High Transverse Momentum Hadron Spectra at sqrt{s_{NN}}=17.3 GeV, in Pb+Pb and p+p Collisions

Abstract

Transverse momentum spectra up to 4.5 GeV/c around midrapidity of pi^{+/-}, p, pbar, K^{+/-} in Pb+Pb reactions were measured at sqrt{s_{NN}}=17.3 GeV by the CERN-NA49 experiment. The nuclear modification factors R_{AA} for pi^{+/-} and R_{CP} for pi^{+/-},p,pbar,K^{+/-} 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. This indicates that the Cronin effect is the dominating effect in our energy range. The modification factor R_{CP}, in which the contribution of the Cronin effect is reduced, 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, except for pi^{+/-} above 2.5 GeV/c transverse momentum. There the measured suppression is smaller than that observed at RHIC.