Embedding the Zee-Wolfenstein neutrino mass matrix in an SO(10) x A4 GUT scenario

We consider renormalizable SO(10) Yukawa interactions and put the three fermionic 16-plets into the 3-dimensional irreducible A_4 representation. Scanning the possible A_4 representation assignments to the scalars, we find a unique case which allows to accommodate the down-quark and charged-lepton masses. Assuming type II seesaw dominance, we obtain a viable scenario with the Zee-Wolfenstein neutrino mass matrix, i.e., the Majorana mass matrix with a vanishing diagonal. Contributions from the charged-lepton mass matrix resolve the well-known problems with lepton mixing arising from the vanishing diagonal. In our scenario, fermion masses and mixings are well reproduced for both normal and inverted neutrino mass spectra, and b-tau Yukawa unification and definite predictions for the effective mass in neutrinoless double-beta decay are obtained.Comment: 19 pages, 3 figures, v2: final version for Phys. Rev.

A renormalizable SO(10) GUT scenario with spontaneous CP violation

We consider fermion masses and mixings in a renormalizable SUSY SO(10) GUT with Yukawa couplings of scalar fields in the representation 10 + 120 + 126 bar. We investigate a scenario defined by the following assumptions: i) A single large scale in the theory, the GUT scale. ii) Small neutrino masses generated by the type I seesaw mechanism with negligible type II contributions. iii) A suitable form of spontaneous CP breaking which induces hermitian mass matrices for all fermion mass terms of the Dirac type. Our assumptions define an 18-parameter scenario for the fermion mass matrices for 18 experimentally known observables. Performing a numerical analysis, we find excellent fits to all observables in the case of both the normal and inverted neutrino mass spectrum.Comment: 16 pages, two eps figure