Search for $B^0\to \ddot{I}{„}^{\pm }{\ell }^{\mp }$ ($\ell =e,\hat{I}¼$) with a hadronic tagging method at Belle

Abstract

We present a search for the lepton-flavor-violating decays $B^0\to \ddot{I}{„}^{\pm }{\ell }^{\mp }$, where $\ell =(e,\hat{I}¼)$, using the full data sample of $772\times 10^6$ $B\overline{B}$ pairs recorded by the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. We use events in which one $B$ meson is fully reconstructed in a hadronic decay mode. The $\ddot{I}{„}^{\pm }$ lepton is reconstructed indirectly using the momentum of the reconstructed $B$ and that of the ${\ell }^{\mp }$ from the signal decay. We find no evidence for $B^0\to \ddot{I}{„}^{\pm }{\ell }^{\mp }$ decays and set upper limits on their branching fractions at 90% confidence level of $\mathcal{B}$($B^0\to \ddot{I}{„}^{\pm }\hat{I}{¼}^{\mp }$)$<1.5\times 10^{-5}$ and $\mathcal{B}$($B^0\to \ddot{I}{„}^{\pm }{e}^{\mp }$)$<1.6\times 10^{-5}$.

8 pages, 2 figures