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 ${\mathit{F}}_2$ at DESY HERA, of the asymmetry of the rapidity distributions of ${\mathit{W}}^{\pm }$ production at the Fermilab pp¯ collider and of the asymmetry in Drell-Yan production in pp and pn collisions. We also incorporate data to determine the flavor dependence of the quark sea distributions. We find that the behavior of the partons at small x is consistent with the precocious onset of BFKL leading ln(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 Fermilab pp¯ collider.