scholarly journals Effects of Leptonic Nonunitarity on Lepton Flavor Violation, Neutrino Oscillation, Leptogenesis, and Lightest Neutrino Mass

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Gayatri Ghosh ◽  
Kalpana Bora
Keyword(s):  
Neutrino Oscillation ◽  
Neutrino Mass ◽  
Type I ◽  
Lepton Flavor Violation ◽  
Neutrino Mixing ◽  
Inverted Hierarchy ◽  
Planck Data ◽  
Mixing Angles ◽  
Lepton Flavor ◽  
Mixing Matrix

Neutrino physics is a mature branch of science with all the three neutrino mixing angles and two mass squared differences determined with high precision. In spite of several experimental verifications of neutrino oscillations and precise measurements of two mass squared differences and the three mixing angles, the unitarity of the leptonic mixing matrix is not yet established, leaving room for the presence of small nonunitarity effects. Deriving the bounds on these nonunitarity parameters from existing experimental constraints, on cLFV decays such as μ→eγ, μ→τγ, and τ→eγ, we study their effects on the generation of baryon asymmetry through leptogenesis and neutrino oscillation probabilities. We consider a model where see-saw is extended by an additional singlet S which is very light but can give rise to nonunitarity effects without affecting the form on see-saw formula. We do a parameter scan of a minimal see-saw model in a type I see-saw framework satisfying the Planck data on baryon to photon ratio of the Universe, which lies in the interval 5.8×10-10<YB<6.6×10-10(BBN). We predict values of lightest neutrino mass and Dirac and Majorana CP-violating phases δCP, α, and β, for normal hierarchy and inverted hierarchy for one-flavor leptogenesis. It is worth mentioning that all these four quantities are unknown yet, and future experiments will be measuring them.

scholarly journals Lepton mass and mixing in a neutrino mass model based onS4flavor symmetry

2016 ◽  
Vol 31 (09) ◽  
pp. 1650039 ◽  
Author(s):  
V. V. Vien
Keyword(s):  
Cp Violation ◽  
Neutrino Mass ◽  
Tree Level ◽  
Neutrino Mixing ◽  
Mass Model ◽  
Mixing Angles ◽  
Neutrino Sector ◽  
Neutrino Mass And Mixing ◽  
Model Based ◽  
Mixing Matrix

We study a neutrino mass model based on [Formula: see text] flavor symmetry which accommodates lepton mass, mixing with nonzero [Formula: see text] and CP violation phase. The spontaneous symmetry breaking in the model is imposed to obtain the realistic neutrino mass and mixing pattern at the tree-level with renormalizable interactions. Indeed, the neutrinos get small masses from one [Formula: see text] doublet and two [Formula: see text] singlets in which one being in [Formula: see text] and the two others in [Formula: see text] under [Formula: see text] with both the breakings [Formula: see text] and [Formula: see text] are taken place in charged lepton sector and [Formula: see text] in neutrino sector. The model also gives a remarkable prediction of Dirac CP violation [Formula: see text] or [Formula: see text] in both the normal and inverted spectrum which is still missing in the neutrino mixing matrix. The relation between lepton mixing angles is also represented.

scholarly journals IS Ue3 REALLY RELATED TO THE SOLAR NEUTRINO SOLUTIONS?

2000 ◽  
Vol 15 (37) ◽  
pp. 2257-2263
Author(s):  
N. HABA ◽  
TOMOHARU SUZUKI
Keyword(s):  
Physical Parameter ◽  
Neutrino Oscillation ◽  
Neutrino Mass ◽  
Solar Neutrino ◽  
Mass Matrix ◽  
Majorana Neutrino ◽  
Lepton Flavor ◽  
Flavor Mixing ◽  
Mixing Matrix ◽  
Majorana Neutrino Mass

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.

scholarly journals NEUTRINO OSCILLATIONS AND LEPTON FLAVOR MIXING

2001 ◽  
Vol 16 (33) ◽  
pp. 2169-2175 ◽  
Author(s):  
KYUNGSIK KANG ◽  
SIN KYU KANG ◽  
C. S. KIM ◽  
SUN MYONG KIM
Keyword(s):  
Neutrino Mass ◽  
Mass Matrix ◽  
Neutrino Masses ◽  
Input Constraints ◽  
Neutrino Mixing ◽  
Lepton Flavor ◽  
Invariance Violation ◽  
The Family ◽  
Flavor Mixing ◽  
Mixing Matrix

In view of the recent announcement on nonzero neutrino mass from Super-Kamiokande experiment, it would be very timely to investigate all the possible scenarios on masses and mixings of light neutrinos. Recently suggested mass matrix texture for the quark CKM mixing, which can be originated from the family permutation symmetry and its suitable breakings, is assumed for the neutrino mass matrix and determined by the four combinations of solar, atmospheric and LSND neutrino data and cosmological hot dark matter bound as input constraints. The charged-lepton mass matrix is assumed to be diagonal so that the neutrino mixing matrix can be identified directly as the lepton flavor mixing matrix and no CP invariance violation originates from the leptonic sector. The results favor hierarchical patterns for the neutrino masses, which follow from the case when the solar-atmospheric data is used.

