Measurement of $v_{n}$ coefficients and event plane correlations in 2.76 TeV Pb-Pb collisions with ATLAS

Abstract

Measurements of flow harmonics $v_1-v_6$ are presented in a broad range of transverse momentum and centrality for $\sqrt{s_{NN}} = 2.76$ TeV Pb-Pb collisions with the ATLAS experiment. The fourier coefficients of two-particle correlations are shown to factorize as products of the single particle $v_n$ for $n=2-6$. The factorization breaks for $n=1$ due to effects of global momentum conservation. The dipolar $v_1$ associated with the initial dipole asymmetry is extracted from the two-particle correlations via a two component fit that accounts for momentum conservation. The magnitude of the extracted dioplar $v_1$ is comparable to $v_3$. Measurements of correlations between harmonic planes of different orders, which give additional constraints on the initial geometry and expansion mechanism of the medium produced in the heavy ion collisions, are also presented.