Isolated-photon production in polarized pp collisions Original Research Article

We perform a detailed study of the production of isolated prompt photons in polarized hadronic collisions, in the centre-of-mass energy range relevant to RHIC. We compare the results obtained for a traditional cone-isolation prescription, with those obtained by imposing an isolation condition that eliminates any contribution to the cross section from the fragmentation mechanism. The latter prescription will allow us to present the first fully consistent next-to-leading order calculation in polarized prompt-photon production. We will discuss the theoretical uncertainties affecting the cross section, addressing the issue of the reliability of the perturbative expansion, for both inclusive isolated-photon and photon-plus-jet observables. Finally, we will study the dependence of our predictions upon the polarized parton densities, and the implications for the measurability of the gluon density.