CP violation in two meson tau decays

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.