CMS results on collectivity in PbPb collisions at √sNN = 2.76 and 5.02 TeV

University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia

^a e-mail: Jovan.Milosevic@cern.ch

Published online: 3 August 2018

Abstract

Nonlinear response coeffcients of higher-order vn anisotropy harmonics for charged particles, as a function of transverse momentum (pT) and collision centrality, are measured in PbPb collisions at √sNN = 2.76 and 5.02 TeV. The nonlinear response coefficients are obtained using vn harmonics measured with respect to their own plane and the mixed harmonics. Using a fine splitting between v₂{4} and v₂{6} cumulants, the centrality dependence of the elliptic flow skewness is measured at 5.02 TeV PbPb collisions. The CMS also measured the v₂ and v₃ anisotropy harmonics of charged particles and prompt D⁰ mesons at |y| ≤ 1 as a function of pT and centrality in PbPb data at √sNN = 5.02 TeV collected with the CMS detector. Prompt D⁰ mesons, formed from the c quarks produced via initial hard scatterings, are separated up to a high extent from nonprompt D⁰ mesons emerged from decays of b hadrons. The results indicate that the charm quarks interact strongly with the QGP medium. Comparisons between theoretical models and data provide new constraints on the initial-state conditions and the interaction between charm quarks and the QGP medium.