage calculation within the JETSCAPE Framework [2]. The highly virtual and very energetic portion of the shower inside the QGP is modeled using the MATTER generator, while the LBT generator models the energetic and close-to-on-shell heavy quark’s showering inside with the QGP. The shower transitions from one stage to the other at a parton-by-parton level depending on the energy and virtuality of the parton, and the local density. The boundary between these stages can be extracted from a comparison with data. This allows us to explore the effect and interplay between the different regimes of energy loss on the propagation and radiation from hard heavy quarks in a dense medium. Energy momentum exchange with the medium, essential for the study of jet modification, is carried out using a weak coupling recoil approach.

        Speaker: Gojko Vujanovic for the JETSCAPE Collaboration (Wayne State University)
      • 17:20
        Quarkonium Production in Heavy Ion Collisions: from Open Quantum System to Transport Equation 20m

        The production of heavy quarkonium in heavy ion collisions has been used as an important probe of the quark-gluon plasma. The initial insight was that due to the plasma screening effect, the color attraction between the heavy quark-antiquark pair is significantly suppressed at high temperature and thus no bound states can exist, i.e., they “melt”. In addition to the screening of the color attraction, quarkonium dissociates when enough energy is transferred to it in a dynamical process. The inverse process of dissociation, recombination, can also happen inside the medium when the plasma temperature allows quarkonium formation and is as crucial as dissociation. To explain experimental results on quarkonium production, we have to account for static screening, dissociation and recombination in a consistent way. One traditional approach is to use a transport equation through which the phase space distribution of quarkonium is evolved. In recent years, another approach based on the open quantum system formalism started being used. It is learnt that dissociation can be understood as a decoherence of the wavefunction of the heavy quark-antiquark pair. Recombination is automatically included in this framework.

        In this talk, I will present a connection between the open quantum system formalism and the transport equation. I will discuss new insights about the quarkonium dynamics inside the quark-gluon plasma from the perspective of quantum information. I will show that under the weak coupling and Markovian approximations, the evolution equation of the open system, the Lindblad equation, turns to a Boltzmann transport equation after a Wigner transform is applied to the system density matrix. I will demonstrate how the separation of physical scales justifies the approximations, by using effective field theory of QCD. Finally, by coupling the transport equations of quarkonia and open heavy flavors, I will study how the system of open and hidden heavy flavors reaches thermal equilibrium inside a quark-gluon plasma box. Phenomenological results on the nuclear modification factor and the azimuthal angular anisotropy of quarkonium, based on the coupled transport equations will also be presented.

        Speaker: Xiaojun Yao (Duke University)
      • 17:40
        Nuclear modification factors, directed and elliptic flow of electrons from open heavy flavor decays in Au+Au collisions from STAR 20m

        Measurements of nuclear modification factors (RAA) and elliptic flow (v2) for open heavy flavor hadrons are essential probes of the Quark Gluon Plasma produced in heavy-ion collisions. Single electrons from semi-leptonic decays are an excellent channel to study open heavy flavor due to their large branching fractions and triggering possibilities. Additionally, semi-leptonic c-hadron decays can provide a complimentary measurement of charm hadron directed flow (v1).
        In this talk we will present the analyses of single electrons from semi-leptonic b- and c- hadron decays at mid-rapidity in sNN = 200, 54.4, and 27 GeV Au+Au collisions. The data at sNN = 200 GeV incorporate the Heavy Flavor Tracker which enables the topological separation of electrons originating from b- and c-hadron decays. We will report the first STAR measurements at sNN = 200 GeV of v2 for bottom-decayed electrons as a function of pT and v1 for charm-decayed electrons as a function of electron rapidity. Additionally, improved measurements of RAA and a new measurement of the double ratio of RCP between bottom- and charm-decayed electrons will be presented as a function of pT and centrality. We will also present the measurement of non-photonic electron v2 in sNN = 54.4 and 27 GeV data, collected during the 2017 and 2018 RHIC runs. These data samples contain roughly an order of magnitude more statistics than the previous STAR analysis at sNN = 62.4 GeV, which allows a more precise measurement of v2 for electrons from heavy flavor hadron decays at lower energies. Our data will be compared to theoretical models and implications will be discussed.

        Speaker: Matthew Kelsey for the STAR Collaboration (Lawrence Berkeley National Lab (LBNL))
      • 18:00
        Quantifying heavy quark transport coefficients within an improved transport model LIDO 20m

        The heavy-flavor transport coefficients contain important information on the strong interaction at finite temperatures. Extraction of these numbers from experimental data requires dynamical modeling of heavy-flavor transport that is coupled to a realistic medium evolution. Furthermore, meaningful extractions necessitate both a faithful implementation of the physical inputs to be tested and the quantification of model uncertainty. For these purposes, we have developed a partonic transport model LIDO. It has improved treatment of in-medium parton bremsstrahlung, which has been calibrated to analytical theoretical baselines in a simple medium to reduce modeling uncertainty. Regarding the interaction between heavy quarks and the medium, few-body perturbative scatterings are applied to large-momentum transfer (Q) processes, while a diffusion equation models the dynamics of small-Q processes. Such a separation restricts the explicit use of medium quasi-particles to large-Q processes only. Another advantage is that deviations from the leading-order probe-medium coupling can be parameterized as an additional contribution to the diffusion coefficient.

        The heavy quark transport coefficients are then extracted with uncertainty quantification from a Bayesian analysis including both RHIC and LHC data. The results are found to be consistent with earlier extractions of the light-quark transport coefficients at high momentum and are comparable to lattice calculations of the heavy-flavor diffusion coefficient in the static limit at low momentum.

        Speaker: Weiyao Ke (Duke University)
      • 18:20
        Longitudinal dependence of B and D mesons and heavy flavor leptons observables in relativistic heavy ion collisions 20m

        It is largely acknowledged that heavy flavor probes are sensitive to the properties of the quark gluon plasma and as such they are often considered an important tool for the plasma tomography studies. In the past several years there has been an astounding amount of work aimed at understanding the heavy quarks coupling with the medium. Nevertheless, the longitudinal dependence of common observables have not yet been throughly explored. Forward rapidity observables can provide further insight on the dynamics of the medium due to the interplay between the medium size directly affecting the path length of the heavy quark probes, and the differences in the production spectra. In this work we investigate the nuclear modification factor $R_\text{AA}$ and flow coefficients $v_n$ of B and D mesons, as well as heavy flavor leptons, in the rapidity range $-4.0 < y < 4.0$. We use relativistic Langevin equation with gluon radiation coupled with the CLVisc (3+1)D viscous hydrodynamics medium background for AuAu at $\sqrt{s_\text{NN}} = 200$ GeV, and PbPb at $\sqrt{s_\text{NN}} = 2.76$ TeV and $\sqrt{s_\text{NN}} = 5.02$ TeV collisions. Comparison with current data is shown for mid-rapidity observables as well as forward rapidity muons. We provide predictions for different rapidity ranges for B and D mesons observables.

        Speaker: Caio A. G. Prado (Central China Normal University (CN))
    • 16:20 18:40
      Parallel Session - Initial state I Ball Room 2

      Ball Room 2

      Wanda Reign Wuhan Hotel

      Convener: In Kwon Yoo (Pusan National University (KR))
      • 16:20
        Event shape dependence of anisotropic flow for inclusive and identified hadrons in Pb-Pb and Xe-Xe collisions with ALICE 20m

        Anisotropic flow provides valuable information on the key properties and the evolution of the matter created in heavy-ion collisions. In this talk, we present the elliptic and triangular flow of inclusive and identified particles measured in Xe-Xe collisions at $\sqrt{s_{\rm NN}} = 5.44$ TeV recorded by the ALICE detector. The measurements are reported for a wide range of particle transverse momenta, $p_{\rm T}$, within the pseudo-rapidity region $|\eta|<0.8$. Strong constraints on the initial conditions of a collision and hydrodynamic medium response are placed comparing these results to those from Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV. In addition, the flow harmonics of inclusive and identified particles are studied using Event Shape Engineering technique in Pb-Pb collisions. The effect of the event-shape selection is within uncertainties independent of particle species up to $p_{\rm T} \sim 8$ GeV/$c$ and the origin of this observation is discussed.

        Speaker: Mihaela Gabriela Besoiu for the ALICE Collaboration (Institute of Space Science (RO))
      • 16:40
        Constraining nPDFs with electroweak boson measurements in pPb collisions with the CMS detector 20m

        Nuclear parton distribution functions (nPDFs) of quarks and antiquarks affect the production of electroweak bosons in proton-lead (pPb) collisions. In this presentation, the measurements of the neutral Drell-Yan (DY) process and of the W bosons are presented in pPb collision at the center of mass energy of 8.16 TeV with the CMS detector. The rapidity dependence of these processes is particularly sensitive to nPDFs, but further information can be gained by studying the mass dependence of DY production, measured for the first time in pPb collisions at 8.16 TeV, down to 15 GeV. In addition, differential measurements in the dimuon $p_{\text{T}}$ or $\phi^{*}$ (an angular variable correlated with $p_{\text{T}}$ measured for the first time in pPb) provide insights on soft gluon emission at low $p_{\text{T}}$. Comparisons to theory calculations show that these data are sensitive to the presence of nuclear modifications to the parton distributions in the lead nucleus, and can help improve and constrain theoretical calculations.

        Speaker: Hyunchul Kim for the CMS Collaboration (Chonnam National University (KR))
      • 17:00
        Exploring Longitudinal Observables with 3+1D IP-Glasma 20m

        We present a formulation of the initial state of heavy ion collisions that generalizes the 2+1D boost invariant IP-Glasma [1] to 3+1D through JIMWLK rapidity evolution of the pre-collision Wilson lines. The rapidity dependence introduced by the JIMWLK evolution means that 1) the system no longer trivially satisfies Gauss’ law at the initial time and 2) the form of the 2+1D initial gauge fields will give rise to nonphysical energy deposition outside of the interaction region of the colliding nuclei. To address these issues, we enforce Gauss’ law locally and modify the form of the initial gauge fields in order to accommodate non-vanishing rapidity derivatives. This makes the initial condition consistent with a non-boost invariant system, and thus allows for temporal evolution on a 3-dimensional lattice.

        While the transverse physics of QGP has been studied nearly exhaustively, the effect of longitudinal fluctuations introduced by the JIMWLK evolution has yet to be studied in detail phenomenologically. Hence, we couple our 3+1D IP-Glasma model to MUSIC+UrQMD, for completely 3+1D simulations of heavy ion collisions. Specifically, we consider Pb-Pb collisions at \sqrt{s} = 2.76 TeV and study the rapidity dependence of the charged hadron v_n (η) via the η-dependent flow factorization ratios r_n(ηa,ηb) as measured by CMS [2], as well as the charged hadron multiplicity dN_ch /dη.

        REFERENCES
        [1] Bjoern Schenke and Soeren Schlichting. “3D glasma initial state for relativistic heavy ion collisions”. In: Phys. Rev. C94.4 (2016).
        [2] Vardan Khachatryan et al. “Evidence for transverse momentum and pseudorapidity dependent event plane fluctuations in PbPb and pPb collisions”. In: Phys. Rev. C92.3 (2015).

        Speaker: Sangyong Jeon (McGill University)
      • 17:20
        Probing modification of the initial state in small systems via jets detected in PHENIX 20m

        Previous measurements in small systems indicate that the modifications to jets relative to p+p collisions is small. However, looking at more differential measurements may reveal if any modifications do exist. In particular, we compare $\pi^0$-hadron correlations measured with PHENIX in small systems to those observed in p+p collisions to probe any initial state effects. Several systematic uncertainties cancel when comparing the ratio of the awayside yield to the nearside yield in d+Au and $^3$He+Au systems to p+p revealing a quantifiable modification in these systems. In addition, $p_{out}$ distributions for the p+A collisions is measured. An increasing trend in the width of the $p_{out}$ distributions in p+Al and p+Au compared to p+p is observed as a function of $N_{coll}$. The potential implications of these measurements in conjunction with the PHENIX results for reconstructed jets in small systems will be discussed.

        Speaker: Jonathan Runchey for the PHENIX Collaboration (Iowa State University)
      • 17:40
        Heavy quark momentum diffusion coefficient in 3D gluon plasma 20m

        We study the heavy-quark momentum diffusion coefficient in far from equilibrium gluon plasma in a self-similar regime using real-time lattice techniques. We use 3 methods for the extraction: an unequal time electric field 2-point correlator integrated over the time difference, hard loop (HTL) perturbation theory and a kinetic theory formula, both using our recently acquired data on the gluon spectral function. The time-evolution of the momentum diffusion coefficient extracted from all three methods is consistent with an approximate $t^\frac{-1}{2}$ power law. We also study the extracted diffusion coefficient as a function of the upper limit of the time integration. We find that combining HTL expressions with the infrared enhancement of the equal-time correlation function that we have observed improves the agreement with the data for transient time behavior considerably. This is a gauge invariant confirmation of the infrared enhancement previously observed only in gauge fixed correlation functions.

        Speaker: Jarkko Peuron (FBK - Fondazione Bruno Kessler (IT))
      • 18:00
        Impact of dijet and D-meson data from 5.02 TeV p+Pb collisions on nuclear PDFs 20m

        Based on Refs. [1] and [2], we discuss the new constraints on gluon parton distribution function (PDF) in lead nucleus, derivable with the Hessian PDF reweighting method from the 5.02 TeV p+Pb measurements of CMS dijet [3] and LHCb $D^0$-meson [4] nuclear modification ratios. The impact is found to be significant, placing stringent constraints in the mid- and previously unconstrained small-$x$ regions. The CMS dijet data confirm the existence of gluon anti-shadowing and onsetting of small-$x$ shadowing, as well as reduce the gluon PDF uncertainties in the larger-$x$ region. The gluon constraints from the LHCb $D^0$ data, reaching down to $x \sim 10^{-5}$ and derived for the first time in a fully NLO perturbative QCD based approach, provide a remarkable reduction in the small-$x$ uncertainties with a strong direct evidence of gluon shadowing. Furthermore, we find a good description of the data even down to zero transverse momentum of the produced $D^0$-meson within a purely DGLAP-based approach without the need of imposing any non-linear effects. Importantly, the constraints obtained from the dijet and $D^0$ data are mutually fully consistent, supporting the universality of nuclear PDFs in hard-scattering processes.

        [1] K.J. Eskola, P. Paakkinen, H. Paukkunen, Eur. Phys. J. C79 (2019) 511
        [2] K.J. Eskola, I. Helenius, P. Paakkinen, H. Paukkunen, arXiv:1906.02512 [hep-ph]
        [3] CMS Collaboration, JHEP 10 (2017) 090
        [4] LHCb Collaboration, Phys. Rev. Lett. 121 (2018) 062002

        Speaker: Petja Paakkinen (University of Jyväskylä)
      • 18:20
        Early thermalization and shear viscosity to entropy ratio in heavy-ion collisions at energies of BES, FAIR and NICA. 20m

        Equilibration of highly excited baryon-rich matter is studied within the
        microscopic model calculations in A+A collisions at energies of BES, FAIR
        and NICA. It is shown that the system evolution from the very beginning
        of the collision can be approximated by relativistic hydrodynamics, although
        the hot and dense nuclear matter is not in local equilibrium yet.
        During the evolution of the fireball the extracted values of energy density,
        net baryon and net strangeness densities are used as input to Statistical
        Model (SM) in order to calculate temperature, chemical potentials and entropy
        density of the system. Also, they are used as an input for the box with
        periodic boundary conditions to investigate influence of initial cut-off
        time on momentum correlators in the infinite nuclear matter. Shear viscosity
        is calculated according to the Green-Kubo formalism.
        At all energies, shear viscosity to entropy density ratio shows minimum
        at time corresponding to maximum baryon density. The ratio dependence on
        the SM temperature, baryon chemical potential and strangeness chemical
        potential is investigated.

        Speaker: Evgeny Zabrodin (Universiyu of Oslo)
    • 08:40 10:40
      Parallel Session - Jet modifications II Ball Room 2

      Ball Room 2

      Wanda Reign Wuhan Hotel

      Convener: Marco Van Leeuwen (Nikhef National institute for subatomic physics (NL))
      • 08:40
        Studies of quark and gluon contributions to jet production using jet charge measurements in pp and PbPb collisions with the CMS detector 20m

        Jets can be used to study in-medium modifications of the parton shower and the energy loss mechanisms in heavy ion collisions. Several recent works at LHC have hinted that quark and gluon fractions in measured jets may be modified in QGP due to quenching. Jet charge is defined as the momentum-weighted sum of charges of particles inside a jet. It is sensitive to the charge of the initiating parton and can be used to discriminate between gluon-initiated and quark-initiated jets. In this talk, jet charge distributions, unfolded for detector and background effects, are presented using data with pp and PbPb collisions in different centrality classes at $\sqrt{s_{NN}} = 5.02 TeV$ collected by the CMS experiment. The pp results are compared to predictions from leading and next-to-leading-order generators. We also present a template fitting technique for estimating the quark and gluon jet fractions in pp and PbPb collisions based on Monte Carlo templates.

