Rare K decays in a model of quark and lepton masses

An extension of a model of neutrino masses to the quark sector provides an interesting link between these two sectors. A parameter which is important to describe neutrino oscillations and masses is found to be a crucial one appearing in various ``penguin’’ operators, in particular the so-called Z penguin. This parameter is severely constrained by the rare decay process $K_L\to {\mu }^{+}{\mu }^{-}$. This in turn has interesting implications on the decay rates of other rare processes such as $K_L\to \mu e$, etc…, as well as on the masses of the neutrinos and the masses of the vector-like quarks and leptons which appear in our model.