Azimuthal angle dependence of dijet production in unpolarized hadron scattering

Zhun Lu and Ivan Schmidt

Phys. Rev. D 78, 034041 – Published 29 August 2008

Abstract

We study the azimuthal angular dependence of back-to-back dijet production in unpolarized hadron scattering $H_{A} + H_{B} \to J_{1} + J_{2} + X$ , arising from the product of two Boer-Mulders functions, which describe the transverse spin distribution of quarks inside an unpolarized hadron. We find that when the dijet is of two identical quarks ( $J_{q} + J_{q}$ ) or a quark-antiquark pair ( $J_{q} + J_{\bar{q}}$ ), there is a $\cos δ ϕ$ angular dependence of the dijet, with $δ ϕ = ϕ_{1} - ϕ_{2}$ , and $ϕ_{1}$ and $ϕ_{2}$ are the azimuthal angles of the two individual jets. In the case of $J_{q} + J_{q}$ production, we find that there is a color factor enhancement in the gluonic cross section, compared with the result from the standard generalized parton model. We estimate the $\cos δ ϕ$ asymmetry of dijet production at RHIC, showing that the color factor enhancement in the angular dependence of $J_{q} + J_{q}$ production will reverse the sign of the asymmetry.