scholarly journals The Effects of Majorana Phases in Estimating the Masses of Neutrinos

2018 ◽  
Vol 47 ◽  
pp. 1860100
Author(s):  
Ng. K. Francis ◽  
Ankur Nath
Keyword(s):  
Neutrino Mass ◽  
Upper Bound ◽  
Mass Matrix ◽  
Majorana Neutrino ◽  
Double Beta Decay ◽  
Diagonal Form ◽  
Type I ◽  
Unknown Parameters ◽  
Mixing Angle ◽  
The Masses

Majorana CP violating phases coming from heavy right-handed Majorana mass matrices([Formula: see text]) are considered to estimate the masses of neutrinos. The effects of phases on quasi-degenerate neutrinos mass matrix obeying [Formula: see text] symmetry predicts the results consistent with observations for (i) solar mixing angle([Formula: see text]) below TBM, (ii) absolute neutrino mass parameters[[Formula: see text]] in neutrinoless double beta([Formula: see text]) decay, and (iii) cosmological upper bound [Formula: see text]. Analysis is carried out through parameterization of light left-handed Majorana neutrino matrices ([Formula: see text]) using only two unknown parameters ([Formula: see text]) within [Formula: see text] symmetry. We consider the charge lepton and up quark matrices as diagonal form of Dirac neutrino mass matrix ([Formula: see text]), and [Formula: see text] are generated using [Formula: see text] through inversion of Type-I seesaw formula. The analysis shows that the masses of neutrinos are in agreement with the upper bound from cosmology and neutrinoless double beta decay. The results presented in this article will have important implications in discriminating the neutrinos mass models.

scholarly journals Investigating two heavy neutral leptons neutrino seesaw mechanism at SHiP

2019 ◽  
Vol 34 (08) ◽  
pp. 1950047
Author(s):  
Marco Chianese ◽  
Damiano F. G. Fiorillo ◽  
Gennaro Miele ◽  
Stefano Morisi
Keyword(s):  
Neutrino Mass ◽  
Double Beta Decay ◽  
Type I ◽  
Mass Generation ◽  
Seesaw Mechanism ◽  
Mixing Angle ◽  
Mechanism Model ◽  
Neutrino Mass Generation ◽  
Generation Mechanisms ◽  
The Masses

One of the main purposes of SHiP experiment is to shed light on neutrino mass generation mechanisms like the so-called seesaw. We consider a minimal type-I seesaw neutrino mass mechanism model with two heavy neutral leptons (right-handed or sterile neutrinos) with arbitrary masses. Extremely high active-sterile mixing angle requires a correlation between the phases of the Dirac neutrino couplings. Actual experimental limits on the half-life of neutrinoless double beta decay [Formula: see text]-rate on the active-sterile mixing angle are not significative in constraining the masses or the mixing measurable by SHiP.

scholarly journals PHENOMENOLOGY OF "BIMAXIMAL + DEMOCRATIC" TYPE NEUTRINO MASS MATRIX

2006 ◽  
Vol 21 (13) ◽  
pp. 1067-1073 ◽  
Author(s):  
AMBAR GHOSAL ◽  
DEBASISH MAJUMDAR
Keyword(s):  
Neutrino Mass ◽  
Mass Matrix ◽  
Atmospheric Neutrino ◽  
Double Beta Decay ◽  
Neutrino Mass Matrix ◽  
Experimental Results ◽  
Neutrino Mixing ◽  
Mixing Angle ◽  
Mixing Angles ◽  
The Masses

We demonstrate that "Bimaximal + Democratic" type neutrino mass matrix can accommodate the deviation of θ⊙ from its maximal value along with the other present-day neutrino experimental results, namely, atmospheric, CHOOZ, neutrinoless double beta decay (ββ0ν) and result obtained from WMAP experiment. We define a function χp in terms of solar and atmospheric neutrino mass squared differences and solar neutrino mixing angle (obtained from different experiments and our proposed texture). The masses and mixing angles are expressed in terms of three parameters in our proposed texture. The allowed region of the texture parameters is obtained through minimization of the above function. The proposed texture crucially depends on the value of the experimental results of ββ0ν experiment among all other above-mentioned experiments. If, in future, ββ0ν experiments, namely, MOON, EXO, GENIUS shift the lower bound on 〈mee〉 at the higher side by one order, the present texture will be ruled out.

