Model-independent results for the decay B+ -> l+ nu gamma at BABAR

TL;DR

This paper reports a model-independent search for rare radiative leptonic B+ decays using BABAR data, setting upper limits on their branching fractions with a novel analysis method.

Contribution

It introduces a model-independent analysis technique for B+ -> l+ nu gamma decays using full hadronic B reconstruction at BABAR.

Findings

No significant signal observed.

Upper limit on branching fraction BR(B+ -> l+ nu gamma) < 15.6 x 10^-6.

Method achieves sensitivity comparable to Standard Model predictions.

Abstract

We present a search for the radiative leptonic decays B+ -> e+ nu gamma and B+ -> mu+ nu gamma using data collected by the BABAR detector at the PEP-II B factory. We fully reconstruct the hadronic decay of one of the B mesons in Upsilon(4S) -> B+B- and then search for evidence of the signal decay within the rest of the event. This method provides clean kinematic information on the signal's missing energy and high momentum photon and lepton, and allows for a model-independent analysis of this decay. Using a data sample of 465 million B-meson pairs, we obtain sensitivity to branching fractions of the same order as predicted by the Standard Model. We report a model-independent branching fraction upper limit of BR(B+ -> l+ nu gamma) < 15.6e-6 (l= e or mu) at the 90% confidence level.