Study of $τ$ Decays to Six Pions and Neutrino

Abstract

The $τ$ decays to six-pion final states have been studied with the CLEO detector at the Cornell Electron Storage Ring. The measured branching fractions are ${\cal B}(τ^-\to 2π^-π^+3π^0ν_τ)=(2.2 \pm 0.3 \pm 0.4)\times 10^{-4}$ and ${\cal B}(τ^-\to 3π^-2π^+π^0ν_τ)=(1.7 \pm 0.2 \pm 0.2)\times 10^{-4}$. A search for substructure in these decays shows that they are saturated by intermediate states with $η$ or $ω$ mesons. We present the first observation of the decay $τ^-\to 2π^-π^+ων_τ$ 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.