High pT Suppression in CuCu Collsions at 200 GeV/NN at RHIC

Abstract

Collisions between hadronic systems at relativistic energies provide a window on the small-x gluon distributions of fast moving nuclei. It has been predicted that gluon saturation effects will manifest themselves as a suppression in the transverse momentum (pT) distribution at a scale which is connected with the rapidity of the measured particles. Saturation effects are most evident at large (pseudo)-rapidity, i.e., at small angles relative to the beam direction. The dependence of the nuclear modification factor on the number of participants provides a constraint on the mechanism underlying the high-pT suppression. Here we present results for the nuclear modification factor Rcp at forward rapidity as a function of system mass comparing results from CuCu, AuAu and dAu collsions at 200 GeV/NN.