Single-top-quark production viaW-gluon fusion at next-to-leading order

Single-top-quark production via $W$-gluon fusion at hadron colliders provides an opportunity to directly probe the charged-current interaction of the top quark. We calculate the next-to-leading-order corrections to this process at the Fermilab Tevatron, the CERN Large Hadron Collider, and DESY HERA. Using a $b$-quark distribution function to sum collinear logarithms, we show that there are two independent corrections, of order $1/\ln {(m}_t^2{/m}_b^2)$ and ${\alpha }_s.$ This observation is generic to processes involving a perturbatively derived heavy-quark distribution function at an energy scale large compared with the heavy-quark mass.