  In this paper, I study final state QCD radiative corrections to off-shell
single top production via decaying $W$ at hadron collider energies. The tree
level Breit-Wigner distribution of the produced top invariant mass is distorted
by final state QCD radiation, while the peak position remains unchanged. The
exact one loop QCD calculation and the narrow width approximation agree in
predicting the cross section, the hadronic transverse energy distribution and
the bottom-lepton invariant mass distribution.
