Neutrino Mass Matrix Model Research Articles

Trimaximal mixing and extended magic symmetry in a model of neutrino mass matrix

The trimaximal mixing scheme results in “magic” neutrino mass matrix which is known to accommodate neutrino oscillation data. In this paper, we propose a phenomenological ansatz for by extending the magic symmetry that leads to further reduction in the number of free parameters, thereby increasing the predictability of the model. The neutrino mixing parameters, effective Majorana mass m ee and CP invariants (J CP , I 1, I 2) are found to exhibit strong correlations for mixing paradigm. One of the generic feature of the model is the requirement of non-maximal for possible CP violation measurable in neutrino oscillation experiments. The observables m ee and sum of neutrino masses have imperative implications for yet unknown neutrino mass hierarchy. For inverted hierarchy, the lower bound on , predicted by the model, is found to be within the sensitivity reach of the decay experiments. Also, cosmological bound of 0.12 eV on , at 95% CL, refutes inverted hierarchy implying with normal hierarchy as the only viable possibility in the model. We have, also, illustrated a scenario wherein such a construction of the neutrino mass matrix can be realized using symmetry in the framework of Type-I+II seesaw mechanism.

A radiative type-II seesaw model with broken symmetry ansatz

Parametrization of the neutrino mass matrix in terms of well-known measured quantities is an attractive way to obtain a phenomenologically viable form. We propose a model of neutrino mass matrix based on type-II seesaw mechanism adhering the concept of badly broken symmetry. Two of the mixing angles are coming out as θ 23 ∼ 46.08°, θ 13 ∼ 8.69°. However, to accommodate the other oscillation parameters, we further add an extra doublet and the neutrino masses are generated through the Zee mechanism at the one loop level, and the modified model can admit all the extant data for a suitable choice of model parameters.

Neutrino mass generation with large SU(2)L multiplets under local [formula omitted] symmetry

We propose a model of neutrino mass matrix with large SU(2) multiplets and gauged U(1)Lμ−Lτ symmetry, in which we introduce SU(2) quartet scalar and quintet fermions with nonzero Lμ−Lτ charge. Then we investigate the neutrino mass structure and explore phenomenologies of large multiplet fields at the collider, particularly, focusing on doubly- and singly- charged exotic leptons from the quintet.

CP violating phase from minimal texture neutrino mass matrix: Test of the phase relevant to leptogenesis

The model of neutrino mass matrix with minimal texture is now tightly constrained by experiment so that it can yield a prediction for the phase of CP violation. This phase is predicted to lie in the range $\delta_{CP}=0.77\pi - 1.24\pi$. If neutrino oscillation experiment would find the CP violation phase outside this range, this means that the minimal-texture neutrino mass matrix, the element of which is all real, fails and the neutrino mass matrix must be complex, i.e., the phase must be present that is responsible for leptogenesis.

Neutrino mass matrix model with a bilinear form

A neutrino mass matrix model with a bilinear form $M_\nu = k_\nu (M_D M_R^{-1} M_D^T)^2$ is proposed within the framework of the so-called yukawaon model, which has been proposed for the purpose of a unified description of the lepton mixing matrix $U_{PMNS}$ and the quark mixing matrix $V_{CKM}$. The model has only two adjustable parameters for the PMNS mixing and neutrino mass atios. (Other parameters are fixed from the observed quark and charged lepton mass ratios and the CKM mixing.) The model gives reasonable values $\sin^2 2\theta_{12} \simeq 0.85$ and $\sin^2 2\theta_{23} \sim 1$ and $\sin^2 2\theta_{13} \sim 0.09$ together with $R_\nu \equiv \Delta m^2_{21}/\Delta m^2_{32} \sim 0.03$. Our prediction of the effective neutrino mass $<m>$ in the neutrinoless double beta decay takes a sizable value $< m >\simeq 0.0034$ eV.

Neutrino Mixing Matrix and Leptogenesis from Quantum Gravity

We assume that the neutrino masses and mixing arise through physics at a scale intermediate between Planck Scale and the electroweak scale. Quantum gravitational (Planck scale) effects lead to an effective SU(2)L×U(1) invariant dimension-5 Lagrangian involving neutrino and Higgs fields, which gives rise to additional terms in neutrino mass matrix. There additional term can be considered to be perturbation of the GUT scale bi-maximal neutrino mass matrix. We assume that the gravitational interaction is flavor blind. In this paper, we point out that due to Planck scale effects, in exact bimaximal model of neutrino mass matrix, measure \(J_{\mathrm{CP}}^{\max}\neq0\), it is possible to have lepton asymmetry of the universe.

