The 4th International Workshop on QCD Collectivity at the Smallest Scales

24 Jun 2024, 07:07 → 28 Jun 2024, 19:07 Asia/Shanghai

Qingdao Haitian Financial Center Hotel, Qingdao, China

Zhenyu Chen (Shandong University (CN))

The 4th edition of the International Workshop on QCD Collectivity at the Smallest Scales will be held June 24-28, 2024 in Qingdao. The workshop is organized by the institute of frontier and interdisciplinary science, Shandong University. It is dedicated to bring together experimentalist and theorist to discuss the recent experimental results and theoretical developments, to improve our understanding of collectivity in small systems, and to explore the future opportunities. 

The main topics of focus will be:

• Towards a universal paradigm of collectivity from small to large systems
• Solving the ‘puzzle’ of parton energy loss in small systems
• Collectivity as a tool for nuclear structure of small sized nuclei
• Opportunities & predictions for coming LHC runs and future colliders

 

Local Organizing Committee

Zhenyu Chen (Chair, Shandong University)

Li Yi (Shandong University)

Maowu Nie (Shandong University)

Yaxuan Qiao (Shandong University)

 

Monday 24 June

1 Welcom

Speaker: Zhenyu Chen (Shandong University (CN))

Welcome_v1.pdf

2 Experimental overview - RHIC

Speaker: Fuqiang Wang (Purdue University (US))

fqwang.pdf

fqwang.pptx

10:05 Coffee and photo

3 Experimental overview - LHC

Speaker: You Zhou (Niels Bohr Institute (DK))

YouZhou_Qingdao.pdf

4 Hyperon polarization in pPb collisions

Speaker: Chenyan Li (Shandong University (CN))

chenyan_20240624.pdf

11:55 Lunch

5 Dynamical core-corona initialization in small colliding systems

Speaker: Tetsufumi Hirano

hirano.pptx

6 Hydro Overview 2

Speaker: Huichao Song

06_Small-systems2024-HSONG.pdf

15:20 Coffee

7 EPOS Overview

Speakers: Klaus WERNER (subatech), Klaus WERNER

qingdao.pdf

8 AMPT Overview

Speaker: Zi-Wei Lin (East Carolina University)

08_qingdao-ampt-june2024.pdf

9 Collectivity in small systems from a multi-phase transport model point of view

The striking collectivity like behavior found in high-multiplicity proton-proton (pp) collisions and ultra-peripheral collisions (UPC) at the LHC challenges our conventional wisdom on the formation of the quark-gluon plasma (QGP). A microscopic explanation to the origin of collectivity in these collision systems at rather small scales will help us understand the mechanism that leads to the QGP-like signals in small systems. In our recent work, we have coupled PYTHIA8 initial conditions with sub-nucleon spatial fluctuations to the final state parton and hadron interactions and quark coalescence of the string melting AMPT model to study the small system collective effects. In this approach, the AMPT initial condition originally provided by HIJING is replaced by the PYTHIA/Angantyr model and includes the sub-nucleon structure for the struck nucleon and photon. We have found that the collective flow features in small collision systems can be well described by the AMPT model with sub-nucleon spatial fluctuation, indicating its importance for the small system evolution. In this talk, we will present these model results and comparisons to the experimental data.

Speaker: Dr Liang Zheng (China University of Geosciences (CN))

09_liangzheng_smallsystem_talk.pdf

09_liangzheng_smallsystem_talk.pptx

10 Discussion

Tuesday 25 June

11 PYTHIA Overview

Speaker: Leif Lönnblad (Lund University (SE))

Qingdao24.pdf

12 Initial State Overview

Speaker: Oscar Garcia-Montero

IC_Summary_OGM.pdf

10:20 Coffee

13 Collectivity in DIS/photo-production/UPC

Speaker: Nicole Lewis (Rice University (US))

Nicole_Lewis_Qingdao.pdf

14 Collectivity in e+e- (remote)

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

20240625-SmallSystemWorkshop_yenjie_v6.pdf

12:00 Lunch

15 Collectivity in jets: exp

Speaker: Austin Alan Baty (University of Illinois Chicago)