        Speaker: Dhanush Anil Hangal for the CMS Collaboration (University of Illinois at Chicago (US))
      • 09:00
        Exploring the phase space of jet splittings in Pb—Pb and pp collisions at $\sqrt{s}_{\rm NN}$ =5.02 TeV in ALICE 20m

        Recent ALICE measurements of jet splittings in Pb—Pb and pp collisions using the new 2018 data at $\sqrt{s}_{\rm NN}$ = 5.02 TeV will be shown. These measurements scan the phase space of emissions inside of the jet in search of a medium-induced signal, which are expected to emerge at different scales and include effects such as multiple soft-radiation, single hard emissions, and color coherence. The Lund plane will be explored, including projections onto distributions of the splitting scale $k_{\rm T}$ in bins of the splitting angle. Soft Drop (SD) grooming will be applied to access hard splittings within the jet such that various groomed substructure variables can be measured. These include the shared momentum fraction $z_{\rm g}$ between the two hardest sub-jets, the number of Soft Drop splittings $n_{\rm SD}$, the splitting angle $R_{\rm g}$, and the groomed mass.

        These variables will be shown as a function of collision centrality and jet $p_{\rm T}$. A selection on splitting formation time will be explored as an attempt to identify in and out of medium splittings. The results will be shown in Pb—Pb collisions compared to pp collisions that have been embedded into a Pb—Pb background to separate out background from in-medium effects.

        Speaker: Laura Brittany Havener for the ALICE Collaboration (Yale University (US))
      • 09:20
        Constraining parton energy loss via angular and momentum based differential jet measurements in Au+Au collisions at STAR 20m

        Parton energy loss has been established as an essential signature of the QGP in heavy ion collisions since the earliest measurements at RHIC indicating suppression of hadron spectra at high $p_{T}$ and coincidence yields. Understanding this phenomenon of jet quenching is a requirement for extracting the microscopic properties of the QGP via jet-tomography. STAR has recently introduced a technique called Jet Geometry Engineering (JGE) wherein we enforce particular selection criteria imposed on the jet collection, such as recoiling off a high $p_{T}$ hadron trigger along with an additional transverse momentum threshold for jet finding in events with back-to-back di-jets. With JGE, we are able to control the extent of energy loss ranging from quenched/imbalanced to recovered/balanced recoil jets. Since jet quenching is also expected to be dependent on the resolution/transverse-length scales with which the jet probes the medium, it is necessary to perform differential measurements with a handle on both momentum and angular scales. With the large 2014 Au+Au data sample at $\sqrt{s_{NN}} = 200$ GeV we are able to quantitatively constrain parton energy loss via JGE and measure it differentially as a function of both the jet $p_{T}$ and opening angle between the two leading sub-jets ($\theta_{sj}$). We probe the medium response to jets at varying resolution scales by measuring the recoil jet yield and the di-jet asymmetry and search for significant differences between wide and narrow $\theta_{sj}$ jets. These double differential measurements in $p_{T}$ and angle, along with JGE, enable us to probe the medium and its coherent or decoherent interaction with a hard scattered parton leading to partonic energy loss.

        Speaker: Raghav Kunnawalkam Elayavalli for the STAR Collaboration (Wayne State University)
      • 09:40
        Jet quenching in a multi-stage approach 20m

        Jets engender physics over a multitude of scales, from the hardest interactions in a heavy-ion collision (up to a TeV at the LHC), down to the scale of the freeze-out temperature. A complete description of jet modification must address the role and interplay of the physics at each of these scales and their effect on a wide variety of integrated and differential jet observables.

        In this talk, we present such a comprehensive study by performing a model-to-data comparison for leading hadrons, inclusive jets, and jet substructure observables [1,2]. Using the JETSCAPE framework [3], we succeed in providing a simultaneous description of the nuclear modification factor for single hadrons and jets, jet shape, and jet fragmentation function within a unified multi-stage framework which spans multiple centralities, energies and jet radii. This multi-scale approach includes a high virtuality (radiation dominated) generator (MATTER), followed by an on-shell energy loss generator (LBT/MARTINI) or a strongly coupled drag energy loss (AdS/CFT) stage [4]. Each stage transitions to the next at a parton-by-parton level, depending on local quantities such as the parton’s energy, virtuality, and the local density. Measurements of jet and single hadron $R_{AA}$ set strong constraints on the phase-space available for each stage of the energy-loss. We also incorporate jet-medium response through a weakly-coupled transport description with recoil particles excited from the QCD medium. We highlight the central role played by recoil in the description of both integrated jet observables and the sub-structure of the jet.

        [1] JETSCAPE Collaboration, C. Park et al., PoS HardProbes2018 (2019) 072.

        [2] JETSCAPE Collaboration, Y. Tachibana et al., PoS HardProbes2018 (2019) 099.

        [3] JETSCAPE Collaboration, J. H. Putschke et al., arXiv:1903.07706 [nucl-th].

        [4] JETSCAPE Collaboration, S. Cao et al., Phys. Rev. C96 (2017) 024909.

        Speaker: Amit Kumar (Wayne State University)
      • 10:00
        Interplaying mechanisms behind inclusive jet $R_{AA}$ and extraction of jet energy loss distributions 20m

        The observed suppression of inclusive jets in heavy-ion collisions at LHC has a very weak $p_{T}$ dependence over a large range of $p_{T}$ = 50-1000 GeV and is almost independent of the colliding energy, though the initial energy density of the formed QGP has increased significantly from $\sqrt{s}$ = 2.76 to 5.02 TeV. This interesting phenomenon is fully investigated in the linear Boltzmann transport(LBT) model for jet propagation combined event-by-event 3+1D hydro backgrounds. We found that the $p_{T}$ dependence of jet $R_{AA}$ is determined by the initial spectrum in $pp$ collisions and jet quenching in which medium response has a significant contribution. Furthermore, the energy loss distribution is extracted directly from experimental data within a Beyesian method, which provides a model-independent approach to understand jet quenching in detail. The extracted jet energy loss distributions have a scaling behavior and indicate that jet quenching is caused on the average by only a few out-of-cone scatterings.

        Speaker: Yayun He (Central China Normal University)
      • 10:20
        How to infer the shape of the QGP droplet from high pt data 20m

        The spatial anisotropy of QGP, formed in ultrarelativistic heavy-ion collisions, is commonly inferred form models of early QGP evolution. These studies (e.g. MC-Glauber, EKRT, IP-Glasma, MC-KLN), based on different methods, lead to notably different predictions, with a notable effect in the resulting predictions for both low and high pt data. On the other hand, energy loss of high-pt particles traversing QCD medium is an excellent probe of QGP properties, particularly since there is a wealth of accumulated high pt experimental data. Therefore, as a novel and complementary approach, we here propose using high pt theory and data to infer the shape of initial QGP droplet.

        To achieve this, we use DREENA framework, which is fully optimized computational procedure based on our state-of-the art dynamical energy loss formalism. Our most recent results show that, when embedded in 3+1D hydro medium model, DREENA provides a very good joint agreement with both $v_2$ and $R_{AA}$ data, contrary to the $v_2$ puzzle faced by models with simpler energy loss mechanisms. This, together with good joint agreement of our model with a wide range of $R_{AA}$ and $v_2$ data (obtained with no fitting parameters used in model testing) shows that DREENA can realistically descibe high pt parton-medium interactions. By using DREENA framework, we show, through analytical arguments, numerical calculations, and comparison with experimental data, that $v_2$/(1−$R_{AA}$) reaches a well-defined saturation value at high pt, which is in turn proportional to the initial anisotropy. We provide first anisotropy estimates from our approach, and compare them with the predictions of early QGP evolution models. With expected future significant reduction of experimental errors, the anisotropy extracted from experimental data will strongly constrain the calculations of initial particle production in heavy-ion collisions, and thus test our understanding of QGP physics.

        Speaker: Magdalena Djordjevic (Institute of Physics Belgrade)
    • 08:40 10:40
      Parallel Session - Collective dynamics IV Ball Room 3

      Ball Room 3

      Wanda Reign Wuhan Hotel

      Convener: Yasuyuki Akiba (RIKEN)
      • 08:40
        Fluid dynamics far-from-equilibrium: a concrete example 20m

        The applicability of fluid-dynamical models in the extreme conditions produced in heavy ion collisions has not yet been properly understood from a theoretical point of view. This happens mostly because the derivation of hydrodynamics from microscopic theory often relies on the assumption that the system is sufficiently close to local equilibrium -- something difficult to justify in the rapidly expanding systems created in heavy ion collisions.

        In this contribution we propose a more general derivation of relativistic fluid dynamics from kinetic theory, in which the fluid is assumed to be close to an isotropic non-equilibrium state instead of an equilibrium one. We demonstrate that, for a wide variety of non-equilibrium states, one obtains a hydrodynamic theory described by equations of motion that are identical to those commonly solved in heavy ion collisions. The only difference appears in the form of the transport coefficients that enter the equations of motion. Simulations of the relativistic Boltzmann equation equation in 0+1D Bjorken flow in the ultrarelativistic limit are performed to demonstrate this effect, showing that the time evolution of the energy-momentum tensor appears to be fluid-dynamical even when the momentum distribution of the underlying degrees of freedom differs significantly from an equilibrium distribution.

        Speaker: Gabriel Denicol (Universidade Federal Fluminense)
      • 09:00
        Revealing QCD thermodynamics in ultra-relativistic nuclear collisions 20m

        The ATLAS collaboration has recently shown that anisotropic flow exhibits a strong centrality dependence in ultracentral collisions [arXiv:1904.04808]. In particular, the 4-particle cumulant of elliptic flow changes sign, and the centrality at which this change of sign occurs depends on the observable which is used to determine the centrality. We show that these features are universal consequences of impact parameter fluctuations within a centrality bin. More precisely, they naturally follow from the fact that the relation between the impact parameter and the experimentally-determined centrality is not one to one.

        Speaker: Jean-Yves Ollitrault (CNRS)
      • 09:20
        Linear and non-linear flow modes of charged and identified particles in Pb-Pb collisions with ALICE 20m

        One of the primary goals of flow studies in heavy-ion collisions during recent years is a better understanding of the transport properties of the quark-gluon plasma (QGP), such as the temperature dependence of the shear viscosity to entropy density ratio, $\eta/s(T)$. The higher order harmonic flow observables ($n > 3$) and their non-linear response to the initial state anisotropy has the strong potential to constrain $\eta/s(T)$ because of different sensitivities to various stages of heavy-ion collisions.

        In this talk, we present the measurements of the flow harmonic power spectra, the symmetry-plane correlations and the non-linear coefficients up to the eighth harmonic order in Pb--Pb collisions at $\sqrt{s_{NN}}$=5.02 TeV for unidentified charged hadrons. In addition, we present the results of $p_T$-differential non-linear flow modes for charged pions, kaons, (anti-)protons, lambdas, K0s and phi.

        We discuss differences and similarities in the number of constituent quark scaling for identified particles for the total flow harmonics and their non-linear modes that could have implications in particle production models based on coalescence. The results are compared to the lower energy measurements at 2.76 TeV and with calculations from state-of-the-art hydrodynamic models.

        Speaker: Jasper Parkkila for the ALICE Collaboration (University of Jyvaskyla (FI))
      • 09:40
        Beam-energy and collision-system dependence of the linear and mode-coupled flow harmonics from STAR 20m

        Recent measurements and hydrodynamic model calculations suggest that the higher-order flow coefficients, $v_{n}$ (n $>$ 3), have two contributions: a linear contribution driven by the initial-state eccentricities, $\epsilon_{n}$, and a mode-coupled contribution derived from the lower-order eccentricity coefficients $\epsilon_{2}$ and $\epsilon_{3}$. Measurement of these two contributions to $v_{n}$ provides crucial insights to discern initial-state models and to constrain the temperature-dependent specific shear viscosity, $\eta/s(T)$, of the plasma produced in heavy-ion collisions. In this work, we have employed the traditional, two- and three-subevents cumulant techniques to provide the first beam-energy and collision-system dependence of the linear and mode-coupled contributions to the higher-order flow harmonics and the associated correlations between different flow symmetry planes. Our results will be presented and discussed for several transverse momenta selections, particle species, and centrality intervals for U+U collisions at $\sqrt{s_{NN}}$= 193 GeV, Au+Au collisions at $\sqrt{s_{NN}}$=200, 54.4, 39 and 27 GeV and Cu+Au collisions at $\sqrt{s_{NN}}$=200 GeV. The results are compared with similar studies performed by ALICE/CMS/ATLAS experiments at LHC. The measurements will also be compared to several viscous hydrodynamic calculations to pin down the respective influence of initial-state fluctuations, mixed harmonic correlations, system-size, shape ($\varepsilon$) and $\eta/s(T)$ on $v_{n}$.

        Speaker: Niseem Abdelrahman for the STAR Collaboration (University of Illinois at Chicago)
      • 10:00
        Momentum-dependent flow fluctuations as a hydrodynamic response to initial geometry 20m

        We propose a new and improved principal component analysis (PCA), which characterizes the fluctuations of anisotropic flow and how these fluctuations are correlated in transverse momentum. Then, using state-of-the-art hydrodynamic simulations, we make an explicit connection between the initial geometry and these principal components. The usual eccentricity scaling of anisotropic flow implies only a leading principal component, but by including more terms in a cumulant expansion, we can also describe subleading PCA modes, and explicitly show what properties of the initial state generate these subleading fluctuations. In particular, subleading elliptic flows are generated by higher order cumulants, and therefore probe small length scales of the initial state. Conversely, subleading triangular flow is more sensitive to nonlinear, mixed harmonic geometric anisotropies. With this information, it will be possible to put new constraints on properties of the early-time dynamics of a heavy-ion collision, including small-scale structure, as well as properties of the Quark-Gluon Plasma.

        References:
        [1] M. Hippert, D. Dobrigkeit Chinellato, M. Luzum, J. Noronha, T. Nunes da Silva and J. Takahashi, arXiv:1906.08915
        [2] M. Hippert, D. Dobrigkeit Chinellato, M. Luzum, J. Noronha, T. Nunes da Silva and J. Takahashi, in preparation

        Speaker: Mauricio Hippert (Universidade de São Paulo)
      • 10:20
        Correlation of flow harmonics and mean transverse momentum in 5.02 TeV $p$+Pb and Pb+Pb collisions and event-plane dependence of HBT radii in high-multiplicity $p$+Pb collisions with the ATLAS detector 20m

        To assess the properties of the quark-gluon plasma formed in heavy ion collisions, correlations between the mean transverse momentum, [$p_{T}$], and the magnitude of the flow harmonics, $v_{n}$, are measured by the ATLAS experiment at the LHC. The analysis uses data samples of lead-lead collisions at $\sqrt{s_{NN}} =5.02$~TeV and proton-lead collisions at $\sqrt{s_{NN}} =5.02$~TeV, corresponding to integrated luminosities of 22 $\mu$b$^{-1}$ and 28 nb$^{-1}$, respectively. The correlations are measured using a modified Pearson coefficient that is independent of multiplicity fluctuations. To suppress any short-range correlations, the [$p_{T}$] is measured at mid-rapidity and the flow harmonics are measured at forward rapidity.
        In Pb+Pb collisions, significant (non-zero) values of the correlation coefficients are observed for all studied harmonics, which show a strong centrality dependence but vary only weakly with the charged particle $p_{T}$ range used in the measurement. On the other hand, in $p$+Pb collisions, the correlation coefficient measured for the 2$^{nd}$ harmonic is found to show only a weak centrality dependence. The predictions of a 3+1D viscous-hydrodynamic model are found to be qualitatively consistent with the data, indicating hydrodynamic origin of these correlations in $p$+Pb collisions.
        As an independent test for the hydrodynamic description of collectivity observed in $p$+Pb collisions, measurements of two-pion HBT correlations as a function of the angle of the pion pair with respect to the second-order event plane angle are presented. The HBT correlation functions, corrected for event plane resolution, are measured as a function of $q_{out}$, $q_{side}$ and $q_{long}$ in intervals of pair transverse momentum and second-order flow-vector magnitude. The correlation functions are fit using the Bowler-Sinyukov form with the exponential HBT correlation function. The extracted HBT radii, $R_{out}$, $R_{side}$ and $R_{long}$ and a significant out-side cross-term are found to exhibit significant modulation with respect to the second-order event plane, similar to that observed in heavy ion collisions. Results of the measurements and physics implications of the result, will be discussed.

        Speaker: Tomasz Bold (AGH Univ. of Science and Technology, Krakow)
    • 08:40 10:40
      Parallel Session - New theoretical developments II HongKong Room

      HongKong Room

      Wanda Reign Wuhan Hotel

      Convener: Sourendu Gupta (TIFR)
      • 08:40
        Fast resonance decays in nuclear collisions 20m

        We present a new method to calculate the final decay spectrum of direct resonance decays directly from hydrodynamic fields on a freeze-out surface. The method is based on identifying components of the final particle spectrum that transform in an irreducible way under rotations in the fluid-restframe. Corresponding distribution functions can be pre-computed including all resonance decays. Just a few of easily tabulated scalar functions then determine the Lorentz invariant decay spectrum from each space-time point, and simple integrals of these scalar functions over the freeze-out surface determine the final decay products. This by-passes numerically costly event-by-event calculations of the intermediate resonances. The method is of considerable practical use for making realistic data to model comparisons of the identified particle yields and flow harmonics, and for studying the viscous corrections to the freeze-out distribution function.

