Partial wave analysis of ${\tau }^{-}\to {\pi }^{-}{\pi }^{+}{\pi }^{-}{\nu }_{\tau }$ at Belle

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.