scholarly journals The A4, S4 and A5 flavor symmetries in light of data on neutrino mixing

2018 ◽  
Vol 33 (31) ◽  
pp. 1844024 ◽  
Author(s):  
S. T. Petcov ◽  
A. V. Titov
Keyword(s):  
Precision Measurement ◽  
Neutrino Mixing ◽  
Prospective Data ◽  
Mixing Angles ◽  
Lepton Flavor ◽  
Flavor Symmetries ◽  
Mixing Parameters ◽  
Mixing Matrix ◽  
Global Data

We consider the [Formula: see text], [Formula: see text] and [Formula: see text] discrete lepton flavor symmetries broken down to nontrivial residual symmetries in the charged lepton and neutrino sectors in such a way that at least one of them is a [Formula: see text]. Such symmetry breaking patterns lead to predictions for some of the three neutrino mixing angles and/or the Dirac CP violation phase [Formula: see text] of the neutrino mixing matrix. First, we perform a statistical analysis of these predictions, which uses as input the latest global data on the neutrino mixing parameters. We find 14 phenomenologically viable cases. Further, we assess the viability of these cases taking into account the prospective uncertainties in the determination of the mixing angles, planned to be achieved in current and future neutrino oscillation experiments. We find that only six cases would be compatible with the assumed prospective data. We show that this number will be further reduced by a precision measurement of [Formula: see text].

scholarly journals A systematic analysis of perturbations for hexagonal mixing matrix

2019 ◽  
Vol 34 (01) ◽  
pp. 1950005
Author(s):  
Sumit K. Garg
Keyword(s):  
Neutrino Mixing ◽  
Inverted Hierarchy ◽  
Systematic Analysis ◽  
Mixing Angle ◽  
Mixing Angles ◽  
Angle Data ◽  
Mixing Matrix ◽  
Global Fit ◽  
Pmns Matrix ◽  
The Impact

We present a systematic analysis of perturbative Hexagonal (HG) mixing for describing recent global fit neutrino mixing data with normal and inverted hierarchy. The corrections to unperturbed mixing are parametrized in terms of small orthogonal rotations [Formula: see text] with modified PMNS matrix of the forms [Formula: see text]. Here, [Formula: see text] is rotation in [Formula: see text] sector and [Formula: see text] is unperturbed Hexagonal mixing matrix. The detailed numerical investigation of all possible cases is performed with scanning of parameter space using [Formula: see text] approach. We found that the perturbative schemes governed by single rotation are unable to fit the mixing angle data even at [Formula: see text] level. The mixing schemes which involve two rotation matrices only [Formula: see text] are successful in fitting all neutrino mixing angles within [Formula: see text] range for normal hierarchy (NH). However for inverted hierarchy (IH), only [Formula: see text] is most preferable as it can fit all mixing angles at [Formula: see text] level. The remaining perturbative cases are either excluded at [Formula: see text] level or successful in producing mixing angles only at [Formula: see text] level. To study the impact of phase parameter, we also looked into CP violating effects for single rotation case. The predicted value of [Formula: see text] lies in the range [Formula: see text] for [Formula: see text] and [Formula: see text] case with normal (inverted) hierarchy.

scholarly journals TETRAHEDRAL FAMILY SYMMETRY AND THE NEUTRINO MIXING MATRIX

2005 ◽  
Vol 20 (34) ◽  
pp. 2601-2605 ◽  
Author(s):  
ERNEST MA
Keyword(s):  
Neutrino Mass ◽  
Mass Matrix ◽  
Neutrino Mass Matrix ◽  
Neutrino Mixing ◽  
Symmetry Limit ◽  
Family Symmetry ◽  
Seesaw Mechanism ◽  
Mixing Angles ◽  
Mixing Matrix ◽  
Natural Symmetry

In a new application of the discrete non-Abelian symmetry A4 using the canonical seesaw mechanism, a three-parameter form of the neutrino mass matrix is derived. It predicts the following mixing angles for neutrino oscillations: θ13=0, sin 2θ23=1/2, and sin 2θ12 close, but not exactly equal to 1/3, in one natural symmetry limit.

scholarly journals Connecting leptonic CP violation, lightest neutrino mass and baryon asymmetry through type II seesaw

2015 ◽  
Vol 30 (09) ◽  
pp. 1550045 ◽  
Author(s):  
Rupam Kalita ◽  
Debasish Borah
Keyword(s):  
Cp Violation ◽  
Neutrino Mass ◽  
Mass Matrix ◽  
Baryon Asymmetry ◽  
Type I ◽  
Type Ii ◽  
Neutrino Mixing ◽  
Mixing Angles ◽  
The Universe ◽  
Mass Type