        Reference: A. Mazeliauskas, S. Floerchinger, E. Grossi, D. Teaney, Eur. Phys. J. C79

        Speaker: Eduardo Grossi (Heidelberg University)
      • 09:00
        An Effective Theory of Quarkonia in QCD Matter 20m

        The problem of quarkonium production in heavy ion collisions presents a set of unique theoretical challenges – from the relevant production mechanism of $J/\psi$s and $\Upsilon$s
        to the relative significance of distinct cold and hot nuclear matter effects in the observed attenuation of quarkonia. In the well-defined leading power factorization limit of non-relativistic Quantum Chromodynamics (NRQCD) we show conclusively that in spite of certain similarities in the suppression of $J/\psi$s of moderate transverse momenta to the one of light/heavy hadrons, the familiar parton energy loss picture is distinctly incompatible with the hierarchy of the attenuation of ground and excited quarkonium states. With this in mind, for heavy quarkonia of moderate energy we generalize the relevant successful theory NRQCD to include interactions in nuclear matter. The new resulting theory, NRQCD with Glauber gluons, provides for the first time a universal microscopic description of the interaction of heavy quarkonia with a strongly interacting medium, consistently applicable to a range of phases, such as cold nuclear matter, dense hadron gas, and quark-gluon plasma. The effective field theory we present in this work is derived from first principles and is an important step forward in understanding the common trends in proton-nucleus and nucleus-nucleus data on quarkonium suppression. We explicitly show the lowest order (LO) and next-to-leading order (NLO) interaction terms in the Lagrangian and discuss the connection of the LO result to existing phenomenology.

        Speaker: Ivan Vitev
      • 09:20
        Beyond Color Glass Condensate: particle production at both low and high transverse momenta 20m

        We propose and develop a new formalism that generalizes the Color Glass Condensate approach to high energy scattering by including both small and large $x$ gluons in the wave function of a target proton or nucleus. This allows one to treat particle production at both low and high transverse momenta on the same footing. We illustrate the formalism by calculating the differential cross section for scattering of a quark (or gluon) on a target proton or nucleus and show that inclusion of both small and large $x$ gluon modes in the target allows one to investigate forward-backward (in rapidity) asymmetries in high energy collisions. It also leads to both even and odd anisotropic flow coefficients $v_n$ in proton-proton and proton-nucleus collisions as well as double spin asymmetry $A_{LL}$ in polarized proton-proton (light nucleus) scattering. We comment on how the formalism can be extended to study jet energy loss in Quark-Gluon Plasma created in high energy heavy ion collisions.

        Speaker: Jamal Jalilian-Marian (Baruch College)
      • 09:40
        QCD factorization and universality of jet cross sections in heavy-ion collisions 20m

        Nowadays powerful accelerators collide heavy-ions at high energies in order to recreate the Quark Gluon Plasma (QGP) which is a hot and dense state of matter that is believed to have filled our universe shortly after the Big Bang. We propose a new approach to study the QGP by using very energetic jets produced in the same collisions which can be utilized as controllable hard probes. Measuring the properties of the QGP such as the temperature or transport coefficients relies on whether it is possible to reliably separate the production of the probe and the formation of the medium. This concept is known as QCD factorization. Starting from an established factorization formalism in proton-proton collisions, we introduce medium modified jet functions to capture the interaction of jets with the QGP. Within a global analysis using a Monte Carlo sampling technique we find that it is indeed possible to describe the data obtained at the LHC. Our results thus support the validity of QCD factorization in the complex heavy-ion environment, and open up a new door to analyze heavy-ion jet data. In addition, our results may serve as guidance for constructing microscopic models of the QGP.

        Speaker: Felix Ringer (Lawrence Berkeley National Laboratory)
      • 10:00
        Holographic collisions with baryon number at intermediate coupling 20m

        In holographic heavy ion collisions it is possible to follow both the energy density and a globally conserved (baryon) number density throughout the evolution, dual to a metric and Maxwell field in the dual bulk theory, respectively. At infinite coupling, past work has shown that after the collision the baryon number ends up around mid-rapidity, which is different from high energy heavy ion collisions. In this talk I will present first results for the flow of baryon number in holographic collisions away from the infinite coupling limit, which also means we study the collisions at a larger shear viscosity over entropy density ratio than 1/4π. I will give an introduction to the holographic set-up, which is interesting since it contains an extra coupling of the gravitational Ricci scalar with the Maxwell field. Remarkably, depending on the value of this extra coupling, we find that the flow of baryon number during the collision can be affected drastically. In particular, we find that at intermediate coupling it is possible for almost no baryon number to end up at mid-rapidity. We further show how the matter produced in the collision relaxes into a flow as described by hydrodynamics with a conserved baryon current.

        Speaker: Wilke Van Der Schee (MIT)
      • 10:20
        Improved opacity expansion for medium-induced parton splitting 20m

        Medium-induced parton splitting is the building block for jet evolution in the presence of a hot QCD medium and plays a central role in quantitative studies of jet quenching. It exhibits two regimes: the one dominated by one single hard scattering at high frequency, and the other by multiple soft scattering at low frequency. A closed analytic formula encompassing both regimes is so far lacking. Some progress in this direction was recently achieved [1,2], where we propose an improved opacity expansion approach in which instead of expanding around vacuum the expansion is performed around the harmonic oscillator providing a better convergence of the series at low frequencies We show that the first two orders account for the two known analytic limits.

        [1] Y. Mehtar-Tani, "Gluon bremsstrahlung in finite media beyond multiple soft scattering approximation," arXiv:1903.00506 [hep-ph] (to appear in JHEP)
        [2] Y. Mehtar-Tani, K. Tywoniuk, in preparation

        Speaker: Yacine Mehtar-Tani (Brookhaven National Laboratory)
    • 08:40 10:40
      Parallel Session - Search for the CP II Ball Room 1

      Ball Room 1

      Wanda Reign Wuhan Hotel

      Convener: Yuxin Liu (Peking University)
      • 08:40
        A machine learning study to identify spinodal clumping in high energy nuclear collisions 20m

        In this talk I will discuss possible observables of baryon number clustering due to the instabilities occurring at a first order QCD phase transition.
        The dynamical formation of baryon clusters at a QCD phase transition can be described by numerical fluid dynamics, augmented with a gradient term and an equation of state with a mechanically unstable phase [1]. I will show that
        the dynamical description of this phase transition, in nuclear collisions, will lead to the formation of dense baryon clusters at the phase boundary [2]. Using state-of-the-art machine learning methods I will show that the coordinate space clumping leaves characteristic imprints on the spatial net density distribution in almost every event. On the other hand the momentum distributions do not show any clear event-by-event features. In fact only a few events can be systematically differentiated when only the momentum space information is available. In such a scenario conventional observables, like the baryon number cumulants seem to be the best hope at finding signals for the phase transition. Indeed it is shown that the third order cumulant, the skewness, shows a peak at the beam energy where the system, created in the heavy ion collision, reaches the deconfinement phase transition. Most of this talk will be based on [3].

        [1] J. Steinheimer and J. Randrup,
        Phys. Rev. Lett. 109, 212301 (2012).
        [2] J. Steinheimer and V. Koch,
        Phys. Rev. C 96, no. 3, 034907 (2017)
        [3] J. Steinheimer, LongGang Pang, Kai Zhou, Volker Koch, Jorgen Randrup and Horst Stoecker,
        arXiv:1906.06562 [nucl-th].

        Speaker: Jan Steinheimer
      • 09:00
        Light Nuclei (d, t) Production in Au+Au Collisions at $\sqrt{s_{\rm{NN}}}$=7.7-200 GeV from the STAR experiment 20m

        In high energy nuclear collisions, light nuclei can be regarded as a cluster of baryons and their yields are sensitive to the baryon density fluctuations. Thus, the production of light nuclei can be used to study the QCD phase transition, at which the baryon density fluctuation will be enhanced. For example, the ratio of proton ($N(p)$) and triton ($N(t)$) to deuteron ($N(d)$) yields, which is defined as $N(t)$$\cdot$$N(p)$/$N^2(d)$, could be used as a sensitive observable to search for the signature of the 1st order phase transition and/or QCD critical point in heavy-ion collisions [1][2].

        In this talk, we will present the energy and centrality dependence of (anti-)deuteron and triton production in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 7.7, 11.5, 14.5, 19.6, 27, 39, 54.4, 62.4, and 200 GeV measured by the STAR experiment at RHIC. Especially, the new results from 14.5, 27, and 54.4 GeV high statistics data allow us to examine the previously observed hint of a non-monotonic behavior in the neutron density fluctuations around 20 GeV with much better precision. Further, we will show the beam energy dependence for the coalescence parameter $B_2(d)$ and $B_3(t)$, particle ratios ($d/p$, $t/p$, and $t/d$), and the yield ratio of $N(t)$$\cdot$$N(p)$/$N^2(d)$. Their physics implications on QCD critical point search and change of equation of state will be discussed.

        [1] K. J. Sun et al., Phys. Lett. B 774 (2017) 103.
        [2] K. J. Sun et al., Phys. Lett. B 781 (2018) 499.

        Speaker: Dingwei Zhang for the STAR Collaboration (Central China Normal University (CCNU))
      • 09:20
        Relativistic dynamics of fluctuations away and near the QCD critical point 20m

        To describe dynamics of bulk and fluctuations near the QCD critical point we develop general relativistic fluctuation formalism for a fluid carrying baryon charge. Feedback of fluctuations modifies hydrodynamic coefficients including bulk viscosity and conductivity. We perform necessary UV renormalization to obtain cutoff independent deterministic equations suitable for numerical implementation. Focusing on the critical mode we show how this general formalism matches existing Hydro+ description of fluctuations near the QCD critical point and nontrivially extends it inside and outside of the critical region.

        Speaker: Xin An
      • 09:40
        Understanding the out-of-equilibrium dynamics near a critical point via a Hydro+ simulation 20m

        Upcoming experimental programs, like the Beam Energy Scan at RHIC, will look for signatures of a possible critical point in the QCD phase diagram in fluctuation observables. To understand and predict these signatures, one must account for the fact that the dynamics of any critical fluctuations must be out-of-equilibrium: because of critical slowing down, the fluctuations cannot stay in equilibrium as the droplet of QGP produced in a collision expands and cools. Furthermore, their out-of-equilibrium dynamics must also influence the hydrodynamic evolution of the cooling droplet. The recently developed Hydro+ formalism allows for a consistent description of both the hydrodynamics and the out-of-equilibrium fluctuations, including the feedback between them. We shall provide the first demonstration of how this works, setting up a Hydro+ simulation in a simplified setting: a rapidity-independent fireball undergoing radial flow with an equation of state in which we imagine a critical point close to the μB = 0 axis of the phase diagram. Within this setup, we show that we can quantitatively capture non-equilibrium phenomena, including critical fluctuations over a range of scales and memory effects. Furthermore, we show the interplay between the dynamics of the fluctuations and the hydrodynamic flow of the fireball: as the fluid cools and flows, the dynamical fluctuations lag relative to how they would evolve if they stayed in equilibrium; there is then a backreaction on the flow itself due to the out-of-equilibrium fluctuations; and, in addition, the radial flow transports fluctuations outwards by advection.

        Speaker: Yi Yin (MIT)
      • 10:00
        The QCD phase diagram and statistics friendly distributions 20m

        We demonstrate that the bimodal proton multiplicity distribution, possibly present close to the QCD first order phase transition (or the QCD critical point), reproduces the preliminary data for the proton cumulants measured by the STAR collaboration at 7.7 GeV very well. This model then predicts very large values for the fifth, sixth and higher order factorial cumulants. We argue that the bimodal distribution is statistics friendly and can be successfully measured in terms of the factorial cumulants of surprisingly high orders with a relatively small number of events.

        Speaker: Volker Koch (LBNL)
      • 10:20
        Exploring dense baryonic matter and multi-strangeness at J-PARC Heavy-Ion Project 20m

        J-PARC is one of the world’s highest-intensity proton accelerators for material and life sciences, neutrino physics, and hadron and nuclear physics. By acceleration of heavy-ion beams, J-PARC could also become a high-intensity frontier heavy-ion beam facility. For heavy-ion acceleration, we will build a new compact heavy-ion linac and a booster ring as an injector, while we utilize the existing RCS and MR synchrotrons to accelerate $10^{11}$ Hz heavy-ion beams at 1-12 AGeV/c. We aim at exploring phase structures of the QCD phase diagram in a high baryon density regime such as the first-order phase boundary and the QCD critical point, and also at searching for various multi-strangeness particles/nuclei and studying hadron interactions. We are developing the design for a large acceptance spectrometer based on a large dipole magnet. In this presentation, physics feasibility such as flow and hypernuclear measurements will be shown. We will show a plan to transport heavy-ion beams in the primary proton beam line at Hadron Experimental Facility, and an upgrade plan to study heavy-ion collisions at J-PARC E16, which will start in early 2020 to study dielectron spectra in p+A collisions.

        Speaker: Hiroyuki Sako for the J_PARC-HI Collaboration (Japan Atomic Energy Agency)
    • 10:40 11:00
      Coffee Break 20m
    • 11:00 12:40
      Parallel Session - Chirality II Ball Room 3

      Ball Room 3

      Wanda Reign Wuhan Hotel

      Convener: Dmitri Kharzeev
      • 11:00
        Spin alignment measurements of vector mesons with ALICE at the LHC 20m

        In the presence of the large initial angular momentum occurring in non-central heavy-ion collisions, vector mesons can be polarized due to spin-orbital-angular-momentum interaction or they can be polarized during the hadronization process from polarized quarks. Experimentally, this phenomenon can be studied by measuring the angular distribution of the decay daughters of vector mesons with respect to a quantization axis in the rest frame of vector meson. This quantization axis can be the normal to the production plane (defined by the momentum of vector meson and the beam axis) or normal to the reaction plane (defined by the impact parameter and the beam axis) of the system. The study of the angular distribution leads to the estimation of the spin density matrix element $\rho_{00}$. A significant deviation of the value of $\rho_{00}$ from 1/3, which causes a non-uniform angular distribution, would indicate the presence of spin alignment.

        We will present recent measurements of spin alignment for K$^{*}(892)^{0}$ and $\phi(1020)$ mesons at mid-rapidity in Pb-Pb and pp collisions with the ALICE detector. The transverse momentum, centrality and energy dependence of $\rho_{00}$ will be shown. The results will be discussed together with those obtained for the K$_{\rm S}^{0}$ scalar meson and obtained with respect to the random orientations of the production and event planes.

        Speaker: Sourav Kundu for the ALICE Collaboration (National Institute of Science Education and Research (IN))
      • 11:20
        Measurement of global spin alignment of $K^{*0}$, $K^{*\pm}$ and $\phi$ vector mesons using the STAR detector at RHIC 20m

        Measurements of the polarization of the particles produced in relativistic heavy-ion collisions can provide insights into the initial conditions and evolution of the strongly interacting system during a collision. The global spin alignment is quantified by the diagonal spin density matrix element ($\rho_{00}$) with respect to the quantization axis, i.e. normal to the reaction plane. In non-central heavy-ion collisions, a large initial global angular momentum is expected to be present. This can induce a non-vanishing polarization for hadrons with non-zero spin reflecting the dynamics of the medium. Furthermore, since the magnetic moment of charged and neutral $K^{*}$ mesons differ by about a factor of seven, the comparison of their $\rho_{00}$ may offer an additional insight into the rotation of the fireball.

        We will present transverse momentum ($p_{T}$) and collision centrality dependence of $\rho_{00}$ of $K^{*0} (d\bar{s})$, $\overline{K}^{*0}(\bar{d}s)$, $K^{*+} (u\bar{s})$, $K^{*-}(\bar{u}s)$ and $\phi (s\bar{s})$ vector mesons in Au + Au collisions at $\sqrt{s_{\rm NN}}$ = 27, 54.4 and 200~GeV using high statistics data sets collected by the STAR experiment at RHIC. The improved precision relative to previous results allows us to perform the first detailed study of the centrality and $p_{T}$ dependence of the $\rho_{00}$ at these three energies. The $\rho_{00}$ results of the $K^{*0}$ and $\phi$ mesons will be compared with the earlier data from RHIC and LHC energies. Physics implication of our results to the vorticity of the medium will also be discussed.

        Speaker: Subhash Singha for the STAR Collaboration (Kent State University)
      • 11:40
        Local spin polarization in high energy heavy ion collisions 20m

        We revisit the azimuthal angle dependence of the local spin polarization of hyperons in heavy-ion collisions at 200 GeV in the framework of the (3+1)D viscous hydrodynamic model CLVisc. Two different initial conditions are considered in our simulation: the optical Glauber initial condition without initial orbital angular momentum and the AMPT initial condition with an initial orbital angular momentum. We find that the azimuthal angle dependence of the hyperon polarization strongly depends on the choice of the so-called 'spin chemical potential'. If it is chosen to be proportional to the temperature vorticity, our simulation shows qualitatively coincidental results with the recent measurements at RHIC for both the longitudinal and transverse polarization. We argue that such a coincidence may be related to the fact that the temperature vorticity is approximately conserved in the hot quark-gluon matter.

