Flow fluctuations in Pb plus Pb collisions at root s(NN)=5.02 TeV with the ATLAS detector

Authors：Zhou Mingliang; Aaboud M; Aad G; Abbott B; Abdinov O; Abeloos B; Abhayasinghe D K; Abidi S H; AbouZeid O S; Abraham N L; Abramowicz H; Abreu H; Abulaiti Y; Acharya B S; Adachi S; Adam L; Adamczyk L; Adelman J; Adersberger M; Adiguzel A; Adye T; Affolder A A; Afik Y; Agheorghiesei C; Aguilar Saavedra J A; Ahmadov F; Aielli G; Akatsuka S; Akesson T P A; Akilli E; Akimov A V; Alberghi G L; Albert J; Albicocco P; Alconada Verzini M J; Alderweireldt S; Aleksa M; Aleksandrov I N; Alexa C

Source：Nuclear Physics A, 2019, 982: 323-326.

DOI：10.1016/j.nuclphysa.2018.09.012

• Multi-Particle Correlation
• Cumulants
• Heavy-ion
• Flow Fluctuation

Measurements of four-particle cumulants c(n){4} for n = 1, 2, 3, 4 are presented using 470 mu b(-1) of Pb+Pb collisions at root s(NN) = 5.02 TeV with the ATLAS detector at the LHC. These cumulants provide information on the event-by-event fluctuations of single harmonics p(v(n)). For the first time, a negative c(1){4} is observed. The c(4){4} is found to be negative in central collisions but changes sign around 20-25% centrality. This behavior is consistent with a nonlinear contribution to v(4) that is proportional to v(2)(2). c(2){4} and c(3){4} are calculated using two reference event classes in order to investigate the influence of volume fluctuations. Over most of the centrality range, c(2){4} and c(3){4} are found to be negative, while in the ultra-central collisions, c(2){4} changes sign and becomes positive, suggesting a deviation from Gaussian behavior in the event-by-event fluctuation of v(2). The magnitudes of the sign change are also found to be dependent of the event class definition .

• Institution
  中国科学院; 上海交通大学; 清华大学; 香港大学; 香港科技大学; 山东大学; 中国地震局; 香港理工大学; 香港中文大学; 南京大学