Single-top-quark production via q qbar -> t bbar

We consider single-top-quark production via the weak process $q\bar q to t\bar b$ at hadron colliders. This process may provide the best measurement of the magnitude of the Cabbibo-Kobayashi-Maskawa matrix element $V_{tb}$. We show that a signal can potentially be observed at the Fermilab Tevatron with 3 $fb^{-1}$ of integrated luminosity. In contrast, the signal is masked at the CERN Large Hadron Collider by top-quark pair production and single-top-quark production via $W$-gluon fusion.