Measurement of the elliptic flow with multi-particle cumulants in lead-lead collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV with the ATLAS detector at the LHC

We report on a measurement of the anisotropy of charged particle flow in lead-lead collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV with the ATLAS detector at the LHC. The anisotropy is characterized by coefficients of the Fourier expansion of charged particle azimuthal angle distributions measured with respect to the symmetry plane defining the initial configuration of the collision geometry. The Fourier coefficients have been evaluated using multi-particle cumulants calculated with the generating function method. The results on the transverse momentum and pseudorapidity dependence of the elliptic flow ($v_2$) obtained from the two- and four-particle cumulants are presented. Comparison to $v_2$ measurements reported from other experiments is also shown. A reduction of contributions not related to the initial geometry is observed for $v_2$ studied with cumulant expansion of correlations between four particles. Event-by-event fluctuations of the elliptic flow have been also evaluated with multi-particle cumulants and are shown as a function of transverse momentum and the collision centrality.