First observation of the decay tau(-)-> K*(-)eta nu(tau)

Abstract

The decay tau(-) --> K*(-) eta nu(tau) has been observed with the CLEO II detector. The K*(-) is reconstructed in two decay channels, K*(-) -->, KSpi- --> pi(-)pi(+)pi(-) and K*(-) --> K- pi(0). The eta is reconstructed from the decay eta --> gamma gamma. The measured branching fraction is B(tau(-) --> K- pi(0)eta nu(tau)) = (2.9 +/- 0.8 +/- 0.3) x 10(-4). We also measure the inclusive branching fractions without requiring the K* resonance, B(tau(-) --> K(S)pi(-) eta nu(tau)) = (1.10 +/- 0.35 +/- 0.11) x 10(-4) and B(tau(-) --> K- pi(0)eta nu(tau)) = (1.77 +/- 0.56 +/- 0.71) x 10(-4). The results indicate that the K*(-) resonance dominates the K(S)pi(-) mass spectrum.