We calculated the next-to-leading order (NLO) QCD corrections to the cross sections for direct top quark productions induced by model-independent flavor-changing neutral current couplings at hadron colliders. The NLO results increase the experimental sensitivity to the anomalous couplings. Our results show that the NLO QCD corrections enhance the leading order (LO) total cross sections at the Tevatron Run 2 about $60\%$ for both ${\kappa }_{tc}^g$ and ${\kappa }_{tu}^g$ couplings, and enhance the LO total cross sections at the LHC about $40\%$ for ${\kappa }_{tc}^g$ couplings and $50\%$ for ${\kappa }_{tu}^g$ couplings, respectively. Moreover, the NLO QCD corrections vastly reduce the dependence of the total cross sections on the renormalization or factorization scale, which leads to increased confidence in predictions based on these results.

• Received 1 August 2005

DOI:https://doi.org/10.1103/PhysRevD.72.074018