Identified Hadron Compositions in p+p and Au+Au Collisions at High Transverse Momenta at √sNN=200 GeV
We report transverse momentum (pT≤15 GeV/c) spectra of π±, K±, p, p¯, K0S, and ρ0 at midrapidity in p+p and Au+Au collisions at √sNN=200 GeV. Perturbative QCD calculations are consistent with π± spectra in p+p collisions but do not reproduce K and p(p¯) spectra. The observed decreasing antiparticle-to-particle ratios with increasing pT provide experimental evidence for varying quark and gluon jet contributions to high-pT hadron yields. The relative hadron abundances in Au+Au at pT≳8 GeV/c are measured to be similar to the p+p results, despite the expected Casimir effect for parton energy loss.