QCD_Collectivity_2024Qingdao_Baty.pdf

16 Collectivity in jets: theory (remote)

Speaker: Wenbin Zhao (Wayne State University)

Wenbin_Zhao_small_system_workshop.pdf

17 Investigating the elliptic anisotropy of hard probes in small collision systems

Speaker: Siyu Tang (Central China Normal University CCNU (CN))

15:40 Coffee

18 Understanding non-flow in small systems talk1

Speaker: Mr Yicheng Feng (Purdue University)

19 Understanding non-flow in small systems talk2

Speaker: Sanghoon Lim (Pusan National University (KR))

20 Understanding non-flow in small systems talk3

Speaker: Jiangyong Jia (Stony Brook University (US))

21 Discussion

Wednesday 26 June

22 OO and nuclear structure in small systems

Speaker: Shengli Huang

QindaoHuang6.pdf

23 Impact of nuclear structure on collectivity in small collision systems

Speaker: Chunjian Zhang (Stony Brook University)

smallSystem_CZhang_2024.pdf

24 Mapping of the nuclear structure on the small and medium-sized systems via collectivity

Speakers: Xinli Zhao (Shanghai Institute of Applied Physics, Chinese Academy of Scien), Xinli Zhao

O-Ne-ampt-xinlizhao.pdf

25 Theory overview of nuclear structure in small system

Speaker: Giuliano Giacalone (Universität Heidelberg)

Qingdao_Giacalone.pdf

10:35 Coffee

26 Speed of sound: exp

Speaker: Cesar Bernardes (UNESP - Universidade Estadual Paulista (BR))

slides_smallsystems_workshop_Qingdao2024.pdf

27 Speed of sound: theory1

Speaker: Dr Wilke Van Der Schee (CERN)

Talk_Qingdao.pdf

Talk_Qingdao.pptx

28 Speed of sound: theory2

Speaker: Govert Hugo Nijs (CERN)

trajectumtalk.pdf

12:10 Lunch and free afternoon

Thursday 27 June

29 Flow decorrelation in small systems

Speaker: Yuko Sekiguchi (University of Tokyo (JP))

SmallsystemWS_YS_20240623_corrected.pdf

30 3D modeling of small system collisions from RHIC to LHC

Speaker: Chun Shen (Wayne State University)

smallSystem3D_Shen.key

smallSystem3D_Shen.pdf

10:20 Coffee

31 Jet quenching in small sized systems: exp

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

Jacobs_JetsSmallSystems.pdf

Jacobs_JetsSmallSystems.pptx

32 Multiparticle vn at high pT in small system from CMS

Speaker: Rohit Kumar Singh (Indian Institute of Technology Madras (IN))

04_Small_systems_talk_final.pdf

33 Jet quenching and RAA in small systems: theory

Speaker: Isobel Kolbe (University of the Witwatersrand (ZA))

05_240627_Qingdao_Kolbe.pdf

12:30 Lunch

34 Heavy flavor production and collectivity in small system: exp

Speaker: Wei Xie (Purdue University (US))

talk_Wei_Xie_CollSmallSys.pdf

talk_Wei_Xie_CollSmallSys.pptx

35 Study of Upsilon(1S) flow in CMS

The second-order Fourier coefficients ($v_{2}$) are expected to reflect the overlap region of colliding heavy ions. However, a non-zero $v_{2}$ has been observed in high-multiplicity pp and pPb collisions where overlap does not exist. The CMS experiment collected data at a nucleon-nucleon center-of-mass energies 5.02 and 8.16 TeV for PbPb and pPb collisions, respectively. The dimuons were used to reconstruct the $\Upsilon$(1S) mesons. The Q-vector method is used for PbPb collisions while the long-range two-particle correlation technique is used for pPb collisions. The measurement of the $\Upsilon$(1S) $v_{2}$ is reported for both heavy ion and small collision systems. The results are discussed in the context of collectivity and modification of heavy quark dynamics.

