Search for the charged lepton flavor violating decay $J/\ddot{I}ˆ\to e\ddot{I}„$

Abstract

A search for the charged lepton flavor violating decay $J/\ddot{I}ˆ\to e^{\pm }\ddot{I}{„}^{\mp }$ with $\ddot{I}{„}^{\mp }\to \ddot{I}{€}^{\mp }\ddot{I}{€}^0\hat{I}{½}_{\ddot{I}}„$ is performed with about $10$ billion $J/\ddot{I}ˆ$ events collected with the BESIII detector at the BEPCII. No significant signal is observed, and an upper limit is set on the branching fraction $\mathcal{B}(J/\ddot{I}ˆ\to e^{\pm }\ddot{I}{„}^{\mp })<7.5\times 10^{-8}$ at the 90$\%$ confidence level. This improves the previously published limit by two orders of magnitude.

9 pages, 4 figures, 2 tables