Measurement of the presence of $\mathrm{a}_1(1420)$ and $\omega(782)$ in $\tau^-\to\pi^-\pi^-\pi^+\nu_\tau$ at Belle

TL;DR

This paper reports a partial-wave analysis of tau decays at Belle, identifying the presence of the a1(1420) and omega(782) states, which enhances understanding of tau decay dynamics and improves related models.

Contribution

It provides the first evidence of a1(1420) and omega(782) in tau decays, refining decay models and aiding future measurements of tau properties.

Findings

Observation of a1(1420) in tau decays

Detection of G-parity-violating omega(782) wave

Results will improve tau decay simulation models

Abstract

We present preliminary results of a partial-wave analysis of $\tau^-\to\pi^-\pi^-\pi^+\nu_\tau$ using data from the Belle experiment at the KEKB $\mathrm{e}^+\mathrm{e}^-$ collider. We validate our model with a model-independent analysis. We see the $\mathrm{a}_1(1420)$ and a G-parity-violating $1^-[\omega(782)\pi]_\mathrm{P}$ wave in tauon decays. Our results will improve models used in simulation studies necessary for measuring the electric and magnetic dipole moments and Michel parameters of the $\tau$.