Boucenna, M. S., Morisi, S., Tortola, M., & Valle, J. W. F. (2012). Bilarge neutrino mixing and the Cabibbo angle. Phys. Rev. D, 86(5), 051301–4pp.
Abstract: Recent measurements of the neutrino mixing angles cast doubt on the validity of the so-far popular 2 tribimaximal mixing Ansatz. We propose a parametrization for the neutrino mixing matrix where the reactor angle seeds the large solar and atmospheric mixing angles, equal to each other in first approximation. We suggest such a bilarge mixing pattern as a model-building standard, realized when the leading order value of theta(13) equals the Cabibbo angle lambda(C).
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Dorame, L., Morisi, S., Peinado, E., Valle, J. W. F., & Rojas, A. D. (2012). New neutrino mass sum rule from the inverse seesaw mechanism. Phys. Rev. D, 86(5), 056001–9pp.
Abstract: A class of discrete flavor-symmetry-based models predicts constrained neutrino mass matrix schemes that lead to specific neutrino mass sum rules. One of these implies a lower bound on the effective neutrinoless double beta mass parameter, even for normal hierarchy neutrinos. Here we propose a new model based on the S-4 flavor symmetry that leads to the new neutrino mass sum rule and discuss how to generate a nonzero value for the reactor angle theta(13) indicated by recent experiments, and the resulting correlation with the solar angle theta(12).
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Boucenna, M. S., Morisi, S., Peinado, E., Valle, J. W. F., & Shimizu, Y. (2012). Predictive discrete dark matter model and neutrino oscillations. Phys. Rev. D, 86(7), 073008–5pp.
Abstract: Dark matter stability can be achieved through a partial breaking of a flavor symmetry. In this framework we propose a type-II seesaw model where left-handed matter transforms nontrivially under the flavor group Delta(54), providing correlations between neutrino oscillation parameters, consistent with the recent Daya-Bay and RENO reactor angle measurements, as well as lower bounds for neutrinoless double beta decay. The dark matter phenomenology is provided by a Higgs-portal.
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Meloni, D., Morisi, S., & Peinado, E. (2012). Predicting leptonic CP violation in the light of the Daya Bay result on theta(13). Eur. Phys. J. C, 72(9), 2160–4pp.
Abstract: In the light of the recent Daya Bay result theta(DB)(13) = 8.8 degrees +/- 0.8 degrees, we reconsider the model presented in Meloni et al. (J. Phys. G 38: 015003, 2011), showing that, when all neutrino oscillation parameters are taken at their best fit values of Schwetz et al. (New J. Phys. 10: 113011, 2008) and where theta(13) = theta(DB)(13), the predicted values of the CP phase are delta approximate to pi/4.
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Meloni, D., Morisi, S., & Peinado, E. (2011). Fritzsch neutrino mass matrix from S-3 symmetry. J. Phys. G, 38(1), 015003–10pp.
Abstract: We present an extension of the standard model (SM) based on the discrete flavor symmetry S-3 which gives a neutrino mass matrix with two-zero texture of Fritzsch type and nearly diagonal charged lepton mass matrix. The model is compatible with the normal hierarchy only and predicts sin(2) theta(13) approximate to 0.01 at the best-fit values of solar and atmospheric parameters and maximal leptonic CP violation.
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Meloni, D., Morisi, S., & Peinado, E. (2011). Neutrino phenomenology and stable dark matter with A(4). Phys. Lett. B, 697(4), 339–342.
Abstract: We present a model based on the A(4) non-Abelian discrete symmetry leading to a predictive five-parameter neutrino mass matrix and providing a stable dark matter candidate. We found an interesting correlation among the atmospheric and the reactor angles which predicts theta(23) similar to pi/4for very small reactor angle and deviation from maximal atmospheric mixing for large theta(13). Only normal neutrino mass spectrum is possible and the effective mass entering the neutrinoless double beta decay rate is constrained to be vertical bar m(ee)vertical bar > 4 x 10(-4) eV.
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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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Morisi, S., & Peinado, E. (2011). Admixture of quasi-Dirac and Majorana neutrinos with tri-bimaximal mixing. Phys. Lett. B, 701(4), 451–457.
Abstract: We propose a realization of the so-called bimodal/schizophrenic model proposed recently. We assume 54, the permutation group of four objects as flavor symmetry giving tri-bimaximal lepton mixing at leading order. In these models the second massive neutrino state is assumed quasi-Dirac and the remaining neutrinos are Majorana states. In the case of inverse mass hierarchy, the lower bound on the neutrinoless double beta decay parameter m(ee) is about two times that of the usual lower bound, within the range of sensitivity of the next generation of experiments.
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