        Speaker: Qun Wang (University of Science and Technology of China)
      • 12:00
        Does spin tensor play a role in relativistic hydrodynamics ? 20m

        Mostly based on: F. Becattini, W. Florkowski, Phys. Lett. B 789 (2019) 419-425

        The search for and the recent evidence of polarization in relativistic heavy
        ion collisions has raised fundamental questions about the most general theoretical
        description of a relativistic polarizable neutral medium and especially about
        the role of the spin tensor in relativistic hydrodynamics. The so-called pseudo-
        gauge invariance under transformations of the stress-energy and spin tensors
        prescribes that all final state measurements should be independent of the particular
        tensor operators chosen to describe the relativistic fluid. In this talk, I will
        review the subject and discuss the fundamental definitions of local equilibrium,
        spin potential and polarization in a Quantum Field Theory framework. As the local
        equilibrium density operator turns out not to be pseudo-gauge invariant, I will
        discuss the phenomenological consequences for polarization.

        Speaker: Francesco Becattini (University of Florence, Italy)
      • 12:20
        Toward a microscopic description for polarization in particle scatterings 20m

        We propose a microscopic description for the polarization from the first principle through the spin-orbit coupling in particle collisions. The model is different from previous ones based on local equilibrium assumptions for the spin degree of freedom. It is based on scatterings of particles as wave packets, an effective method to deal with particle scatterings at specified impact parameters. The polarization is then the consequence of particle collisions in a non-equilibrium state of spins. The spin-vorticity coupling naturally emerges from the spin-orbit one encoded in polarized scattering amplitudes of collisional integrals when one assumes local equilibrium in momentum but not in spin.

        Speaker: Jun-jie Zhang (University of Science and Technology of China)
    • 11:00 12:40
      Parallel Session - Jet Modification III Ball Room 2

      Ball Room 2

      Wanda Reign Wuhan Hotel

      Convener: Magdalena Djordjevic (Institute of Physics Belgrade)
      • 11:00
        Measurement of jet structure and substructure in heavy ion collisions with ATLAS 20m

        Studies of jet structure in heavy-ion collisions can provide information about the mechanism of jet quenching in the hot and dense QCD medium created in these collisions and about its properties over a range of distance scales. This talk presents the latest ATLAS measurement of the internal structure of jets to shed more light on the modification of the parton showering process in the presence of the medium. A measurement of the angular distribution of charged particles around the jet axis in Pb+Pb and $pp$ collisions at $\sqrt{s_{NN}} = 5.02$~TeV is presented. The measurement is performed for jets with radius parameter $R = 0.4$ and is extended outside the jet cone to a radial distance of 0.8 in intervals of charged particle and jet transverse momentum. The talk also presents studies of fragmentation functions and distributions of transverse momentum of charged particles inside a jet.
        Furthermore, a new measurement of how the suppression of large-radius jets depends on the internal jet structure is presented. This measurement brings new information about the evolution of the parton shower in the medium and tests the sensitivity of the jet quenching to color coherence effects.

        Speaker: Martin Rybar for the ATLAS Collaboration (Columbia University (US))
      • 11:20
        Mapping the redistribution of jet energy in PbPb collisions using jets with various radius parameters with CMS 20m

        Measurements of jets produced in collisions of heavy ions, such as dijet asymmetry, boson-jet momentum imbalance, and inclusive jet spectra, have consistently indicated final states of less energy as compared to pp collisions. This energy loss is interpreted as a signature of the quark-gluon plasma. Subsequent studies have shown that the energy lost by jets is redistributed to large angle and in multiplicities of softer particles. In this talk, we report on the CMS results on jet energy redistribution using PbPb data at a nucleon-nucleon center-of-mass energy of $\sqrt{s_\mathrm{NN}} = 5.02 TeV$, including new results on radial scans of anti-$k_\mathrm{t}$ jet spectra with resolution parameter R from 0.2 to 1.0. These measurements are complementary to jet substructure measurements, which will also be discussed in this talk. These results can distinguish between mechanisms of parton-medium interaction as encoded in various Monte Carlo event generators and provide insight into the medium response.

        Speaker: Molly Taylor for the CMS Collaboration (Massachusetts Inst. of Technology (US))
      • 11:40
        Jet quenching and acoplanarity via hadron+jet measurements in pp and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV with ALICE 20m

        We present measurements of the semi-inclusive distribution of charged jets recoiling from a trigger hadron in pp and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV. This
        technique provides precise, data-driven suppression of the large uncorrelated background in such measurements. It uniquely enables the exploration of medium-induced modification of jet production and acoplanarity over wide phase space, including low $p_\mathrm{T}$ for large jet resolution parameter $R$. This talk will report measurements of medium-induced jet energy redistribution through the comparison of trigger-normalized recoil jet yields
        in different centrality intervals and in pp reference collisions, and of jets with different $R$. Medium-induced jet deflection may also occur, with multiple soft scatterings broadening
        the overall azimuthal correlation, and possible Moliere scatterings off quasi-particles in the medium broadening the tail of the correlation with respect to pp collisions. A search
        for these phenemona in Run-1 data using hadron-jet acoplanarity showed no evidence of
        large-angle jet broadening with respect to vacuum expectation within experimental
        uncertainties. However, recent theoretical work has highlighted that low hadron trigger $p_\mathrm{T}$ and low recoiling jet $p_\mathrm{T}$ configurations show more sensitivity to in-medium modifications to the acoplanarity. We present a new measurement of hadron-jet acoplanarity using high-statistics Run-2 data, with emphasis on the region of low recoil jet $p_\mathrm{T}$.

        To study the jet profile, jet-hadron correlations will also be discussed. Jet-hadron correlations are measured in Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV using ALICE data. The radial distribution of charged-hadrons is studied with respect to the jet axis. The associated charged hadron yields and peak widths are extracted from two-dimensional angular correlations as a function of associated hadron transverse momentum and event plane orientation and compared in different centrality intervals. The measurements are also compared to model predictions.

        Speaker: Yaxian Mao for the ALICE Collaboration (Central China Normal University CCNU (CN))
      • 12:00
        Dijet Acoplanarity as a Probe of the Nonperturbative Color Structure of QCD Perfect Fluids with CUJET3 20m

        Using the CUJET3 framework [1], we predict dijet acoplanarity observables using jet-medium couplings that are $\chi^2$ constrained by global RHIC&LHC $R_{AA}$ data, thereby significantly extending our previous work in [2]. We compare the predicted dijet relative azimuthal angle distributions for jets propagating through both perturbative (wQGP/HTL) and nonperturbative (sQGMP) models of the color structure of QCD perfect fluids as described by the VISHNU viscous hydro framework. Our strategy to discriminate between these pictures of the QGP is based on the different parametric dependence of the jet path energy loss functionals, $\Delta E[x[t]] \propto <\hat{q}L^2>$; and the width of the dijet azimuthal angle distribution, which is proportional the transverse saturation squared path functional, $Q_s^2[x[t]] \propto <\hat{q}L>$. By constraining $\Delta E[x[t]]$ using inclusive hadron and jet suppression data, the medium-induced dijet acoplanarity is predicted by CUJET3 to be approximately twice as large in sQGMP than in wQGP. Future trigger+jet coincidence measurements at RHIC and LHC will have sufficient precision to resolve this difference on top of the expected large acoplanarity background due to vacuum Sudakov radiation. (refs: [1] S.Shi et al, Chin.Phys. C43 (2019) 044101, [2] M.Gyulassy et al, NPA982(2019)627)

        Speaker: Miklos Gyulassy (CCNU Wuhan, LBNL, Columbia University)
      • 12:20
        Modification of jet substructure in heavy ion collisions as a probe of the resolution length of quark-gluon plasma 20m

        In this work we present an analysis of the role that the quark-gluon plasma resolution length, the minimal distance by which two nearby colored charges in a jet must be separated such that they engage with the plasma independently, plays in the understanding of modifications of jet substructure modification due to interaction with QGP. The shorter the resolution length of QGP is the better the resolving power of this medium. We identify a set of observables that are very sensitive to whether jets are quenched as if they are single energetic colored objects or whether the medium has the ability to resolve the internal structure of the jet instead. Using the hybrid strong/weak coupling model, we find that although the ungroomed jet mass is not suitable for this purpose because it is very sensitive to effects of the particles coming from medium response, groomed observables such as the number of Soft Drop splittings, the momentum sharing fraction, or the groomed mass are particularly well suited to discriminate the degree to which the medium resolves substructure within the jet. In order to find the optimal grooming configuration, we explore different cuts on the Lund plane that allow for a clear identification of the regions of phase space that enhance the difference in jet substructure between vacuum and quenched jets. Comparison with present data seems to disfavor an “infinite resolution length”, which is to say it disfavors the hypothesis that the medium interacts with the jet as if it were a single energetic colored object. Our analysis indicates that as the precision of experimental measurements of jet substructure observables and the control over uncertainties in their calculation improves, it will become possible to use comparisons like this to constrain the value of the resolution length of quark-gluon plasma as well as to see how the substructure of jets is modified via their passage through it.

        Speaker: Daniel Pablos (McGill)
    • 11:00 12:40
      Parallel Session - QCD at finite temperature II HongKong Room

      HongKong Room

      Wanda Reign Wuhan Hotel

      Convener: Masayuki Asakawa (Osaka University)
      • 11:00
        First experimental test of HAL QCD lattice calculations for the multi strange hyperon - nucleon interaction with ALICE 20m

        A precise understanding of the Equation of State of dense objects like neutron stars is limited by the knowledge about the hyperon interaction and the precision of the models describing the latter. Traditionally, meson exchange models are used to describe the hyperon sector and are constrained by the scarce scattering and hypernuclei data, almost exclusively available for $\Lambda$ hyperons. Recently the HAL-QCD collaboration conducted calculations without relying on constraints by data and with quarks and gluons as degrees of freedom. Their results converge for the interactions between heavier $\Xi$ and $\Omega$ hyperons and nucleons and in the p-$\Omega$ system they predict a bound state.
        Femtoscopy measurements in small systems make it possible to map the core of the potential at small distances and are currently the only viable way to provide a sensitive experimental measurement to test the lattice potentials. In this talk, we present the first precise study of the p$\Xi^-$ and p$\Omega^-$ interactions measured in pp collisions at 13 TeV with the ALICE detector. For the first time, clear signatures of the strong attractive interaction can be observed for these particles. The potentials provided by HAL-QCD calculations and meson-exchange are transformed so they can be compared to the measured correlation functions. For the p$\Xi^-$ interaction the HAL-QCD prediction is strongly favoured by the data with respect to the meson-exchange model. For the p$\Omega^-$ channel, strongly bound systems are excluded and the comparison between data and calculations leaves only room for binding energies below 1 MeV.

        Speaker: Dimitar Lubomirov Mihaylov for the ALICE Collaboration (Technische Universitaet Muenchen (DE))
      • 11:20
        Chemical freeze-out parameters of net-kaons in heavy-ion collisions 20m

        We calculate the mean-over-variance ratio of the net-kaon fluctuations in the Hadron Resonance Gas (HRG) model for the five highest energies of the RHIC Beam Energy Scan (BES) for different particle data lists. We compare these results with the most recent experimental data from the STAR collaboration in order to extract sets of chemical freeze-out parameters for each list. We focused on particle lists which differ largely in the number of resonant states. By doing so, our analysis determines the effect of the amount of resonances included in the HRG model on the freeze-out conditions. In view of the future $\Lambda$ fluctuation measurements, we predict the $\Lambda$ variance over mean and skewness times variance at the light and strange chemical freeze-out parameters. We observe that the $\Lambda$ fluctuations are sensitive to the difference in the freeze-out temperatures established in this analysis. Our findings have a potential impact on various other models in the field of relativistic heavy ion collisions.

        Speaker: Jamie Stafford (University of Houston)
      • 11:40
        Strangeness production in $\sqrt{s_{\rm{NN}}}$ = 54.4, 27 GeV Au+Au collisions and fixed-target program at STAR 20m

        Strangeness (especially the multi-strangeness) production has been suggested as a sensitive probe to the early dynamics of the deconfined matter created in heavy ion collisions. The ratios of particle yields involving strange particles are often utilized to study various properties of nuclear matter, such as the strangeness chemical potential and the chemical freeze-out temperature. The yield ratios $(N_{K}N_{\Xi})/(N_{\phi}N_{\Lambda})$ and $(N_{K}N_{\Omega})/(N_{\phi}N_{\Xi})$ are suggested in [1] to be sensitive to strange quark density fluctuations. Studying these ratios as a function of collision energy may provide a unique probe to the fluctuation of strange quark densities during the phase transition from the QGP to hadronic matter. Furthermore, the STAR fixed-target program extends the low energy reach from $\sqrt{s_{\rm{NN}}}$ = 7.7 GeV to 3.0 GeV, corresponding to baryon chemical potential from 420 MeV to about 700 MeV. The comparison between the asymmetric system (Al+Au) and symmetric system (Au+Au) at almost equal number of participating nucleons from most central to mid-central collisions provides useful information on nucleon stopping, which is key to understanding the baryon chemical potential. Moreover, in the asymmetric Al+Au system, the peaks of the rapidity density distributions ($dN/dy$) are not aligned with the nucleon-nucleon center-of-mass rapidity. The magnitude of the peak shift varies with particle species and also with centrality and can serve as a measure of the baryon stopping.

        In this talk, we will present new measurements of mid-rapidity $K^0_{S}$, $\Lambda$, $\Xi$ and $\Omega$ from Au+Au collisions at $\sqrt{s_{\rm{NN}}}$ = 54.4 and 27 GeV. We will report their spectra, nuclear modification factors and particle ratios compared with thermal calculations. The identified and strange particle distributions in Al+Au at $\sqrt{s_{\rm{NN}}}$ = 4.9 GeV and Au+Au collisions at $\sqrt{s_{\rm{NN}}}$ = 3.0 GeV from the STAR fixed-target program will also be presented. These fixed-target results include the transverse mass spectra, rapidity density distributions, particle ratios and centrality dependence of charged and strange hadrons. The physics implications on the collision dynamics will be discussed.

        [1] Che Ming Ko, EPJ Web of Conferences 171 (2018) 03002.

        Speaker: Muhammad Usman Ashraf for the STAR Collaboration (Central China Normal University / Tsinghua University)
      • 12:00
        Equation of state for hot QCD and compact stars from a mean field approach 20m

        The thermodynamic properties of high temperature and high density QCD-matter are explored within the Chiral SU(3)-flavor parity-doublet Polyakov-loop quark-hadron mean-field model, CMF. The applications of the CMF model to the lattice QCD data, heavy-ions physics, and static neutron stars are presented. In the CMF-model the transition between hadron-dominated and quark-dominated regimes is performed according to the lattice QCD data at zero net-baryon density. At low temperatures the CMF model reproduces known properties of nuclear matter while quarks become dominant at densities $\approx 7$ times nuclear saturation density. In the scope of the lattice QCD data the CMF model predictions for lines of constant physics as well as the baryon number susceptibilities are discussed. The calculated skewness and kurtosis predict three consecutive transitions in phase diagram, the nuclear first-order liquid-vapor phase transition, chiral symmetry restoration, and the cross-over transition to pure quark matter. The deviations from the free ideal hadron gas baseline at $\mu_B=0$ and $T\approx 100-200$ MeV can be attributed to remnants of the first order phase transition in the nuclear matter. The chiral crossing transition and cross-over to quark matter determine the baryon fluctuations at much higher $\mu_B$. The trajectories of heavy-ion collisions along the phase diagram are calculated. The CMF model also describe well the static properties of neutron stars in agreement with data extracted from GW170817 neutron star merger event.

        [1] A. Motornenko, J. Steinheimer, V. Vovchenko, S. Schramm and H. Stoecker, arXiv:1905.00866 [hep-ph]

        Speaker: Anton Motornenko (Frankfurt Institute for Advanced Studies)
      • 12:20
        Towards a reliable lower limit on the location of the critical endpoint 20m

        There have been various attempts to give lower limits on the location of the QCD critical endpoint via lattice simulations. These mostly rely on expanding the pressure in a Taylor series near zero chemical potential, and use estimators for the radius of convergence, mostly the ratio estimator. If the radius of convergence can be found, it gives a lower limit on the location of a true phase transition. I will give an analytic argument that shows that the ratio estimator will not converge in the generic case and explain how to obtain improved estimators with guaranteed and faster convergence, as was described in Phys. Rev. D 99, 114510.
        As a next step in this research program, we calculate these estimators for the case of Nf=2+1 flavour QCD with physical quark masses, using a stout improved staggered action, two different lattice spacings, and several volumes. On the roughest lattice spacing, we perform a full finite volume scaling study of the radius of convergence of the Taylor series. We also compare with results using an alternative algorithm that directly looks for the closest singularity of the free energy in the complex chemical potential plane, without relying on Taylor expansion coefficients.

