Measurement of Angular Distributions of Drell-Yan Dimuons in p + d Interaction at 800 GeV/c

TL;DR

This study measures angular distributions of Drell-Yan dimuons from 800 GeV/c proton-deuterium interactions, finding no significant cos2φ dependence and providing constraints on sea-quark transverse-momentum-dependent structure functions.

Contribution

It provides the first detailed angular distribution measurements in proton-induced Drell-Yan and compares results with models involving QCD vacuum effects and Boer-Mulders functions.

Findings

No significant cos2φ dependence observed.

Constraints placed on sea-quark Boer-Mulders functions.

Data contrast with pion-induced Drell-Yan results.

Abstract

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.