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

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.

Comments: 25 pages, 11 figures. Minor changes to match published version