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

• Main Authors: Amina Khatun, Adam Smetana, Fedor Šimkovic
• Format: Article
• Language: English
• Published: MDPI AG 2020-08-01
• Series: Symmetry
• Subjects: quasi-Dirac; neutrino oscillation; Majorana neutrino mass; neutrinoless double beta decay
• Online Access: https://www.mdpi.com/2073-8994/12/8/1310

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 <inline-formula><math display="inline"><semantics><mrow><mn>6</mn><mo>×</mo><mn>6</mn></mrow></semantics></math></inline-formula> unitary matrix for parameterizing the mixing among three flavors of quasi-Dirac neutrino. This mixing matrix is constructed by two <inline-formula><math display="inline"><semantics><mrow><mn>3</mn><mo>×</mo><mn>3</mn></mrow></semantics></math></inline-formula> unitary matrices that diagonalizes the Dirac mass term in the Lagrangian. By only assuming the Standard Model <inline-formula><math display="inline"><semantics><mrow><mi>V</mi><mo>−</mo><mi>A</mi></mrow></semantics></math></inline-formula> 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 <inline-formula><math display="inline"><semantics><mrow><mn>3</mn><mo>×</mo><mn>3</mn></mrow></semantics></math></inline-formula> unitary matrix relevant to mixing of active neutrino flavors. Further, by considering <inline-formula><math display="inline"><semantics><mrow><mn>1</mn><mi>σ</mi></mrow></semantics></math></inline-formula> and <inline-formula><math display="inline"><semantics><mrow><mn>3</mn><mi>σ</mi></mrow></semantics></math></inline-formula> 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.