scholarly journals Effective Lagrangian approach to neutrinoless double beta decay and neutrino masses

2012 ◽  
Vol 2012 (6) ◽  
Author(s):  
Francisco del Aguila ◽  
Alberto Aparici ◽  
Subhaditya Bhattacharya ◽  
Arcadi Santamaria ◽  
Jose Wudka
Keyword(s):  
Beta Decay ◽  
Neutrinoless Double Beta Decay ◽  
Double Beta Decay ◽  
Lagrangian Approach ◽  
Neutrino Masses ◽  
Effective Lagrangian

NEUTRINOLESS DOUBLE BETA DECAY

2012 ◽  
Vol 12 ◽  
pp. 80-89
Author(s):  
OLIVIERO CREMONESI
Keyword(s):  
Beta Decay ◽  
Present Status ◽  
Neutrinoless Double Beta Decay ◽  
Mass Scale ◽  
Present Knowledge ◽  
Double Beta Decay ◽  
Neutrino Masses ◽  
Mixing Parameters ◽  
Absolute Mass ◽  
Practical Tool

Neutrinoless double beta decay (ββ(0ν)) is presently the only practical tool for probing the character of neutrinos. In case neutrinos are Majorana particles ββ(0ν) can provide also fundamental informations on their absolute mass scale. The present status of experiments searching for ββ(0ν) is reviewed and the most relevant results discussed. A possibility to observe ββ(0ν) at a neutrino mass scale in the range 10-50 meV looks possible according to our present knowledge of the neutrino masses and mixing parameters. A review of the future projects and of the most relevant parameters contributing to the experimental sensitivity iss finally outlined.

scholarly journals CONSTRAINTS OF MIXING ANGLES FROM LEPTON NUMBER VIOLATING PROCESSES

1999 ◽  
Vol 14 (06) ◽  
pp. 433-445 ◽  
Author(s):  
HIROYUKI NISHIURA ◽  
KOUICHI MATSUDA ◽  
TAKESHI FUKUYAMA
Keyword(s):  
Beta Decay ◽  
Neutrinoless Double Beta Decay ◽  
Lepton Number ◽  
Double Beta Decay ◽  
Neutrino Masses ◽  
Mixing Angles ◽  
Left Handed ◽  
Majorana Neutrinos ◽  
Mixing Matrix ◽  
Lepton Number Violating

We discuss the constraints of lepton mixing angles from lepton number violating processes such as neutrinoless double beta decay, μ--e+ conversion and K decay, K-→π+μ-μ- which are allowed only if neutrinos are Majorana particles. The rates of these processes are proportional to the averaged neutrino mass defined by [Formula: see text] in the absence of right-handed weak coupling. Here a, b(j) are flavor(mass) eigenstates and Uaj is the left-handed lepton mixing matrix. We give general conditions imposed on <mν>ab in terms of mi, lepton mixing angles and CP violating phases (three phases in Majorana neutrinos). These conditions are reduced to the constraints among mi, lepton mixing angles and <mν>ab which are irrelevant to the concrete values of CP phases. Given a <mν>ab experimentally, these conditions constrain mi and the lepton mixing angles. Though these constraints are still loose except for neutrinoless double beta decay, they will become helpful through rapid improvements of experiments. By using these constraints we also derive the limits on averaged neutrino masses for μ--e+ conversion and K decay, K-→π+μ-μ-, respectively. We also present the bounds for CP phases in terms of mi, mixing angles and <mν>ab.

scholarly journals A realistic model of neutrino masses with a large neutrinoless double beta decay rate

2012 ◽  
Vol 2012 (5) ◽  
Author(s):  
Francisco del Aguila ◽  
Alberto Aparici ◽  
Subhaditya Bhattacharya ◽  
Arcadi Santamaria ◽  
Jose Wudka
Keyword(s):  
Decay Rate ◽  
Beta Decay ◽  
Neutrinoless Double Beta Decay ◽  
Realistic Model ◽  
Double Beta Decay ◽  
Neutrino Masses

scholarly journals Super-Kamiokande neutrino oscillations and the supersymmetric model

2020 ◽  
Vol 9 ◽  
pp. 14
Author(s):  
A. Faessler
Keyword(s):  
Beta Decay ◽  
Neutrino Mass ◽  
Mass Matrix ◽  
Neutrinoless Double Beta Decay ◽  
Double Beta Decay ◽  
Electron Neutrino ◽  
Tree Level ◽  
Supersymmetric Model ◽  
Neutrino Masses ◽  
Muon Neutrinos

