  We present the calculations of the complete next-to-leading order (NLO) QCD
effects on the single top productions induced by model-independent $tqg$
flavor-changing neutral-current couplings at hadron colliders. Our results show
that, for the $tcg$ coupling the NLO QCD corrections can enhance the total
cross sections by about 60% and 30%, and for the $tug$ coupling by about 50%
and 20% at the Tevatron and LHC, respectively, which means that the NLO
corrections can increase the experimental sensitivity to the FCNC couplings by
about 10%$-$30%. Moreover, the NLO corrections reduce the dependence of the
total cross sections on the renormalization or factorization scale
significantly, which lead to increased confidence on the theoretical
predictions. Besides, we also evaluate the NLO corrections to several important
kinematic distributions, and find that for most of them the NLO corrections are
almost the same and do not change the shape of the distributions.
