Search for the Rare Leptonic Decays \boldmath{\Blnu} ($\ell=e,\mu$)

TL;DR

This study searches for rare leptonic B meson decays into electrons and muons, using a large dataset, but finds no evidence and sets upper limits on their branching fractions.

Contribution

First search for munu and enu decays at BaBar, establishing upper limits with a large dataset and Bayesian analysis.

Findings

No evidence for munu and enu decays

Upper limits set at 90% confidence level

Branching fraction limits: munu < 1.0×10^{-6}, enu < 1.9×10^{-6}

Abstract

We have performed a search for the rare leptonic decays \Bp \to \ellp \nul ($l=e,\mu$), using data collected at the \FourS resonance by the \babar\ detector at the \pep2 storage ring. In a sample of 468 million \BB pairs we find no evidence for a signal and set an upper limit on the branching fractions $\BR(\bmunu) < 1.0\times10^{-6}$ and $\BR(\benu) < 1.9\times10^{-6}$ at the 90% confidence level, using a Bayesian approach.