Partial wave analysis of $\tau^-\to\pi^-\pi^+\pi^-\nu_\tau$ at Belle

Abstract

We present simulation studies in preparation for analyzing $\tau^-\to\pi^-\pi^+\pi^-\nu_\tau$ in data from the Belle experiment at the KEK $\mathrm{e}^+\mathrm{e}^-$ collider. Analyzing this decay can shed light on the $\mathrm{a}_1(1260)$ and $\mathrm{a}_1(1420)$ resonances and yield results that improve measurement of the $\tau$ electric and magnetic dipole moments. We show that we can achieve a higher signal efficiency than previous analyses of the same decay. We also demonstrate that neural networks can model our complicated six-dimensional background distributions and that quasi-model-independent partial-wave analysis can extract resonance masses, widths, and production amplitudes and phases.