Stefan Wallner

28 May 2024
International Workshop on Partial Wave Analyses and Advanced Tools for Hadron Spectroscopy

Abstract: We present a partial-wave analysis of $\tau^-\to \pi^-\pi^-\pi^+ \nu_\tau$ decays using the world`s largest sample of these decays from the Belle experiment at KEK, Japan. We discuss the employed covariant tensor formalism and the treatment of large incoherent backgrounds in our sample. We give preliminary results on light-meson resonances appearing in the $\pi^-\pi^-\pi^+$ system, including $a_1(1420)$, and in the $\pi^-\pi^+$ subsystem, measured using the so-called freed-isobar method; and we give prospects for measurements at Belle II.