Scaling properties of azimuthal anisotropy of mesons and baryons at RHIC

Abstract

Detailed measurements of the azimuthal anisotropy (\v2) for identified charged particles are reported as a function of transverse momentum ($p_T$) and centrality for Au+Au collisions at \sqrtsNN = 200 GeV. The measurements indicate clear evidence for eccentricity and particle flavor scaling over a broad range of centralities and transverse rapidity $y_T$, indicating a hydrodynamical origin of the fine structure of azimuthal anisotropy at RHIC. The observed scaling supports the picture of a suddenly hadronizing (recombining) fluid of quarks. An apparent breaking of flavor scaling at relatively large values of $y_T$ points to an important change in the mechanism for particle emission.