Next-to-leading order QCD corrections to the top quark decay via the Flavor-Changing Neutral-Current operators with mixing effects

Abstract

In this paper detailed calculations of the complete $\mathcal{O}(α_s)$ corrections to top quark decay widths $Γ(t\to q+V)$ are presented ($V=g,γ,Z$). Besides describing in detail the calculations in our previous paper (arXiv:0810.3889), we also include the mixing effects of the Flavor-Changing Neutral-Current (FCNC) operators for $t\to q+γ$ and $t\to q+Z$, which were not considered in our previous paper. The results for $t\to q+g$ are the same as in our previous paper. But the mixing effects can either be large or small, and increase or decrease the branching ratios for $t\to q+γ$ and $t\to q+Z$, depending on the values of the anomalous couplings ($κ^{g,γ,Z}_{\mathrm{tq}}/Λ$, $f^{g,γ,Z}_{\mathrm{tq}}$ and $h^{g,γ,Z}_{\mathrm{tq}}$).

21 pages, 12 figures