CP violation in two meson tau decays

TL;DR

This paper explores CP violation in two-meson tau decays, analyzing the potential for current and future experiments to detect asymmetries and clarify the BaBar anomaly using an effective field theory approach.

Contribution

It extends the effective field theory analysis to other two-meson tau decay channels, providing predictions for experimental sensitivity to CP asymmetries.

Findings

Experiments can detect CP asymmetries with 5% precision in $K^\pm K_S$ modes.

Current data constrains the maximum CP rate asymmetry.

Future measurements can confirm or challenge the BaBar anomaly.

Abstract

CP violation in $\tau\to K_S \pi\nu_\tau$ decays has attracted a lot of attention recently, due to the BaBar anomaly in the corresponding rate asymmetry. Within an effective field theory formalism, only extreme fine-tuning would allow to understand such measurement, which is currently being scrutinized at Belle(-II), as will be in the future super-charm-tau factory. Here we summarize the results of applying the same formalism to the other two-meson tau decay channels, which can help solve this conundrum. Our main conclusion is that current and future experiments would be sensitive to the maximum allowed CP rate asymmetry in the related $K^\pm K_S$ modes with a measurement having 5$\%$ precision, that will either support or cast further doubts on the BaBar anomaly.