Abstract
We report a measurement of the angular distributions of Drell-Yan dimuons produced using an proton beam on a hydrogen target. The polar and azimuthal angular distribution parameters have been extracted over the kinematic range (excluding the resonance region), , and . The angular distributions are similar to those of , and both data sets are compared with models which attribute the distribution either to the presence of the transverse-momentum-dependent Boer-Mulders structure function or to QCD effects. The data indicate the need to include QCD effects before reliable information on the Boer-Mulders function can be extracted. The validity of the Lam-Tung relation in Drell-Yan data is also tested.
- Received 27 November 2008
DOI:https://doi.org/10.1103/PhysRevLett.102.182001
©2009 American Physical Society