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

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.