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

Abstract

We report a measurement of the angular distributions of Drell-Yan dimuons produced using an 800 GeV/c proton beam on a hydrogen target. The polar and azimuthal angular distribution parameters have been extracted over the kinematic range $4.5<m_{\mu \mu }<15$ GeV/c${}^2$ (excluding the ${\rm Y}$ resonance region), $0<p_T<4$ GeV/c, and $0<x_F<0.8$. The $p+p$ angular distributions are similar to those of $p+d$, and both data sets are compared with models which attribute the $\cos 2\varphi$ distribution either to the presence of the transverse-momentum-dependent Boer-Mulders structure function $h_1^{\perp }$ or to QCD effects. The data indicate the presence of both mechanisms. The validity of the Lam-Tung relation in $p+p$ Drell-Yan is also tested.

4 pages, 3 figures

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