Figure. Upper panel: h- pT spectra for the 5% most central Au+Au collisions at midrapidity (|eta| < 0.1) for several systems. The curves are power-law fits to the data. Lower panel: ratio of STAR and scaled UA1 pT distributions.

The multiplicity and inclusive single particle p_T distributions of hadrons are important tools for understanding the evolutionary path of the system created in heavy-ion collisions and help to determine the characteristics of the early, hot, and dense phase.

Particle production was studied in Au+Au collisions at sqrt(s_nn) = 130 GeV at STAR through the yield of primary negative hadrons, comprising mostly pi- and an admixture of K- and pbar. The h- distribution includes the products of strong and electromagnetic decays. Negatively charged hadrons were studied in order to exclude effects due to participant nucleons. The particle production per participant in central Au+Au collisions at sqrt(s_nn) = 130 GeV increases by 38% relative to pbarp and 52% compared to nuclear collisions at sqrt(s_nn) = 17 GeV. The p_T distribution is harder than that of the pbarp reference system for the p_T < 2 GeV/c (see upper panel in the Figure). Scaling of produced particle yield with the number of participants shows a strong p_T dependence, with wounded nucleon scaling achieved only at the lowest measured p_T (see lower panel in the Figure).

Positive charged particles were also analyzed, and for the 5% most central collisions, STAR measures a total charged multiplicity density of dN_ch/deta|_eta=0 = 567 +- 1(stat) +- 38(syst). This result should be compared to the PHOBOS measurement of dN_ch/deta|_|eta|<1 = 555 +- 12(stat) +- 35(syst) for the 6% most central collisions and to the PHENIX measurement of dN_ch/deta|_eta=1 = 622 +- 1(stat) +- 41(syst) for the 5% most central collisions.