Measurement of Decay Angular Distributions of Drell-Yan Events for p- d Interaction at 800 GeV/c

We report preliminary results from a measurement of the angular distributions of Drell‐Yan dimuons produced using an 800 GeV/c proton beam on a deuterium target. No significant cos2φ dependence is found in these proton‐induced Drell‐Yan data, in contrast to the situation for pion‐induced Drell‐Yan. The data are compared with expectations from models which attribute the cos2φ distribution to a QCD vacuum effect or to the presence of the transverse‐momentum‐dependent Boer‐Mulders structure function h1.