Centrality dependence of identified particle elliptic flow in relativistic heavy ion collisions at root s(NN)=7.7-62.4 GeV

Abstract

Elliptic flow (v(2)) values for identified particles at midrapidity in Au + Au collisions measured by the STAR experiment in the Beam Energy Scan at the Relativistic Heavy Ion Collider at root s(NN) = 7.7-62.4 GeV are presented for three centrality classes. The centrality dependence and the data at root s(NN) = 14.5 GeV are new. Except at the lowest beam energies, we observe a similar relative v(2) baryon-meson splitting for all centrality classes which is in agreement within 15% with the number-of-constituent quark scaling. The larger v(2) for most particles relative to antiparticles, already observed for minimum bias collisions, shows a clear centrality dependence, with the largest difference for the most central collisions. Also, the results are compared with a multiphase transport (AMPT) model and fit with a blast wave model.