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

Nov 3, 2019, 8:00 AM → Nov 9, 2019, 1:10 PM Asia/Shanghai

Wanda Reign Wuhan Hotel

Ben-Wei Zhang (Central China Normal University), Enke Wang (South China Normal University), Feng Liu (Central China Normal University)

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 Website: QM2019 (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

1st_Announcement_QM2019.pdf

2nd_Announcement_QM2019.pdf

Final_Announcement_QM2019.pdf

QM19-NPA-template.zip

QM2019_booklet_ForWeb.pdf

QM2019_Logo.png

QM2019_Poster_final.pdf

QM2019_Video_Wuhan_final.mp4

Timetable_QM2019.pdf

PhotoGallery

• 20191104.zip
• 20191105.zip
• 20191106.zip
• 20191107.zip
• 20191108.zip
• Closing_Day_20191109.zip
• GroupPhoto_QM2019.jpg
• QM2019_HanShow.jpg
• StudentDay_20191103.zip

Practical_Information

• Excursion_Line1.pdf
• Excursion_Line2.pdf
• Excursion_Line3.pdf
• Excursion_Line4.pdf
• Hanshow_Sample.mp4
• Instructions_Drivers_to_Hotel.pdf
• InvitationLetterForm_IndicoRegistrationID_LastName_FirstName.doc
• LocalDiningGuide_QM2019.pdf
• MapGuide_ChuheHanjieStation_toHotels.png
• mapGuide_GalleryF.png
• mapGuide_Hongyi.png
• mapGuide_Jingjiang.png
• mapGuide.png
• MapGuide_toJinguiyuanRestaurant.png
• Wuhan_Metro_Map.png

Sun, November 3

Student Day

Conveners: Mei Huang (University of Chinese Academy of Sciences), Bowen Xiao (Central China Normal University)

1 Search for the Critical End Point

Speaker: Volker Koch (LBNL)

Koch_lecture.pdf

10:30 AM Coffee Break

2 Overview of Collectivity

Speaker: Zhenyu Chen (Shandong University)

Zhenyu_QM2019_Lecture_v6.pdf

12:30 PM Lunch Break

3 Initial States of Heavy Ion Collisions

Speaker: Raju Venugopalan (Brookhaven National Laboratory)

QuarkMatter2019-lecture_Venugopalan.pdf

QuarkMatter2019-lecture_Venugopalan.pptx

3:30 PM Coffee Break

4 Overview of EIC Physics

Speaker: Bernd Surrow (Temple University)

BSurrow-EIC-Lecture-QM2019.pdf

Mon, November 4

Plenary Session I

Convener: John William Harris (Yale University (US))

5 Welcome

Speaker: TBD

6 Quark Matter - Status & Challenges

Speaker: Barbara Jacak (University of California Berkeley (US))

QM_Jacak.pptx

7 Highlights from the ALICE experiment

Speaker: Michael Weber for the ALICE Collaboration (Stefan Meyer Institute for Subatomic Physics (SMI), Austrian Academy of Sciences (AT))

QM2019_ALICEoverview_Final.pdf

8 Highlights from the ATLAS experiment

Speaker: Martin Spousta for the ATLAS Collaboration (Charles University)

Spousta_QM2019_2011024_v5.pdf

10:40 AM Coffee Break

Plenary Session II

Convener: William Zajc (Columbia University)

9 Highlights from the CMS experiment

Speaker: Émilien Chapon for the CMS Collaboration (CERN)

chapon_CMS_overview_QM2019.pdf

10 Highlights from the LHCb experiment

Speaker: Benjamin Audurier for the LHCb Collaboration (Universita e INFN, Cagliari (IT))

Audurier_LHCb_summary_Final.pdf

11 Highlights from the PHENIX experiment

Speaker: Megan Connors for the PHENIX Collaboration (Georgia State University)

connors_phenixoverview_qm2019.pptx

12 Highlights from the STAR experiment

Speaker: Zhangbu Xu for the STAR Collaboration (Shandong University & Brookhaven National Laboratory)

STAR_QM2019_xzb_112019_v11.pdf

12:40 PM Lunch Break

Plenary Session III

Convener: Maria Paola Lombardo (INFN)

