Physical review D Particles, fields, gravitation, and cosmology/Physical review D, Particles, fields, gravitation, and cosmology(2015)
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摘要
We present a search for the rare leptonic decays B + → e + ν e and B + → µ + ν µ , using the full Υ(4S) data sample of 772 × 10 6 B B pairs collected with the Belle detector at the KEKB asymmetric-energy e + e -collider.One of the B mesons from the Υ(4S) → B B decay is fully reconstructed in a hadronic mode, while the recoiling side is analyzed for the signal decay.We find no evidence of a signal in any of the decay modes.Upper limits of the corresponding branching fractions are determined as B(B + → e + ν e ) < 3.5 × 10 -6 and B(B + → µ + ν µ ) < 2.7 × 10 -6 at 90% confidence level.