Measurement of Angular Distributions of Drell-Yan Dimuons in $p+d$ Interactions at $800\mathrm{GeV}/c$

We report a measurement of the angular distributions of Drell-Yan dimuons produced using an $800\mathrm{GeV}/c$ proton beam on a deuterium target. The muon angular distributions in the dilepton rest frame have been measured over the kinematic range $4.5<m_{\mu \mu }<15\mathrm{GeV}/c^2$, $0<p_T<4\mathrm{GeV}/c$, and $0<x_F<0.8$. No significant $\cos 2\varphi$ dependence is found in these proton-induced Drell-Yan data, in contrast with the situation for pion-induced Drell-Yan data. The data are compared with expectations from models which attribute the $\cos 2\varphi$ 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.

Figure 1

Parameters $\lambda$, $\mu$, $\nu$, and $2\nu -(1-\lambda )$ vs $p_T$ in the Collins-Soper frame. Open circles are for E866 $p+d$ at $800\mathrm{GeV}/c$, crosses are for NA10 ${\pi }^{-}+W$ at $194\mathrm{GeV}/c$, and diamonds are E615 ${\pi }^{-}+W$ at $252\mathrm{GeV}/c$. 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 $M_C=2.4\mathrm{GeV}/c^2$ 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 $800\mathrm{GeV}/c$. The error bars correspond to the statistical uncertainties only.