Search for the Decays B0->e+e-gamma and B0->mu+mu-gamma

TL;DR

This study searches for rare B0 meson decays into lepton pairs with a photon, using a large dataset, but finds no evidence and sets upper limits on their branching fractions.

Contribution

First search for B0→ℓ+ℓ−γ decays with extensive data, establishing upper bounds on their occurrence rates.

Findings

No significant signals detected.

Upper limits set at 90% confidence level.

Branching fraction limits: <1.2×10⁻⁷ for e+e−γ and <1.5×10⁻⁷ for μ+μ−γ.

Abstract

We present results of a search for the decays $B^0 \to \ell^+\ell^-\gamma$ ($\ell=e$, $\mu$). The search is performed using $320\times 10^{6}$ $B\bar{B}$ pairs collected at the $\Upsilon(4S)$ resonance with the BABAR detector at the PEP-II $B$ Factory at SLAC. We find no significant signal and set the following branching fraction upper limits at the 90% confidence level: $\mathcal{B}(B^0\to e^+e^-\gamma)<1.2\times 10^{-7}$ and $\mathcal{B}(B^0\to \mu^+\mu^-\gamma)<1.5\times 10^{-7}$.