Initial-State Interactions and the Drell-Yan Process

Abstract

It is shown that initial-state interactions violate the usual QCD factorization predictions for massive lepton-pair production in leading twist. The initial-state collisions correct $\frac{d\ensuremath{\sigma}}{d{Q}^{2}}d{x}_{\mathrm{F}}$ and also smear the lepton-pair transverse momentum distribution.