Novel tools and observables for jet physics in heavy-ion collisions / 5th Heavy Ion Jet Workshop

21 Aug 2017, 09:00 → 1 Sept 2017, 17:00 Europe/Zurich

4/3-006 - TH Conference Room (CERN)

The deadline for application is currently extended to Aug 11. There is still the possibility for financial support for a limited of participants.

Welcome to the CERN TH institute “Novel tools and observables for jet physics in heavy-ion collisions”, which will be organised together with the 5th Heavy Ion Jet Workshop. The workshop and ensuing institute aims at bringing together theorists and experimentalists interested in jet observables in heavy-ion collisions.

The study of QCD jets and their modifications in the dense environment provided in heavy-ion collisions is motivated by two main aspects. Most prominently, jets serve as perturbative and well-controlled probes of the characteristics of the underlying medium. In this, they complement the physics information obtained by analysing the features of bulk particle production, such as flow observables and heavy-quark measurements. However, the processes underlying jet quenching share many similar features with generic equilibration mechanisms. In this respect, characterizing the medium-modification of the jet substructure may open a window of testing the dynamics responsible for medium collective behaviour, for which there is ample experimental evidence.

The scope of the workshop will span a wide range of topics, striving to connect theoretical ideas with clearly defined observables and exploring the related technical challenges. A focal point of the discussions will also be novel grooming techniques for jet substructure observables. We invite interested participants to reflect on the following points:

• How to extract meaningful information about medium properties from jet measurements, in particular jet substructure?

• What are the physical mechanisms and what are the relevant observables?

• What do we learn from jet grooming and declustering techniques, and what are the right tools?

• What are the prospects for jet measurements in heavy-ion collisions for the future (for example, sPHENIX, HL-LHC)?

The format of the meeting is twofold. We open with a 2,5 day workshop with a relatively dense programme of presentations. The remaining time (2,5 days + 1 week) will be devoted to the TH institute during which the discussion will be organised in working groups whose concrete topics will be guided by the participants’ interests. There will be ample time for informal discussions and collaboration, and we will reconvene sporadically to take the pulse of the ongoing discussions. As a final product of the workshop, we envision a brief report summarising the status of the discussions and a statement of interest for the future that will be finalised during Autumn 2017.

We would like to ask you to provide a few key topics that you would be interested in discussing during the workshop in the registration form in order for us to set up the working groups. Besides, if you wish to give a talk during the workshop, please indicate so during the registration. We encourage the participants to stay at least for one week at the meeting.

We strongly invite you to participate in this collaborative effort in a friendly atmosphere, and look forward to your contribution!

The Institute is funded by CERN and is supported by LPCC .

Registration: There is no registration fee.  Registration will be open until Aug 11, 2017. We can only provide financial support for a limited number of participants.

Organisers: Matteo Cacciari, Leticia Cunqueiro, Yen-Jie Lee, Yacine Mehtar-Tani, Guilherme Milhano, Matthew Nguyen, Dennis Perepelitsa, Konrad Tywoniuk, Marta Verweij, Urs Wiedemann, Korinna Zapp

 

 

THinstitute_introduction.pdf

Welcome_PracticalInformation.pdf

Monday, 21 August

Workshop session: Session 1

Convener: Konrad Tywoniuk (CERN)

1 Welcome

2 Quenching of Hadron Spectra in Heavy Ion Collisions at the LHC

Speaker: Francois Arleo (Laboratoire Leprince-Ringuet)

arleo_THInstitute.pdf

3 Heavy ion jet measurements at RHIC and LHC: a common approach

Speaker: Peter Martin Jacobs (Lawrence Berkeley National Lab. (US))

HIJets_RHIC_LHC_Jacobs_v2.pptx

10:30 Coffee break

Workshop session: Session 2

Convener: Leticia Cunqueiro Mendez (Westfaelische Wilhelms-Universitaet Muenster (DE))

4 Role of flavor and color coherence in the jet quenching

Speaker: Martin Spousta (Charles University)

Spousta_CERN-HIJet-Workshop_20170803.pdf

5 An event-by-event picture for medium-induced jet evolution

Speaker: Edmond Iancu (CEA/IRFU,Centre d'etude de Saclay Gif-sur-Yvette (FR))

Cern2017-Jets.pdf

6 Energy loss of a hard collinear gluon

Speaker: Fabio Dominguez (Universidade de Santiago de Compostela)

DominguezCERN.pdf

12:30 Lunch

Workshop session: Session 3

Convener: Guilherme Teixeira De Almeida Milhano (LIP-Lisbon & CERN TH)

7 Prospects for jet and heavy flavor measurements with sPHENIX

Speaker: Gunther Roland (Massachusetts Inst. of Technology (US))