scholarly journals NEUTRINO MASSES, LEPTON FLAVOR MIXING AND LEPTOGENESIS IN THE MINIMAL SEESAW MODEL

2007 ◽  
Vol 16 (01) ◽  
pp. 1-50 ◽  
Author(s):  
WAN-LEI GUO ◽  
ZHI-ZHONG XING ◽  
SHUN ZHOU
Keyword(s):  
Beta Decay ◽  
Neutrino Mass ◽  
Mass Matrix ◽  
Majorana Neutrino ◽  
Double Beta Decay ◽  
Neutrino Mixing ◽  
Lepton Flavor ◽  
Seesaw Model ◽  
Flavor Mixing ◽  
Majorana Neutrinos

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.

scholarly journals Investigating the Hybrid Textures of Neutrino Mass Matrix for Near Maximal Atmospheric Neutrino Mixing

2018 ◽  
Vol 2018 ◽  
pp. 1-16
Author(s):  
Madan Singh
Keyword(s):  
Neutrino Mass ◽  
Mass Matrix ◽  
Atmospheric Neutrino ◽  
Zero Element ◽  
Majorana Neutrino ◽  
Neutrino Mixing ◽  
Mixing Angle ◽  
The Comparative Study ◽  
Reactor Mixing ◽  
Majorana Neutrino Mass

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.

scholarly journals Type II seesaw origin of nonzero θ13, δCP and leptogenesis

2014 ◽  
Vol 29 (22) ◽  
pp. 1450108 ◽  
Author(s):  
Debasish Borah
Keyword(s):  
Neutrino Mass ◽  
Mass Matrix ◽  
Neutrino Mass Matrix ◽  
Type I ◽  
Type Ii ◽  
Mixing Angle ◽  
Yukawa Couplings ◽  
Minimal Structure ◽  
Reactor Mixing ◽  
The Universe

We discuss the possible origin of nonzero reactor mixing angle θ13 and Dirac CP phase δ CP in the leptonic sector from a combination of type I and type II seesaw mechanisms. Type I seesaw contribution to neutrino mass matrix is of tri-bimaximal (TBM) type which gives rise to vanishing θ13 leaving the Dirac CP phase undetermined. If the Dirac neutrino mass matrix is assumed to take the diagonal charged lepton (CL) type structure, such a TBM type neutrino mass matrix originating from type I seesaw corresponds to real values of Dirac Yukawa couplings in the terms [Formula: see text]. This makes the process of right-handed heavy neutrino decay into a light neutrino and Higgs (N → νH) CP preserving ruling out the possibility of leptogenesis. Here we consider the type II seesaw term as the common origin of nonzero θ13 and δ CP by taking it as a perturbation to the leading order TBM type neutrino mass matrix. First, we numerically fit the type I seesaw term by taking oscillation as well as cosmology data and then compute the predictions for neutrino parameters after the type II seesaw term is introduced. We consider a minimal structure of the type II seesaw term and check whether the predictions for neutrino parameters lie in the 3σ range. We also compute the predictions for baryon asymmetry of the universe by considering type II seesaw term as the only source of CP violation and compare it with the latest cosmology data.

scholarly journals TEXTURE-ZERO MODEL FOR THE LEPTON MASS MATRICES

2012 ◽  
Vol 27 (28) ◽  
pp. 1250159 ◽  
Author(s):  
P. M. FERREIRA ◽  
L. LAVOURA
Keyword(s):  
Mass Spectrum ◽  
Neutrino Mass ◽  
Mass Matrix ◽  
Type I ◽  
Mixing Angle ◽  
Mass Matrices ◽  
Neutrino Mass Spectrum ◽  
Texture Zero ◽  
Vanishing Elements ◽  
Reactor Mixing

We suggest a simple model, based on the type-I seesaw mechanism, for the lepton mass matrices. The model hinges on an Abelian symmetry which leads to mass matrices with some vanishing matrix elements. The model predicts one massless neutrino and Meμ = 0 (M is the effective light-neutrino Majorana mass matrix). We show that these predictions agree with the present experimental data if the neutrino mass spectrum is inverted, i.e. if m3 = 0, provided the Dirac phase δ is very close to maximal (±π/ 2). In the case of a normal neutrino mass spectrum, i.e. when m1 = 0, the agreement of our model with the data is imperfect — the reactor mixing angle θ13 is too small in our model. Minimal leptogenesis is not an option in our model due to the vanishing elements in the Yukawa-coupling matrices.

scholarly journals Hybrid textures of neutrino mass matrix under the lamppost of latest neutrino and cosmology data

2016 ◽  
Vol 31 (06) ◽  
pp. 1650008 ◽  
Author(s):  
Rupam Kalita ◽  
Debasish Borah
Keyword(s):  
Neutrino Mass ◽  
Parameter Space ◽  
Mass Formula ◽  
Mass Matrix ◽  
Zero Element ◽  
Baryon Asymmetry ◽  
Double Beta Decay ◽  
Neutrino Mass Matrix ◽  
Type I ◽  
Mass Matrices

