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Das, S. P., Deppisch, F. F., Kittel, O., & Valle, J. W. F. (2012). Heavy neutrinos and lepton flavor violation in left-right symmetric models at the LHC. Phys. Rev. D, 86(5), 055006–20pp.
Abstract: We discuss lepton flavor violating processes induced in the production and decay of heavy right-handed neutrinos at the LHC. Such particles appear in left-right symmetrical extensions of the standard model as the messengers of neutrino mass generation, and can have masses at the TeV scale. We determine the expected sensitivity on the right-handed neutrino mixing matrix, as well as on the right-handed gauge boson and heavy neutrino masses. By comparing the sensitivity of the LHC with that of searches for low energy lepton flavor violating processes, we identify favorable areas of the parameter space to explore the complementarity between lepton flavor violating at low and high energies.
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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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Campos, F., Eboli, O. J. P., Magro, M. B., Porod, W., Restrepo, D., Das, S. P., et al. (2012). Probing neutralino properties in minimal supergravity with bilinear R-parity violation. Phys. Rev. D, 86(7), 075001–8pp.
Abstract: Supersymmetric models with bilinear R-parity violation can account for the observed neutrino masses and mixing parameters indicated by neutrino oscillation data. We consider minimal supergravity versions of bilinear R-parity violation where the lightest supersymmetric particle is a neutralino. This is unstable, with a large enough decay length to be detected at the CERN Large Hadron Collider. We analyze the Large Hadron Collider potential to determine the lightest supersymmetric particle properties, such as mass, lifetime and branching ratios, and discuss their relation to neutrino properties.
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Forero, D. V., Tortola, M., & Valle, J. W. F. (2012). Global status of neutrino oscillation parameters after Neutrino-2012. Phys. Rev. D, 86(7), 073012–8pp.
Abstract: Here we update the global fit of neutrino oscillations in Refs. [T. Schwetz, M. Tortola, and J. W. F. Valle, New J. Phys. 13, 063004 (2011); T. Schwetz, M. Tortola, and J. W. F. Valle, New J. Phys. 13, 109401 (2011)] including the recent measurements of reactor antineutrino disappearance reported by the Double Chooz, Daya Bay, and RENO experiments, together with latest MINOS and T2K appearance and disappearance results, as presented at the Neutrino-2012 conference. We find that the preferred global fit value of theta(13) is quite large: sin(2)theta(13) similar or equal to 0.025 for normal and inverted neutrino mass ordering, with theta(13) = 0 now excluded at more than 10 sigma. The impact of the new theta(13) measurements over the other neutrino oscillation parameters is discussed as well as the role of the new long-baseline neutrino data and the atmospheric neutrino analysis in the determination of a non-maximal atmospheric angle theta(23).
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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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Ding, G. J., Morisi, S., & Valle, J. W. F. (2013). Bilarge neutrino mixing and Abelian flavor symmetry. Phys. Rev. D, 87(5), 053013–13pp.
Abstract: We explore two bilarge neutrino mixing Anzatze within the context of Abelian flavor symmetry theories: (BL1) sin theta(12) similar to lambda, sin theta(13) similar to lambda, sin theta(23) similar to lambda, and (BL2) sin theta(12) similar to lambda, sin theta(13) similar to lambda, sin theta(23) similar to 1 – lambda. The first pattern is proposed by two of us and is favored if the atmospheric mixing angle theta(23) lies in the first octant, while the second one is preferred for the second octant of theta(23). In order to reproduce the second texture, we find that the flavor symmetry should be U(1) x Z(m), while for the first pattern the flavor symmetry should be extended to U(1) x Z(m) x Z(n) with m and n of different parity. Explicit models for both mixing patterns are constructed based on the flavor symmetries U(1) x Z(3) x Z(4) and U(1) x Z(2). The models are extended to the quark sector within the framework of SU(5) grand unified theory in order to give a successful description of quark and lepton masses and mixing simultaneously. Phenomenological implications are discussed.
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Forero, D. V., Morisi, S., Romao, J. C., & Valle, J. W. F. (2013). Neutrino mixing with revamped A(4) flavor symmetry. Phys. Rev. D, 88(1), 016003–7pp.
Abstract: We suggest a minimal extension of the simplest A(4) flavor model that can induce a nonzero theta(13) value, as required by recent neutrino oscillation data from reactors and accelerators. The predicted correlation between the atmospheric mixing angle theta(23) and the magnitude of theta(13) leads to an allowed region substantially smaller than indicated by neutrino-oscillation global fits. Moreover, the scheme correlates CP violation in neutrino oscillations with the octant of the atmospheric mixing parameter theta(23) in such a way that, for example, maximal mixing necessarily violates CP. We briefly comment on other phenomenological features of the model.
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Morisi, S., Nebot, M., Patel, K. M., Peinado, E., & Valle, J. W. F. (2013). Quark-lepton mass relation and CKM mixing in an A(4) extension of the minimal supersymmetric standard model. Phys. Rev. D, 88(3), 036001–8pp.
Abstract: An interesting mass relation between down-type quarks and charged leptons has been recently predicted within a supersymmetric SU(3)(c) circle times SU(2)(L) circle times U(1)(Y) model based on the A(4) flavor symmetry. Here we propose a simple extension which provides an adequate full description of the quark sector. By adding a pair of vectorlike up quarks, we show how the CKM entries V-ub, V-cb, V-td and V-ts arise from deviations of the unitarity. We perform an analysis including the most relevant observables in the quark sector, such as oscillations and rare decays of kaons, B-d and B-s mesons. In the lepton sector, the model predicts an inverted hierarchy for the neutrino masses, leading to a potentially observable rate of neutrinoless double beta decay.
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Lattanzi, M., Riemer-Sorensen, S., Tortola, M., & Valle, J. W. F. (2013). Updated CMB and x- and gamma-ray constraints on Majoron dark matter. Phys. Rev. D, 88(6), 063528–8pp.
Abstract: The Majoron provides an attractive dark matter candidate, directly associated with the mechanism responsible for spontaneous neutrino mass generation within the standard model SU(3)(c) circle times SU(2)(L) circle times U(1)(Y) framework. Here we update the cosmological and astrophysical constraints on Majoron dark matter coming from the cosmic microwave background and a variety of x- and gamma-ray observations.
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