Search for B+ --> mu+ nu_mu with inclusive reconstruction at BaBar

Abstract

We search for the purely leptonic decay $B^{\pm }\to {\mu }^{\pm }{\nu }_{\mu }$ in the full BaBar dataset, having an integrated luminosity of approximately 426 fb${}^{-1}$. We adopt a fully inclusive approach, where the signal candidate is identified by the highest momentum lepton in the event and the companion $B$ is inclusively reconstructed without trying to identify its decay products. We set a preliminary upper limit on the branching fraction of $\BR(B^{\pm} \to μ^{\pm} ν_μ) < 1.3 \times 10^{-6}$ at the 90% confidence level, using a Bayesian approach.

10 pages, 8 postscript figures, submitted to ICHEP2008