13 New developments in lattice QCD

Speaker: Heng-Tong Ding (Central China Normal University)

QM2019_HTD.pdf

14 An experimenter’s assessment of correlations and flow in small systems

Speaker: James Lawrence Nagle (University of Colorado Boulder)

nagle_qm2019_final.pptx

15 Dynamics of critical fluctuation

Speaker: Derek Teaney (Stony Brook University)

dteaney_qm2019.pdf

16 A new laboratory to study hadron-hadron interactions

Speaker: Laura Fabbietti (Technische Universitaet Muenchen (DE))

QM2019Fabbietti.pdf

17 Machine learning in heavy-ion physics

Speaker: Long-Gang Pang (lbnl)

QM2019_LongGang_Updated.pptx

Poster Session

18 "Mid-rapidity J/ψ production as a function of charged-particle multiplicity in proton-proton collisions at √s=13 TeV."

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)

conference_presentation-quarkmatter.pdf

19 $\it{R}_{\rm{AA}}$ of electrons from beauty-hadron decays in Pb-Pb collisions at 5.02 TeV with ALICE

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))

20 $\pi^0$ Azimuthal Anisotropy in Central d+Au Collisions Measured with PHENIX at RHIC

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

QM19_pi0v2-3.pdf

21 $\rm \Xi_{c}^{0}$ reconstruction via hadronic decay channel in pp collisions at $\sqrt{s}=$ 13 TeV

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))

22 $K^*(892)^0$ and $\overline{K^*}(892)^0$ production in p+p interactions at SPS energies from NA61/SHINE

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))

ATefelska_poster.pdf

23 (Non-)Strange particle production at RHIC and LHC energies using HYDJET++

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)

24 [Poster] Using Ξ(1820) baryons to test for parity doubling at ALICE

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))

25 A Comprehensive Study of Bottomonium Production in Heavy-ion Collision

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)

26 A hydrodynamic approach for multiplicity fluctuations in heavy-ion collisions

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)

UFposter.pdf

27 A MAPS based Inner Tracking System of the Multi-Purpose Detector at the NICA collider

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)

Poster_ITS_QM-2019-final.PDF

28 A multivariate approach to measuring low-mass dielectrons in p-Pb collisions at sqrt(sNN) = 5.02 TeV with ALICE

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))

pPb_LMee_MVA_acapon_QM19.pdf

29 An object-oriented software framework for anisotropic flow analysis

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))

PosterLukas.pdf

30 Analytical solutions and attractors of relativistic viscous hydrodynamics for Bjorken flow

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)

sunil.jaiswal_poster_QM2019.pdf

31 Anisotropic flow measurements from the NA61/SHINE and NA49 beam momentum scan programs at CERN SPS

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)

201911_QM2019_NA61_Flow_Poster.pdf

32 Anomaly Effects in Transport Coefficients

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)

33 Anomaly with a non-relativistic dispersion relation

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)

34 Application of Principal Component Analysis on Collective Flow

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)

35 Azimuthal anisotropy correlations and fluctuations in PbPb collisions at the LHC energies from HYDJET++ and AMPT model

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)

36 Azimuthal anisotropy measurement of strange hadrons in Au+Au collisions at $\sqrt{s_{NN}}$ = 27 and 54.4 GeV at STAR

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)

37 Azimuthal anisotropy of heavy-flavour decay electrons in p-Pb collisions with ALICE

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))

2019-oct-26-conference_presentation-poster (1).pdf

38 b-jet quenching in Pb+Pb collisions measured by the ATLAS detector

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

39 Background study of the CME-related correlations in heavy-ion collisions within a multiphase transport mode

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)

40 Baryon number fluctuations from DSEs

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)

41 Beam test results of the sPHENIX HCal prototype

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

42 Beam Test Results of the sPHENIX HCal Prototype

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)

43 Beam-energy dependence of spatial and temporal characteristics of shape-selected events in Au+Au collisions at STAR

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)

44 Beyond scattering and hypernuclei experiments: $p-\Lambda$ and $p-\Sigma^0$ correlation studies at ALICE

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))

45 Bottom and Charm production in $p$+$p$ collisions at $\sqrt{s}$=200 GeV measured by PHENIX

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))

