First Observation of the Decay $\tau^{-}\to K^{*-}\eta\nu_{\tau}$

TL;DR

This paper reports the first measurement of the branching fraction for the decay of tau lepton into K* eta neutrino, providing new experimental data on tau decay modes.

Contribution

It presents the first observation and measurement of the branching fraction for the decay tau- to K*- eta nu_tau, expanding understanding of tau decay channels.

Findings

Branching fraction for tau- to K*- eta nu_tau is (2.9 +- 0.8 +- 0.4) x 10^-4.

Inclusive branching fractions for tau- to K_S pi- eta nu_tau and tau- to K- pi0 eta nu_tau are measured.

First experimental data on this specific tau decay mode.

Abstract

Using data recorded by the CLEO-II detector at CESR, we report the first measurement of the branching fraction for the decay of $\tau^-$ into $K^{*-}\eta \nu_{\tau}$. 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: $\tau^-$ into $K_S \pi^- \eta \nu_{\tau}$, $\tau^-$ into $K^- \pi^0 \eta \nu_{\tau}$. The measured branching fractions are (1.10 +- 0.35 +- 0.11) $10^{-4}$, (1.77 +- 0.56 +- 0.71) $10^{-4}$ respectively.