First observation of the decay K+ -> e+ nu mu+ mu-
  Experiment 865 at the Brookhaven AGS has observed the decay K^+ -> e^+ nu mu^+ mu^-. The branching ratio extracted is (1.72 +/- 0.37(stat) +/- 0.17(syst) +/- 0.19(model)) x 10^{-8} where the third term in the error results from the use of a model to extrapolate into a kinematic region dominated by background. 
H.Ma, R. Appel, G.S. Atoyan, B. Bassalleck, D.R. Bergman, N. Cheung,   S. Dhawan, H. Do, J. Egger, S. Eilerts, W. Herold, V....