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Boucenna, S. M., Fonseca, R. M., Gonzalez-Canales, F., & Valle, J. W. F. (2015). Small neutrino masses and gauge coupling unification. Phys. Rev. D, 91(3), 031702–5pp.
Abstract: The physics responsible for gauge coupling unification may also induce small neutrino masses. We propose a novel gauge-mediated radiative seesaw mechanism for calculable neutrino masses. These arise from quantum corrections mediated by new SU(3)(C) circle times SU(3)(L) circle times U(1)(X) (3-3-1) gauge bosons and the physics driving gauge coupling unification. Gauge couplings unify for a 3-3-1 scale in the TeV range, making the model directly testable at the LHC.
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Aranda, A., Bonilla, C., Morisi, S., Peinado, E., & Valle, J. W. F. (2014). Dirac neutrinos from flavor symmetry. Phys. Rev. D, 89(3), 033001–5pp.
Abstract: We present a model where Majorana neutrino mass terms are forbidden by the flavor symmetry group Delta(27). Neutrinos are Dirac fermions and their masses arise in the same way as those of the charged fermions, due to very small Yukawa couplings. The model fits current neutrino oscillation data and correlates the octant of the atmospheric angle theta(23) with the magnitude of the lightest neutrino mass, with maximal mixing excluded for any neutrino mass hierarchy.
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Chen, P., Ding, G. J., Gonzalez-Canales, F., & Valle, J. W. F. (2016). Classifying CP transformations according to their texture zeros: Theory and implications. Phys. Rev. D, 94(3), 033002–26pp.
Abstract: We provide a classification of generalized CP symmetries preserved by the neutrino mass matrix according to the number of zero entries in the associated transformation matrix. We determine the corresponding constrained form of the lepton mixing matrix, characterized by correlations between the mixing angles and the CP violating phases. We compare with the corresponding restrictions from current neutrino oscillation global fits and show that, in some cases, the Dirac CP phase characterizing oscillations is highly constrained. Implications for current and upcoming long baseline neutrino oscillation experiments T2K, NO nu A, and DUNE, as well as neutrinoless double beta decay experiments are discussed. We also study the cosmological implications of such schemes for leptogenesis.
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Ge, S. F., Pasquini, P., Tortola, M., & Valle, J. W. F. (2017). Measuring the leptonic CP phase in neutrino oscillations with nonunitary mixing. Phys. Rev. D, 95(3), 033005–14pp.
Abstract: Non-unitary neutrino mixing implies an extra CP violating phase that can fake the leptonic Dirac CP phase delta(CP) of the simplest three-neutrino mixing benchmark scheme. This would hinder the possibility of probing for CP violation in accelerator-type experiments. We take T2K and T2HK as examples to demonstrate the degeneracy between the “standard” (or “unitary”) and “nonunitary” CP phases. We find, under the assumption of nonunitary mixing, that their CP sensitivities severely deteriorate. Fortunately, the TNT2K proposal of supplementing T2(H)K with a μDAR source for better measurement of delta(CP) can partially break the CP degeneracy by probing both cos delta(CP) and sin delta(CP) dependences in the wide spectrum of the μDAR flux. We also show that the further addition of a near detector to the μDAR setup can eliminate the degeneracy completely.
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Reig, M., Valle, J. W. F., & Vaquera-Araujo, C. A. (2016). Realistic SU(3)(c) x SU(3)(L) x U(1)(X) model with a type II Dirac neutrino seesaw mechanism. Phys. Rev. D, 94(3), 033012–4pp.
Abstract: Here we propose a realistic SU(3)(c) circle times SU(3)(L) circle times U(1)(X) electroweak gauge model with enlarged Higgs sector. The scheme allows for the natural implementation of a type II seesaw mechanism for Dirac neutrinos, while charged lepton and quark masses are reproduced in a natural way thanks to the presence of new scalars. The new SU(3)(c) circle times SU(3)(L) circle times U(1)(X) energy scale characterizing neutrino mass generation could be accessible to the current LHC experiments.
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