T-odd asymmetries in radiative top-quark decays

TL;DR

This paper calculates T-odd asymmetries in radiative top-quark decays caused by one-loop QCD effects, predicting observable asymmetries at future colliders that could test CP violation and QCD dynamics.

Contribution

It provides the first calculation of T-odd asymmetries in top decay including gluon radiation at one-loop level, highlighting potential experimental observability.

Findings

Asymmetries of a few percent are predicted.

Asymmetries originate from the absorptive part of decay amplitudes.

Potential observability at future collider experiments.

Abstract

We study the angular distribution of the charged lepton in the top-quark decay into a bottom quark and a W boson which subsequently decays into \ell\nu_{\ell}, when a hard gluon is radiated off. The absorptive part of the t \to bWg decay amplitudes, which gives rise to T-odd asymmetries in the distribution, is calculated at the one-loop level in perturbative QCD. The asymmetries at a few percent level are predicted, which may be observable at future colliders.