In this paper, we study all possible neutrino mass matrices with one zero element and two equal nonzero elements, known as hybrid texture neutrino mass matrices. In the diagonal charged lepton basis, we consider 39 such possible cases which are consistent with the latest neutrino data. Using the two constraints on neutrino mass matrix elements imposed by hybrid textures, we numerically evaluate the neutrino parameters like the lightest neutrino mass [Formula: see text], one Dirac CP phase [Formula: see text] and two Majorana CP phases [Formula: see text], [Formula: see text] by using the global fit [Formula: see text] values of three mixing angles and two mass squared differences. We then constrain this parameter space by using the cosmological upper bound on the sum of absolute neutrino masses given by Planck experiment. We also calculate the effective neutrino mass [Formula: see text] for this region of parameter space which can have relevance in future neutrinoless double beta decay experiments. We finally discriminate between these hybrid texture mass matrices from the requirement of producing correct baryon asymmetry through type I seesaw leptogenesis. We also constrain the light neutrino parameter space as well as the lightest right-handed neutrino mass from the constraint on baryon asymmetry of the Universe from Planck experiment.

A NEUTRINO MASS MODEL WITH REFLECTION SYMMETRY

2004 ◽  
Vol 19 (34) ◽  
pp. 2579-2586 ◽  
Author(s):  
AMBAR GHOSAL
Keyword(s):  
Neutrino Mass ◽  
Present Model ◽  
Majorana Neutrino ◽  
Double Beta Decay ◽  
Reflection Symmetry ◽  
Neutrino Mixing ◽  
Mass Model ◽  
Mixing Angle ◽  
Mass Matrices ◽  
Majorana Neutrino Mass

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.

scholarly journals μ − τ reflection symmetry and its explicit breaking for leptogenesis in a minimal seesaw model

2019 ◽  
Vol 34 (39) ◽  
pp. 1950329 ◽  
Author(s):  
Newton Nath
Keyword(s):  
Neutrino Mass ◽  
Mass Matrix ◽  
Majorana Neutrino ◽  
Neutrino Mass Matrix ◽  
Type I ◽  
Reflection Symmetry ◽  
Matrix Formula ◽  
Set Up ◽  
Majorana Neutrino Mass ◽  
The Given

The minimal seesaw framework, embroiling the Dirac neutrino mass matrix [Formula: see text] and the Majorana neutrino mass matrix [Formula: see text], is quite successful to explain the current global-fit results of neutrino oscillation data. In this context, we consider the most predictive forms of [Formula: see text] and [Formula: see text] with two simple parameters, respectively. Considering these matrices, we obtain the low-energy neutrino mass matrix under type-I seesaw formalism which obeys [Formula: see text] reflection symmetry and predicts [Formula: see text] and [Formula: see text]. In the given set-up, we also evaluate the Baryon Asymmetry of the Universe (BAU) through successful leptogenesis and find that perturbation of [Formula: see text] leads to the observed BAU and breaks exactness of the symmetry. Moreover, we also perform various correlation studies among different parameters in the framework of broken symmetry.

scholarly journals RIGHT-HANDED MAJORANA NEUTRINO MASS MATRICES FOR GENERATING BIMAXIMAL MIXINGS IN DEGENERATE AND INVERTED MODELS OF NEUTRINOS

2003 ◽  
Vol 18 (05) ◽  
pp. 743-753 ◽  
Author(s):  
MAHADEV PATGIRI ◽  
N. NIMAI SINGH
Keyword(s):  
Neutrino Mass ◽  
Atmospheric Neutrino ◽  
Majorana Neutrino ◽  
Double Beta Decay ◽  
Diagonal Form ◽  
Left Handed ◽  
Mass Matrices ◽  
Neutrino Mass Models ◽  
The Right ◽  
Majorana Neutrino Mass

An attempt is made to generate the bimaximal mixings of the three species of neutrinos from the textures of the right-handed Majorana neutrino mass matrices. We extend our earlier work in this paper for the generation of the nearly degenerate as well as the inverted hierarchical models of the left-handed Majorana neutrino mass matrices using the non-diagonal textures of the right-handed Majorana neutrino mass matrices and the diagonal form of Dirac neutrino mass matrices, within the framework of the see-saw mechanism in a model independent way. Such Majorana neutrino mass models are important in explaining the recently reported result on the neutrinoless double beta decay (0νββ) experiment, together with the earlier established data on LMA MSW solar and atmospheric neutrino oscillations.

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