CP violation in tau -> K pi pi nu_tau

TL;DR

This paper investigates CP violation in tau decays to K pi pi nu_tau, exploring how a charged Higgs could induce observable CP asymmetries, with some potentially reaching about 1% in magnitude.

Contribution

It introduces four CP-odd observables in tau decays and assesses their sensitivity to new physics from a charged Higgs, highlighting the potential for measurable CP asymmetries.

Findings

Regular rate asymmetry is expected to be small.

Modified and triple-product asymmetries could reach about 1%.

Some CP asymmetries are promising for detecting new physics.

Abstract

We consider CP-violating effects in tau->K pi pi nu_tau, assuming that a charged Higgs boson provides a new amplitude that can interfere with the usual Standard Model amplitude. We consider four CP-odd observables -- the regular rate asymmetry, two modified rate asymmetries and a triple-product asymmetry. The regular rate asymmetry is expected to be small because it requires the interference of the new physics amplitude with the standard model amplitude containing the hadronic scalar form factor. The other CP asymmetries may be more promising in terms of their new physics reach. Numerical estimates indicate that the maximum obtainable values for the modified and triple-product asymmetries are on the order of a percent.