Three Flavor Quasi-Dirac Neutrino Mixing, Oscillations and Neutrinoless Double Beta Decay

Amina Khatun,Adam Smetana,Fedor Šimkovic

doi:10.3390/sym12081310

Amina Khatun, Adam Smetana + Show 1 more

Open Access

https://doi.org/10.3390/sym12081310

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Abstract

The extension of the Standard model by three right-handed neutrino fields exhibit appealing symmetry between left-handed and right-handed sectors, which is only violated by interactions. It can accommodate three flavor quasi-Dirac neutrino mixing scheme, which allows processes with violation of both lepton flavor and total lepton number symmetries. We propose a 6×6 unitary matrix for parameterizing the mixing among three flavors of quasi-Dirac neutrino. This mixing matrix is constructed by two 3×3 unitary matrices that diagonalizes the Dirac mass term in the Lagrangian. By only assuming the Standard Model V−A weak interaction, it is found that probabilities of neutrino oscillations among active flavor states and effective masses measured by single beta decay, by neutrinoless double-beta decay and by cosmology only depend on single 3×3 unitary matrix relevant to mixing of active neutrino flavors. Further, by considering 1σ and 3σ uncertainties in the measured oscillation probability of electron antineutrino from reactor, derivation of the constraint on the Majorana neutrino mass component is demonstrated. The consequence for effective Majorana neutrino mass governing the neutrinoless double-beta decay is discussed.

Highlights

The discovery of neutrino oscillations in experiments with atmospheric, solar, reactor, and accelerator neutrinos have provided compelling evidence that flavor neutrinos oscillate from one flavor to another due to neutrino mixing and that neutrinos possess nonzero masses [1], which offer an insight on new physics beyond the Standard Model (SM) [2]
The observation of neutrino oscillations implies that the flavor lepton numbers Le, Lμ, and Lτ are not conserved, which follows from the presence of flavor-mixing neutrino mass term in Lagrangian of the theory
The diagonalization of the Dirac-Majorana mass term with 6 × 6 unitary neutrino mixing matrix, which is generally parametrized with 15 mixing angles and

Summary

Introduction

The discovery of neutrino oscillations in experiments with atmospheric, solar, reactor, and accelerator neutrinos have provided compelling evidence that flavor neutrinos oscillate from one flavor (electron-, muon-, and tau-) to another due to neutrino mixing and that neutrinos possess nonzero masses [1], which offer an insight on new physics beyond the Standard Model (SM) [2]. The observation of neutrino oscillations implies that the flavor lepton numbers Le , Lμ , and Lτ are not conserved, which follows from the presence of flavor-mixing neutrino mass term in Lagrangian of the theory. The Dirac-Majorana mass term can accommodate the seesaw scenario [8,9,10,11], which helps to understand the smallness of the neutrino masses constrained by laboratory and cosmological measurements. In the classical realization of the seesaw scenario with three right-handed neutrino fields, the Dirac-Majorana mass term is dominated by the lepton-number-violating right-handed neutrino Majorana masses giving rise to three light and active neutrinos, and three very heavy sterile neutrinos. The goal of this paper is to discuss an opposite scenario, in which the Dirac-Majorana mass term is dominated by the Dirac masses. Restriction on this parameter coming from oscillations of electron antineutrinos will be studied and consequences for observation of the 0νββ-decay will be given

Theory

The Survival Probabilities of Electron Antineutrino

Constraints on Majorana Component of Neutrino Masses

Conclusions