        Speaker: Attila Pasztor (Eotvos University)
    • 11:00 12:40
      Parallel Session - Small systems III Ball Room 1

      Ball Room 1

      Wanda Reign Wuhan Hotel

      Convener: Norbert Herrmann (Univ. Heidelberg)
      • 11:00
        Constraining the production mechanism of light (anti-)nuclei in small systems with ALICE at the LHC 20m

        The large samples of high-quality data taken in pp collisions at $\sqrt{s} = 5$, 7 and 13 TeV and in p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV at the LHC with the ALICE detector allows a systematic study of light (anti-)nuclei production to be performed in these collision systems. The excellent performance of the Inner Tracking System, Time-Projection Chamber and Time-Of-Flight detectors provide a clear identification and separation of primary produced light (anti-)nuclei from secondaries. Additionally, the high-energy deposit of Z=2 particles in the Transition Radiation Detector has been exploited to collect a hardware-triggered data sample in the high-interaction rate pp collision at $\sqrt{s} = 13$ TeV and p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 8.16 TeV. New results on deuteron production as a function of multiplicity in pp and p-Pb collisions will be presented, as well as the measurement of $^{3}$He in (triggered) p-Pb collisions. The goal is to study whether (anti-)nuclei production in small systems is better described by the coalescence model or by the statistical hadronisation model. The coalescence parameter $B_{A}$ is studied as a function of transverse momentum in the different systems and as a function of the event multiplicity. In addition, the measurement of the (anti-)deuteron production in jets will be presented and compared with theoretical models.

        Speaker: Luca Barioglio for the ALICE Collaboration (Universita e INFN Torino (IT))
      • 11:20
        Including momentum and stress in a systematic framework for understanding the evolution of a heavy-ion collision 20m

        The evolution of a heavy-ion collision is typically understood as a process that transmutes the initial geometry of the system into the final momentum distribution of observed hadrons, which can be described via a cumulant expansion of the initial distribution of energy density and is represented at leading order as the well-known eccentricity scaling of anisotropic flow.

        We extend this framework to include the contribution from initial momentum-space properties, as encoded in other components of the energy-momentum tensor. We confirm the validity of the framework in state-of-the-art hydrodynamic simulations of large and small systems. With this new framework, it is possible to separate the effects of early-time dynamics from those of final-state evolution, even in the case when the distribution of energy does not fully determine subsequent evolution, as expected in small systems.

        Specifically, we answer the question of when and how azimuthal correlations from the initial state survive to the final state. Additionally, this framework elucidates the generic features of the system evolution that are responsible for the impressive success of hydrodynamic simulations, but which may still hold even in cases when hydrodynamics is not applicable.

        Speaker: Matthew Luzum
      • 11:40
        Light flavour hadron production vs. multiplicity in pp and in p-Pb collisions with ALICE 20m

        The study of light flavour (u,d,s) hadron production plays an important role in understanding the dynamics of the strongly-interacting system created in nucleus-nucleus collisions, the
        Quark-Gluon Plasma (QGP). Historically, it has been assumed that no QGP is formed in small collision systems, but this paradigm is challenged by the observation of collective-like behaviour and strangeness enhancement in high-multiplicity pp and p-Pb collisions. Exploiting its optimal particle identification capabilities, the ALICE experiment is able to measure pion, kaon (anti-)proton, strange and multi-strange hadron production in a wide transverse momentum range. We report on the study of the light-flavour hadron production as a function of multiplicity in pp and p-Pb collisions in ALICE, showing results which
        suggest qualitatively similar mechanisms in play in Pb-Pb collisions and high-multiplicity pp or p-Pb ones. These results are compared to statistical hadronisation models and
        Monte Carlo predictions to shed light on the hadron production mechanism in small systems.

        Speaker: Silvia Pisano for the ALICE Collaboration (INFN e Laboratori Nazionali di Frascati (IT))
      • 12:00
        Modification of hadron productions in small systems observed by PHENIX 20m

        Collisions of small systems exhibit evidence of collective behavior through various flow type measurements, which suggests that quark gluon plasma could be produced in these collisions. If so, there could also be evidence for energy loss in the plasma, which would present itself in the spectra of hadrons. PHENIX has studied the nuclear modification factor $R_{AB}$ of various hadron species at central and forward/backward rapidities. We measured $\pi^0$s in the central rapidity region $|eta|<0.35$ in $p$+Au, $d$+Au and $^3$He+Au collisions at 200 GeV. For central collisions, the $R_{AB}$ shows an ordering with collision system size with a pronounced peak in the range $2< p_T <7$ GeV/$c$ in $p$+Au. This peak decreases in magnitude as the projectile size increases. At higher $p_T$, $R_{AB}$ is below unity and converges towards a common value. We observe a similar centrality dependence for all three systems. The $R_{AA}$ of $\phi$ mesons has been measured at forward, backward, and central rapidities in $p$+Au and $^3$He+Au collisions. The implications of the combined results for the role of initial and final state effects will be discussed.

        Speaker: Yuri Mitrankov for the PHENIX Collaboration (St. Petersburg State Technical University)
      • 12:20
        The Angantyr model for heavy ions in Pythia8 20m

        Pythia8 is the only general purpose event generator able to produce
        fully exclusive hadronic final states in collisions involving heavy
        ions. This is done by carefully stacking individual parton-level
        nucleon-nucleon collisions together according to the so-called
        Angantyr model. The sub-events are produced using the full Pythia8
        machinery with initial and final state parton showers and multi-parton
        interactions, and the combined heavy-ion event is hadronised with the
        Lund String Fragmentation model to give a detailed picture of the
        hadronic final state.

        The Angantyr model, which will be described in this talk, includes an
        advanced Glauber model where fluctuations in the nucleon wave function
        are taken into account to characterise the nature of each individual
        nucleon-nucleon collision. This information is then used to steer the
        generation of the corresponding sub-event.

        The model successfully describes general features, such as
        multiplicity and rapidity distributions, in both AA and pA events at
        the LHC and elsewhere. Together with the excellent overall description
        of pp data provided by Pythia8 itself, this gives a perfect platform
        for studying the the transition from small to large systems.

        Currently there are, however, no collective effects included for
        heavy-ion collisions in Pythia8, and the program is mainly used as a
        baseline for investigating eg. non-flow effects on observables
        sensitive to collective effects. However, it can also be used as a
        framework for implementing and testing microscopic models of
        collective behaviour. In this talk we will present preliminary results
        for a few such models, based on extending the Lund Model to include
        interactions between strings.

        Speaker: Leif Lönnblad for the LHCb Collaboration (Lund University (SE))
    • 12:40 14:00
      Lunch Break 1h 20m
    • 14:00 16:00
      Parallel Session - Chirality III Ball Room 1

      Ball Room 1

      Wanda Reign Wuhan Hotel

      Convener: Fuqiang Wang (Purdue University (US))
      • 14:00
        Differential measurements of $\Lambda$ polarization in Au+Au collisions and a search for the magnetic field by STAR 20m

        Lambda polarization $P_{\Lambda/\bar{\Lambda}}$ was measured by the STAR collaboration [1], confirming the existence of extremely large vorticities within the Quark-Gluon Plasma (QGP). A recent study using a high-statistics data set at $\sqrt{s_{NN}} = 200$ GeV has shown the dependence of $P_{\Lambda/\bar{\Lambda}}$ on collision centrality, azimuthal angle ($\varphi$), transverse momentum ($p_T$), pseudorapidity ($\eta$), etcetera [2][3]. Additionally suggested in [1] is an enhanced $P_{\bar{\Lambda}}$ relative to $P_{\Lambda}$ across all beam energies; however, the statistics are too limited to make a significant measurement. No such splitting is observed in the high-statistics $\sqrt{s_{NN}} = 200$ GeV data set, but this splitting is expected to increase at lower beam energies. The splitting in polarization would be consistent with the effects of hyperon magnetic-moment coupling with the magnetic field sustained in the QGP; it would have far-reaching consequences important to magnetic-field-dependent observables such as the chiral magnetic effect and would set the scale on the conductivity of the QGP.

        Recently, STAR has taken high-statistics data sets at $\sqrt{s_{NN}} = 27$ and 54.4 GeV. The 27 GeV data set is considered suitable to study the splitting between $P_{\Lambda}$ and $P_{\bar{\Lambda}}$ since it includes the recently installed Event-Plane Detector (EPD), which significantly increases the event-plane resolution. Both data sets are used to study the splitting between $P_{\Lambda}$ and $P_{\bar{\Lambda}}$ as well as the various differential measurements of $P_{\Lambda/\bar{\Lambda}}$. Implications of these measurements will also be discussed.

        [1] The STAR Collaboration, Global $\Lambda$ hyperon polarization in nuclear collisions, Nature 548 (2017) 62.
        [2] The STAR Collaboration, Global polarization of Lambda hyperons in Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV, Phys. Rev. C 98 (2018) 14910.
        [3] The STAR Collaboration, Polarization of $\Lambda(\bar{\Lambda})$ hyperons along the beam direction in Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV, arXiv:1905.11917.

        Speaker: Joseph Adams for the STAR Collaboration (Ohio State University)
      • 14:20
        Magnetic Field in the Charged Subatomic Swirl 20m

        We suggest a novel link between rotation and magnetic field in a charged fluid system: a magnetic field naturally arises along the fluid vorticity direction from the currents associated with the swirling charges. This general connection is demonstrated both for a single particle and for a fluid vortex. Applying the idea for heavy ion collisions we propose it as a new mechanism for generating long-lived in-medium magnetic fields. We estimate the magnitude of this new magnetic field in the AuAu colliding systems across a wide span of collisional beam energy. Such a magnetic field is found to rapidly increase toward lower beam energy and could account for a significant amount of the experimentally observed global polarization difference between hyperons and anti-hyperons. Its time-integrated effect could make considerable contributions to the Chiral Magnetic Effect. Further predictions are discussed and experimental tests are suggested.

        Speaker: Xingyu Guo (South China Normal Univeristy)
      • 14:40
        Mass Correction to Chiral Kinetic Equations 20m

        We study fermion mass correction to chiral kinetic equations in electromagnetic fields. Different from the chiral limit where fermion number density is the only independent distribution, the number and spin densities are coupled to each other for massive fermion systems. To the first order in ̄h, we derived the quantum correction to the classical on-shell condition and the Boltzmann-type transport equations. To the linear order in the fermion mass, the mass correction does not change the structure of the chiral kinetic equations and behaves like additional collision terms. While the mass correction exists already at classical level in general electromagnetic fields, it is only a first order quantum correction in the study of chiral magnetic effect.

        Speaker: Ziyue Wang (Tsinghua University)
      • 15:00
        Kinetic theory for massive spin-1/2 particles from the Wigner-function formalism 20m

        We calculate the Wigner function for massive spin-1/2 particles in an inhomogeneous electromagnetic field to leading order in the Planck constant. Going beyond leading order in $\hbar$ we then derive a generalized Boltzmann equation in which the force exerted by an inhomogeneous electromagnetic field on the particle dipole moment arises naturally. Furthermore, a kinetic equation for this dipole moment is derived. Carefully taking the massless limit we find agreement with previous results. The case of global equilibrium with rotation is also studied. Finally, we outline the derivation of fluid-dynamical equations from the components of the Wigner function. The conservation of total angular momentum is promoted as an additional fluid-dynamical equation of motion. Our framework can be used to study polarization effects induced by vorticity and magnetic field in relativistic heavy-ion collisions.

        Speaker: Nora Weickgenannt (Goethe University Frankfurt)
      • 15:20
        Hydrodynamics of particles with spin 1/2 20m

        The formulation of relativistic hydrodynamics of particles with spin 1/2 will be shortly reviewed. The proposed framework is based on the Wigner function treated in a semi-classical approximation or, alternatively, on a classical treatment of spin 1/2. The consistency of the two approaches will be demonstrated and first numerical solutions of the obtained scheme will be shown. Several theoretical issues regarding the proper choice of the energy-momentum and spin tensors used to construct the hydro framework with spin will be also discussed.

        The talk will be based mainly on extracts from arXiv:1811.04409 (invited article for Progress in Particle and Nuclear Physics) and arXiv:1901.09655.

        Speaker: Wojciech Florkowski (Institute of nuclear Physics, Krakow)
      • 15:40
        Quantum Kinetic Theory of Spin Polarization of Massive Quarks in Perturbative QCD 20m

        We present the quantum kinetic equation for spin polarization of massive quarks in leading log order of perturbative QCD, which describes time evolution of the spin density matrix in momentum space of a massive quark interacting with a background QCD plasma. We find that the time evolution operator of the spin density matrix, or the quantum kinetic collision terms, are universally of order $\alpha_s^2\log(1/\alpha_s)$ in terms of the QCD coupling constant $\alpha_s=g^2/(4π)$. Our quantum kinetic equation is valid for an arbitrary quark mass $m\gg m_D∼gT$, where $m_D$ is the Debye mass, and can be used to study relaxation dynamics of spin polarization of massive quarks in perturbative QCD regime.

        Speaker: Shiyong Li (University of illinois at chicago)
    • 14:00 16:00
      Parallel Session - Initial state II HongKong Room

      HongKong Room

      Wanda Reign Wuhan Hotel

      Convener: Bolek Wyslouch (Massachusetts Inst. of Technology (US))
      • 14:00
        First observation of diffraction in proton-lead collisions with the CMS detector 20m

        We present the first measurements of diffraction in $\sqrt{s_{NN}}=8.16$ TeV proton-lead collisions within CMS. The very large angular coverage of CMS is used to tag rapidity gaps on both the proton-going and lead-going sides and to identify both pomeron-lead and pomeron-proton topologies. Since the previous highest energy measurement of these processes was at $\sqrt{s_{NN}}=30$ GeV, the current data provides essentially unique information. The rapidity gap distributions are sensitive to the gluon distribution within nuclei but also provide important information for modeling cosmic ray collisions. The results are compared to predictions from the EPOS, QGSJET and HIJING event generators.

        Speaker: Dmitry Sosnov for the CMS Collaboration (NRC Kurchatov Institute PNPI (RU))
      • 14:20
        Adiabatic hydrodynamization in rapidly-expanding quark-gluon plasma 20m

        We propose a new scenario characterizing the transition of the quark-gluon plasma (QGP) produced in heavy-ion collisions from a highly non-equilibrium state at early times toward a fluid described by hydrodynamics at late times. In this scenario, the bulk evolution is governed by a set of slow modes, after an emergent time scale τ_{Redu} when the number of modes that govern the bulk evolution of the system is reduced. These slow modes are "pre-hydrodynamic" in the sense that they are initially distinct from, but evolve continuously into, hydrodynamic modes in hydrodynamic limit. This picture is analogous to the evolution of a quantum mechanical system that is governed by the instantaneous ground states under adiabatic evolution, and will be referred to as "adiabatic hydrodynamization". We shall illustrate adiabatic hydrodynamization using a kinetic description of weakly-coupled Bjorken expanding plasma. We first show the emergence of τRedu due to the longitudinal expansion. We explicitly identify the pre-hydrodynamic modes for a class of collision integrals and find that they represent the angular distribution (in momentum space) of those gluons that carry most of the energy. We use the relaxation time approximation for the collision integral to show quantitatively that the full kinetic theory evolution is indeed dominated by pre-hydrodynamic modes. We elaborate on the criterion for the dominance of pre-hydrodynamic modes and argue that the rapidly-expanding QGP could meet this criterion. Based on this discussion, we speculate that adiabatic hydrodynamization may describe the pre-equilibrium behavior of the QGP produced in heavy-ion collisions.

        Speaker: Jasmine Brewer (Massachusetts Institute of Technology)
      • 14:40
        Prescaling and far-from-equilibrium hydrodynamics in the quark-gluon plasma 20m

        We use the leading-order QCD kinetic equations with quarks and gluons to study the QGP in the far-from-equilibrium state. At weak coupling, we demonstrate the emergence of early hydrodynamic behavior--prescaling--around a nonthermal fixed point, which is qualitatively different from the more conventional hydrodynamics around equilibrium. Prescaling is a far-from-equilibrium phenomenon which describes the rapid establishment of a universal scaling form of distributions much before the universal values of their scaling exponents are realized. The dynamics in the prescaling regime is encoded in a few time-dependent scaling exponents, whose slow evolution gives rise to far-from-equilibrium hydrodynamic description.

        Reference: A. Mazeliauskas and J. Berges, Phys. Rev. Lett. 122, 122301 (2019), arXiv:1810.10554

        Speaker: Aleksas Mazeliauskas
      • 15:00
        Connecting far-from-equilibrium hydrodynamics to resummed transport coefficients and attractor solutions 20m

        We show how far-from-equilibrium hydrodynamics may be systematically defined, for arbitrary flow profiles, in terms of a generalized tensorial expansion with transport coefficients that contain an all order resummation in gradients. In this formulation, the transport coefficients of far-from-equilibrium fluid dynamics depend not only on the microscopic properties of the system but also on the nonlinear properties of the underlying state of the fluid itself. In contrast to previous works, no additional assumptions about the symmetries of the flow are necessary. An example of this proposal is constructed using Israel-Stewart theory and, in this case, the resummed transport coefficients decrease with increasing Knudsen number according to formulas that can be readily investigated in current numerical simulations of the quark-gluon plasma. We check numerically the existence of attractor solutions in simulations of AA and pA collisions. This is particularly important to understand the apparent hydrodynamic behavior observed in small systems where gradients are extremely large and resummation techniques should be employed.

