Saturation of azimuthal anisotropy in Au+Au collisions at √s_NN=62-200 GeV

Abstract

New measurements are presented for charged hadron azimuthal correlations at midrapidity in Au+Au collisions at √s_NN=62.4 and 200 GeV. They are compared to earlier measurements obtained at √s_NN=130 GeV and in Pb+Pb collisions at √s_NN=17.2 GeV. Sizeable anisotropies are observed with centrality and transverse momentum (p_T) dependence characteristic of elliptic flow (v₂). For a broad range of centralities, the observed magnitudes and trends of the differential anisotropy, v₂(p_T), change very little over the collision energy range √s_NN=62-200 GeV, indicating saturation of the excitation function for v₂ at these energies. Such a saturation may be indicative of the dominance of a very soft equation of state for √s_NN~60-200 GeV.