Search for charged lepton flavor violation in J/ decays at BESIII

In the Standard Model, charged lepton flavor violation (CLFV) is heavily suppressed by tiny neutrino mass, while many theoretical models can enhance CLFV effects up to detectable level. The observation of any CLFV process would be a clear signal of new physics beyond SM. BESIII experiment collected 10 billion J/ data and searched for CLFV processes J/ e and e. The upper limits at the 90% confidence level are determined to be B (J/ e) <7. 5 10^-8 and B (J/ e) <4. 5 10^-9, respectively. Improving the previously experimental limits by two orders of magnitudes, the results are the most stringent CLFV searches in heavy quarkonium system.