Dr Elizaveta Nazarova (Lomonosov Moscow State University)

Event-by-event Elliptic Flow Fluctuations in PbPb collisions at sqrt{s_NN} = 5.02 TeV with CMS detector

Event-by-event elliptic flow harmonic distributions p(v_2) are measured in PbPb collisions at sqrt{s_NN} = 5.02 TeV using the CMS detector for the integrated p_T range 0.3 < p_T < 3.0 GeV/c and pseudorapidity range |eta|<1.0 . In order to gain insight on the nature of the initial geometry fluctuations, cumulant flow harmonics are calculated from the moments of the v_2 probability distribution p(v_2). A fine-level splitting between the higher-order cumulants is observed. The skewness with respect to the reaction plane is estimated from the cumulants and found to be negative, which suggests a non-Gaussian nature for the initial-state fluctuations, as predicted by hydrodynamic models. These observations suggest a non-Gaussian nature of the initial-state fluctuations. Furthermore, assuming that the flow harmonics are linearly proportional to the initial-state eccentricities, the p(v_2) distributions are fitted using an elliptic power law parametrization to study the initial-state geometry fluctuations.