Energy dependence of transverse particle production from SPS to RHIC

Abstract

Transverse momentum spectra up to 4.5 GeV/c were measured around midrapidity in Pb+Pb collisions at sqrt{s_{NN}}=17.3 GeV, for pi^{+/-}, p, pbar and K^{+/-}, by the NA49 experiment. The nuclear modification factors R_{AA}, R_{AA/pA} and R_{CP} were extracted and are compared to RHIC results at sqrt{s_{NN}}=200 GeV. The modification factor R_{AA} shows a rapid increase with transverse momentum in the covered region. The modification factors R_{AA/pA} and R_{CP} shows a saturation well below unity in the pi^{+/-} channel. The extracted R_{CP} values follow the 200 GeV RHIC results closely in the available transverse momentum range for all particle species, except for pi^{+/-}. For pi^{+/-} above 2.5 GeV/c transverse momentum, the measured suppression is smaller than that observed at RHIC. The K^{+}/pi^{+} and K^{-}/pi^{-} ratios were also extracted from the data and are compared to the 200 GeV RHIC results. The values of the former ratio is above, whereas the values of the latter ratio is slightly below the 200 GeV RHIC points.