arXiv subjects

E. Peinado

Publications and source records attributed to E. Peinado.

At least 37 records · Page 2Linked to original sources

arXiv2012

Proceedings of the first workshop on Flavor Symmetries and consequences in Accelerators and Cosmology (FLASY2011)

The main goals of the first "Workshop on FLAvor SYmmetries and consequences in accelerators and cosmology" (FLASY) was to summarize the theoretical status of flavor symmetries, bringing together young researchers in the field to stimulate discussions and new collaborations, with the aim of investigating possible new physics scenarios to be tested at the LHC, as well as in future neutrino, cosmology experiments and dark matter searches.

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arXiv2012

The reactor mixing angle and CP violation with two texture zeros in the light of T2K

We reconsider the phenomenological implications of two texture zeros in symmetric neutrino mass matrices in the light of the recent T2K result for the reactor angle and the new global analysis which gives also best fit values for the Dirac CP phase delta. The most important results of the analysis are: Among the viable cases classified by Frampton et al. only A1 and A2 predict the reactor mixing angle to be different from zero at 3 sigma. Furthermore these two cases are compatible only with a normal mass spectrum in the allowed region for the reactor angle. At the best fit value A1 and A2 predict 0.024 >= sin^2(theta13) >= 0.012 and 0.014 <= sin^2(theta13) <= 0.032, respectively, where the bounds on the right and the left correspond to cos(delta)=-1 and cos(delta)=1, respectively. The cases B1, B2, B3 and B4 predict nearly maximal CP violation, i.e. cos(delta) is approximately zero.

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arXiv2011

Dark matter stability from non-Abelian discrete flavor symmetries

We present a mechanism for the dark matter stability in the framework of a non-Abelian avour symmetry renormalizable model. The same non-abelian discrete avor symmetry which accounts for the observed pattern of neutrino oscillations, spontaneously breaks to a Z2 subgroup which renders DM stable. The simplest scheme leads to a scalar doublet DM potentially detectable in nuclear recoil experiments, inverse neutrino mass hierarchy, hence a neutrinoless double beta decay rate accessible to upcoming searches.

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arXiv2011

Constraining neutrinoless double beta decay

A class of discrete flavor-symmetry-based models predicts constrained neutrino mass matrix schemes that lead to specific neutrino mass sum-rules (MSR). We show how these theories may constrain the absolute scale of neutrino mass, leading in most of the cases to a lower bound on the neutrinoless double beta decay effective amplitude.

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arXiv2011

Relating quarks and leptons without grand-unification

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)xSU(2)xU(1) model where both supersymmetry and the assumed A4 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 characterizing CP violation in neutrino oscillations.

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arXiv2011

Model for T2K indication with maximal atmospheric angle and tri-maximal solar angle

Recently T2K gives hint in favor of large reactor angle. Most of the models, with tri-bimaximal 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 of the Cabibbo angle. In this letter, we discuss the possibility to have large reactor angle within the T2K region with maximal atmospheric mixing angle and trimaximal solar mixing angle, through the deviation from tri-bimaximal. We derive the structure of neutrino mass matrix that leads to the large reactor angle leaving maximal atmospheric angle and trimaximal solar angle. It is shown that such a structure of neutrino mass matrix can arise in a model with S4 flavor symmetry.

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arXiv2011

Admixture of quasi-Dirac and Majorana neutrinos with tri-bimaximal mixing

We propose a realization of the so-called bimodal/schizophrenic model proposed recently. We assume S4, 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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arXiv2011

Phenomenology of Dark Matter from A4 Flavor Symmetry

We investigate a model in which Dark Matter is stabilized by means of a Z2 parity that results from the same non-abelian discrete flavor symmetry which accounts for the observed pattern of neutrino mixing. In our A4 example the standard model is extended by three extra Higgs doublets and the Z2 parity emerges as a remnant of the spontaneous breaking of A4 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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arXiv2011

Stability of dark matter from the D4xZ2 flavor group

We study a model based on the dihedral group D4 in which the dark matter is stabilized by the interplay between a remnant Z2 symmetry, of the same spontaneously broken non-abelian group, and an auxiliary Z2 introduced to eliminate unwanted couplings in the scalar potential. In the lepton sector the model is compatible with normal hierarchy only and predicts a vanishing reactor mixing angle. Since m1=0, we also have a simple prediction for the effective mass in terms of the solar angle. There also exists a large portion of the model parameter space where the upper bounds on lepton flavor violating processes are not violated. We incorporate quarks in the same scheme finding that a description of the CKM mixing matrix is possible and that semileptonic K and D decays mediated by flavour changing neutral currents are under control.

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arXiv2011

Neutrino phenomenology and stable dark matter with A4

We present a model based on the A4 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 ~ pi/4 for 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 |m_ee| > 4 10^{-4} eV.