Speaker: Kisoo Lee (Korea University (KR))

20240627_QCDinSS_KisooLee.pdf

36 Measurements of quarkonia suppression in small system in CMS with LHC Run2 data

Quarkonium production in small systems has been extensively studied in LHC and RHIC to understand the suppression effects which may be described by the existence of a small QGP droplet. To further elaborate, it is necessary to obtain experimental data where models can describe the suppression from the hot medium effect and the cold nuclear matter effect. In this talk, we present recent studies of quarkonia in CMS using pp and pPb collision data taken from LHC in Run 2. We will focus on the nuclear suppression $R_{\rm pPb}$ for charmonia and bottomonia and compare our results with theoretical model predictions.

Speaker: Soohwan Lee (Korea University (KR))

SmallSystem_Qingdao_v2.pdf

15:20 Coffee

37 Study of quarkonia suppression in pO and OO with SHINCHON MC

Speaker: Yongsun Kim (Sejong University (KR))

2024.06.27 small system workshop yongsun.kim v6.pdf

38 charmonium collective flows in nuclear collisions: (directed, elliptic, triangular) flows

We employ a detailed transport model coupled with realistic hydrodynamics in heavy-ion collisions to study the anisotropic flows of charmonium, including directed flow, elliptic flow, and triangular flows. The directed flow ($v_1$) of $J/\psi$ is induced by the rapidity-odd initial energy density, which arises from the rotation of the quark-gluon plasma (QGP). Meanwhile, the elliptic flow ($v_2$) of $J/\psi$ primarily depends on two factors: the initial spatial energy density in the nuclear collision region and the degree of thermalization of charm kinetics. The triangular flow of $J/\psi$ originates from the triangular flows of charm quarks, which acquire anisotropic flows from the surrounding bulk medium with fluctuating initial energy densities. These anisotropic flows ($v_1, v_2, v_3$) of $J/\psi$ contribute to our understanding of the detailed evolutions of charm and charmonium in the fluctuating and rotational QGP.

Speaker: Baoyi Chen (Tianjin University)

baoyi--4th-collectivity.pdf

39 Discussion

40 Banquet

Friday 28 June

41 Anisotropic flow and the valence quark skeleton of hadrons

Speaker: Hong Zhang

01_20240628_Qingdao_HongZhang.pdf

42 Unraveling QGP and jet physics via perturbing attractors

The rapid longitudinal expansion characteristic of heavy-ion collisions leads to universal attractor behavior of the resulting drop of Quark-Gluon Plasma already at very early times. Assuming approximate boost invariance, we incorporate transverse dynamics and parton evolution by linearizing the Mueller-Israel-Stewart theory around the attractor. This yields a system of coupled ordinary differential equations which describe the proper-time evolution of perturbations encoding the transverse structure of the initial and jet energy deposition across a wide range of geometric configurations and parton energy loss scenarios. The late-time asymptotic behavior of the solutions is described by transseries which manifest the stability of the attractor against transverse perturbations, as well as a dominant power-law series attributed to the parton source. Although most of the physically relevant initial information resides in the exponentially suppressed transseries corrections to the evolution along the attractor, they are not yet negligible at freeze-out. These findings advocate for a simple numerical approach to QGP dynamics which accounts for the transverse dynamics and jet-medium interactions via a finite set of Fourier modes. Physical observables can be expressed in terms of the asymptotic data evaluated at freeze-out. We demonstrate the efficacy of this approach in describing key observables such as collectivity across various system scales, as well as the consequential effects of jet wakes.

Speaker: Xin An (National Center for Nuclear Research)

XA_SDU.pdf

43 Multi-particle cumulants from transverse momentum conservation and flow

Speaker: Jialin Pei (Fudan University)

10:40 Coffee

44 EicC Overview

Speaker: yuxiang zhao

04_Yuxiang_EicC_physics_detector.pdf

45 Closing remarks

Speaker: Zhenyu Chen (Shandong University (CN))

WechatIMG159.jpg

12:00 Lunch