Transverse single spin asymmetries in photon production

Abstract

Transverse single-spin asymmetries (SSA) in inclusive reactions are now considered to be directly related to the transverse momentum ${\mathbf{k}}_T$ of the fundamental partons involved in the process. We find that the ideal probe to extract information on the gluon Sivers function is the transverse SSA of prompt photon production $p{p}^{\uparrow }\to \gamma X$, at large $p_T$. The following related processes, $p{p}^{\uparrow }\to \gamma +jet+X$, $p{p}^{\uparrow }\to {\gamma }^{\ast }+X\to {\mu }^{+}{\mu }^{-}+X$ and $\bar{p}{p}^{\uparrow }\to \gamma +X$ are also briefly discussed.

9 pages, 1 figure, to appear Physics Letters B