Morisi, S., & Peinado, E. (2010). S-4 model for quarks and leptons with maximal atmospheric angle. Phys. Rev. D, 81(8), 085015–8pp.
Abstract: We consider a model for quark and lepton masses and mixings based on S-4 flavor symmetry. The model contains six Higgs doublets where three of them give mass to the leptons, and the other three gives mass to the quarks. Charged fermion and quark masses arise from renormalizable interactions while neutrino Majorana masses are generated through effective dimension five Weinberg operator. From the study of the minimization of the scalar potential we found a residual μ<-> tau symmetry in the neutrino sector predicting zero reactor angle and maximal atmospheric angle and for the quark sector we found a four-zero texture. We give a fit of the mass hierarchies and mixing angles in the quark sector.
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Mondragon, A., Mondragon, M., & Peinado, E. (2011). Neutrino Masses, Mixings, and FCNC's in an S(3) Flavor Symmetric Extension of the Standard Model. Phys. Atom. Nuclei, 74(7), 1046–1054.
Abstract: By introducing three Higgs fields that are SU(2) doublets and a flavor permutational symmetry, S(3), in the theory, we extend the concepts of flavor and generations to the Higgs sector and formulate a Minimal S(3)-Invariant Extension of the Standard Model. The mass matrices of the neutrinos and charged leptons are re-parameterized in terms of their eigenvalues, then the neutrino mixing matrix, V(PMNS), is computed and exact, explicit analytical expressions for the neutrino mixing angles as functions of the masses of neutrinos and charged leptons are obtained in excellent agreement with the latest experimental data. We also compute the branching ratios of some selected flavor-changing neutral current (FCNC) processes, as well as the contribution of the exchange of neutral flavor-changing scalars to the anomaly of the magnetic moment of the muon, as functions of the masses of charged leptons and the neutral Higgs bosons. We find that the S(3) x Z(2) flavor symmetry and the strong mass hierarchy of the charged leptons strongly suppress the FCNC processes in the leptonic sector, well below the present experimental bounds by many orders of magnitude. The contribution of FCNC's to the anomaly of the muon's magnetic moment is small, but not negligible.
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Morisi, S., Peinado, E., Shimizu, Y., & Valle, J. W. F. (2011). Relating quarks and leptons without grand unification. Physical Review D, 84(3), 036003.
Abstract: In combination with supersymmetry, flavor symmetry may relate quarks with leptons, even in the absence of a grand-unification group. We propose an SU(3) x SU(2) x U(1) model where both supersymmetry and the assumed A(4) flavor symmetries are softly broken, reproducing well the observed fermion mass hierarchies and predicting: (i) a relation between down-type quarks and charged lepton masses, and (ii) a correlation between the Cabibbo angle in the quark sector and the reactor angle theta(13) characterizing CP violation in neutrino oscillations.
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Boucenna, M. S., Hirsch, M., Morisi, S., Peinado, E., Taoso, M., & Valle, J. W. F. (2011). Phenomenology of dark matter from A_4 flavor symmetry. J. High Energy Phys., 05(5), 037–20pp.
Abstract: We investigate a model in which Dark Matter is stabilized by means of a Z(2) parity that results from the same non-abelian discrete flavor symmetry which accounts for the observed patter of neutrino mixing. In our A(4) example the standard model is extended by three extra Higgs doublets and the Z(2) parity emerges as a remnant of the spontaneous breaking of A(4) after electroweak symmetry breaking. We perform an analysis of the parameter space of the model consistent with electroweak precision tests, collider searches and perturbativity. We determine the regions compatible with the observed relic dark matter density and we present prospects for detection in direct as well as indirect Dark Matter search experiments.
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Morisi, S., Patel, K. M., & Peinado, E. (2011). Model for T2K indication with maximal theta(23) and trimaximal theta(12). Phys. Rev. D, 84(5), 053002–6pp.
Abstract: Recently T2K experiment gives hint in favor of large reactor angle theta(13). Most of the models, with tribimaximal mixing at the leading order, can not reproduce such a large mixing angle since they predict typically corrections for the reactor angle of the order theta(13) similar to lambda(2)(C), where lambda(C) similar to 0.2. In this paper, we discuss the possibility to achieve large theta(13) within the T2K region with maximal atmosphericmixing angle, sin(2)theta(23) = 1/2, and trimaximal solar mixing angle, sin(2)theta(12) = 1/3, through the deviation from the exact tribimaximal mixing. We derive the structure of neutrino mass matrix that leads to the large theta(13) leaving maximal theta(23) and trimaximal theta(12). It is shown that such a structure of neutrino mass matrix can arise in a model with S(4) flavor symmetry.
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