Measurement of Angular Distributions of Drell-Yan Dimuons in p + d   Interaction at 800 GeV/c
  We report a measurement of the angular distributions of Drell-Yan dimuons produced using an 800 GeV/c proton beam on a deuterium target. The muon angular distributions in polar angle $\theta$ and azimuthal angle $\phi$ have been measured over the kinematic range $4.5 < m_{\mu \mu} < 15$ GeV/c$^2$, $0 < p_T < 4 $ GeV/c, and $0 < x_F < 0.8$. No significant cos$2\phi$ 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 cos$2\phi$ distribution to a QCD vacuum effect or to the presence of the transverse-momentum-dependent Boer-Mulders structure function $h_1^\perp$. Constraints on the magnitude of the sea-quark $h_1^\perp$ structure functions are obtained. 
L.Y. Zhu, J.C. Peng, P.E. Reimer, T.C. Awes, M.L. Brooks, C.N. Brown,   et al