Velkovska_QM19_poster.pdf

46 Bottomonia Suppression in Heavy-Ion Collisions from AdS/CFT

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)

QM19_NNBarnard.pdf

47 Bottomonium anisotropic flow from an escape mechanism

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)

Poster_Nina_Kersting_final.pdf

48 Bottomonium production in p+p and Pb+Pb collisions with ATLAS

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))

20191103_songkyo_QM2019_poster_v3.pdf

49 Bulk properties of QCD matter using S-matrix based hadron resonance gas model

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

50 Can jet quenching constrain the evolution history of parton showers?

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)

QM2019_poster_Adam_Takacs_Jet_quenching.pdf

51 Causality and dissipation in relativistic polarizeable fluids

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)

52 Central Membrane Studies for the sPHENIX TPC

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

53 Centrality dependence of bottom and charm production at PHENIX

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)

54 Centrality determination with the Event Plane Detector for fluctuation measurements from STAR

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)

QM2019_poster_remake_final.pdf

55 Challenges and prospects for the Silicon Tracking System of CBM in the first tests with heavy ions collisions

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)

56 Characterization and operation of the front-end electronics of the CBM Silicon Tracking System

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)

57 Charge dependent flow and the search for the chiral magnetic wave at the LHC with ALICE

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)

201911QMposter_shou.pdf

58 Charge separation in Au+Au collisions at $\sqrt{{\it{s}}_{NN}} = 200$ GeV at STAR

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)

59 Charged particle multiplicity dependence of $\Lambda(1520)$ production in pp collisions at $\sqrt{s}$ = 13 TeV with ALICE at the LHC

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)

60 Charged-particle multiplicity dependence of $\rm K^{*}(892)^{\rm \pm}$ resonance production in pp collisions at $\sqrt{\rm s}$ = 13 TeV with ALICE

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))

QM2019_DPistone.pdf

61 Charged-particle multiplicity dependence of $\Sigma(1385)^{\pm}$ and $\Xi(1530)^{0}$ production in pp collisions at 13 TeV with ALICE at the LHC

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))

20191103_QM2019_Poster_BHLIM_rev3.5.pdf

62 Charged-particle production as function of event multiplicity in ALICE

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))

QM19_PatrickHuhn_final.pdf

63 Charm and beauty isolation in heavy flavor electron measurements in Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV at RHIC

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)

poster_cb2e.pdf

64 Charm baryon production measurements in small systems with the ALICE experiment at the LHC

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))

QM2019CharmBaryon_terrevoli.pdf

65 Charm production in pp and p-Pb collisions with ALICE at the LHC

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)

66 Charmonia production in pPb collisions at LHCb

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))

QM2019_Crkovska_poster.pdf

67 Chiral Kinetic Theory from High Density Effective Theory and Reparametrization Invariance

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)

Aradhya_Quark Matter 19 Poster.pdf

68 Chiral Magnetic Hydrodynamics

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

69 Chiral soliton lattice in dense matter under rotation

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)

70 Chiral Vortices and Pseudoscalar Condensation due to Rotation

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)

Poster_Lingxiao.pdf

71 Cold Nuclear Matter Effects on J/$\psi$ and $\Upsilon$ Productions at RHIC with the STAR Experiment

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)

72 Collective effects in pp collisions with the balance function of the identified particles

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)

poster_QM_Khabanova.pdf

73 Collision energy dependence of the freeze-out in nuclear collisions at RHIC BES and the LHC

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))

QMposter19.pdf

74 Collision-system dependence of charge separation relative to the second- and third-order event planes; Implications for the Chiral Magnetic Effect in STAR

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)

QM18poster_CME_R.pdf

75 Comparison of Chemical freeze-out parameters in p+p, p+Pb, Xe+Xe and Pb+Pb collisions at LHC energies

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))

76 Conserved charge fluctuations at vanishing net-baryon density from Lattice QCD

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)

A01_poster.pdf

77 Constraining Particle Production in Au+Au Collisions at RHIC Energies Using A Multi Phase Transport Model

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))

AMPTPoster_QM2019_v4.pdf

78 Constraining the initial stages of heavy-ion collisions with high-$p_{\perp}$ theory and data

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)

