Small$-x$ Resummation Effects in Electroweak Processes

Abstract

We investigate small$-x$ resummation effects in QCD coefficient functions for $Z_0g$ and $Wg$ fusion processes, and we compare them with the known ones of $\gamma g$ type. We find a strong process dependence, that we argue to be due to the possible presence of collinear singularities for either small or large $\k$ of the exchanged gluon. For top quark production, we find that the $gg\ra t\bar{t}$ and $Z_0g\ra t\bar{t}$ channels have larger resummation enhancements than the $Wg\ra t\bar{t}$ one.