Flow Components and Initial State CM Fluctuations

Abstract

At the LHC, the strong collective flow is observed in Pb+Pb collisions, as shown by the azimuthal correlations in the transverse-momentum distributions of the produced particles. We calculate flow components in a relativistic fluid dynamical model at constant time freeze out (FO) for massless equilibrated post FO pion gas. Our results indicate that at the LHC the v1 flow is expected to peak at forward rapidities, at the same side and direction as the projectile residue. The effect of initial state center-of-mass rapidity fluctuations is taken into account. In order to better study the transverse-momentum flow dependence, we suggest a new “symmetrized” v1S function; and we also propose a new method to disentangle global v1 flow from the contribution generated by the random fluctuations in the initial state. The result is sensitive to the global initial state, where different parameterizations exist.