QM19_BI_4.pdf

79 Cross-correlators of conserved charges in QCD

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)

Poster_Parotto_QM19_v2.pdf

80 Curing the numerical Cherenkov instability in 3+1D Glasma simulations

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)

poster.pdf

81 D + meson production as a function of charged- particle multiplicity in pp collisions at √s =13 TeV with ALICE

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))

82 D+ meson production in pp, p--pb and Pb--Pb collisions at √s= 5 TeV with ALICE

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))

83 D-meson production in Pb--Pb collisions with ALICE at the LHC

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))

QM_Poster_2019_v5.pdf

84 D0-meson elliptic flow using event-shape-engineering technique in Au+Au collisions at √sNN = 200 GeV from STAR

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 )

QM19poster_Yue_Final.pdf

85 Data-driven constraints on the drag and diffusion of light partons

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)

QM19_poster_Tianyu.pdf

86 Development and characterization of high-density interconnection technologies for the CBM Silicon Tracking System at FAIR

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)

87 Development of a Muon Chamber System at the CBM Experiment at FAIR

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)

88 Development of Hadron Identification Detector Using MRPC for J-PARC E16 Experiment

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

89 Development of large area silicon pixel detector assembly for heavy-ion collision experiments

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))

QM2019_v2-YPedit_v4.pdf

90 Dielectron Production in Au+Au Collisions at $\sqrt{s_\textrm{NN}}=$ 27 GeV with the STAR Experiment

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)

91 Dielectron production in Au+Au collisions at $\sqrt{s_{\rm {NN}}}=54$ GeV at STAR

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)

ZhenWang_QM19poster_v3.pdf

92 Differential measurements of global polarization of $\Lambda$ hyperon in Au+Au collision at $\sqrt{s_{\mathrm{NN}}}$ = 54.4\ GeV\ with STAR

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)

QM2019_poster_ver11.pdf

93 Dijet invariant mass in pp and p--Pb collisions with ALICE

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))

QM19-Dijet-Inv-Mass-Poster-Oskari-Saarimaki-v7.pdf

94 Directed flow of pions, kaons and protons in Au+Au collisions at $\sqrt{s_{NN}} $= 54.4 GeV in STAR

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)

95 Discharge propagation in GEM detectors

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))

QMposter19.pdf

96 Dissipation and causality in fluids with polarization

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)

97 DREENA framework as a multipurpose tool for QGP tomography

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)

QM19_DZ-DREENAFramework.pdf

98 Dynamical initialization at RHIC-BES energies

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.)

QM2019PosterOtsukaVer.final.pdf

99 Early-Stage Shear Viscosity far from Equilibrium via Holography

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))

Michael_F._Wondrak-QM2019-Wuhan-2019_10_04.pdf

Wondrak,_Michael_F.-Flash-QM2019-Wuhan-2019_11_09.pdf

100 Effect of longitudinal asymmetry on pseudorapidity distributions in Pb-Pb collisions at 5.02 TeV with ALICE

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)

QM-LongAsymm-Poster-Raniwala.pdf

101 Effect of Magnetic field on Electrical Conductivity of QCD Plasma

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)

102 Effect of simulating parity-odd observables in high energy heavy ion collisions on balance functions of charged particles and elliptic flow of pions

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)

103 Effects of hydrodynamic fluctuations on azimuthal flow in ultra-central heavy-ion collisions

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)

poster_kuroki.pdf

104 Electromagnetic field from asymmetric to symmetric heavy-ion collisions at 200 GeV/c

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

105 Electroweak boson and forward jet probes of the initial state in Pb+Pb and p+Pb collisions with ATLAS

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

106 Elliptic flow of electrons from heavy-flavor decays in 54.4 and 27 GeV Au+Au collisions from the STAR experiment at RHIC

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)

QM19poster_v5c.pdf

107 Elliptic flow of electrons from heavy-flavour hadron decays in Pb-Pb collisions at $\sqrt{s_{NN}} = $ 5.02 TeV with ALICE

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)

108 Energy calibration and signal waveform analysis of the CBM Projectile Spectator Detector

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))

QM2019_poster_karpushkin.pdf

109 Enhancement of $\bar\Lambda$ / $\bar{p}$ in central heavy-ion collisions and it's implication for strangeness enhancement at RHIC and SPS energies.

