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

TL;DR

This paper calculates the complete next-to-leading order QCD corrections to top quark decay via flavor-changing neutral-current operators, including mixing effects, which significantly impact decay branching ratios depending on anomalous couplings.

Contribution

It provides detailed NLO QCD corrections to top FCNC decays, incorporating mixing effects of operators, extending previous calculations and offering more accurate predictions.

Findings

Mixing effects can significantly alter decay branching ratios.

Corrections for t→q+g remain consistent with previous results.

Branching ratios depend strongly on anomalous couplings.

Abstract

In this paper detailed calculations of the complete $\mathcal{O}(\alpha_s)$ corrections to top quark decay widths $\Gamma(t\to q+V)$ are presented ($V=g,\gamma,Z$). 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 $t\to q+\gamma$ 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 $t\to q+\gamma$ and $t\to q+Z$, depending on the values of the anomalous couplings ($\kappa^{g,\gamma,Z}_{\mathrm{tq}}/\Lambda$, $f^{g,\gamma,Z}_{\mathrm{tq}}$ and $h^{g,\gamma,Z}_{\mathrm{tq}}$).