The parton momentum distributions of the nucleon and A(_QCD)

Abstract

Next-to-leading order QCD fits are performed to F(_2)(^up), F(_2)(^un)/F(_2)(^up), F(_2)(^uFe) and xF(_3)(^vFe) deep-inelastic scattering data using the F^^ data of either the EMC or BCDMS collaborations, appropriately renormalized for consistency with the re- analysed SLAC F(_2)(^ep) data. The parton distributions from these fits are then used to predict next-to- leading order prompt photon production cross-sections. The variation in the quality of the overall description of the deep-inelastic scattering and prompt photon production data simultaneously determines A(_MS) and the form of the gluon distribution of the proton. Next, cross-sections are predicted at next-to-leading order for the Drell-Yan process. Here, the quality of the overall description determines the antiquark content of the proton. Two sets of parton distributions are presented according to whether the EMC or BCDMS F(_2)(^up) data were used in the analysis. Possible alternatives for the low-x behaviour of the gluon distribution - outside the range of the fitted data - are discussed and predictions are made for future experiments which have the potential to distinguish between these alternatives.