Elliptic Flow of Identified Hadrons in Au+Au Collisions at sqrt(s_NN) = 200 GeV
The anisotropy parameter v_2, the second harmonic of the azimuthal particles distribution, has been measured with the PHENIX detector in Au+Au collisions at sqrt(s_NN) = 200 GeV for identified and inclusive charged particles at central rapidities (|eta| < 0.35) with respect to the reaction plane defined at high rapidities (|eta| = 3-4). The v_2 for all particles reaches a maximum at mid-centrality, and increases with p_T up to 2 GeV/c and then saturates or decreases slightly. Our results depart from hydrodynamically predicted behavior above 2 GeV/c. A quark coalescence model is also investigated.