        Speaker: Jorge Noronha (University of Sao Paulo)
      • 15:20
        Initial Condition for Matter in the Fragmentation Region 20m

        The initial conditions for matter produced in the fragmentation region of high
        energy hadronic collisions can be computed using the theory of the Color Glass Condensate. We consider the scattering of a classical color charge from a large nucleus and compute produced radiation in the fragmentation region of the classical color charge. Our results are to all order in the strength of the color field of the nucleus. We compare our results against first order computation in the strength of the nuclear field. We evaluate the transverse momentum dependence in various transverse momentum ranges.

        Speaker: Larry McLerran (INT, University of Washington)
      • 15:40
        Collinear resummation for the non-linear evolution in QCD at high energy 20m

        The next-to-leading order (NLO) Balitsky-Kovchegov (BK) equation describing the high-energy evolution of the scattering between a dilute projectile and a dense target suffers from instabilities unless it is supplemented by a proper resummation of the radiative corrections enhanced by large transverse logarithms. These instabilities are associated with large, anti-collinear, double logarithms which occur when the NLO corrections are computed from the evolution of the dilute projectile. We explain how to rewrite the NLO evolution in terms of the rapidity of the dense target. This avoids the large anti-collinear contributions but introduces new, collinear, instabilities, which are however milder since disfavoured by the typical BK evolution. We propose several prescriptions for resumming these new double logarithms and find only little scheme dependence. The resummed equations are non-local in rapidity and can be extended to full NLO accuracy. We present the first applications of these resummed equations to proton-nucleus collisions at the LHC and deep inelastic scattering at the proposed Electron-Ion Collider.

        Speaker: Edmond Iancu (Université Paris-Saclay (FR))
    • 14:00 16:00
      Parallel Session - Jet modifications IV Ball Room 2

      Ball Room 2

      Wanda Reign Wuhan Hotel

      Convener: Carlos Salgado (Norfolk State University and Jefferson Lab)
      • 14:00
        Heavy-flavour jet production and correlations with ALICE 20m

        Heavy quarks (charm and beauty) are ideal probes to investigate the properties of the Quark-Gluon Plasma (QGP) produced in ultra-relativistic heavy-ion collisions, being produced in hard-parton scatterings in the collision early stages and experiencing the whole QGP evolution.
        Measurements of heavy-flavour jets give a direct access to the initial parton kinematics and can provide constraints to heavy-quark energy-loss models, in particular adding information on how the radiated energy is dissipated in the medium.
        Studies of angular correlations between heavy-flavour particles and charged particles allow us to characterize the heavy-quark fragmentation process and its possible modification in a hot nuclear matter environment.

        Measurements in pp collisions provide the necessary reference for the interpretation of heavy-ion collision results, allowing us to characterise the heavy-quark production and fragmentation in vacuum.
        Studies in p--Pb collisions give insight on how the heavy-quark production and hadronisation into jets are affected by the cold nuclear matter effects.

        This contribution will focus on the latest studies of heavy-flavour jets and D-meson correlations with charged particles with the ALICE detector.
        Measurements of azimuthal D meson-charged particle correlations, jets tagged with D mesons and jet-momentum fraction carried by the D meson will be presented in pp collisions at $\sqrt{s} = 5.02$, $7$ and $13$ TeV and compared with expectations from various Monte Carlo event generators.
        Production of heavy-flavour jets in pp collisions at $\sqrt{s} = 5.02$ TeV will be also addressed with studies of charged jets tagged by heavy-flavour hadron decay electrons and beauty secondary vertices.
        The nuclear modification factor in p--Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV of the aforementioned heavy-flavour tagged jets will be also presented and complemented with measurement of the D-tagged jet nuclear modification factor in Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV.

        Speaker: Jakub Kvapil for the ALICE Collaboration (University of Birmingham (GB))
      • 14:20
        Parton modification and medium response studies using EW-boson-tagged jets and hadrons with pp and PbPb collisions at 5.02 TeV with the CMS detector 20m

        Photons and Z boson can be used to constrain the kinematics, as well as the flavor, of the recoiling parton, before its interaction with the quark-gluon plasma. While photons are more abundant, they suffer from larger systematic uncertainties, particularly at low $p_\mathrm{T}$, from the background photons from neutral meson decays. Tagging with Z bosons is a complementary way to study modifications of low $p_\mathrm{T}$ partons as well as the soft particles from the medium response. The talk will present studies of kinematics correlations between Z bosons and charged particles, photon-tagged jet fragmentation functions and the jet shapes in pp and PbPb collisions at $\sqrt{s_\mathrm{NN}} = 5.02\,\mathrm{TeV}$ using data collected with the CMS detector.

        Speaker: Ran Bi (Massachusetts Inst. of Technology (US))
      • 14:40
        Measurements of electroweak boson tagged jet energy loss and modification by ATLAS 20m

        Measurements of reconstructed jets produced in conjunction with a high-$p_\mathrm{T}$ electroweak boson (photon or Z) offer a discerning way to study the quark gluon plasma (QGP) created in ultrarelativistic nucleus-nucleus collisions. The high-$p_\mathrm{T}$ boson tags the initial energy, direction, and flavor of the opposing parton or partons before they begin to shower and propagate through the QGP, offering a valuable handle for understanding the mechanism of parton energy loss. ATLAS has previously reported measurements in 2015 Pb+Pb data of the photon plus inclusive jet $p_{T}$ balance, and the photon-tagged jet fragmentation functions. The significantly larger luminosity of 2018 Pb+Pb data delivered by the LHC, as well as improvements to the photon, electron, and jet reconstruction in heavy ion events with the ATLAS detector, have enabled qualitatively new measurements in these channels, including the first Z-tagged measurements. This talk will present new results on the energy loss and modification of jets created in coincidence with a high-$p_\mathrm{T}$ photon or Z boson in Pb+Pb collisions.

        Speaker: Dennis Perepelitsa (University of Colorado Boulder)
      • 15:00
        Observation of top quark pair production in nucleus-nucleus collisions with the CMS detector 20m

        The high energies available at the CERN LHC have opened up the possibility to measure various large-mass elementary particles for the first time in heavy ion collisions. The first observation of top quark pair ($\mathrm{t\bar{t}}$) production is reported using lead-lead collisions recorded in 2018 by the CMS experiment at a nucleon-nucleon center-of-mass energy of $\sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = 5.02\,\mathrm{TeV}$. The data sample corresponds to an integrated luminosity of about $1.7\,\mathrm{nb^{-1}}$. Dilepton events ( $\mathrm{e}^\pm \mu^\mp$, $\mu^\pm \mu^\mp$, and $\mathrm{e}^\pm \mathrm{e}^\mp$ ) are selected, and the inclusive cross section ($\sigma_\mathrm{t\bar{t}}$) is measured from a likelihood fit to a multivariate discriminator using lepton kinematic variables. The $\sigma_{\mathrm{t\bar{t}}}$ measurement is additionally performed in categories defined using the multiplicity of jets and b-tagged jets, which improve the sensitivity to the $\mathrm{t\bar{t}}$ signal process. Top quark production in heavy ion collisions is a novel tool for probing the nuclear parton distribution functions, the mechanisms of parton energy loss, and the medium opacity at different space-time scales.

        Speaker: Georgios Krintiras for the CMS Collaboration (The University of Kansas (US))
      • 15:20
        Deciphering the $z_g$ distribution in ultrarelativistic heavy ion collisions 20m

        Within perturbative QCD, we develop a new picture for the parton shower generated by a jet propagating through a dense quark-gluon plasma. In this picture, the vacuum-like parton branchings, as triggered by the parton virtualities, are factorized in time from the medium-induced emissions responsible for the energy loss by the jet. We implement this picture in a Monte Carlo generator that we use to study two phenomenologically important observables: the jet nuclear modification factor $R_{AA}$ and the $z_g$ distribution reflecting the jet substructure. In both cases, the outcome of our Monte Carlo simulations is in good agreement with the LHC measurements. We find that the energy loss by the jet is increasing with the jet transverse momentum, due to a rise in the number of partonic sources via vacuum-like emissions. This is a key element in our description of both $R_{AA}$ and $z_g$. For the latter, we identify two main nuclear effects: incoherent jet energy loss and hard medium-induced emissions. As the jet transverse momentum increases, we predict a qualitative change in the ratio between the $z_g$ distributions in PbPb and pp collisions: from increasing at small $z_g$, this ratio becomes slightly decreasing.

        Speaker: Paul Caucal (IPhT)
      • 15:40
        The problem of overlapping formation times: In-medium virtual corrections 20m

        High energy particles traversing through medium primarily
        lose energy by showering through hard bremsstrahlung and pair production. These splitting
        processes are coherent over large distances in the very high energy limit, leading to suppression
        from the Landau-Pomeranchuk-Migdal (LPM) effect. Avoiding soft-emission approximations,
        we study the cases where the coherence lengths of two consecutive splittings overlap (which is
        important for calculating corrections to LPM effect in QCD). In this work, we will show how to compute in-medium virtual corrections to the leading order LPM emission rates for QCD. These loop corrections will be necessary for calculating properties of in-medium high energy parton showers. To simplify the calculations, we will focus on the all-gluon case and work in the large-Nc limit of QCD, where Nc is the number of colors.

        Speaker: Shahin Iqbal (Central China Normal University)
    • 14:00 16:00
      Parallel Session - Small systems IV Ball Room 3

      Ball Room 3

      Wanda Reign Wuhan Hotel

      Convener: Jiangyong Jia (Stony brook Universty (US))
      • 14:00
        Small system scan within a combined color glass condensate and hydrodynamic model 20m

        We present results for azimuthal anisotropies in p+p, p+Au, d+Au, and 3He+Au collisions at 200 GeV center of mass energy, using a hybrid IP-Glasma + MUSIC + UrQMD model, which is fully constrained by experimental data on Au+Au collisions. We compare to experimental data for $v_n(p_T)$, $c_2\{4\}$, and $C_{112}$ from the PHENIX and STAR Collaborations. We discuss the role of initial state momentum anisotropies and the shear stress tensor from the color glass condensate effective theory, which are included in the energy momentum tensor provided by the IP-Glasma model as initial condition for the hydrodynamic simulation. We find that the systematic ordering of the magnitude of elliptic and triangular momentum anisotropies between different small systems requires the presence of final state effects. We further study the time evolution of the momentum ansiotropy and the correlation between the orientation of the spatial geometry and the momentum flow, which reveals qualitative differences between large and small systems. We also present results from the same framework for multi-particle cumulants in Pb+Pb and p+Pb collisions at LHC energies, as well as predictions for O+O collisions at both RHIC and LHC energies.

        Speaker: Bjoern Schenke (Brookhaven National Lab)
      • 14:20
        Flow in collisions of light nuclei 20m

        We explore features of harmonic flow in ultra-relativistic collisions involving light nuclei. For the light-light nuclear collisions, such as 16O-16O reaction considered for the upcoming experimental program at RHIC and the LHC, we make definite predictions based on ratios of cumulants. We also point out very interesting aspects of the light-heavy collisions, where the light nucleus is clustered, thus carries intrinsic deformation. There has been a quest for alpha clustering in nuclei over the last 80 years, but evidence at low energies has usually been rather indirect through theoretical studies of binding energies and nuclear sizes. We present here direct experimental signatures of clusterization of light nuclei in ultra-relativistic collisions of 7,9Be, 12C, and 16O on heavy nuclei. Clustering leads to very specific spatial correlations of the nucleon distributions in the ground state of the light nucleus and in the formed fireball, which via collective evolution become manifest in the harmonic flow coefficients of the produced hadron distributions [1-3]. In particular, the elliptic flow is sensitive to clusterization in 7,9Be, and the triangular flow to clusterization in 12C and 16O.

        1. Wojciech Broniowski, Enrique Ruiz Arriola, Phys.Rev.Lett. 112 (2014) 112501
        2. Piotr Bozek, Wojciech Broniowski, Enrique Ruiz Arriola, Maciej Rybczynski, Phys.Rev. C90 (2014) 064902
        3. Maciej Rybczynski, Milena Piotrowska, Wojciech Broniowski, Phys.Rev. C97 (2018) 034912
        Speaker: Wojciech Broniowski (IFJ PAN)
      • 14:40
        Collectivity in novel geometric configurations of proton-proton collisions and in photo-nuclear collisions with ATLAS 20m

        Measurements of two-particle correlations in $pp$ collisions have demonstrated long-range azimuthal correlations between charged particle pairs, commonly interpreted as arising from a single particle azimuthal anisotropy. To better illuminate the origin and nature of these collective signatures, ATLAS presents studies in proton-proton collisions with a novel handle on event geometry, and in photo-nuclear collisions. In proton-proton collisions, the impact-parameter dependence of these correlations are studied in events containing a Z-boson, which acts as an independent handle on the impact parameter. This talk presents updated measurements of the azimuthal anisotropy in such Z-tagged $pp$ collisions at 8 and 13 TeV. The measurements include studies of the $p_{T}$, event-multiplicity, and collision energy dependence of the anisotropy as well as their comparisons to the inclusive $pp$ collisions. In addition, two-particle correlations are presented in a qualitatively new collision system of ultra-peripheral Pb+Pb collisions. Even if the passing nuclei are well-separated and do not interact hadronically in these collisions, a quasi-real photon from the EM field of one nucleus can interact with the other nucleus. The photons may reach energies up to 80 GeV and readily fluctuate into vector meson configurations. Thus these photo-nuclear collisions may proceed as rho-nucleus collisions albeit at a significantly lower collision energy than the equivalent nucleon-nucleon energy. This talk presents new measurements of two-particle correlations and characterizes particle production in photo-nuclear collisions, which have multiplicities significantly smaller than $pp$ collisions and center of mass energies between those available at RHIC and the LHC.

        Speaker: Brian Cole for the ATLAS Collaboration (Columbia University (US))
      • 15:00
        Measurement of long-range two- and multi-particle correlations by ALICE 20m

        Measurements of long-range two- and multi-particle correlations have long provided critical insights into the properties of the strong coupled matter created in heavy-ion collisions. They have also provided hints that a shorty lived QGP may exist in smaller systems. We will present new results on long-range two-particle correlations for different charged particles multiplicities in pp at $\sqrt{s} = 13~\rm{TeV}$ and in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02~\rm{TeV}$. These measurements utilize the the Forward Multiplicity Detector (FMD), which allows for unprecedented $\Delta\eta$ ranges to be explored (up to $\Delta\eta ~\sim 8$). We will compare such measurements to predictions from Monte Carlo generators, which helps us to understand the contribution from non QGP like processes in an unexplored kinematic regime. We will also present the first measurements of the $\eta$ dependence of two- and multi-particle cumulants in Pb-Pb 5.02 TeV collisions. These provide key constraints to the temperature dependence of $\eta/s$, and by comparing to AMPT, will provide the most precise information yet on the 3D evolution of the hot and dense matter created in heavy-ion collisions.

        Speaker: Yuko Sekiguchi for the ALICE Collaboration (University of Tokyo (JP))
      • 15:20
        Unified description from small to large colliding systems within dynamical core--corona initialization 20m

        We investigate whether the quark gluon plasma (QGP) is created in small colliding systems through the analysis of strangeness enhancement using the dynamical core--corona initialization model [1].

        The yield ratios of (multi-)strange hadrons to charged pions in various colliding systems exhibit monotonic increase and scale with multiplicity at the LHC energies [2]. Motivated by these data, we develop a unified and a phenomenological description of the QGP formation based on the dynamical initialization model [3].

        First we obtain the initially produced partons using PYTHIA8 on an event-by-event basis. From these initial partons, we generate initial conditions of QGP fluids as a dynamical process. Here we assume the core--corona picture: Local equilibrium is likely to be achieved among highly populated partons
        due to multi-secondary scatterings, while partons tend to traverse without being QGP components when these are in low density regions.
        Next we separate dynamically initial partons into QGP fluids (core: dense/soft components) and surviving partons (corona: dilute/hard components) under this assumption. After hydrodynamic evolution, the QGP fluids (the core) are particlized in the decoupling hypersurface, while surviving partons (the corona) are hadronized through string fragmentation in PYTHIA. The final hadron spectra is a sum of both contributions from the core and the corona in this model.

        We show the (multi-)strangeness yield ratios monotonically increase with multiplicity due to the competition between core and corona components and successfully reproduce the tendency of experimental data [2]. We also find that the ratios scale with multiplicity regardless of collision energies or system size, which is consistent with experimental findings [2]. Moreover, we calculate the fraction of fluidized energy as a function of multiplicity from small to large systems and find that initial partons are almost fluidized in mid-rapidity even in $\langle dN/d\eta \rangle > \sim 10$.

        [1] Y.Kanakubo, M.Okai, Y.Tachibana and T.Hirano, Progress of Theoretical and Experimental Physics 2018, no.12, 121D01 (2018).

        [2] J.Adam et al. [ALICE Collaboration], Nature Phys. 13, 535 (2017).

        [3] M.Okai, K.Kawaguchi, Y.Tachibana and T.Hirano, Phys.Rev.C 95, no. 5, 054914 (2017).

