scholarly journals Predictions for the neutrino parameters in the minimal model extended by linear combination of U(1)$$_{L_e-L_\mu }$$, U(1)$$_{L_\mu -L_\tau }$$ and U(1)$$_{B-L}$$ gauge symmetries

Author(s):  
Kento Asai

Abstract We study the minimal extensions of the Standard Model by a linear combination of U(1)$$_{L_e-L_\mu }$$Le-Lμ, U(1)$$_{L_\mu -L_\tau }$$Lμ-Lτ and U(1)$$_{B-L}$$B-L gauge symmetries, where three right-handed neutrinos and one U(1)-breaking SU(2)$$_L$$L singlet or doublet scalar are introduced. Because of the dependence on the lepton flavor, the structures of both Dirac and Majorana mass matrices of neutrinos are restricted. In particular, the two-zero minor and texture structures in the mass matrix for the active neutrinos are interesting. Analyzing these structures, we obtain uniquely all the neutrino parameters, namely the Dirac CP phase $$\delta $$δ, the Majorana CP phases $$\alpha _{2,3}$$α2,3 and the mass eigenvalues of the light neutrinos $$m_i$$mi as functions of the neutrino mixing angles $$\theta _{12}$$θ12, $$\theta _{23}$$θ23, and $$\theta _{13}$$θ13, and the squared mass differences $$\Delta m^2_{21}$$Δm212 and $$\Delta m^2_{31}$$Δm312. In 7 minimal models which are consistent with the recent neutrino oscillation data, we also obtain the predictions for the sum of the neutrino masses $$\Sigma _i m_i$$Σimi and the effective Majorana neutrino mass $$\langle m_{\beta \beta }\rangle $$⟨mββ⟩ and compare them with the current experimental limits. In addition, we also discuss the implication of our results for leptogenesis.

2007 ◽  
Vol 16 (01) ◽  
pp. 1-50 ◽  
Author(s):  
WAN-LEI GUO ◽  
ZHI-ZHONG XING ◽  
SHUN ZHOU

We present a review of neutrino phenomenology in the minimal seesaw model (MSM), an economical and intriguing extension of the Standard Model with only two heavy right-handed Majorana neutrinos. Given current neutrino oscillation data, the MSM can predict the neutrino mass spectrum and constrain the effective masses of the tritium beta decay and the neutrinoless double-beta decay. We outline five distinct schemes to parameterize the neutrino Yukawa-coupling matrix of the MSM. The lepton flavor mixing and baryogenesis via leptogenesis are investigated in some detail by taking account of possible texture zeros of the Dirac neutrino mass matrix. We derive an upper bound on the CP-violating asymmetry in the decay of the lighter right-handed Majorana neutrino. The effects of the renormalization-group evolution on the neutrino mixing parameters are analyzed, and the correlation between the CP-violating phenomena at low and high energies is highlighted. We show that the observed matter-antimatter asymmetry of the Universe can naturally be interpreted through the resonant leptogenesis mechanism at the TeV scale. The lepton-flavor-violating rare decays, such as μ→e+γ, are also discussed in the supersymmetric extension of the MSM.


2018 ◽  
Vol 2018 ◽  
pp. 1-16
Author(s):  
Madan Singh

We have studied that the implication of a large value of the effective Majorana neutrino mass in case of neutrino mass matrices has either two equal elements and one zero element (popularly known as hybrid texture) or two equal cofactors and one zero minor (popularly known as inverse hybrid texture) in the flavor basis. In each of these cases, four out of sixty phenomenologically possible patterns predict near maximal atmospheric neutrino mixing angle in the limit of large effective Majorana neutrino mass. This feature remains irrespective of the experimental data on solar and reactor mixing angles. In addition, we have also performed the comparative study of all the viable cases of hybrid and inverse hybrid textures at 3σ CL.


2006 ◽  
Vol 21 (25) ◽  
pp. 1917-1921 ◽  
Author(s):  
ERNEST MA

The discrete subgroup Δ(27) of SU(3) has some interesting properties which may be useful for understanding charged-lepton and neutrino mass matrices. Assigning leptons to the 3 and [Formula: see text] representations of Δ(27), a simple form of the Majorana neutrino mass matrix is obtained and compared to present data.


2000 ◽  
Vol 15 (37) ◽  
pp. 2257-2263
Author(s):  
N. HABA ◽  
TOMOHARU SUZUKI

It is important to measure Ue3 in the lepton flavor mixing matrix in order to understand the structure of Majorana neutrino mass matrix. Recently it is conjectured that the measurement of Ue3 would discriminate one solution among various solar neutrino ones provided that the three mass eigenvalues of neutrinos have the relation m1≪m2≪m3 or m1~m2≪m3. In this letter we show that this conjecture is rather restrictive and the relation [Formula: see text] is derived by a nontrivial assumption and Ue3 cannot discriminate among solar neutrino oscillation solutions without the information on another physical parameter.


