Search for Lepton Flavor Violation Process J/$\psi \to e\mu$

TL;DR

This study searches for lepton flavor violation in J/ψ decays, finding no significant signal and setting an upper limit on the branching fraction, thus constraining new physics models.

Contribution

First search for the decay J/ψ → eμ using a large dataset, establishing an upper limit on its branching fraction.

Findings

Four candidate events observed, consistent with background

Upper limit on branching fraction set at 1.1×10⁻⁶

No evidence of lepton flavor violation found

Abstract

Using a sample of 5.8X10E7 J/$\psi$ events, the Beijing Spectrometer experiment has searched for the decay J/$\psi \to e\mu$. Four candidates, consistent with the estimated background, are observed, and an upper limit on the branching fraction of J/$\psi \to e\mu$ of 1.1X10E-6 at the 90% C.L. is obtained.