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)

110 Equation of State for BES with EPOS model

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)

111 Event activity dependence of $\Upsilon$ production in p+p collisions at the STAR experiment

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)

QM2019_poster_LK_v13.pdf

112 Event activity, direct photons and photon/hadron ratios in asymmetric collisions

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)

QM19_gdavid.pdf

113 Event anisotropy $v_{2}$ in Au+Au collisions at $\sqrt{s_{NN}}$ = 27 and 54.4 GeV with STAR

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)

QM19_poster_shaowei_v6.pdf

114 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

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))

EventShape_Multiplicity_dependence_phi_v7.pdf

115 Event shape and multiplicity dependence of identified particle production and freeze-out scenario in pp collisions at $\sqrt{s}$ = 13 TeV using PYTHIA8

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))

116 Event-by-Event measurement of charge separation in Pb-Pb collisions at √sNN = 5.02 TeV in ALICE

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))

117 Evolution of jet shapes in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV with the STAR experiment at RHIC

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))

Quark-Matter_2019_poster_Joel-Mazer-354.pdf

118 Evolving Charge Correlations and the Diffusivity of Light Quarks

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

QM2019Poster.pdf

119 Exploring the QCD phase diagram via collision energy dependence of multi-particle Bose-Einstein correlations in Au+Au collisions with PHENIX

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

120 Extracting fluctuation of thermal parameters at freezeout

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)

quarkmatterfinalized.pdf

121 Extracting jet transport coefficient via single hadron and dihadron productions in high-energy heavy-ion collisions

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)

QM2019-poster-xieman.pdf

122 Extracting jet transport parameter $\hat{q}$ from a multiphase transport model}

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)

123 Factorization breaking in transverse momentum from hydrodynamic fluctuations

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)

ポスターQM.pdf

124 First results from hybrid hadronization in small and large systems

“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)

125 First, second, third and fourth flow harmonics of deuterons and protons in Au+Au reactions at 1.23 A GeV

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

Paula_Hillmann_QM_flow.pdf

126 Fixed-target collisions at LHCb

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))

1 1 Poster_QM-2.pdf

127 Flow harmonic power spectrum with ALICE at LHC

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))

QM19_DJKIM-2.pdf

128 Fluctuation dynamics near the QCD critical point

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)

QM2019_DU_POSTER.pdf

129 Fluctuation-dissipation relation and fluctuation theorem for causal hydrodynamic fluctuations

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)

20191102.murase-QM2019-Poster.pdf

130 Fluctuations of anisotropic flow in transport

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)

Poster_QM19_Hendrik_Roch.pdf

131 Forward-backward centrality fluctuation and its influence on experimental observables in heavy-ion collisions

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)

QM2019_poster_v8.pdf

132 Future opportunities of small system scan at RHIC

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)

QM19Poster_Zhenyu.pdf

133 Generalized High Twist Approach to Parton Energy Loss

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)

Flash Talk_YYZ.pdf

134 GLISSANDO 3: the known software tool with new possibilities

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))

QM2019_poster_GS_IS9.pdf

135 Gluon emission from heavy quarks in dense nuclear medium

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)

1F0624D8-A57B-466E-B9E5-2429A3EEC733.pdf

136 Gluon propagator in two-color dense QCD: Massive Yang-Mills approach at one-loop

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)

137 Hadronic resonance production in asymmetric collisions with ALICE at the LHC

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))

qm2019_KstarPhi_rapidity_dependnece_poster.pdf

138 Hanbury-Brown-Twiss radii at 200 GeV using anisotropic hydrodynamics

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)

139 Hard symmetry breaking effects in effective theories of the QCD phase diagram

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)

RishiPosterQM2019.pdf

140 Hawking radiation from acoustic black hole in relativistic heavy-ion collisions

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)

141 High transverse momentum direct photons in p+Au collisions in PHENIX at RHIC

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)

QM2019Poster_High_pT_DirectPhotons_sunzd.pdf

142 Hydrodynamic Attractor in Viscous Hubble Flow

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)

qm2019_zwDU.pdf

143 Hypernuclei Production in CBM at FAIR - A Feasibility Study

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)

