Spin dependence of massive lepton pair production in proton-proton collisions - art. no. 014014

We calculate the transverse momentum distribution for the production of mas sive lepton pairs in longitudinally polarized proton-proton reactions at co llider energies within the context of perturbative quantum chromodynamics. For values of the transverse momentum Q(T) greater than roughly half the pa ir mass Q, Q(T) >Q/2, we show that the differential cross section is domina ted by subprocesses initiated by incident gluons, provided that the polariz ed gluon density is not too small. Massive lepton-pair differential cross s ections should be a good source of independent constraints on the polarized gluon density, free from the experimental and theoretical complications of photon isolation that beset studies of prompt photon production. We provid e predictions for the spin-averaged and spin-dependent differential cross s ections as a function of Q(T) at energies relevant for the Relativistic Hea vy Ion Collider at Brookhaven, and we compare these with predictions for re al prompt photon production.