Jet Event Topology as a probe of QGP in heavy-ion collisions Shi-Yong Chen (Central China Normal University) in collaboration with :Ben-Wei Zhang, En-Ke Wang and Wei Dai 2019/4/14 1

Outline: Motivation event shape in pp and PbPb collisions Results and discussion Summary and outlook 2019/4/14 2

Motivation Xin - Nian Wang, M.Gyulassy, PRL68(1992)1480 Quenching of full jet observable is one of the most valuable hard probe, leading and subleading jets, what about the modification of third or forth jets...? Show jet quenching effect manifest itself on global obsverables: event shape. J. KAPUSTA and D. STROTTMAN, PLB (1982) 106 (1) :33-37 G. Hanson, G. S. Abrams, et. al... Phys. Rev. Lett. 35, 1609 2019/4/14 3

Definition of event shape transverse Thrust transverse Sphericity The individual eigenvalues are normalized and ordered such that J. KAPUSTA and D. STROTTMAN, PLB (1982) 106 (1) :33-37 G. Hanson, G. S. Abrams, et. al... Phys. Rev. Lett. 35, 1609 2019/4/14 4

. event shape jet like sphere like both thrust and sphericity describe the isotropy distribution of energy-momentum in a collision final state hadrons and full jets J. KAPUSTA and D. STROTTMAN, PLB (1982) 106 (1) :33-37 G. Hanson, G. S. Abrams, et. al... Phys. Rev. Lett. 35, 1609 2019/4/14 5

event shape measurement in pp: many uses: 1, Fit strong coupling constant; 2, Fit Colour factor; 3, Tuning of Monte Carlos models; 4, Study analytical hadronization models. CDF： thrust, hadrons. arXiv:1103.5143 ALICE: sphericity, charged hadrons. arXiv:1205.3963 ATLAS：sphericity, thrust, jets. arXiv:1206.2135 thrust, sphericity, hadrons. arXiv:1207.6915 CMS: thrust, charged hadrons. arXiv:1102.0068 thrust,charged jets. arXiv:1407.2856 NNLL and NLO+Resummation arXiv: 1001.4082 arXiv: 0709.2709 2019/4/14 6

pp baseline:POWHEG+PYTHIA NLO partonic QCD dijet process: POWHEG The POWHEG BOX is a general computer framework for implementing NLO calculations in shower Monte Carlo programs according to the POWHEG method. Homepage for POWHEG: http://powhegbox.mib.infn.it/ parton shower and hadronization: pythia6 full jets reconstruction: Fastjet our baseline are compare with ATLAS data. S. Alioli, K. Hamilton, P. Nason, C. Oleari and E. Re, JHEP 1104 (2011) 081 2019/4/14 7

pp baseline:POWHEG+PYTHIA our baseline are compared with ATLAS data. arXiv:1206.2135 arXiv:1206.2135 2019/4/14 8

parton energy loss: the radiative energy loss during t1,t2 by probability: gluon radiate spructurm: the collisional energy loss: Hard Thermal Loop calculation Xiao-feng Guo , Xin-Nian Wang Phys. Rev. Lett. 85 (2000) 3591-3594 Ben-Wei Zhang , Xin-Nian Wang Phys. Rev. Lett. 93 (2004) 072301 Medium expansion: 2+1 D viscose hydrodynamic Comput. Phys.Commun 199(2016) 61 2019/4/14 9

event shape in PbPb event selection: the symmetrical characteristic in pp collisions is modified low region: enhancement high region: suppression 2019/4/14 10

event shape in PbPb initial jet prodtion position： the symmetrical characteristic of events may be modified by: initial jet prodtion position： jets transport through QGP with different lengh flavour dependence of parton energy loss 2019/4/14 11

initial jet prodtion position partons produced at central point ：r0(0,0,0) Glauber model the modification for transverse sphericity is slightly weaker 2019/4/14 12

process dependence of event shape: to clarify the modifications from flavour dependence of parton energy loss , we categorize the full events to: quark jets dominant process gluon jets dominant process quark & gluon jets process 2019/4/14 13

process dependence of event shape: Distinct behaviour can be found among these three processes. Gluon jets dominant events are much more spherical. 2019/4/14 14

process dependence of event shape: nuclear modification ratio for these three processes: all the three processes are more spherical, opposite to full process. 2019/4/14 15

number of jets in event: quark jets dominant process: quark & gluon jets process: gluon jets dominant process: the portion for the three process is changed 2019/4/14 16

different energy loss pattern of quark and gluon: previous calculations is based on: other parton energy loss pattern and fit inclusive jet Raa: case 1: hybrid model case 2: Jorge Casalderrey-Solana, Doga Can Gulhan .et .al JHEP10(2014)019 Xiaofang Chen , Hanzhong Zhang , Ben-Wei Zhang, Enke Wang J.Phys. 37 (2010) 015004 2019/4/14 17

different energy loss pattern of quark and gluon: nuclear modification ratio from different energy loss pattern: event shape is sensitive to the portion of quark and gluon jets dominat process, providing opportunity to study flavour dependence of parton energy loss 2019/4/14 18

Summy and outlook transverse Thrust and transverse sphericity can be sucessfully described by POWHEG+PYTHIA distinct behaviour can be found between quark and gluon dominant process medium modification of event shape is sensitive to the portion of quark and gluon jets dominat process, providing opportunity to study flavour dependence of parton energy loss our calculations are base on QCD dijet process, what about boson tagged jets events or heavy flavour jets events? 2019/4/14 19

Thank you for your attention ! 2019/4/14 20