Search for Decays of B^{0} Mesons into Pairs of Leptons: B{0} -> e^{+}e^{-}, B^{0} -> \mu^{+}\mu^{-} and B^{0} -> e^{\pm}\mu^{\mp}

TL;DR

This paper reports a search for rare B0 meson decays into lepton pairs, setting upper limits on their branching fractions and establishing a new lower limit on leptoquark mass, thus constraining new physics models.

Contribution

The study provides the first experimental upper limits on B0 decays into lepton pairs and sets a new lower limit on Pati-Salam leptoquark mass, improving constraints on beyond Standard Model physics.

Findings

No signal observed for B0 decays into leptons.

Upper limits on branching fractions are established.

Lower limit on leptoquark mass is set at 27 TeV.

Abstract

We search for the decays of the $B^0$ meson into $e^+e^-$, $\mu^+\mu^-$ $e^{\pm}\mu^{\mp}$ pairs in a sample of $9.7\times 10^6$ $B{\bar B}$ pairs recorded by CLEO detector. No signal is found, and the following upper limits on the corresponding branching fractions are established: $<8.3\times 10^{-7}$, $<6.1\times 10^{-7}$, $< 15\times 10^{-7}$ at 90% confidence level. A new lower limit on the Pati-Salam leptoquark mass $M_{LQ}>27$ TeV is established at 90% confidence level.