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

TL;DR

This study searches for the rare leptonic decay of B mesons into muons and neutrinos using the BaBar dataset, employing an inclusive reconstruction method to set an upper limit on its branching fraction.

Contribution

It introduces an inclusive reconstruction approach to search for B+ to mu+ nu_mu decays and provides a new upper limit on its branching fraction.

Findings

Set a 90% CL upper limit of 1.3 x 10^{-6} on the branching fraction.

Utilized a fully inclusive method with the highest momentum lepton identification.

Analyzed approximately 426 fb^{-1} of BaBar data.

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 $\BR(B^{\pm} \to \mu^{\pm} \nu_{\mu}) < 1.3 \times 10^{-6}$ at the 90% confidence level, using a Bayesian approach.