Study of $\tau$ Decays to Six Pions and Neutrino

TL;DR

This study measures branching fractions of tau decays to six pions, identifies intermediate meson states, and reports the first observation of a specific decay mode, providing insights into tau decay dynamics.

Contribution

It presents the first observation of the tau decay to two pions and an omega meson, with measured branching fractions, and analyzes decay substructure in detail.

Findings

Branching fractions measured for two six-pion tau decays.

First observation of tau to 2 pions and omega decay mode.

Decay substructure dominated by eta and omega intermediate states.

Abstract

The $\tau$ decays to six-pion final states have been studied with the CLEO detector at the Cornell Electron Storage Ring. The measured branching fractions are ${\cal B}(\tau^-\to 2\pi^-\pi^+3\pi^0\nu_{\tau})=(2.2 \pm 0.3 \pm 0.4)\times 10^{-4}$ and ${\cal B}(\tau^-\to 3\pi^-2\pi^+\pi^0\nu_{\tau})=(1.7 \pm 0.2 \pm 0.2)\times 10^{-4}$. A search for substructure in these decays shows that they are saturated by intermediate states with $\eta$ or $\omega$ mesons. We present the first observation of the decay $\tau^-\to 2\pi^-\pi^+\omega\nu_{\tau}$ and the branching fraction is measured to be $(1.2 \pm 0.2 \pm 0.1) \times 10^{-4}$. The measured branching fractions are in good agreement with the isospin expectations but somewhat below the Conserved-Vector-Current predictions.