A Search for the $B^0 \to e^+e^-\gamma$ and $B^0 \to \mu^+\mu^-\gamma$ Decays

TL;DR

This paper reports the first search for rare $B^0$ decays to lepton pairs with a photon, using BaBar data, setting upper limits on their branching fractions due to no observed significant signals.

Contribution

It presents the first experimental search for $B^0 o ext{lepton}^+ ext{lepton}^- ext{gamma}$ decays and establishes upper limits on their branching fractions.

Findings

No significant signals observed.

Upper limits set: $<0.7 imes 10^{-7}$ for $e^+e^- ext{gamma}$.

Upper limits set: $<3.4 imes 10^{-7}$ for $\mu^+\mu^- ext{gamma}$.

Abstract

With the BaBar detector at the PEP-II asymmetric $B$ Factory at SLAC, we present the first search for the decays $B^0\to\ell^+\ell^-\gamma$ ($l=e, \mu$). Using a data set of 292 $fb^{-1}$ collected at the $\Upsilon(4S)$ resonance, we find no significant signal and set the following branching fraction upper limits at 90% confidence level: $\mathcal{B}(B^0\to e^+e^-\gamma)<0.7\times 10^{-7}$ and $\mathcal{B}(B^0\to \mu^+\mu^-\gamma)<3.4\times 10^{-7}$.