HOW CAN CP VIOLATION IN THE NEUTRINO SECTOR BE LARGE IN A 2 ↔ 3 SYMMETRIC MODEL?

Based on a neutrino mass matrix model in which a 2 ↔ 3 symmetry is only broken by a phase parameter, it is investigated how the lepton mixing matrix can deviate from the so-called tribimaximal mixing under a condition that CP is maximally violated.

Neutrino mass hierarchies in a mass matrix form versus its inverse form

A neutrino mass matrix model M{sub {nu}} with M{sub {nu}}{sup T}=M{sub {nu}} and a model with its inverse matrix form M-tilde{sub {nu}}=m{sub 0}{sup 2}(M{sub {nu}}*){sup -1} can be diagonalized by the same mixing matrix U{sub {nu}}. It is investigated whether a scenario which provides a matrix model M{sub {nu}} with normal mass hierarchy can also give a model with an inverted mass hierarchy by considering a model with an inverse form of M{sub {nu}}.

Bimaximal neutrino mixing in a Zee-type model with badly broken flavor symmetry

A Zee-type neutrino mass matrix model with a badly broken horizontal symmetry $\mathrm{SU}{(3)}_{H}$ is investigated. By putting a simple ansatz on the symmetry breaking effects of $\mathrm{SU}{(3)}_{H}$ for transition matrix elements, it is demonstrated that the model can give nearly bimaximal neutrino mixing with the ratio $\ensuremath{\Delta}{m}_{\mathrm{solar}}^{2}/\ensuremath{\Delta}{m}_{\mathrm{atm}}^{2}\ensuremath{\simeq}\sqrt{2}{m}_{e}{/m}_{\ensuremath{\mu}}=6.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3},$ which is in excellent agreement with the observed data. In the near future, the lepton-number violating decay $\stackrel{\ensuremath{\rightarrow}}{Z}{\ensuremath{\mu}}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\tau}}^{\ensuremath{\mp}}$ will be observed.

A Neutrino Mass Matrix Model with Many Quantum Charges and No SUSY

We present a model based on our favorite gauge group which we call Anti-GUT and which in its extended form to be applied for neutrinos in the see-saw picture consists in that we have for each family separately a set of gauge fields as in the Standard Model plus a gauged (B – L)-charge. It may function as a concrete model manifestation of the type of model suggested by some general statistical considerations as to what a mass matrix model is to be to match naturally the rough features of the spectrum and the baryon asymmetry so nicely obtained in see-saw models along the Fukugita–Yanagida scheme.

Neutrino mass matrix suppression by Abelian charges with see-saw mechanism

We have investigated a neutrino mass matrix model without supersymmetry including three see-saw right-handed neutrinos around order $10^{12}$ GeV masses, aiming at a picture with all small numbers explained as being due to approximately conserved gauge charges. The prediction of the solar neutrino mixing angle is given by $\sin^22\theta_{\odot}= 3 {+3\atop -2}\times10^{-2}$; in fact, the solar mixing angle is, apart from detailed order unity corrections, equal to the Cabibbo angle. Furthermore the ratio of the solar neutrino mass square difference to that for the atmospheric neutrino oscillation is predicted to $6 {+11\atop -4}\times10^{-4}$ and is given by the same Cabibbo angle related parameter $\xi$ as $6 \xi^4$.

NEUTRINO OSCILLATIONS IN A 3νL+3νR FRAMEWORK WITH FIVE LIGHT NEUTRINOS

We propose a neutrino mass matrix model in which five neutrino species remain light through the seesaw mechanism within a supersymmetric 3νL+3νR framework. We construct such a model based on the nonrenormalizable terms in the superpotential constrained by the discrete symmetry which may be expected in the models at the high energy scale such as superstring. We study the possible oscillation phenomena by fixing mass parameters so as to explain the solar and atmospheric neutrino deficits and also include a candidate of the suitable dark matter. We also discuss the charged lepton mass matrix based on this neutrino model. LSND results may be consistently explained within this model.

Neutrino oscillations in a $3\nu_L+3\nu_R$ framework with five light neutrinos

We propose a neutrino mass matrix model in which five neutrino species remain light through the seesaw mechanism within a supersymmetric 3νL+3νR framework. We construct such a model based on the nonrenormalizable terms in the superpotential constrained by the discrete symmetry which may be expected in the models at the high energy scale such as superstring. We study the possible oscillation phenomena by fixing mass parameters so as to explain the solar and atmospheric neutrino deficits and also include a candidate of the suitable dark matter. We also discuss the charged lepton mass matrix based on this neutrino model. LSND results may be consistently explained within this model.