CP violation in two-meson Tau decays induced by heavy new physics

TL;DR

This paper investigates CP violation in two-meson tau decays induced by heavy new physics using effective field theory, focusing on decay rates and asymmetries, and assesses experimental sensitivities at Belle-II and future facilities.

Contribution

It extends the effective field theory approach to additional two-meson tau decay channels and evaluates their potential to reveal new physics through CP violation measurements.

Findings

Current experiments can detect maximum CP asymmetry in $K^ ext{±}K_S$ modes with 5% precision.

Probing new physics in $ ext{π}^ ext{±} ext{π}^0$ channels is challenging with current sensitivity.

Disentangling new CP violation sources is most difficult in $K^ ext{±} ext{π}^0$ and similar modes.

Abstract

We apply the effective field theory formalism that was used to study CP violation induced by heavy new physics in the $\tau\to K_S \pi\nu_\tau$ decays to the other two-meson tau decay channels. We focus on the rate and the forward-backward asymmetries, that are predicted using current bounds on the complex Wilson coefficients of the effective Lagrangian. We discuss our outcomes for the modes with $(K/\pi)\pi^0$ and $K K_S$, that can be studied at Belle-II and a super-tau-charm facility. Our main finding is that current and forthcoming experiments would be sensitive to the maximum allowed CP rate asymmetry in the $K^\pm K_S$ modes if a precision of $5\%$ is reached on this observable, that can check as well the BaBar anomaly in $K_S\pi$. For the $\pi^\pm\pi^0$ channels, new physics would be difficult to probe at present. Disentangling new sources of CP violation would be most challenging in $K^\pm\pi^0$ and the other modes.