Jet Production with Polarized Beams at Next-to-Leading Order

The last decade has seen an important advance in our understanding of polarized nucleon structure functions as a result of the analysis of deep inelastic scattering (DIS) data. Unfortunately, the use of DIS data alone does not allow an accurate determination of the polarized parton densities. This is true in particular for the gluon, since this quantity contributes to DIS in leading order (LO) only via the Q-dependence of the spin asymmetry (A 1 ). At variance with DIS, collider physics offers a relatively large number of processes whose dependence upon the gluon density is dominant already at LO. The study of these processes is therefore crucial in order to measure this density in a direct way. Among them, jet production is an obvious candidate, because of the large rates. In order to make reliable quantitative predictions for high-energy processes, it is crucial to determine the NLO QCD corrections to the Born approximation. The key issue here is to check the perturbative stability of the process considered. Only if the corrections are under control can a process that shows good sensitivity to, say, ∆g at the lowest order be regarded as a genuine probe of the polarized gluon distribution and be reliably used to extract it from future data. NLO QCD corrections are expected to be particularly important for the case of jet-production, since it is only at NLO that the QCD structure of the jet starts to play a rôle in the theoretical descrip-