Particle production
The ratio, R, of the rate of particle production at mid-rapidity in nuclear collisions to that seen in proton-proton collisions, plotted as a function of the particle transverse momentum. This ratio scales the observed production rates in nuclear collisions by the number of nucleon-nucleon collisions, and is 1.0 if there are no effects other than this scaling. In the RHIC data shown here at √sNN = 200 GeV, high-pT particle production is clearly suppressed in central gold-gold collisions, while this suppression is not seen in the deuteron-gold collision data. Left, results for charged hadrons from the STAR experiment; right, π0 production results from PHENIX.