Type II seesaw mechanism for Higgs doublets and the scale of new physics

We elaborate on an earlier proposal by Ernest Ma of a type II seesaw mechanism for suppressing the vacuum expectation Values of some Higgs doublets. We emphasize that, by nesting this form of seesaw mechanism into various other seesaw mechanisms, one may obtain light neutrino masses in such a way that the new-physics scale present in the seesaw mechanism-the masses of scalar gauge-SU(2) triplets, scalar SU(2) doublets, or right-handed neutrinos-does not need to be higher than a few 10 TeV. We also investigate other usages of the type II seesaw mechanism for Higgs doublets. For instance, the suppression of the vacuum expectation values of Higgs doublets may realize Froggatt-Nielsen suppression factors in some entries of the fermion mass matrices. (C) 2009 Elsevier B.V. All rights reserved.