Scaling properties of proton and antiproton production in √s_NN=200 GeV Au+Au collisions

Abstract

We report on the yield of protons and antiprotons, as a function of centrality and transverse momentum, in Au+Au collisions at √s_NN=200 GeV measured at midrapidity by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider. In central collisions at intermediate transverse momenta (1.5<p_T<4.5 GeV/c) a significant fraction of all produced particles are protons and antiprotons. They show a centrality-scaling behavior different from that of pions. The p^- /π and p/π ratios are enhanced compared to peripheral Au+Au, p+p, and e⁺e^- collisions. This enhancement is limited to p_T<5 GeV/c as deduced from the ratio of charged hadrons to π ⁰ measured in the range 1.5<p_T<9 GeV/c.