Dependence in nuclear Drell-Yan processes including QCD corrections

In treating leading-order QCD corrections to deep-inelastic scattering and the Drell-Yan process, one assumes that collinear singularities arising from the massless nature of the non-Abelian gauge theory be absorbed into parton distributions through redefinition. It has also been suggested that terms which are not perfectly finite near q/sub perpendicular/ = 0 be suitably exponentiated in the impact-parameter space in order to yield proper predictions on q/sub perpendicular/-dependent effects. These steps may lead to negative partial Drell-Yan cross sections for certain QCD diagrams of order α/sub s/. We modify the formalism developed by Altarelli et al. to ensure that all partial cross sections are non-negative. We use the revised formalism to make predictions on A-dependent effects in the nuclear Drell-Yan process. Our numerical results indicate strongly the potential usefulness of measuring lepton pair production cross sections in a region with a large M/sub μ//sub <+/μ/sup =/ and a large q/sub perpendicular/ so that perturbative QCD theory is expected to play a critical role