Low-Mass Drell-Yan Pairs at RHIC and LHC

Abstract

We summarize the calculation of Drell-Yan transverse-momentum distributions using QCD perturbation theory. In particular, the transversemomentum spectrum of low-mass Drell-Yan pairs is calculated with all-order resummation. We demonstrate that the transverse-momentum distribution of low-mass Drell-Yan pairs is an advantageous source of constraints on the gluon distribution and its nuclear dependence. We argue that low-mass Drell-Yan pairs in the forward region provide a good and clean probe of small-x gluons at RHIC and LHC.