        Speaker: Yuuka Kanakubo (Sophia Univ.)
      • 15:40
        One fluid may not rule them all 20m

        Anisotropic flow is a useful observable to quantify the transport properties of the Quark Gluon Plasma (QGP) produced in heavy-ion collisions and to probe the hydrodynamic flow in small collision systems e.g. proton-proton (pp) and proton-lead (p--Pb) collisions. The experimental observed "correct" signs of multi-particle cumulants of $v_n$ coefficient in small collision systems, in particular, the negative sign of $c_{2}\{4\}$, are usually interpreted as the signature of hydrodynamic flow. In this talk, I present the investigations on 2- and multi-particle cumulants in high-multiplicity pp collisions, using iEBE-VISHNU hybrid model with HIJING initial condition. Although the model with tuned parameters could nicely describe almost all experimental measurements of two-particle correlations, however, it could not generate the negative $c_{2}\{4\}$. In addition, I will show that this positive $c_{2}\{4\}$ in hydro is not caused by possible non-flow contributions (resonances decay), multiplicity fluctuations (fake flow) or the multi-particle cumulant method itself (statistical stability). Further investigations by replacing HIJING initial conditions with super-MC and TRENTo initial conditions, and by including pre-equilibrium effects and kinetic theory, can not have the ability to reproduce the observed negative $c_{2}\{4\}$. It is also seen that the hydrodynamic evolution generates an additional non-linear (cubic) response of $v_{2}$ to initial eccentricity $\varepsilon_2$, which results in a positive $c_{2}\{4\}$ despite the negative $\varepsilon_{2}\{4\}$ obtained in the first place.

        Two new questions then appear, whether the success of hydrodynamic calculations in 2-particle correlations and failure of hydrodynamic descriptions of multi-particle cumulants requires a novel understanding of initial conditions or the one fluid may not rule them all. In this talk, together with the new calculations from AMPT transport model with various scenarios and also PYTHIA model (with and without color reconnection, with and without string shoving), I will address that using the well known 2- and multi-particle cumulants we can answer the unknown initial versus final stage effects in small collision systems.

        Speaker: You Zhou (University of Copenhagen (DK))
    • 16:00 16:20
      Coffee Break 20m
    • 16:20 18:00
      Parallel Session - EM probes II Ball Room 3

      Ball Room 3

      Wanda Reign Wuhan Hotel

      Convener: Yifei Zhang (University of Science and Technology of China (CN))
      • 16:20
        Measurements of dielectron production in Au+Au collisions at $\sqrt{s_{\text{NN}}}$ = 27, 54.4 and 200 GeV with the STAR experiment 20m

        Dielectrons are suggested as excellent probes of the hot and dense medium created in relativistic heavy-ion collisions due to their minimal interactions with the partonic and hadronic medium. They can carry the information from the initial to the final stage of a collision. The study of the dielectron mass spectrum could help to disentangle various contributions. In the low mass region (LMR, $M_{ee}$<$M_{\phi}$), the mass spectra of vector mesons are modified due to their interaction with the medium which is related to the chiral symmetry restoration. In the intermediate mass region (IMR, $M_{\phi}$<$M_{ee}$<$M_{J/\Psi}$), dielectrons from thermal radiation are predicted as a QGP thermometer, although the contributions from heavy quark semi-leptonic decays make the extraction of the thermal radiation contribution very challenging.

        In this talk, we will present the dielectron spectra in Au+Au collisions at $\sqrt{s_{\text{NN}}}$ = 27, 54.4 and 200 GeV with the STAR experiment. The 1.3B (1.5B) minimum-bias events of Au+Au collisions at $\sqrt{s_{\text{NN}}}$ = 27 (54.4) GeV taken in 2018 (2017) significantly enhance the precision of the in-medium $\rho$ modification measurement compared to the published STAR BES-I results. Lower heavy quark semi-leptonic decay contributions compared to those at top RHIC energies and the large data samples may allow the first extraction of the medium temperature with IMR dielectrons at RHIC. The Heavy Flavor Tracker (HFT) installed at STAR in 2014 enables a better understanding of the semi-leptonic decay contributions by providing high-precision tracking and vertex information. The first measurement of the dielectron spectra with the HFT in $\sqrt{s_{\text{NN}}}$ = 200 GeV Au+Au collisions will be presented. The physics implications of these measurements will be discussed and put into context of previous results.

        Speaker: Florian Seck for the STAR Collaboration (TU Darmstadt)
      • 16:40
        Low-mass dielectron measurements in pp, p-Pb and Pb-Pb collisions with ALICE at the LHC 20m

        The production of low-mass dielectrons is the most promising tool for the understanding of the chiral symmetry restoration and of the properties of the Quark-Gluon Plasma (QGP)
        created in heavy-ion collisions. At low invariant mass, the dielectron production is sensitive to the properties of vector mesons in the medium related to the chiral symmetry
        restoration. In the intermediate-mass region, the main component of the dielectron continuum is coming from correlated electron pairs from heavy-flavour hadron decays, which carry information about heavy-quark energy loss and collectivity. In this mass region, thermal
        radiation from the QGP gives insight into the early temperature of the medium. Finally,
        at very low momenta initial photon annihilation and photonuclear processes, triggered by
        the coherent electromagnetic fields of the incoming nuclei, are expected to play a role
        in more peripheral collisions.

        To study the dielectron production in heavy-ion collisions, it is crucial to first understand the primordial e$^{+}$e$^{-}$ pair production in vacuum with minimum-bias proton-proton collisions and to disentangle hot from cold-nuclear matter effects with p--Pb collisions. Moreover, observations of collective effects in high-multiplicity pp and p--Pb collisions show surprising similarities with those in heavy-ion collisions, which can be further investigated with the measurement of dielectrons in such collisions.

        In this talk, we will give an overview of the latest measurements of e$^{+}$e$^{-}$
        pair production in pp, p--Pb and Pb--Pb collisions recorded by ALICE at different energies. The results will be shown as a function of the charged-particle multiplicity in the event,
        or the centrality of the collision. They will be compared to the expected dielectron yield from known hadronic sources and in Pb-Pb collisions with several predictions for the
        thermal radiation from the hadron gas and QGP phases and photo-production of correlated e$^{+}$e$^{-}$. Their implications for the production of heavy quarks and quasi-real
        virtual-photons will be discussed as well.

        Speaker: Horst Sebastian Scheid for the ALICE Collaboration (Johann-Wolfgang-Goethe Univ. (DE))
      • 17:00
        Signatures of chiral symmetry restoration in dilepton production 20m

        We study the structural change of the vector spectral function and integrated production rates
        of dileptons in the presence of the chiral mixing induced exclusively at finite density. The mixing
        produces multiple bumps and peaks around the vacuum masses of the rho, omega and phi resonances in the spectral function. The arising modifi?cation becomes pronounced when the mass difference between parity partners decreases. In particular, the emergent peaks around the vacuum phi meson in the production rates serves as an excellent signature of the partially-restored chiral symmetry in heavy-ion collisions.

        Reference:
        [1] C. Sasaki, arXiv:1906.05077.

        Speaker: Chihiro Sasaki
      • 17:20
        Electromagnetic radiation from the pre-equilibrium/pre-hydro stage of the quark-gluon plasma 20m

        A remarkable achievement of the relativistic heavy-ion program is the realization that relativistic fluid dynamics can describe the evolving system of quark-gluon plasma (QGP) from its early moments to a time when the growing mean-free-paths drive the system out of equilibrium. The effectiveness of this hydrodynamic description is judged by comparing calculated hadronic observables with experimental measurements. Alternatively, electromagnetic radiation could be considered a more distinguishing signal as it is emitted throughout the evolution of the hadronic system. Considerable work has gone into the calculation of photons [1] and dileptons [2] using modern hydrodynamic approaches, however, the calculation of the electromagnetic emissivity of the pre-hydro stage is currently less advanced.

        In this talk, we use a transport approach that models the time-evolution of gluons and fermions by solving coupled Boltzmann transport equations in the diffusion approximation [3]. The transport equations are solved numerically to study how the system relaxes towards equilibrium. The initial state is a gluon distribution of a form inspired by the colour glass picture, where quarks and anti-quarks are then generated through interactions. The early stage evolution is modeled by a 1D expansion, during which non-equilibrium parton interactions can also produce real and virtual photons. We show how reliably these Glasma photons can report on the initial momentum anisotropy of the early parton distributions and on the presence or absence of a transient Bose-Einstein condensate of gluons. Additionally, we show that the non-equilibrium contribution can leave an imprint on the low $p_T$ spectrum of the measured photons and estimate the effect of the anisotropy on the spectrum measured at RHIC and at the LHC (i.e. the photon $v_2$ puzzle). This opens the exciting possibility that measurements of the electromagnetic signal can access fine details of the partonic distributions as they appear during the very first instants of heavy-ion collisions.

        [1] Jean-François Paquet, Chun Shen, Gabriel S. Denicol, Matthew Luzum, Björn Schenke, Sangyong Jeon, Charles Gale, Phys. Rev. C93 (2016) no.4, 044906.
        [2] Gojko Vujanovic, Jean-François Paquet, Gabriel S. Denicol, Matthew Luzum, Sangyong Jeon, Charles Gale, Phys. Rev. C94 (2016) no.1, 014904.
        [3] Jean-Paul Blaizot, Bin Wu, Li Yan, Nucl. Phys. A930 (2014) 139-162.

        Speaker: Jessica Churchill (McGill University)
      • 17:40
        Thermal photon production in Au+Au collisions from PHENIX 20m

        PHENIX measurements of low $p_T$ direct photons in Au+Au collisions at 200 GeV show large yields and simultaneously large anisotropies with respect to the reaction plane. Calculations of thermal photon emission fall short in describing the yield and the anisotropy at the same time. Furthermore, a recent publication of the STAR collaboration indicates lower direct photon yields in Au+Au collisions than observed by PHENIX. In order to provide new insights, in this talk PHENIX will present new direct photon results from Au+Au data taken in 2014. This analysis adds a third independent measurement from Au+Au collisions to the previously published PHENIX results using a dataset that provides a 10 fold increase in statistics for the measurement of direct photon yields and their anisotropy.

        Speaker: Wenqing Fan (Stony Brook University)
    • 16:20 18:00
      Parallel Session - Heavy flavor IV Ball Room 2

      Ball Room 2

      Wanda Reign Wuhan Hotel

      Convener: Itzhak Tserruya (Weizmann Institute of Science (IL))
      • 16:20
        Studies of beauty quark hadronization with $B_{S}^{0}$ in PbPb collisions with the CMS detector 20m

        Beauty quarks are considered to be one of the best probes of the strongly interacting medium created in relativistic heavy-ion collisions as they are predominantly produced via initial hard scatterings. Measurements of B mesons provide information on the diffusion of beauty quarks as well as the flavor dependence of in-medium energy loss. In these studies, clarifying the hadronization mechanism is crucial for understanding the transport properties of beauty quarks. Measurements of $B_{S}^{0}$ production can shed light on the mechanisms of beauty recombination in the medium. In addition, measurements of the production of mesons containing both strange and beauty quarks can provide more information about strangeness enhancement in the quark-gluon plasma. Measurements of the ratio of $B_{S}^{0}$ over $B^{+}$ yields in PbPb collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV, using full reconstruction of the B mesons with the CMS detector, are presented.

        Speaker: Zhaozhong Shi for the CMS Collaboration (Massachusetts Inst. of Technology (US))
      • 16:40
        Open and hidden beauty production in pPb collisions at LHCb 20m

        Provided by the large beauty quark mass, beauty production is sensitive to test pQCD calculation as well as the nuclear matter effects in heavy ion collisions. In this talk, the measurement of open beauty hadron and Upsilon production in pPb data at nucleon-nucleon center-of-mass energy 8.16 TeV is presented. Nuclear matter effects, including the modification of gluon PDF and beauty hadronization in nuclear environment are discussed. The production of Upsilon excited states is used to investigate final state effects in pPb collisions.

        Speaker: Shanzhen Chen for the LHCb Collaboration (Universita e INFN, Cagliari (IT))
      • 17:00
        Bottomonia in QGP from lattice QCD: Beyond the ground states 20m

        Using novel lattice (non-relativistic) QCD techniques, for the first time, we will present results pertaining to the fate of $\Upsilon(1S)$, $\Upsilon(2S)$ and $\Upsilon(3S)$ in QGP. We will present results on how the masses of these states change with temperature, as well as how their spatial sizes change. Finally, we will also show new lattice QCD results on excited P-wave bottomonia in QGP.

        Speaker: Rasmus Larsen (Brookhaven Nationanl Laboratory)
      • 17:20
        LHCb measurements of the exotic tetraquark candidate X(3872) in high multiplicity pp and pPb collisions 20m

        The last decade of hadron spectroscopy has unveiled a wealth of states that do not have the properties expected of particles composed of 2 or 3 valence quarks. Among the most intriguing of these exotics is the X(3872), which various models attempt to describe as a hadronic molecule, a compact tetraquark, an unexpected charmonium state, or their mixtures. To date, most experimental studies of the X(3872) have focused on its production through B meson decays. Heavy ion collisions, as well as high multiplicity pp collisions, offer a new window on the properties of this poorly understood hadron. In these systems, promptly produced X(3872) hadrons can interact with other particles in the nucleus and/or those produced in the collision. The influence of these interactions on the observed X(3872) yields provides information that can help discriminate between the various models of its structure, as well as give insight into the dynamics of the bulk particles produced in these collisions.

        With a full range of precision vertexing, tracking, and particle ID capabilities covering 2 to 5 in units of rapidity, the LHCb experiment is especially well suited to measurements of both prompt and non-prompt exotic hadrons. This talk will present new LHCb measurements X(3872) production in high multiplicity pp collisions and pPb collisions through the decay to $J/\psi \pi^{+} \pi^{-}$. This is the first measurement of any exotic hadron in collisions involving a large nucleus.

        Speaker: John Matthew Durham for the LHCb Collaboration (Los Alamos National Laboratory)
      • 17:40
        Observation of X(3872) in PbPb collisions with the CMS detector 20m

        The exotic meson $\chi_{c1}(3872)$, also known as $X(3872)$, was discovered a decade ago, but the structure of this new state is still under debate. The masses of possible charmonium states from calculations using constituent quark models are too large, and therefore an explanation of the underlying characteristics of this meson remains a challenge. The similarity of the $\chi_{c1}(3872)$ mass and the $D-\bar{D}^{*}$ mass threshold inspired the interpretation that $\chi_{c1}(3872)$ is a $D-\bar{D}^{*}$ “molecule” with small binding energy. Another explanation is that this meson is a tetra-quark, consisting of a di-quark and di-antiquark. Relativistic heavy ion collisions produce an extremely hot and strongly interacting medium, which provides a new environment in which to study the nature of multi-quark states. Because of the dramatically different radii of a $D-\bar{D}^{*}$ “molecule” and a tetra-quark, the interactions of these two proposed states are expected to interact differently with the medium. Therefore, the yield of $\chi_{c1}(3872)$ in heavy ion collisions can provide insight into its structure. The ratios of production cross-section of fully reconstructed $\chi_{c1}(3872)$ over $\psi(2S)$ in PbPb collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV with the CMS detector are presented.

        Speaker: Yen-Jie Lee for the CMS Collaboration (Massachusetts Inst. of Technology (US))
    • 16:20 18:00
      Parallel Session - QCD at finite temperature III Ball Room1

      Ball Room1

      Wanda Reign Wuhan Hotel

      Convener: Masakiyo Kitazawa (Osaka University)
      • 16:20
        QCD equation of state at finite densities for nuclear collisions 20m

        Elucidation of the quark matter properties at finite densities is one of the goals for the Beam Energy Scan (BES) programs at RHIC. For quantitative predictions and analyses of the experimental data, an equation of state at finite chemical potentials is needed as input to hydrodynamic models.

        We construct the QCD equation of state at finite chemical potentials including net baryon (B), electric charge (Q) and strangeness (S) based on the results of state-of-the-art lattice QCD simulations and the hadron resonance gas model [1]. The situation of strangeness neutrality and matter with a fixed electric charge-to-baryon ratio, resembling that of heavy nuclei, is considered for the application to relativistic heavy-ion collisions. This increases the values of baryon chemical potential, modifying the fireball trajectory in the phase diagram. We perform (3+1)D viscous hydrodynamic simulations and demonstrate the importance of finite electric charge and strangeness chemical potentials for identified particle production as well as differences in the $v_n$ coefficients of particles and anti-particles in heavy ion collisions at BES energies.

        [1] A. Monnai, B. Schenke and C. Shen, arXiv:1902.05095 [nucl-th]

        Speaker: Akihiko Monnai (High Energy Accelerator Research Organization (KEK))
      • 16:40
        Universality driven analytic structure of QCD crossover: radius of convergence and QCD critical point 20m

        Recent lattice QCD calculations show strong indications that the chiral crossover of QCD at zero baryon chemical potential (µ) is a remnant of the second order chiral phase transition. Furthermore, the non-universal parameters needed to map temperature T and µ to the universal properties of the second order chiral phase transition also have been determined by lattice QCD calculations. Motivated by these observations, first, we determine the analytic structure of the partition function - the so-called Lee-Yang edge singularity - in the QCD crossover regime, solely based on universal properties. Then, utilizing the lattice calculated non-universal parameters, we map this singularity to the real T and complex µ plane, and determine the closest singularity to µ=0 in the QCD crossover regime. These results lead to two important implications: (i) An universality based estimate of the radius of convergence for lattice QCD calculations at µ>0; (ii) Universality and lattice QCD based constraints on the location of the QCD critical point in the T-µ plane.

