Key points are not available for this paper at this time.
We give the general form of the angular distribution of lepton pairs produced in hadron collisions, where each dilepton is assumed to come from the decay of a virtual photon. The Drell-Yan model extended to include parton transverse momentum (with on-shell quarks) is then used to calculate the three coefficients in the distribution.
Collins et al. (Sat,) studied this question.