Search for B+ -> l+ nu gamma decays with hadronic tagging using the full Belle data sample

TL;DR

This study searches for rare B+ meson decays into a lepton, neutrino, and photon using the full Belle dataset, setting upper limits on their branching ratios due to no significant signal detection.

Contribution

It provides the first comprehensive search for B+ -> l+ nu gamma decays with hadronic tagging in the full Belle data sample, establishing new upper limits on their branching fractions.

Findings

No significant signal observed for B+ -> l+ nu gamma decays.

Upper limits set on branching ratios: <6.1x10^-6 for e+ and <3.4x10^-6 for mu+ channels.

Results constrain theoretical models of rare B+ decays.

Abstract

We search for the decay B+ -> l+ nu gamma with l+ = e+ or mu+ using the full Belle data set of 772 x 10^6 BBbar pairs, collected at the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We reconstruct one B meson in a hadronic decay mode and search for the B+ -> l+ nu gamma decay in the remainder of the event. We observe no significant signal within the phase space of E_gamma^sig > 1 GeV and obtain upper limits of BR(B+ -> e+ nu gamma) < 6.1 x 10^-6, BR(B+ -> mu+ nu gamma) < 3.4 x 10^-6, and BR(B+ -> l+ nu gamma) < 3.5 x 10^-6 at 90 % credibility level.