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 CESR ($\sqrt{s}\sim 10.6$~GeV) using kaons with momenta below $0.7GeV/c$. The inclusive branching ratio into one charged kaon is $(1.60\pm 0.12\pm 0.19)\%$. For the exclusive decays, $B(\tau \to K^{-})=(0.66\pm 0.07\pm 0.09)\%$, $B(\tau \to K^{-}{\pi }^0)=(0.51\pm 0.10\pm 0.07)\%$, and, based on three events, $B(\tau \to K^{-}{\pi }^0{\pi }^0)<0.3\%$ at the 90\% confidence level. These represent significant improvements over previous results. $B(\tau \to K^{-}{\pi }^0)$ is measured for the first time with exclusive ${\pi }^0$ reconstruction.

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