Neutrino masses and mixings with an S3 family permutation symmetry (original) (raw)
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Family Symmetry and Neutrino Bi-Tri-Maximal Mixing
Nuclear Physics B, 2006
The observed large mixing angles in the lepton sector may be the first signal for the presence of a non-Abelian family symmetry. However, to obtain the significant differences between the mixing of the neutrino and charged fermion sectors, the vacuum expectation values involved in the breaking of such a symmetry in the two sectors must be misaligned. We investigate how this can be achieved in models with an SU (3) f family symmetry consistent with an underlying GUT. We show that such misalignment can be achieved naturally via the seesaw mechanism. We construct a specific example in which the vacuum (mis)alignment is guaranteed by additional symmetries. This model generates a fermion mass structure consistent with all quark and lepton masses and mixing angles. Neutrino mixing is close to bi-tri-maximal mixing.
The S 3 flavour symmetry: Neutrino masses and mixings
Fortschritte der Physik, 2013
In this work, we discuss the neutrino masses and mixings as the realization of an S 3 flavour permutational symmetry in two models, namely the Standard Model and an extension of the Standard Model with three Higgs doublets. In the S 3 Standard Model, mass matrices of the same generic form are obtained for the neutrinos and charged leptons when the S 3 flavour symmetry is broken sequentially according to the chain S 3L ⊗ S 3R ⊃ S diag 3 ⊃ S 2 . In the minimal S 3 -symmetric extension of the Standard Model, the S 3 symmetry is left unbroken, and the concept of flavour is extended to the Higgs sector by introducing in the theory three Higgs fields which are SU (2) doublets. In both models, the mass matrices of the neutrino and charged leptons are reparametrized in terms of their eigenvalues, and exact, explicit analytical expressions for the neutrino mixing angles as functions of the masses of neutrinos and charged leptons are obtained. In the case of the S 3 Standard Model, from a χ 2 fit of the theoretical expressions of the lepton mixing matrix to the values extracted from experiment, the numerical values of the neutrino mixing angles are obtained in excellent agreement with experimental data. In the S 3 extension of the Standard Model, if two of the right handed neutrinos masses are degenerate, the reactor and atmospheric mixing angles are determined by the masses of the charged leptons, yielding θ 23 in excellent agreement with experimental data, and θ 13 different from zero but very small. If the masses of the three right handed neutrinos are assumed to be different, then it is possible to get θ 13 also in very good agreement with experimental data. We also show the branching ratios of some selected flavour changing neutral currents (FCNC) process as well as the contribution of the exchange of a neutral flavour changing scalar to the anomaly of the magnetic moment of the muon.
Towards a grand unified picture for neutrino and quark mixings
Nuclear Physics B - Proceedings Supplements, 2000
The comparison of the CKM mixing angles with the leptonic mixings implied by the recent atmospheric and solar neutrino data exhibits an interesting complementarity. This pattern can be understood in the context of the SU (5) grand unification, assuming that the fermion mass matrices have Fritzsch-like structures but are not necessarily symmetric. (The present contribution is based on the paper in ref. [1].) * Talk given by A. Rossi at the Int. Workshop "Particles in Astrophysics and Cosmology: from Theory to Observation",
A simple grand unification view of neutrino mixing and fermion mass matrices
Physics Letters B, 1999
Assuming three light neutrinos and the see-saw mechanism we present a semiquantitative model of fermion masses based on (SUSY) SU(5) and abelian horizontal charges. A good description of the observed pattern of quark and lepton masses is obtained. For neutrinos we naturally obtain widely split masses and large atmospheric neutrino mixing as a consequence of SU(5)-related asymmetric mass matrices for d quarks and charged leptons.
Fermion masses and mixing angles from SU(3) family symmetry
Physics Letters B, 2001
We propose a model based on SU (3) family symmetry which leads to a successful description of quark and lepton masses and mixing angles including approximate bi-maximal mixing in the neutrino sector suitable for the LOW or quasi-vacuum solar solutions, with the atmospheric angle predicted to be accurately maximal due to the SU (3) symmetry. The model predicts a CHOOZ angle θ 13 ∼ |V ub |. The SU (3) symmetry can also ensure the near degeneracy of squarks and sleptons needed to avoid large flavour changing neutral currents.
