Rare Electroweak Processes $K^0_L \to \mu^+ \mu^-$ and $K^0_L \to \gamma   \gamma$ and Heavy Top Quark
  A brief overview of the recent measurements of the branching ratio of the rare $K_L^0 \to \mu^+ \mu^-$ decay in the context of their agreement with the Standard Model (SM) is given. It is shown that KEK result well correlates with the SM and B-physics, whereas the BNL results are in conflict with the SM with the heavy top quark. 
A.A.Gvozdev, N.V.Mikheev and L.A.Vassilevskaya