We study the possibility of connecting leptonic Dirac CP phase δ, lightest neutrino mass and baryon asymmetry of the universe within the framework of a model where both type I and type II seesaw mechanisms contribute to neutrino mass. Type I seesaw gives rise to Tri-Bimaximal (TBM) type neutrino mixing whereas type II seesaw acts as a correction in order to generate nonzero θ13. We derive the most general form of type II seesaw mass matrix which cannot only give rise to correct neutrino mixing angles but also can generate nontrivial value of δ. Considering both the cases where type II seesaw is subleading and is equally dominant compared to type I seesaw, we correlate the type II seesaw term with δ and lightest neutrino mass. We further constrain the Dirac CP phase δ and hence the type II seesaw mass matrix from the requirement of producing the observed baryon asymmetry through the mechanism of leptogenesis.

scholarly journals Numerical estimate of minimal active-sterile neutrino mixing

2018 ◽  
Vol 191 ◽  
pp. 03003
Author(s):  
Igor Krasnov
Keyword(s):  
Neutrino Mass ◽  
Sterile Neutrino ◽  
Numerical Estimate ◽  
Strong Dependence ◽  
Type I ◽  
Mass Hierarchy ◽  
Neutrino Mixing ◽  
Sterile Neutrinos ◽  
Mixing Angles ◽  
Active Neutrino

Seesaw mechanism constrains from below mixing between active and sterile neutrinos for fixed sterile neutrino masses. Signal events associated with sterile neutrino decays inside a detector at fixed target experiment are suppressed by the mixing angle to the power of four. Therefore sensitivity of experiments such as SHiP and DUNE should take into account minimal possible values of the mixing angles. We extend the previous study of this subject [1] to a more general case of non-zero CP-violating phases in the neutrino sector. Namely, we provide numerical estimate of minimal value of mixing angles between active neutrinos and two sterile neutrinos with the third sterile neutrino playing no noticeable role in the mixing. Thus we obtain a sensitivity needed to fully explore the seesaw type I mechanism for sterile neutrinos with masses below 2 GeV, and one undetectable sterile neutrino that is relevant for the fixedtarget experiments. Remarkably, we observe a strong dependence of this result on the lightest active neutrino mass and the neutrino mass hierarchy, not only on the values of CP-violating phases themselves. All these effects sum up to push the limit of experimental confirmation of sterile-active neutrino mixing by several orders of magnitude below the results of [1] from 10-10 - 10-11 down to 10-12 and even to 10-20 in parts of parameter space; non-zero CP-violating phases are responsible for that.

scholarly journals Effective Neutrino Masses from Four Flavor Neutrino Mixing Matrix

2021 ◽  
Author(s):  
Bipin Singh Koranga ◽  
Vivek Kumar Nautiyal
Keyword(s):  
Neutrino Oscillation ◽  
Neutrino Mass ◽  
Upper Bound ◽  
Majorana Neutrino ◽  
Neutrino Masses ◽  
Neutrino Mixing ◽  
Mixing Parameters ◽  
Normal Mass ◽  
Mixing Matrix ◽  
Majorana Neutrino Mass

AbstractWe consider the four neutrino oscillation that accommodate the all neutrino oscillation data. We consider the range of the corresponding mixing parameters by the result of neutrino oscillation experiments. Implicaion of the neutrino oscillation search for the neutrino mass square difference and mixing are discussed. We determine the possible values of the effective majorana neutrino mass $|<m>|=|{\sum }_{j}U_{ej}^{2}m_{j}|$ | < m > | = | ∑ j U e j 2 m j | in the four neutrino scenario. In the four-neutrino scheme there is an upper bound on | < m > | of the normal mass order is 2.0074eV for α = 0∘,β = 0∘andγ = 0∘. In the case of inverted mass order the upper bound on | < m > | is 2.0069eV for α = 0∘,β = 0∘andγ = 0∘.

Multiscalar B − L model with Σ(18) symmetry for neutrino mass and mixing

2021 ◽  
pp. 2150132
Author(s):  
V. V. Vien
Keyword(s):  
Neutrino Oscillation ◽  
Neutrino Mass ◽  
Tree Level ◽  
Type I ◽  
Normal Ordering ◽  
Seesaw Mechanism ◽  
Mixing Angles ◽  
Neutrino Mass And Mixing ◽  
Text Model ◽  
Best Fit

We construct a non-renormalizable [Formula: see text] model based on [Formula: see text] symmetry, whereby, neutrino mass ordering and the tiny neutrino masses are explained at tree level via type I seesaw mechanism. The model can reproduce the recent observed neutrino oscillation data in which neutrino oscillation parameters including three mixing angles [Formula: see text], Dirac CP phase plus neutrino squared-mass splittings [Formula: see text] get the best-fit values for both Normal ordering (NO) and Inverted ordering (IO). The Majorana phases are predicted to be [Formula: see text] for NO, [Formula: see text] for IO and [Formula: see text] for both NH and IO. The sum of neutrino mass and the effective neutrino mass are, respectively, predicted to be [Formula: see text] for NO while [Formula: see text] for IO and [Formula: see text] for NO while [Formula: see text] for IO which are well compatible with the most recent experimental constraints.

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