CERN_Jet_Workshop_sPHENIX.pdf

8 Overview of jet measurements by ATLAS and perspectives

Speaker: Dennis Perepelitsa (University of Colorado Boulder)

dvp-THinstitute-8-21-17.pdf

9 Measurements of jet spectra and jet-particle correlations with CMS

Jet production has long been used as a probe for the hot and dense medium created in collisions of heavy ions at the LHC. As jets traverse the medium, they are expected to lose energy through radiative and collisional processes. These mechanisms are thought to be responsible for the observed suppression of high-pT hadron and jet production, a phenomenon known as "jet quenching". Recent measurements from CMS have shown that observations of jet energy loss in dijet systems is somewhat obfuscated due to varying energy loss magnitudes between leading and subleading jets. By measuring correlations of jets and tracks in a variety of dimensions, information regarding jet energy loss, jet broadening, and particle production can be obtained. We observe substantial modification of jet structure in Pb+Pb collisions relative to pp collisions out to very large distances from the jet axis, as well as differences in energy loss for both leading and subleading jets.

Speaker: Kurt Eduard Jung (University of Illinois at Chicago (US))

cernHIJetWS_kjung_170821.pdf

15:30 Coffee break

Workshop session: Session 3b

Convener: Yen-Jie Lee (Massachusetts Inst. of Technology (US))

10 Heavy Ion physics with the PytHIa8 event generator

We present ongoing efforts to extend the Pythia8 MC event generator to the heavy ion domain. Using the Glauber-Gribov colour fluctuation model, pp collisions are “stacked” to produce heavy ion events. The formalism shows promising results for pA collisions, as well as AA at mid-rapidity. We include medium effects through the microscopic model “Rope Hadronization”, which allows Lund strings to interact when they overlap in impact parameter space.

Speaker: Christian Bierlich (Lund University (SE))

cbierlich.pdf

11 Evolving Rivet and MCPLOTS for heavy ions

Speaker: Jan Fiete Grosse-Oetringhaus (CERN)

JFGO.pdf

Discussion

SubsDiscussion.pptx.pdf

17:30 Reception

Tuesday, 22 August

Workshop session: Session 4

Convener: Matthew Nguyen (Centre National de la Recherche Scientifique (FR))

12 Groomed jet substructures in heavy ion collisions

Speaker: Dr Yang-Ting Chien (Massachusetts Institute of Technology)

groomed_jet_Chien.pdf

13 Probing medium-induced jet splitting and energy loss in heavy ion collisions

Speaker: Chang ningbo

jet substructure.pdf

14 Investigating the Role of Coherence Effects on Jet Quenching in Pb-Pb Collisions at $\sqrt{s_{NN}} =2.76$ TeV using Jet Substructure

Speaker: Nima Zardoshti (University of Birmingham (GB))

NsubJettiness_Zardoshti_Aug17.pdf

10:30 Coffee break

Workshop session: Session 5

Convener: Matteo Cacciari (LPTHE Paris)

15 Sub-Jet observables in Heavy-ion Collisions

Speaker: Liliana Apolinario (Instituto Superior Técnico)

LApolinario.pdf

16 Jet Substructure through Splitting Functions And Mass in pp and PbPb collisions at 5.02 TeV with CMS

We present recent results on measurements of jet substructures using grooming techniques with pp and PbPb data collected with the CMS detector at a center-of-mass energy of 5.02 TeV per nucleon pair. The grooming technique is used to focus on the hard structure of the jet by extracting the two subjets which correspond to the hardest parton splitting. This allows us to study medium-induced gluon emission properties and the evolution of partons through dense QCD matter. The hard jet structure is sensitive to the virtuality evolution of a parton in the medium, as well as the role of (de)coherent gluon emitters. Results and prospects on the transverse momentum balance, mass and angular difference of the two hard subjets over a wide range of jet transverse momentum and various collision centrality selections are discussed.

Speaker: Yi Chen (CERN)

20170822_JetSDMass_HIJetWorkshop_YiChen_v8.pdf

17 Studies of grooming in Heavy Ion Collisions

Speaker: Harry Arthur Andrews (University of Birmingham (GB))

JetGroomingInHIC_TheoryWkshp.pdf

12:30 Lunch break

Workshop session: Session 6

Convener: Yacine Mehtar-Tani (INT, University of Washington)

18 Photon-tagged Jet Fragmentation Functions in pp and PbPb Collisions at 5.02 TeV with CMS

Correlations of electroweak probes, jets and charged particles have been proposed as one of the most power tools to study medium modifications of jet fragmentation function. Measurements of jet fragmentation functions provide strong constraints on the jet quenching mechanisms in heavy ion collisions. Latest measurements of photon-tagged jet fragmentation function in pp and PbPb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV collision energy using the CMS detector data will be reported. These measurements provide information about the substructure of jets in the previous photon+jet azimuthal and momentum correlation studies performed by the CMS experiment. Significant modification of jet fragmentation function is observed in the kinematics ranges studied.

