Search for the lepton-flavor-violating decay $B^0\to K^{*0}{\mu }^{\pm }{e}^{\mp }$

We have searched for the lepton-flavor-violating decay B⁰ → K*⁰µ^±e^∓ using a data sample of 711 fb^-1 that contains 772 × 10⁶$B\overline{B}$ pairs. The data were collected near the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e⁺e^- collider. No signals were observed, and we set 90% confidence level upper limits on the branching fractions of B(B⁰ → K*⁰µ⁺e^-) < 1.2 × 10^-7, B(B⁰ → K^*0µ^-e⁺) < 1.6 × 10^-7, and, for both decays combined, B(B⁰ → K^*0µ^±e^∓) < 1.8 × 10^-7. These are the most stringent limits on these decays to date.