The effect of a fourth generation on the decay [formula omitted

Abstract

The decay K + → π + ν ν in the four-generation model is studied. It is found that this branching ratio can be one order of magnitude larger than in the three-generation model if mixing between the third and fourth generation of quarks is sizeable. The upper bound for the branching ratio in the four-generation model Br(K + → π + ν ν) <8 × 10 −9 is rather stable under variations in the mass of the fourth generation if Q = 2 3 quark T.