Mass-matrix ansatz and flavor nonconservation in models with multiple Higgs doublets

Motivated by the existence of three fermion generations, we consider models with three Higgs doublets (for each hypercharge). It is shown that, if the basic Yukawa coupling matrices are of the Fritzsch form or some generalizations thereof (two such examples are presented), then the neutral flavor-changing couplings have a hierarchical structure given by ${\Delta }_{\mathrm{ij}}$ √$m_i$ $m_j$ , where ${\Delta }_{\mathrm{ij}}$ is a combination of mixing angles and the $m_i$’s are the relevant fermion masses. These couplings give a lower bound of the order of ${\Delta }_{\mathrm{ds}}$ times 1 TeV on the mass of the exchanged scalar from the neutral-kaon mass difference. If the Higgs-boson mass is not significantly greater than this limit, one expects DD¯ mixing comparable to the present experimental bound.