We show that, for a class of models in which the Higgs doublets which couple to the up quarks can communicate with those coupling to the down quarks only via mass mixing, the requirement that there should be no flavor-changing neutral processes at the tree level is stable under radiative corrections to the one-loop order. This also implies, in the context of effective-field theories, that we may use the low-energy Lagrangean to calculate one-loop corrections. At the two-loop level, however, heavy particles in the yet-unknown complete theory are likely to come into play.

• Received 12 August 1985

DOI:https://doi.org/10.1103/PhysRevLett.55.2386