Heavy-quark and lepton-pair production on nuclei.

Abstract

We present a description of the [ital A] dependence of heavy-quark and Drell-Yan pair production in hadron-nucleus collisions, based on the Reggeon approach to strong interactions at high energies and the parton model. The same method has been successfully applied to the production of light-quark states. The existence of a new energy scale, which depends on the mass and [ital x][sub [ital F]] of the heavy system, is emphasized. A phenomenological model, which includes both the shadowing corrections to the nucleon structure function and the rescattering of the heavy-quark states, is proposed. The model quantitatively describes the available experimental data on [ital J]/[psi] and heavy lepton-pair production in [ital hA] collisions as well as the European Muon Collaboration effect at low [ital x].