Search for charged-lepton flavor violation in $\hat{I}\yen (2S)\to {\ell }^{\mp }\ddot{I}{„}^{\pm }$ ($\ell =e,\hat{I}¼$) decays at Belle

Abstract

We report a search for the charged-lepton flavor violation in $\hat{I}\yen (2S)\to {\ell }^{\mp }\ddot{I}{„}^{\pm }$ ($\ell =e,\hat{I}¼$) decays using a $25~\fbi$ $\hat{I}\yen (2S)$ sample collected by the Belle detector at the KEKB $e^{+}$$e^{-}$ asymmetric-energy collider. We find no evidence for a signal and set upper limits on the branching fractions ($\mathcal{B}$) at 90\% confidence level. We obtain the most stringent upper limits: $\mathcal{B}(\Ytomutau) < 0.23 \times 10^{-6}$ and $\mathcal{B}(\Ytoetau) < 1.12 \times 10^{-6}$.

11 pages, 3 figures, Submitted to JHEP