First Observation of the Decay $τ^{-}\to K^{*-}ην_τ$

Abstract

Using data recorded by the CLEO-II detector at CESR, we report the first measurement of the branching fraction for the decay of $τ^-$ into $K^{*-}ην_τ$. The measured branching fraction is (2.9 +- 0.8 +- 0.4) $10^{-4}$. We also measure the inclusive branching fractions without requiring the $K^*$ resonance: $τ^-$ into $K_S π^- ην_τ$, $τ^-$ into $K^- π^0 ην_τ$. The measured branching fractions are (1.10 +- 0.35 +- 0.11) $10^{-4}$, (1.77 +- 0.56 +- 0.71) $10^{-4}$ respectively.