We present the first evidence for the decay KL→e+e−μ+μ− based on the observation of one event with an estimated background of 0.067-0.025+0.057 event. We determine the branching ratio to be B(KL→e+e−μ+μ−)=(2.9-2.4+6.7)×10-9. In addition, we set a 90% confidence upper limit on the combined branching ratio for the lepton flavor violating decays KL→e∓e∓μ±μ± to be B(KL→e∓e∓μ±μ±<)<6.1×10-9 assuming a uniform phase space distribution.
ASJC Scopus subject areas
- Physics and Astronomy(all)