Search for the lepton flavor violation process J/ψ→eμ at BESIII

Abstract

We search for the lepton-flavor-violating decay of the J/ψ into an electron and a muon using (225.3±2.8)×106 J/ψ events collected with the BESIII detector at the BEPCII. Four candidate events are found in the signal region, consistent with background expectations. An upper limit on the branching fraction of B(J/ψ→eμ)<1.6×10-7 (90% C.L.) is obtained. © 2013 American Physical Society.