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

TL;DR

The data are compared with expectations from models which attribute the cos2phi distribution to a QCD vacuum effect or to the presence of the transverse-momentum-dependent Boer-Mulders structure function h{1}{perpendicular}.

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 $θ$ and azimuthal angle $φ$ have been measured over the kinematic range $4.5 < m_{μμ} < 15$ GeV/c$^2$, $0 < p_T < 4 $ GeV/c, and $0 < x_F < 0.8$. No significant cos$2φ$ 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$2φ$ 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.

Figures (3)

• Figure 1: Parameters $\lambda, \mu, \nu$ and $2\nu - (1-\lambda)$ vs. $p_T$ in the Collins-Soper frame. Solid circles are for E866 $p+d$ at 800 GeV/c, crosses are for NA10 $\pi^- + W$ at 194 GeV/c, and diamonds are E615 $\pi^- + W$ at 252 GeV/c. The error bars include the statistical uncertainties only.
• Figure 2: Parameter $\nu$ vs. $p_T$ in the Collins-Soper frame for three Drell-Yan measurements. Fits to the data using Eq. 3 and $M_C=2.4$ GeV/c$^2$ are also shown.
• Figure 3: Parameter $\nu$ vs. $m_{\mu\mu}$, $x_F$, $x_1$, and $x_2$ in the Collins-Soper frame for $p+d$ at 800 GeV/c. The error bars correspond to the statistical uncertainties only.