Photoproduction of High -PT Jets in Next-to-Leading Order QCD

Theh photoproduction of high pt jets at HERA energies is considered in next-to-leading order perturbative QCD. The cancellation of O(\α_em\α^2_S) dependence of the cross section on the factorisation scale M_\γ of the collinear singularities of the photon is shown explicity to occur when the direct and resolved photon terms are both considered. A detailed numerical analysis is presented and compared with previous studies, showing that the theoretical predictions are affected by large uncertainties related to the poorly known photon structure functions. Sizeable numerical differences in the analyses published so far are also emphasized.