Relating the scalar flavour-changing neutral couplings to the CKM matrix

Abstract

We build a class of two-Higgs-doublet models in which the flavour-changing couplings of the neutral scalars are related in an exact way to elements of the quark mixing matrix. In this framework, we explore the different possibilities for CP violation and find some interesting scenarios, like a realization of the superweak idea without CP violation in the $B$-meson system. In another scenario the neutral scalars can be relatively light, and their contributions to the $B^0$--$\bar{B}^0$ transitions can alter the standard-model predictions for CP violation in that system.