Measurement of cabibbo-suppressed decays of the tau lepton

Abstract

Branching ratios for the dominant Cabibbo-suppressed decays of the tau lepton have been measured by CLEO II in e+e- annihilation at the Cornell Electron Storage Ring (square-root s approximately 10.6 GeV) using kaons with momenta below 0.7 GeV/c. The inclusive branching ratio into one charged kaon is (1.60 +/- 0.12 +/- 0.19)%. For the exclusive decays, B(tau- --> K- nu(tau)) = (0.66 +/- 0.07 +/- 0.09)%, B(tau- --> K-pi0nu(tau) = (0.51 +/- 0.10 +/- 0.07)%, and, based on three events, B(tau- --> K-2pi0nu(tau) < 0.3% at the 90% confidence level. These represent significant improvements over previous results. B(tau- --> K- pi0nu(tau)) is measured for the first time with exclusive pi0 reconstruction.