2004 ◽  
Vol 19 (34) ◽  
pp. 2579-2586 ◽  
Author(s):  
AMBAR GHOSAL

We demonstrate that an SU (2)L× U (1)Y model with the same particle content as Standard Model (SM) and discrete reflection symmetry between second and third generations of leptons gives rise to charged lepton and neutrino mass matrices which can accommodate the present solar, atmospheric, WMAP neutrino experimental results. The model predicts the value of |U13| which could be tested in neutrino factories and the effective Majorana neutrino mass <mee> which is at the lower end of the present experimental value. Neutrino masses are generated through dim=5 operators and the scale of which are constrained by the value of <mee>. If, in future neutrinoless double beta decay experiments namely, MOON, EXO, GENIUS shift the lower bound on <mee> by one order, the present model will fail to accommodate the solar neutrino mixing angle due to LMA solution.


Author(s):  
Abdel Pérez-Lorenzana

Exchange [Formula: see text] symmetry in the effective Majorana neutrino mass matrix does predict a maximal mixing for atmospheric neutrino oscillations asides to a null mixing that cannot be straightforwardly identified with reactor neutrino oscillation mixing, [Formula: see text], unless a specific ordering is assumed for the mass eigenstates. Otherwise, a nonzero value for [Formula: see text] is predicted already at the level of an exact symmetry. In this case, solar neutrino mixing and scale, as well as the correct atmospheric mixing arise from the breaking of the symmetry. I present a mass matrix proposal for normal hierarchy that realizes this scenario, where the smallness of [Formula: see text] is naturally given by the parameter [Formula: see text] and the solar mixing is linked to the smallness of [Formula: see text]. The proposed matrix remains stable under renormalization effects and it also allows to account for CP violation within the expected region without further constrains.


2002 ◽  
Vol 17 (25) ◽  
pp. 3629-3640 ◽  
Author(s):  
N. NIMAI SINGH ◽  
MAHADEV PATGIRI

We study the origin of neutrino masses and mixing angles which can accommodate the LMA MSW solutions of the solar neutrino anomaly as well as the solution of the atmospheric neutrino problem, within the framework of the see-saw mechanism. We employ the diagonal form of the Dirac neutrino mass matrices with the physical masses as diagonal elements in the hierarchical order. Such a choice has been motivated from the fact that the known CKM angles for the quark sector, are relatively small. We consider both possibilities where the Dirac neutrino mass matrix is either the charged lepton or the up-quark mass matrix within the framework of SO(10) GUT with or without supersymmetry. The nonzero texture of the right-handed Majorana neutrino mass matrix M R is used for the generation of the desired bimaximal mixings in a model independent way. Both hierarchical and inverted hierarchical models of the left-handed Majorana neutrino mass matrices are generated and then discussed with examples. The see-saw mass scale which is kept as a free parameter, is predicted in all the examples.


2015 ◽  
Vol 30 (22) ◽  
pp. 1550130 ◽  
Author(s):  
Rupam Kalita ◽  
Debasish Borah

We study the effects of Majorana neutrino phases in lepton flavor violation and the origin of matter–antimatter asymmetry through the mechanism of leptogenesis within the framework of a model where both type I and type II seesaw mechanisms can contribute to tiny neutrino masses. We parametrize the type I seesaw mass matrix by assuming it to give rise to a tri-bimaximal (TBM) type neutrino mixing which predicts [Formula: see text]. The type II seesaw mass matrix is then constructed in such a way that the necessary deviation from TBM mixing and the best fit values of neutrino parameters can be obtained when both type I and type II seesaw contributions are taken into account. Considering both subleading as well as equally dominating type II seesaw term, we first constrain the Majorana CP phases from the requirement of producing correct baryon asymmetry through leptogenesis and then incorporating the experimental bounds on lepton flavor violating decays [Formula: see text] and [Formula: see text].


1993 ◽  
Vol 08 (22) ◽  
pp. 2099-2109 ◽  
Author(s):  
H. DREINER ◽  
G.K. LEONTARIS ◽  
N.D. TRACAS

We extend a fermion mass matrix ansatz by Giudice to include neutrino masses. The previous predictions are maintained. With two additional parameters, a large Majorana neutrino mass and a hierarchy factor, we have seven further low energy predictions: the masses of the neutrinos, the mixing angles and the phase in the leptonic sector. We choose a reasonable hierarchy of Majorana masses and fit the overall mass scale according to a solution of the solar neutrino problem via the MSW mechanism, which is in agreement with the 37 Cl , Kamiokande, SAGE and GALLEX data. We then also obtain a cosmologically interesting tau-neutrino mass.


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