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

TL;DR

This paper investigates the triple-product asymmetry in the tau decay to two pions and a photon using resonance chiral theory, providing predictions for future experimental measurements at Belle-II and tau-charm facilities.

Contribution

The study incorporates minimal resonance chiral Lagrangian and odd-intrinsic parity operators to analyze decay amplitudes and predict asymmetries in tau decay processes.

Findings

Predicted nonzero triple-product asymmetry distributions.

Analyzed invariant-mass distributions revealing resonance dynamics.

Provided theoretical guidance for future experiments.

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.