Description of fully differential Drell-Yan pair production

We investigate the effects of quark distributions of intrinsic transverse momentum and mass on the unpolarised production of Drell-Yan (DY) pairs. The standard leading-order parton model description has shortcomings: a K-factor is necessary to describe invariant mass spectra and no transverse momentum pT is generated in this scheme. In addition e.g. anti PANDA at FAIR will measure at comparatively low hadron centre-of-mass energies of √(s)∼ 5.5 GeV. Therefore non-perturbative effects are expected to play an important role. To address these issues we study a QCD inspired phenomenological parton model which includes leading-order and next-to-leading order production processes. We show that we can describe DY transverse momentum and invariant mass spectra without the need for a K factor. Finally fixing our phenomenological distributions at available data one aim is to make predictions for DY pair production at anti PANDA.