Jet cross sections in polarized photon-hadron collisions

We present a computation of one- and two-jet cross sections in polarized ph oton-hadron collisions, which is accurate to next-to-leading order in QCD. Our results can be used to compute photoproduction cross sections in electr on-proton scattering. To this purpose, we investigate the structure of the polarized Weizsacker-Williams function, where we include a universal, non-l ogarithmic term, neglected in the literature. We construct a Monte Carlo co de, within the framework of the subtraction method, and we use it to study the phenomenology of jet production in the energy range relevant to HERA. I n particular, we investigate the perturbative stability of our results, and we discuss the possibility of constraining polarized parton densities of t he proton and the photon using jet data. (C) 1999 Published by Elsevier Sci ence B.V. All rights reserved.