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arXiv2010

Discrete dark matter

We propose a new motivation for the stability of dark matter (DM). We suggest that the same non-abelian discrete flavor symmetry which accounts for the observed pattern of neutrino oscillations, spontaneously breaks to a Z2 subgroup which renders DM stable. The simplest scheme leads to a scalar doublet DM potentially detectable in nuclear recoil experiments, inverse neutrino mass hierarchy, hence a neutrinoless double beta decay rate accessible to upcoming searches, while reactor angle equal to zero gives no CP violation in neutrino oscillations.

hep-ph↗

arXiv2010

Fritzsch neutrino mass matrix from S3 symmetry

We present an extension of the Standard Model (SM) based on the discrete flavor symmetry S3 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 the sine squared of the reactor angle to be 0.01 at the best fit values of solar and atmospheric parameters and maximal leptonic CP violation.

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arXiv2010

An A4 model for neutrinos

The study of an extension of the standard model based on the flavor symmetry A4 is presented. Neutrino Majorana mass terms arise from dimension five operator and charged lepton masses from renormalizable Yukawa couplings. We introduce three Higgs doublets that belong to one triplet irreducible representation of A4. We study the most general A4-invariant scalar potential and the phenomenological consequences of the model. We find that the reactor angle could be as large as 0.03, while the atmospheric mixing angle is close to maximal.

hep-ph↗

arXiv2010

An S4 model for quarks and leptons with maximal atmospheric angle

We consider a model for quark and lepton masses and mixings based on S4 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 mu-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.

hep-ph↗

arXiv2009

An A4 model for lepton masses and mixings

We study an extension of the standard model based on the flavor symmetry A4 only. Neutrino Majorana mass terms arise from dimension five operator and charged lepton masses from renormalizable Yukawa couplings. We introduce three Higgs doublets that belong to one triplet irreducible representation of A4. We study the most general A4-invariant scalar potential and the phenomenological consequences of the model. We find that the reactor angle could be as large as 0.03, while the atmospheric mixing angle is close to maximal.

hep-ph↗

arXiv2008

Lepton flavour violating processes in an S_3-symmetric model

A variety of lepton flavour violating effects related to the recent discovery of neutrino oscillations and mixings is here systematically discussed in terms of an S_3-flavour permutational symmetry. After presenting some relevant results on lepton masses and mixings, previously derived in a minimal S_3-invariant extension of the Standard Model, we compute the branching ratios of some selected flavour-changing neutral current processes (FCNC) as well as the contribution of the exchange of neutral flavour-changing scalar to the anomaly of the magnetic moment of the muon. We found that the minimal S_3-invariant extension of the Standard Model describes successfully masses and mixings, as well as, all flavour changing neutral current processes in excellent agreement with experiment.

hep-ph↗

arXiv2007

Nearly tri-bimaximal mixing in the S_3 flavour symmetry

We present an analysis of the theoretical neutrino mixing matrix, V_{PMNS}^{th}, previously derived in the framework of the minimal S_3-invariant extension of the Standard Model. All entries in the neutrino mixing matrix, V_{PMNS}^{th}, the mixing angles and the Majorana phases are given as exact, explicit analytical functions of the mass ratios of the charged leptons and neutrinos, and one Dirac phase, in excellent agreement with the the latest experimental data. Here, it will be shown that all entries in V_{PMNS}^{th} are numerically very close to the tri-bimaximal form of the neutrino mixing matrix, so that V_{PMNS}^{th} may be written as V^{tri}+ΔV_{PMNS}^{tri}. The small correction ΔV_{PMNS}^{tri} is expressed as a sum of two terms: first, a small correction term proportional to m_{e}/m_μ depending only on the charged lepton mass ratios and, second, a Cabbibo-like, small term, δt_{12}, which is a function of both the charged lepton and the neutrino mass ratios.

hep-ph↗

arXiv2007

S_3-flavour symmetry as realized in lepton flavour violating processes

A variety of lepton flavour violating effects related to the recent discovery of neutrino oscillations and mixings is here systematically discussed in terms of an S_3-flavour permutational symmetry. After a brief review of some relevant results on lepton masses and mixings, that had been derived in the framework of a Minimal S_3-Invariant Extension of the Standard Model, we derive explicit analytical expressions for the matrices of the Yukawa couplings and compute the branching ratios of some selected flavour changing neutral current (FCNC) processes, as well as, the contribution of the exchange of neutral flavour changing scalars to the anomaly of the muon's magnetic moment as functions of the masses of the charged leptons and the neutral Higgs bosons. We find that the S_3 x Z_2 flavour symmetry and the strong mass hierarchy of the charged leptons strongly suppress the FCNC processes in the leptonic sector well below the present experimental upper bounds by many orders of magnitude. The contribution of FCNC to the anomaly of the muon's magnetic moment is small but non-negligible.

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