Abstract
We present STAR measurements of the azimuthal anisotropy parameter for pions, kaons, protons, , and , along with for pions, kaons, protons, and at midrapidity for Au+Au collisions at and 200 GeV. The values for all hadron species at 62.4 GeV are similar to those observed in 130 and 200 GeV collisions. For observed kinematic ranges, values at 62.4, 130, and 200 GeV are as little as 10–15% larger than those in Pb+Pb collisions at GeV. At intermediate transverse momentum ( from 1.5–5 GeV/), the 62.4 GeV and values are consistent with the quark-number scaling first observed at 200 GeV. A four-particle cumulant analysis is used to assess the nonflow contributions to pions and protons and some indications are found for a smaller nonflow contribution to protons than pions. Baryon is larger than antibaryon at 62.4 and 200 GeV, perhaps indicating either that the initial spatial net-baryon distribution is anisotropic, that the mechanism leading to transport of baryon number from beam- to midrapidity enhances or that antibaryon and baryon annihilation is larger in the in-plane direction.
1 More- Received 6 January 2007
DOI:https://doi.org/10.1103/PhysRevC.75.054906
©2007 American Physical Society