Neutrino masses and mixings in a Minimal S 3-invariant Extension of the Standard Model
2007
The mass matrices of the charged leptons and neutrinos, that had been derived in the framework of a Minimal S 3-invariant Extension of the Standard Model (Kubo J, Mondragón A, Mondragón M, Rodríguez-Jáuregui E. Prog. Theor. Phys. 109, 795, (2003)), are here reparametrized in terms of their eigenvalues. The neutrino mixing matrix, V P M N S , is then computed and exact, explicit analytical expressions for the neutrino mixing angles as functions of the masses of the neutrinos and charged leptons are obtained. The reactor, θ 13 , and the atmosferic, θ 23 , mixing angles are found to be functions only of the masses of the charged leptons. The numerical values of θ th 13 and θ th 23 computed from our theoretical expressions are found to be in excellent agreement with the latest experimental determinations. The solar mixing angle, θ th 12 , is found to be a function of both, the charged lepton and neutrino masses, as well as of a Majorana phase φ ν. A comparison of our theoretical expression for the solar angle θ th 12 with the latest experimental value θ exp 12 ≈ 34 • allowed us to fix the scale and origin of the neutrino mass spectrum and obtain the mass values |m ν 2 | = 0.0507eV , |m ν 1 | = 0.0499eV and |m ν 3 | = 0.0193eV , in very good agreement with the observations of neutrino oscillations, the bounds extracted from neutrinoless double beta decay and the precision cosmological measurements of the CMB.
arXiv: High Energy Physics - Phenomenology, 2013
We propose a 3-3-1 model where the SU(3)CotimesSU(3)LotimesU(1)XSU(3)_{C}\otimes SU(3)_{L}\otimes U(1)_{X}SU(3)CotimesSU(3)LotimesU(1)X symmetry is extended by S3otimesZ3otimesZ3primeotimesZ8otimesZ16S_{3}\otimes Z_{3}\otimes Z_{3}^{\prime }\otimes Z_{8}\otimes Z_{16}S3otimesZ3otimesZ3primeotimesZ8otimesZ16 and the scalar spectrum is enlarged by extra % SU(3)_{L} singlet scalar fields. The model successfully describes the observed SM fermion mass and mixing pattern. In this framework, the light active neutrino masses arise via an inverse seesaw mechanism and the observed charged fermion mass and quark mixing hierarchy is a consequence of the Z3otimesZ3primeotimesZ8otimesZ16Z_{3}\otimes Z_{3}^{\prime }\otimes Z_{8}\otimes Z_{16}Z3otimesZ3primeotimesZ8otimesZ16 symmetry breaking at very high energy. The obtained physical observables for both quark and lepton sectors are compatible with their experimental values. The model predicts the effective Majorana neutrino mass parameter of neutrinoless double beta decay to be mbetabeta=m_{\beta \beta }=mbetabeta= 4 and 48 meV for the normal and the inverted neutrino spectra, respectively. Furthermore, we found a leptonic Dirac CP violating phase close ...
Family Symmetry and Neutrino Mixing
Physical Review Letters, 1998
The observed quark hierarchies suggest a simple family symmetry. Generalized to leptons through grand-unified quantum numbers, it produces a neutrino mixing matrix with order-one ν µ − ν τ mixing, and order-λ 3 ν e − ν µ and ν e − ν τ mixings. The intrafamily hierarchy and observed neutrino mass differences together require this symmetry to be anomalous, suggesting through the Green-Schwarz mechanism a string or M-theory origin for the symmetry.
Broken S 3 symmetry in the neutrino mass matrix
Physics Letters B, 2011
We explore the feasibility of the discrete flavor symmetry S3S3 to explain the pattern of neutrino masses and mixings. In the flavor basis, the neutrino mass matrix is taken to be invariant under S3S3 symmetry at the zeroth order. The effects of breaking S3S3 symmetry by matrices invariant under different S2S2 subgroups of S3S3 are studied. The resulting retrocirculant perturbation matrix leads to the perturbed S3S3 neutrino mass matrix having a trimaximal eigenvector as suggested by the solar neutrino data. It is found that after the third order perturbation the neutrino mixings only depend on the perturbation parameter and are consistent with the current experimental data leading to very small deviations from tribimaximal mixing. These perturbations in the S3S3 invariant neutrino mass matrix result in interesting interplay between the solar and the reactor neutrino mixing angles. We also get a strongly suppressed range of effective Majorana mass which lies well within the reach of...