Triple-product asymmetry in the radiative two-pion tau decay

Abstract

In this work, we perform a detailed study of the ${\tau }^{-}\to {\pi }^{-}{\pi }^0\gamma \nu$ decay process within the resonance chiral theory. We pay special attention to the triple-product asymmetry in the ${\tau }^{-}\to {\pi }^{-}{\pi }^0\gamma \nu$ process. The minimal resonance chiral Lagrangian and the odd-intrinsic parity resonance operators are simultaneously included to calculate the decay amplitudes. Various invariant-mass distributions in the ${\pi }^{-}{\pi }^0$, ${\pi }^{-}\gamma$ and ${\pi }^0\gamma$ systems are studied and they reveal different resonance dynamics. We further predict the intriguing nonzero triple-product asymmetry distributions, which may provide useful guidelines for future experimental measurements conducted at the Belle-II and super tau-charm facilities.

Comments: 32 pages, 9 figures. To match the published version