Search for the lepton-flavor-violating decay B 0 → K *0 μ ± e ∓

Abstract

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 BB̄ pairs. The data were collected near the (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.