Parton distributions of the proton.

To obtain improved parton densities of the proton, we present a new global analysis of deep inelastic and related data including, in particular, the recent measurements of F2 at HERA, of the asymmetry of the rapidity distributions of W production at the FNAL pp̄ collider and of the asymmetry in Drell-Yan production in pp and pn collisions. We also incorporate data to determine the flavour dependence of the quark sea distributions. We find that the behaviour of the partons at small x is consistent with the precocious onset of BFKL leading log(1/x) dynamics. We discuss the ambiguities remaining in the gluon distribution. We present improved predictions for W boson (and t quark) production at the FNAL pp̄ collider.