Search for Lepton Flavor Violating tau^- Decays into l^-eta, l^-eta' and l^-pi^0

Abstract

We have searched for lepton flavor violating $\tau$ decays with a pseudoscalar meson ($\eta$, ${\eta }^{\prime }$ and ${\pi }^0$) using a data sample of 401 fb${}^{-1}$ collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. No evidence for these decays is found and we set the following upper limits on the branching fractions: $\mathcal{B}({\tau }^{-}\to e^{-}\eta )<9.2\times 10^{-8}$, $\mathcal{B}({\tau }^{-}\to {\mu }^{-}\eta )<6.5\times 10^{-8}$, $\mathcal{B}({\tau }^{-}\to e^{-}{\eta }^{\prime })<1.6\times 10^{-7}$, $\mathcal{B}({\tau }^{-}\to {\mu }^{-}{\eta }^{\prime })<1.3\times 10^{-7}$ $\mathcal{B}({\tau }^{-}\to e^{-}{\pi }^0)<8.0\times 10^{-8}$ and $\mathcal{B}({\tau }^{-}\to {\mu }^{-}{\pi }^0)<1.2\times 10^{-7}$ at the 90% confidence level, respectively. These results improve the previously published limits by factors from 2.3 to 6.4.

17 pages, 10 figures, submitted to the ICHEP06 Conference, Moscow, Russia

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