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

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 analysis with a model-independent one. We see an $\mathrm{a}_1(1420)$ resonance 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 tauon electric and magnetic dipole moments and Michel parameters.
Comment: 4 pages, 2 figures, on behalf of the Belle collaboration, submitted to SciPost Physics Proceedings, 17th International Workshop on Tau Lepton Physics (TAU2023). arXiv admin note: text overlap with arXiv:2310.09155