Search for lepton-flavor-violating $\ddot{I}„\to \ell V^0$ decays at Belle

Abstract

We have searched for neutrinoless $\ddot{I}„$ lepton decays into $\ell$ and $V^0$, where $\ell$ stands for an electron or muon, and $V^0$ for a vector meson ($\ddot{I}•$, $\ddot{I}‰$, $K^{\ast 0}$, ${\bar{K}}^{\ast 0}$ or $\ddot{I}{}^0$), using 543 fb${}^{-1}$ of data collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. No excess of signal events over the expected background has been observed, and we set upper limits on the branching fractions in the range $(5.9-18)\times 10^{-8}$ at the 90% confidence level. These upper limits include the first results for the $\ell \ddot{I}‰$ mode as well as new limits that are significantly more restrictive than our previous results for the $\ell \ddot{I}•$, $\ell K^{\ast 0}$, $\ell {\bar{K}}^{\ast 0}$ and $\ell \ddot{I}{}^0$ modes.

7 pages, 16 figures