Measurements of identified particles at intermediate transverse momentum in the STAR experiment from Au+Au collisions at sqrt{s_{NN}}=200 GeV

Abstract

Data for Au+Au collisions at sqrt{s_{NN}}=200 GeV are analyzed to determine the ratios of identified hadrons ($\pi$, $K$, $p$, $\Lambda$) as functions of collision centrality and transverse momentum ($p_T$). We find that ratios of anti-baryon to baryon yields are independent of $p_T$ up to 5 GeV/c, a result inconsistent with results of theoretical pQCD calculations that predict a decrease due to a stronger contribution from valence quark scattering. For both strange and non-strange species, strong baryon enhancements relative to meson yields are observed as a function of collision centrality in the intermediate $p_T$ region, leading to $p/\pi$ and $\Lambda$/K ratios greater than unity. The increased $p_T$ range offered by the $\Lambda$/K$^{0}_{S}$ ratio allows a test of the applicability of various models developed for the intermediate $p_{T}$ region. The physics implications of these measurements are discussed with regard to different theoretical models.