QM2019_Lymanets-poster.pdf

144 Identified light flavor particle production in "jetty" and "isotropic" pp collisions at √s = 13 TeV with ALICE at the LHC

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))

2019-nov-01-conference_presentation-qm2019_poster_v4.pdf

145 Inclusive b-jet production with the ALICE detector at the LHC

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))

146 Inclusive diffractive heavy quarkonium photoproduction in pp, pA and AA collisions

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

147 Inclusive jet measurements in p+Au collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV in STAR

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)

QM2019-TongLiu_final.pdf

148 Influence of Initial-state shape deformations in Ultra Central collisions

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)

Peifeng Liu qm19 poster 0.91.pdf

149 Influence of the neutron skin effect on nuclear isobar collisions at RHIC

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

QM19v2.pdf

150 Influences of electromagnetic field characteristics on the CME and CMW measurements

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)

QM19poster_xinli.pdf

151 Initial Conditions of Conserved Charges in Heavy-Ion Collisions

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)

ICCING_Poster_Portrait.pdf

152 Insight into $K^*(892)^{0}$ production in pp collisions as a function of collision energy, event-shape and multiplicity with ALICE at the LHC

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))

quarkmatter_poster_rutuparna.pdf

153 Insight into Multiplicity Dependence of Strangeness and Resonance Production from Small to Large System with ALICE at the LHC

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))

QuarkMatter_poster_Arvind_v6.pdf

154 Investigating the non-flow effect in proton+proton collisions from two-particle correlation using PYTHIA8

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))

155 Ion Backflow Studies for the sPHENIX TPC

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

156 Isolated photon production in pp collisions at $\sqrt{s}=13$ TeV measured with ALICE

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))

157 Isolated Photon-Hadron Correlations in pp and p--Pb Collisions at $\sqrt s_{\rm NN}$ = 5 TeV in ALICE

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))

Quark_Matter_Poster_19_v7.pdf

158 J/$\psi$ elliptic flow at mid-rapidity in Pb--Pb collsions at $\sqrt{s_{NN}}$= 5.02 TeV with ALICE

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))

Jpsi_v2_midy_aneagu.pdf

159 J/$\psi$ production at mid-rapidity in p-Pb collisions with the ALICE detector

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))

qm2019_shayashi_v5.pdf

160 J/psi polarization measurement in Pb-Pb collisions

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))

QM2019_poster_Luca_Micheletti.pdf

161 J/Psi production at forward rapidities in ultra-peripheral collisions in ALICE

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))

QM_poster_v4.pdf

162 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

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))

QM_Poster_Jpsi_Mult_v7.pdf

163 Jet Shapes in pp at $\sqrt s$ = 5 TeV LHC energy in ALICE

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)

164 JETSCAPE 2.0: Towards a complete event generator for heavy ion collisions

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)

165 K0Short and Λ production in p-Pb collision system at 8.16 TeV

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))

2019-nov-01-conference_presentation-meenakshi_qm_2019_poster_v4.pdf

166 Kibble-Zurek scaling near the QCD critical point

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)

Shanjin_QM2019.pdf

167 Kinetics and hydrodynamics close to the chiral limit

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)

168 Lambda and antilambda hyperons polarization in heavy-ion collisions within transport model

$\Lambda$ 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)

portrait_1.pdf

169 Light Nuclei (d, t) Production in Au+Au Collisions at $\sqrt{s_{\mathrm{NN}}}$ = 27 and 54.4 GeV from the STAR experiment

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)

QM19_poster_HuiLiu.pdf

170 Limitations of Principal Component Analysis in Heavy-Ion Collisions

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)

171 Local Lambda polarization and feed-down effect in heavy-ion collisions

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)

Xia-poster.pdf

172 Locating the critical point in QCD phase diagram using heat capacity

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))

173 Long-range azimuthal correlations arising with HBT suppressions in partially coherent pion emissions in AA and pp collisions

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)

Ru_QM19_p.pdf

174 Low mass dielectron studies with the HADES and CBM experiments at GSI/FAIR*

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)

175 Low-$p_{T}$ $\mu^{+}\mu^{-}$ pair production in Au+Au collisions at $\sqrt{s_{_{\rm NN}}}$ = 200 GeV at STAR

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)