The standard model predicts a ratio of 2 for the number of atmospheric muon to electron neutrinos, while super-Kamiokande and others measure a much smaller value (1.30±0.02 for super-Kamiokande). Super-Kamiokande is also able to measure roughly the direction and the energy of the neutrinos. The zenith-angle dependence for the muon neutrinos suggests that the muon neutrinos oscillate into a third neutrino species, either into the r neutrino or a sterile neutrino. This finding is inves- tigated within the supersymmetric model. The neutrinos mix with the neutralinos, this meaning the wino, the bino and the two higgsinos. The 7 x 7 mass matrix is calculated on the tree level. One finds that the mass matrix has three linearly dependent rows, which means that two masses are zero. They are identified with the two lightest neutrino masses. The fit of the super-Kamiokande data to oscillations between three neutrinos yields, together with the result of supersymmetry, that the third neutrino mass lies between 2x10^-2 and 10^-1 eV. The two lightest neutrino masses are in supersymmetry on the tree level zero. The averaged electron neutrino mass which is the essential parameter in the neutrinoless double-beta decay is given by {m_ve) ~ m_v3 P_ze < 0.8 x10^-2 eV (95% confidence limit). It is derived from the super-Kamiokande data in this supersymmetric model to be two orders smaller than the best value (1 eV) from the neutrinoless double-beta decay.

scholarly journals Oscillating Neutrinos and Majorana Neutrino Masses

Universe ◽  
2020 ◽  
Vol 6 (2) ◽  
pp. 29
Author(s):  
Harald Fritzsch
Keyword(s):  
Beta Decay ◽  
Neutrino Mass ◽  
Neutrinoless Double Beta Decay ◽  
Majorana Neutrino ◽  
Double Beta Decay ◽  
Neutrino Masses ◽  
Quark Masses ◽  
Mass Matrices ◽  
The Matrix ◽  
Flavor Mixing

We discuss the mass matrices with texture zeros for the quarks and leptons. The flavor mixing angles for the quarks are functions of the quark masses and can be calculated. The results agree with the experimental data. The texture zero mass matrices for the leptons and the see-saw mechanism are used to derive relations between the matrix elements of the lepton mixing matrix and the ratios of the neutrino masses. Using the measured neutrino mass differences, the neutrino masses can be calculated. The neutrinoless double beta decay is discussed. The effective Majorana neutrino mass, describing the neutrinoless double beta decay, can be calculated—it is about 4.6 meV. The present experimental limit is at least twenty times larger.

scholarly journals Neutrino masses from low scale partial compositeness

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Zackaria Chacko ◽  
Patrick J. Fox ◽  
Roni Harnik ◽  
Zhen Liu
Keyword(s):  
Beta Decay ◽  
Form Factors ◽  
Neutrinoless Double Beta Decay ◽  
Double Beta Decay ◽  
Neutrino Masses ◽  
Hidden Sector ◽  
Partial Compositeness ◽  
Order Of Magnitude ◽  
Partially Composite ◽  
Compositeness Scale

Abstract We consider a class of models in which the neutrinos acquire Majorana masses through mixing with singlet neutrinos that emerge as composite states of a strongly coupled hidden sector. In this framework, the light neutrinos are partially composite particles that obtain their masses through the inverse seesaw mechanism. We focus on the scenario in which the strong dynamics is approximately conformal in the ultraviolet, and the compositeness scale lies at or below the weak scale. The small parameters in the Lagrangian necessary to realize the observed neutrino masses can naturally arise as a consequence of the scaling dimensions of operators in the conformal field theory. We show that this class of models has interesting implications for a wide variety of experiments, including colliders and beam dumps, searches for lepton flavor violation and neutrinoless double beta decay, and cosmological observations. At colliders and beam dumps, this scenario can give rise to striking signals involving multiple displaced vertices. The exchange of hidden sector states can lead to observable rates for flavor violating processes such as μ → eγ and μ → e conversion. If the compositeness scale lies at or below a hundred MeV, the rate for neutrinoless double beta decay is suppressed by form factors and may be reduced by an order of magnitude or more. The late decays of relic singlet neutrinos can give rise to spectral distortions in the cosmic microwave background that are large enough to be observed in future experiments.

Cobimaximal neutrino mixing in the U(1)B−L extension with A4 symmetry

2020 ◽  
Vol 35 (38) ◽  
pp. 2050311
Author(s):  
V. V. Vien
Keyword(s):  
Beta Decay ◽  
Atmospheric Neutrino ◽  
Neutrinoless Double Beta Decay ◽  
Double Beta Decay ◽  
Tree Level ◽  
Physical Parameters ◽  
Neutrino Masses ◽  
Type I ◽  
Neutrino Mixing ◽  
Best Fit

We propose a renormalizable [Formula: see text] extension of the Standard model with [Formula: see text] symmetry that leads to the successful cobimaximal lepton mixing ansatz, thus providing a predictive explanation for leptonic mixing observables. The smallness of the active neutrino masses and neutrino masses ordering are produced by the type-I seesaw mechanism at the tree-level. The obtained physical parameters are well consistent with the global fit of neutrino oscillation.1 The model is predictive in the sense that it reproduces the experimental values of neutrino parameters in which the reactor neutrino mixing angle [Formula: see text] get the best-fit value and the solar and atmospheric neutrino mixing angles have little deviations from the best-fit values given in Ref. 1, however, they are consistent with the other experimental results.[Formula: see text] The effective neutrino masses governing the neutrinoless double beta decay is predicted to be [Formula: see text] for normal hierarchy and [Formula: see text] for inverted hierarchy which are well consistent with the recent experimental limits on neutrinoless double beta decay.

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