Measurement of cabibbo-suppressed decays of the τ lepton

Branching ratios for the dominant Cabibbo-suppressed decays of the τ lepton have been measured by CLEO II in e+e- annihilation at the Cornell Electron Storage Ring (s∼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(τ-→K-ντ)=(0.66±0.07±0.09)%, B(τ-→K-π0ντ)=(0.51±0.10±0.07)%, and, based on three events, B(τ-→K-2π0ντ)<0.3% at the 90% confidence level. These represent significant improvements over previous results. B(τ-→K-π0ντ) is measured for the first time with exclusive π0 reconstruction. © 1994 The American Physical Society.