QM19_ZhenLiu_v3.pdf

176 Low-mass dielectron measurements in minimum-bias pp collisions at 5.02 TeV with ALICE

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))

2019-oct-30-conference_presentation-poster_lviebach_qm_2019.pdf

177 Machine learning approach for studying of dielectrons from open charm and beauty decays in p-Pb collisions with ALICE at the LHC

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)

PosterLMee_EMeninno_v8.pdf

178 Machine Learning Based Jet $p_{\rm T}$ Reconstruction with Full Jets in ALICE

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))

HBossi_QMPoster.pdf

179 Magnetic Field Induced Polarization Difference between Hyperons and Anti-hyperons

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)

180 MC study of the reconstruction of $\pi^0$ in MPD/ECal

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)

Yan_ECal poster.pdf

181 Measurement of $\text{D}^{0}$ production in d+Au collisions at $\sqrt{s_{\text{NN}}}=200$ GeV by the STAR experiment

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))

QM19poster_kramarik_final.pdf

182 Measurement of $\Xi^{0}_{c}$ baryon in pp collisions with ALICE at the LHC

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))

041119_QM_Xic_5TeV_TiantianCheng.pdf

183 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

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)

QM_Poster_2019_v5.pdf

184 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

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)

QM19poster_Ding_Chen_v7.pdf

185 Measurement of electrons from heavy- flavour hadron decays in proton-proton collisions with ALICE at the LHC

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))

QM_ALICE_SUDHIR_V5.pdf

186 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

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))

poster_HFjetHFE.pdf

187 Measurement of Intermittency for Charged Particles in Au+Au Collisions at $\sqrt{s_{NN}}=7.7-200$ GeV from STAR

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)

QM2019poster-JinWu-STAR-CCNU.pdf

188 Measurement of jet shape observables and their multiplicity dependence in pp collisions at LHC energies with ALICE

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)

189 Measurement of non-flow influence on the CMW-sensitive slope parameter from STAR

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))

190 Measurement of path length-dependent $v_1$ of high-$p_{\mathrm{T}}$ charged hadrons in Au+Au collisions by the STAR experiment

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)

QM2019Poster_highpTv1_ver1f.pdf

191 Measurement of proton-pion mixed cumulants in Au+Au collisions at $\sqrt{s_{NN}}$ = 19.6, 27 and 200 GeV in STAR

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)

192 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

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)

193 Measurement of the Azimuthal Anisotropy of Charged Particle Production in Xe+Xe Collisions at $\sqrt{s_{NN}}$=5.44 TeV with the ATLAS Detector

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

QM19_poster_Pengqi_Yin.pdf

194 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

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)

JpsiRAAin2018PbPb_v6.pdf

195 Measurement of the sixth-order cumulant of net-proton multiplicity distributions from the STAR experiment

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)

tnonaka_QM2019_poster.pdf

196 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

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)

197 Measurements of charge-dependent correlations in Xe-Xe collisions with ALICE

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))

A.Danu_QM19.pdf

198 Measurements of charm and bottom productions via semi-leptonic decays in Au+Au collisions at $\sqrt{s_{\rm NN}}=200$ GeV at STAR

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))

QM19poster_Yingjie.pdf

199 Measurements of HBT correlations and Levy source parameters in Au+Au collisions at the STAR experiment

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)

kincsesd_QM_2019_poster.pdf

200 Measurements of longitudinal flow decorrelations in Xe+Xe collisions with the ATLAS detector

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

201 Measurements of prompt D-meson production in p–Pb collisions with ALICE at the LHC

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))

Qm2019_Poster_SKar_V5.pdf

202 Mechanical design of the sPHENIX MAPS-based vertex detector

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

203 Medium modifications of event shape in high-energy nuclear collisions

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)

204 Meson masses in external magnetic fields from Lattice QCD

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)

QM2019_xdwang.pdf

205 Module and ladder assembly techniques for the Silicon Tracking System of the CBM experiment at FAIR

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)

206 MPD detector for study heavy-ion collisions at NICA: design, performance and construction status

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))

Poster_Babkin_Wuhan_MPD_Detector_v0_1.pdf

207 Multi-harmonic correlations in ALICE

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))

