Next-to-leading order QCD corrections to $tZ$ associated production via the flavor-changing neutral-current couplings at hadron colliders

TL;DR

This paper calculates the complete next-to-leading order QCD corrections to the associated production of a top quark and Z boson via flavor-changing neutral-current couplings at hadron colliders, improving theoretical accuracy.

Contribution

It provides the first comprehensive NLO QCD correction analysis for $tZ$ production via model-independent FCNC couplings, including mixing effects and distribution evaluations.

Findings

NLO corrections significantly increase cross sections (up to 60%).

NLO corrections reduce scale dependence, enhancing prediction reliability.

Mixing effects between couplings can be large or small depending on parameters.

Abstract

We present the complete next-to-leading order (NLO) QCD corrections to $tZ$ associated production induced by the model-independent $tqg$ and $tqZ$ flavor-changing neutral-current couplings at hadron colliders, respectively. Our results show that, for the $tuZ$ coupling the NLO QCD corrections can enhance the total cross sections by about 60% and 42%, and for the $tcZ$ coupling by about 51% and 43% at the Tevatron and LHC, respectively. The NLO corrections, for the $tug$ couplings, can enhance the total cross sections by about 27%, and by about 42% for the $tcg$ coupling at the LHC. We also consider the mixing effects between the $tqg$ and $tqZ$ couplings for this process, which can either be large or small depending on the values of the anomalous couplings. Besides, 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. And we also evaluate the NLO corrections to several important kinematic distributions.