Speaker: Kaya Tatar (Massachusetts Inst. of Technology (US))

170822_jetworkshop2017_KayaTatar.pdf

19 Coherence effects at strong coupling

Speaker: Jorge Casalderrey Solana (University of Oxford)

jcs_HIJTWRKSP.pdf

20 Color coherence in multiple antenna medium radiation

Speaker: Victor Vila Perez (Universidade de Santiago de Compostela (ES))

VilaV_Talk.pdf

15:30 Coffee break

Discussion

Conveners: Leticia Cunqueiro Mendez (Westfaelische Wilhelms-Universitaet Muenster (DE)), Marta Verweij (CERN), Matteo Cacciari (LPTHE Paris)

SubsDiscussion.pptx.pdf

Wednesday, 23 August

Workshop session: Session7

Convener: Dennis Perepelitsa (University of Colorado Boulder)

21 Linear Boltzmann Transport for Jet Propagation in the Quark Gluon Plasma

Speaker: Tan Luo (Central China Normal University)

LBT_TanLuo.pdf

22 JETSCAPE: Quantitative exploration of jet energy-loss in a modular Monte-Carlo framework

Speaker: Shanshan Cao (Lawrence Berkeley National Lab)

JETSCAPE.pdf

23 Towards tomography of quark-gluon plasma using double inclusive di-jets in Pb-Pb collisions

Speaker: Michal Deak (Polish Academy of Sciences (PL))

CERN-5thHIW.pdf

10:30 Coffee break

Workshop session: Session 8

Convener: Urs Wiedemann (CERN)

24 Photon-Jet Correlations in pp and PbPb collisions at 5.02 TeV with CMS

Electromagnetic probes such as photons do not participate in the strong interaction, and thus provide a clean measurement of the initial state in nuclear collisions. Correlations of photons balancing with jets in PbPb collisions constitute the golden channel to study parton energy loss in strongly interacting matter, since the photon not only determines the initial transverse momentum of the balancing parton, but also preferentially selects quark jets. We will present results from pp, pPb, and PbPb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV collision energy, including the high statistics data collected with the CMS detector in the 2015 LHC run. The results include detailed studies of azimuthal and momentum correlations of isolated photons and associated jets, as well as jet $I_{AA}$, as a function of photon $p_{T}$ and collision centrality.

Speaker: Christopher Mc Ginn (Massachusetts Inst. of Technology (US))

jetWorkshop_CFMBosonJet_20170823.pdf

25 Jet-induced medium excitation in gamma-hadron correlation

We use a Linear Boltzmann Transport model (LBT model) coupled to (3+1)D ideal hydrodynamic evolution in real time with fluctuating initial conditions simulate both the transport of jet shower partons and jet-induced medium excitation. In this coupled approach, propagation of energetic shower partons are treated in the Linear Boltzmann transport (LBT) model on the basis of evolving bulk medium information provided by 3+1D hydrodynamic model. Soft partons from both elastic and inelastic processes from the LBT are fed back into the medium as a source term in the 3+1D hydrodynamic. Such source terms in the hydrodynamic will induce medium excitation. With this coupled approach we investigate the hadrons spectrum in the whole transverse momentum region and focus on gamma-hadron to study the effect of jet-induced medium excitations.

Speaker: WEI CHEN (CCNU)

cern_chenwei.pdf

Discussion

SubsDiscussion.pptx.pdf

12:30 Lunch

TH-institute session: Opening

26 Introduction to TH institute

27 Studies of medium response with jets and hadrons, where we are?

Speaker: Yen-Jie Lee (Massachusetts Inst. of Technology (US))

20170823-CERNJetWorkshop_yenjie-v3.pdf

Thursday, 24 August

28 Jet tools from HEP community

Speaker: Philip Coleman Harris (CERN)

PCH_HIJets_CERN.pdf

TH-institute session: Plenary

29 Jet tools from HEP community

Speaker: Philip Coleman Harris (CERN)

PCH_HIJets_CERN.pdf

Friday, 25 August

30 Non-global logarithms in recoil-sensitive observables

Speaker: Dr Dingyu Shao (University of Bern)

CERN_2017_Aug.pdf

31 TH institute recap week 1

Monday, 28 August

32 Week 2 start-up session

Tuesday, 29 August

33 Morning session

Wednesday, 30 August

34 Morning session

Thursday, 31 August

35 Morning session

Friday, 1 September

36 Morning session