        Speaker: Vladimir Skokov (Brookhaven national laboratory)
      • 17:00
        Characterizing baryon dominated matter with HADES measurements 20m

        In heavy-ion reactions at beam energies of a few GeV per nucleon on stationary targets, QCD matter is substantially compressed (2-3 times nuclear saturation density) while temperatures are expected not to exceed T = 70 MeV. Matter under such conditions is being studied with HADES at SIS18.

        This contribution discusses new experimental results on the mechanisms of strangeness production, the emissivity of matter and the role of baryonic resonances herein. The multi-differential representations of hadron and dilepton spectra, collective effects and particle correlations will be confronted with results of other experiments as well as with hitherto model calculations.

        To provide a deeper understanding of the temperature and density dependence of the intriguing results obtained in the Au+Au and Ar+KCl runs, HADES has recently completed a run studying Ag+Ag collisions at $\sqrt{s_{NN}}$=2.55 GeV, optimized to reach a high enough beam energy for abundant strangeness and vector meson production while yet realizing a large interaction volume. The results obtained for heavy-ion collisions are confronted to studies of elementary reactions serving as a reference for medium effects.

        Speaker: Szymon Harabasz (TU Darmstadt)
      • 17:20
        Skewness and kurtosis of net-strangeness, net-baryon number and net-electric charge distributions at non-zero $\mu_B$. 20m

        Using recent results on higher order cumulants of conserved charge fluctuations from lattice QCD, we construct mean, variance, skewness and kurtosis of net-strangeness, net-baryon number and net-electric charge distributions at next-to-leading order in $\mu_B$. For the strangeness neutral case ($\mu_S=0$) at fixed ratio of electric charge to baryon number density ($\frac{n_Q}{n_B}=0.4$), which is appropriate for a comparison with heavy ion collisions, we present results for $\kappa_X \sigma_X^2$ and $S_X \sigma_X$ and $S_X \sigma_X^3/M_X, (X=B,Q,S)$ on the crossover line for the chiral transition ($T_{pc}(\mu_B)$). Continuum extrapolations for this pseudo-critical transition line have recently been reported by HotQCD up to baryon chemical potentials $\mu_B\simeq 300$ MeV (arXiv:1812.08235). These cumulant ratios thus are of direct relevance for comparisons with corresponding ratios measured by STAR in the BES-I and II runs at beam energies $\sqrt{s_{NN}}\ge 20$ GeV. In particular, we point out that recent high statistics results on skewness and kurtosis of net-baryon number distributions obtained by STAR at $\sqrt{s_{NN}} = 54.4$ GeV put strong constraints on freeze-out parameters and are consistent with predictions from thermal QCD. Additionally, we show that, unlike in the case of net-baryon number fluctuations, the kurtosis ratios for strangeness and electric charge are only weakly dependent on $\mu_B$.

        Furthermore, we also construct Taylor series for baryon-strangeness and baryon-charge correlations up to $\mathcal{O}(\mu_B^4)$ and present results for these observables on the crossover transition line. We point out that these correlations are dominated by correlations in the baryon sector of QCD, which is consistent with recent findings of the STAR collaboration (arXiv:1903.05370). Correlations of proton fluctuations with kaon or pion fluctuations, respectively, thus are poor proxies for studying such correlations on the freeze-out line in heavy ion collisions.

        Speaker: Dennis Bollweg (Bielefeld University)
      • 17:40
        Probing thermal nature of matter formed at RHIC via fluctuations 20m

        Evidence for thermalization of the QCD matter created in high-energy nuclear collisions has dominantly come from the agreement of the measured yield of produced hadrons with those from statistical thermal models. Ideally for a thermalized system, in addition to mean, the higher orders of the moments of the multiplicity distribution of produced particles should also show agreement with thermal models. In this respect, studying the moments of the event-by-event distributions of conserved quantities like net-baryon, net-strangeness and net-charge number is best suited.

        We have carried out a systematic study of comparing the results from a thermal hadron resonance gas model with data on higher moments of net-proton, net-kaon and net-charge distributions measured at RHIC beam energy scan program. The experimental acceptances in terms of rapidity and transverse momentum are used in the model calculations carried out for central Au+Au collisions at the centre of mass energies of 7.7, 11.5, 19.6, 27, 39, 62.4 and 200 GeV. For the first time, the hadron resonance gas model results are found to explain the measurements up to third order of moment with a common temperature and baryonic chemical potential. These calculations have tested the thermal nature of produced net-particle distributions up to third order, thereby providing evidence for thermalization of the QCD matter formed in high energy heavy-ion collisions at RHIC. Implications of the findings on our understanding of the phase structure of QCD matter will be discussed.

        Speaker: Debasish Mallick (National Institute of Science Education and Research)
    • 16:20 18:00
      Parallel Session - QM & nuclear astrophysics HongKong Room

      HongKong Room

      Wanda Reign Wuhan Hotel

      Convener: Toru Kojo (Central China Normal University)
      • 16:20
        Measurement of the anti-deuteron nuclear inelastic cross section with ALICE and implications for indirect Dark Matter searches 20m

        The measurement of low-energy cosmic anti-deuterons may reveal the existence of exotic processes such as dark-matter annihilation, since the production rate of these ions through ordinary secondary processes is very low. However, the lack of experimental data at low energies, where both the anti-deuteron production and inelastic cross sections are very poorly known, prevents precise predictions of anti-deuteron fluxes near Earth.

        In ultra-relativistic collisions of protons and lead ions at the CERN LHC, matter and anti-matter is produced in almost equal abundances. This allows us to study the production cross sections of (anti-)deuterons with high precision as well as to measure the absorption process of produced (anti-)deuterons in the detector material.

        In this talk we present the first results on the anti-deuteron absorption cross section in the ALICE detector material. The analysis is performed with p-Pb data collected $\sqrt{s_{\rm NN}}$ = 5.02 TeV. The reconstructed anti-deuteron to deuteron ratio is compared to the results from full-scale GEANT4 simulations of the ALICE detector. Experimental constraints on the anti-deuteron nuclear inelastic cross-section are extracted in the momentum range between 0.5 and 4.0 GeV/$c$. Finally, we discuss the implications of these results for indirect Dark Matter searches using cosmic anti-deuterons.

        Speaker: Ivan Vorobyev for the ALICE Collaboration (Technische Universitaet Muenchen (DE))
      • 16:40
        Quarkyonic Matter and Neutron Stars 20m

        Masses and radii of neutron stars and the recent data from LIGO suggest that
        the sound velocity is greater than or of the order of 1/3 at densities a few times that of nuclear matter. We show that this arises naturally if nuclear matter is Quarkyonic. Quarkyonic matter has a shell in the Fermi surface of nuclear matter
        and Fermi sea of quarks. We discuss how this shell might arise dynamically

        Speaker: Jeon Kiesang (INT, University of Washington)
      • 17:00
        Continuity from neutron matter to color-superconducting quark matter with $^3 P_2$ superfluidity 20m

        Quark-hadron continuity has been well understood for three-flavor symmetric nuclear and quark matter, which is however a theoretically over-idealized environment. In this talk we clarify how quark-hadron continuity can be applied to neutron matter in the realistic neutron star environment. Our key observation is that neutron matter can be smoothly connected to the two-flavor color-superconducting (2SC) state mixed with a condensate of $\langle dd\rangle$. We give three convincing arguments: The first one is the symmetry-breaking argument, the second one is the argument based on rearrangement of gauge-invariant order parameters, and the last one is the dynamical argument associated with nuclear forces in terms of $d$-quark exchanges. Interestingly, in the quark sector, we have found a universal dynamical mechanism to favor $^3 P_2$ superfluidity above a certain threshold density, below which the ground state is a $^0 S_1$ superfluid. Such transitional behavior of the favored ground state has been long known in nuclear physics, and as should be the case if quark-hadron continuity holds for neutron matter, quark matter turns out to share the same properties.
        Our finding provides us with an important theoretical foundation for the phenomenological construction of the equation of state (EoS) in the neutron star environment. We conclude that, even in the presence of a $^3 P_2$ component of superfluidity, a prescription to interpolate the EoS smoothly between the nuclear and quark sides perfectly makes sense. We also emphasize that such a state of the 2SC with tensorial $\langle dd\rangle$ in accord with $^3 P_2$ superfluidity is an absolutely novel state of quark matter that nobody had ever considered. We discuss physical properties of this novel color-superconducting state and give an account of possible enhancement of tensorial $\langle dd\rangle$ due to Fierz mixing with the energy-momentum tensor.

        Speaker: Yuki Fujimoto (The University of Tokyo)
      • 17:20
        Signatures of quark-hadron phase transitions in general-relativistic neutron-star mergers 20m

        Merging binaries of neutron stars are not only strong sources of gravitational waves, but also have the potential of revealing states of matter at densities and temperatures not accessible in laboratories. A crucial and longstanding question in this context is whether quarks are deconfined as a result of the dramatic increase in density and temperature following the merger. We present the first fully general-relativistic simulations of merging neutron stars including quarks at finite temperatures that can be switched off consistently in the equation of state. Within our approach, we can determine clearly what signatures a quark-hadron phase transition would leave in the gravitational-wave signal. We show that if after the merger the conditions are met for a phase transition to take place at several times nuclear saturation density, they would lead to a post-merger signal considerably different from the one expected from the inspiral, that can only probe the hadronic part of the equations of state, and to an anticipated collapse of the merged object. We also show that the phase transition leads to a very hot and dense quark core that, when it collapses to a black hole, produces a ringdown signal different from the hadronic one. Finally, in analogy with what is done in heavy-ion collisions, we use the evolution of the temperature and density in the merger remnant to illustrate the properties of the phase transition in a QCD phase diagram.

        Primary reference: Phys.Rev.Lett. 122 (2019) no.6, 061101.

        Speaker: Verônica Dexheimer (Kent State University)
      • 17:40
        Chirality transfer & chiral turbulence in gauge theories 20m

        Sharing and transfer of chirality between gauge fields and fermion plays a crucial role for understanding the dynamics of anomalous transport phenomena such as the Chiral Megnetic Effect. We present a first principles study of the chirality transfer between gauge fields and fermions based on classical-statistical real-time lattice simulations. We demonstrate that a chirality imbalance in the fermion sector triggers plasma instabilities in the gauge field sector, which ultimately lead to the emergence of turbulent behavior characterized by a self-similar infrared cascade of magnetic helicity. We comment on the differences between abelian and non-abelian gauge theories, and discuss consequences for modeling anomalous transport phenomena in heavy-ion collisions

        Speaker: Soeren Schlichting (Universität Bielefeld)
    • 19:30 20:30
      Social Event 1h Wanda Han Show Theatre

      Wanda Han Show Theatre

    • 09:00 11:00
      Plenary Session IV Wanda Han Show Theatre

      Wanda Han Show Theatre

      Convener: Dirk Rischke (University Frankfurt)
      • 09:00
        Study QGP with flow: Theory 30m
        Speaker: Chun Shen (Brookhaven National Laboratory)
      • 09:30
        Probing QGP with flow: an experimental overview 30m
        Speaker: Katarina Gajdosova (Czech Technical University (CZ))
      • 10:00
        Approach to thermalization and hydrodynamic 30m
        Speaker: Yukinao Akamatsu (Osaka University)
      • 10:30
        Exotic and light nucleus production in heavy-ion collision 30m
        Speaker: Dmytro Oliinychenko (Lawrence Berkeley National Laboratory)
    • 11:00 11:20
      Coffee Break 20m Wanda Han Show Theatre

      Wanda Han Show Theatre

    • 11:20 13:20
      Plenary Session V Wanda Han Show Theatre

      Wanda Han Show Theatre

      Convener: Krishna Rajagopal (Massachusetts Inst. of Technology (US))
      • 11:20
        Fluctuations and correlations: Experiment 30m
        Speaker: Anar Rustamov (National Nuclear Research Center (AZ))
      • 11:50
        Vorticity and spin polarization 30m
        Speaker: Xu-Guang Huang (Fudan University)
      • 12:20
        Chirality, CME, magnetic field and spin polarization: an experimental review 30m
        Speaker: Mike Lisa (Ohio State University (US))
      • 12:50
        Chirality and magnetic field 30m
        Speaker: Jinfeng Liao (Indiana University)
    • 13:20 14:00
      Lunch Break 40m
    • 14:00 18:00
      Excursion
    • 15:00 18:00
      IAC Meeting
    • 09:00 10:30
      Plenary Session VI Wanda Han Show Theatre

      Wanda Han Show Theatre

      Convener: Gunther Roland (MIT)
      • 09:00
        Quenching of heavy and light flavor jets: experimental overview 30m
        Speaker: Barbara Trzeciak (Czech Technical University in Prague)
      • 09:30
        Parton propagation and energy loss: new theoretical progres 30m
        Speaker: Konrad Tywoniuk (University of Bergen (NO))
      • 10:00
        Jet quenching and medium response 30m
        Speaker: Tan Luo (Central China Normal University)
    • 10:30 10:50
      Coffee Break 20m Wanda Han Show Theatre

      Wanda Han Show Theatre

    • 10:50 12:20
      Plenary Session VII Wanda Han Show Theatre

      Wanda Han Show Theatre

      Convener: Helen Caines (Yale University (US))
    • 12:20 14:00
      Lunch Break 1h 40m
    • 14:00 16:00
      Plenary Session - VIII Wanda Han Show Theatre

      Wanda Han Show Theatre

      Convener: Pengfei Zhuang (Tsinghua University)
      • 14:00
        Heavy Quark production and energy loss: experiments 30m
        Speaker: Jing Wang (Massachusetts Inst. of Technology (US))
      • 14:30
        Heavy quark transport: a theoretical overview 30m
        Speaker: Shanshan Cao (Wayne State University)
      • 15:00
        Quarkonium production and suppression: Theory 30m
        Speaker: Alexander Rothkopf (University of Stavanger)
      • 15:30
        Quarkonium Production: an experimental overview 30m
        Speaker: Zebo Tang (University of Science and Technology of China (CN))
    • 16:00 16:20
      Coffee Break 20m Wanda Han Show Theatre

      Wanda Han Show Theatre

    • 16:20 17:50
      Plenary Session IX Wanda Han Show Theatre

      Wanda Han Show Theatre

      Convener: Olga Evdokimov (University of Illinois at Chicago (US))
      • 16:20
        Electromagnetic and weak probes: experiments 30m
        Speaker: Prof. Frank Geurts (Rice University (US))
      • 16:50
        Electromagnetic and weak probes: theory 30m
        Speaker: Ralf-Arno Tripolt (TU Darmstadt)
      • 17:20
        Ultra Peripheral Collisions 30m
        Speaker: Peter Alan Steinberg (Brookhaven National Laboratory (US))
    • 18:40 20:30
      Banquet 1h 50m Jinguiyuan Restaurant

      Jinguiyuan Restaurant

    • 09:00 10:30
      Plenary Session X Wanda Han Show Theatre

      Wanda Han Show Theatre

      Convener: Johanna Stachel (Ruprecht Karls Universitaet Heidelberg (DE))
    • 10:30 10:50
      Coffee Break 20m Wanda Han Show Theatre

      Wanda Han Show Theatre

    • 10:50 12:50
      Plenary Session XI Wanda Han Show Theatre

      Wanda Han Show Theatre

      Convener: Krzysztof Redlich (University of Wroclaw (PL))
      • 10:50
        Nuclear modification factor of isolated photon production in pp and PbPb collisions at 5.02 TeV with the CMS detector 5m
        Speaker: Yeonju Go (Korea University (KR))
      • 10:55
        Early-Stage Shear Viscosity far from Equilibrium via Holography 5m
        Speaker: Michael Florian Wondrak (Johann Wolfgang Goethe-Universität Frankfurt am Main)
      • 11:00
        D-meson production in Pb-Pb collisions with ALICE at the LHC 5m
        Speaker: Stefano Trogolo (Universita e INFN, Padova (IT))
      • 11:05
        Generalized High Twist Approach to Parton Energy Loss 5m
        Speaker: Yuanyuan Zhang (LBL,CCNU)
      • 11:10
        Measurement of the sixth-order cumulant of net-proton multiplicity distributions from the STAR experiment 5m
        Speaker: Toshihiro Nonaka (CCNU)
      • 11:15
        Study of spin polarizations in an angular-momentum conserved chiral kinetic transport model 5m
        Speaker: Shuai Liu (IMPCAS/Texas A&M University)
      • 11:20
        Awards 20m

        (1) Zimanyi Medal in Nuclear Theory
        (2) Elsevier Young Scientist Award

      • 11:40
        Outlook & Future Perspective of Heavy-ion Physics 40m
        Speaker: Constantinos Loizides (ORNL)
      • 12:20
      • 12:35
        Closing 15m