New Limit on Muon and Electron Lepton Number Violation fromKL0→μ±e∓Decay

D. Ambrose, C. Arroyo, M. Bachman, D. Connor, M. Eckhause, S. Graessle, A. D. Hancock, K. Hartman, M. Hebert, C. H. Hoff, G. W. Hoffmann, G. M. Irwin (+16 others)
1998 Physical Review Letters  
The most sensitive experiment to date to search for the muon and electron lepton number violating decay $K^0_L \to \mu^\pm e^\mp$ has detected no events consistent with this process. Based on this result, the 90% confidence level upper limit on the branching fraction is $B(K^0_L \to \mu^\pm e^\mp) < 4.7\times10^{-12}$.
doi:10.1103/physrevlett.81.5734 fatcat:tprsceq3vvgjzd7azuqztzy3wm