Nuclear Dependence of Drell-Yan and J/ψ) Production in FNAL E866

We have studied how lepton pairs from decays of heavy-flavoured mesons produced in pA collisions can be used to determine the modifications of the gluon distribution in the nucleus. Since heavy-quark production is dominated by the gg channel, the ratio of correlated lepton pair cross sections from DD and BB decays in pA and pp collisions directly reflects the ratio RgA≡fgA/fgp. We have numerically calculated the lepton-pair cross sections from these decays in pp and pA collisions at SPS, RHIC and LHC energies. We find that ratio of the pA to pp cross sections agrees quite well with the input RgA. Thus, sufficiently accurate measurements could be used to determine the nuclear modification of the gluon distribution over a greater range of x and Q2 than presently available, putting strong constraints on models.