Top-Quark Decay at Next-to-Next-to-Leading Order in QCD

TL;DR

This paper provides a comprehensive calculation of the top-quark decay width at NNLO in QCD, including electroweak effects and differential decay rates, enabling precise studies of top-quark decay observables.

Contribution

It introduces the first fully differential NNLO QCD calculation of top-quark semileptonic decay rates, incorporating electroweak corrections and finite mass effects.

Findings

First NNLO differential decay rate results for top quark

Enhanced precision in top-quark decay predictions

Method based on effective field theory for invariant mass distribution

Abstract

We present the complete calculation of the top-quark decay width at next-to-next-to-leading order in QCD, including next-to-leading electroweak corrections as well as finite bottom quark mass and $W$ boson width effects. In particular, we also show the first results of the fully differential decay rates for top-quark semileptonic decay $t\to W^+(l^+\nu)b$ at next-to-next-to-leading order in QCD. Our method is based on the understanding of the invariant mass distribution of the final-state jet in the singular limit from effective field theory. Our result can be used to study arbitrary infrared-safe observables of top-quark decay with the highest perturbative accuracy.