Saturation and parton level Cronin effect: enhancement vs suppression of gluon production in p-A and A-A collisions

We note that the phenomenon of perturbative saturation leads to transverse momentum broadening in the spectrum of partons produced in hadronic collisions. This broadening has a simple interpretation as parton level Cronin effect. The effect appears for systems in which saturation is generated by the "tree level" Glauber-Mueller mechanism as well as for those where it results form the nonlinear QCD evolution to high energy. We discuss the relation of this phenomenon to the recent analysis by Kharzeev-Levin-McLerran of the momentum and centrality dependence of particle production in nucleus-nucleus collisions at RHIC.