2019-10-31_Mordasini_QM19_ALICE.pdf

208 Multiparticle correlations from the direct calculation of cumulants using particle azimuthal angles

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))

qm2019_tuo.pdf

209 Multiplicity and $\sqrt{s}$ dependent study of jet properties in pp collisions at LHC energies

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))

210 Multiplicity and rapidity dependence of v2 in small system by using two-particle correlations

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))

Poster-A0-QM19_final.pdf

211 Multiplicity dependent charged jet production in pp collisions at $\sqrt{s}=$ 13 TeV

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))

2019-nov-01-conference_presentation-qm2019poster_yhouv4.pdf

212 Multiplicity scaling in the small system within the non-extensive statistical approach

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))

Barnafoldi-Biro-Papp_QM19.pdf

213 Multiplicity-dependent jet shape analysis in pp collisions at $\sqrt{\textit{s}}$ = 13 TeV with ALICE

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)

214 Muon Forward Tracker: adding vertexing capability to the ALICE MUON Spectrometer

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))

qm19poster_yorito.pdf

215 Net-charge fluctuations in pp, p-Pb, Pb-Pb and Xe-Xe collisions with ALICE Detector

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))

216 Net-lambda fluctuations in Pb-Pb collisions at 5.02 TeV in ALICE at the LHC

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))

217 Net-proton number fluctuations in partial chemical equilibrium

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

Paula_Hillmann_QM_fluc.pdf

218 Neutral kaon femtoscopy in Au+Au collisions measured at the STAR experiment

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)

Pawlowska_QM.pdf

219 New Probes for Cold QCD physics with sPHENIX and potential forward upgrades

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

220 Non-Gaussian sources and the shape of the correlation function

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)

poster_Cimerman.pdf

221 Non-prompt $\rm D^{0}$-meson production in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV with ALICE

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))

QM2019Poster_ver2.pdf

222 Non-static properties of the chiral magnetic conductivity

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

HM_poster_QM2019_2.pdf

223 Non-zero chiral and isospin imbalance in QCD phase diagram: dualities in effective models and lattice QCD

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)

Poster_QM_2019_Wuhan.pdf

224 Nuclear dependence of transverse single-spin asymmetry of charged hadrons in polarized p+p, p+Al and p+Au collisions in PHENIX

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)

Jeongsu_QM19_Poster_692.pdf

225 Nuclear modification factor of isolated photon production in pp and PbPb collisions at 5.02 TeV with the CMS detector

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))

226 Nuclear modification of jet shape for inclusive jets and γ-jets at the LHC energies

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)

poster_qm2019 - v4.pdf

227 On the strength of the QCD crossover at small chemical potentials

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)

Poster_Kara_QM19_v2[1].pdf

228 Open Heavy-Flavour and J/psi production in peripheral PbPb collisions at LHCb

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))

Samuel_BELIN_poster_qm2019.pdf

229 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

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))

230 Parametrized equation of state with critical point and first-order phase transition

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)

QM2019poster_y_yoshida.pdf

231 Passive Gating Grid Studies for a Time Projection Chamber

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)

232 Performance evaluation of a Forward Calorimeter for the ALICE upgrade

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))

20191031_Minatover6.pdf

233 Performance evaluation of sensor module for INTT at sPHENIX

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)

234 Performance of the MPD detector for the study of multi-strange baryon production in heavy-ion collisions at NICA

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))

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QM-2019.pdf

235 Performance studies of scintillator tiles for the sPHENIX hadronic calorimeter

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

236 Phase transitions and transport in dense nuclear matter from relativistic density functional theory

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)

AWergieluk_QM2019.pdf

237 PHENIX measurements of Bottom and Charm in A+A collisions

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)

238 PHENIX probing forward/small-x dynamics from hadron production

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)

239 PHENIX results on $J/\psi$ polarization in p+p collisions

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)

240 Phenomenological formulation of relativistic spin hydrodynamics

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)

taya-QM2019poster.pdf

241 Photon identification in the ALICE EMCal using a neural network and template fit

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))

poster-qm2019-final.pdf

242 Photons associated with jets in p-p and A-A collisions

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 wher