KL-]MU+MU-, THE TOP-QUARK MASS, AND OTHER RELATED TOPICS

Abstract

The dispersive part of the K(L) --> mu+mu- amplitude due to the two-photon intermediate state is reconsidered, including vector-meson contributions in the hidden-symmetry scheme. We find that, contrary to the usual assumption ReA(gamma-gamma) << ReA(EW), these two tend to cancel each other, and B(K(L) --> mu+mu-) is rather insensitive to m(t). If B(K(L) --> mu+mu-) > 7.0 X 10(-9), then a larger value of f(B) is preferred.