Speaker
Tianzi SONG
Description
We present a search for the lepton flavor violating decay 𝐽/𝜓→𝑒𝜇 using 8.998×10^9 𝐽/𝜓 events collected with the BESIII detector at the BEPCII 𝑒+ 𝑒− storage ring. No excess of signal above background is observed; we therefore set an upper limit on the branching fraction of ℬ(𝐽/𝜓→𝑒𝜇)< 4.5×10^(−9) at the 90% confidence level. Improving the previous best result by a factor of more than 30, this measurement places the most stringent limit to date on lepton flavor violation in the heavy quarkonium sector.