Search for the Lepton Flavor Violation Processes $J/ψ\to$ $μτ$ and $eτ$

Abstract

The lepton flavor violation processes $J/ψ\to μτ$ and $eτ$ are searched for using a sample of 5.8$\times 10^7$ $J/ψ$ events collected with the BESII detector. Zero and one candidate events, consistent with the estimated background, are observed in $J/ψ\to μτ, τ\to e\barν_eν_τ$ and $J/ψ\to eτ, τ\toμ\barν_μν_τ$ decays, respectively. Upper limits on the branching ratios are determined to be $Br(J/ψ\toμτ)<2.0 \times 10^{-6}$ and $Br(J/ψ\to eτ) < 8.3 \times10^{-6}$ at the 90% confidence level (C.L.).