Neutrinoless double-beta decay and physics beyond the standard model

Neutrinoless double-beta decay is a forbidden, lepton-number-violating nuclear transition whose observation would have fundamental implications for neutrino physics, theories beyond the Standard Model, and cosmology. In this review, we summarize the theoretical progress to understand this process, the expectations and implications under various particle physics models, and the nuclear physics challenges that affect the precise predictions of the decay half-life. We also provide a synopsis of the current and future large-scale experiments that aim to discover this process in physically well-motivated half-life ranges.

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

Symmetry ◽

10.3390/sym12081310 ◽

2020 ◽

Vol 12 (8) ◽

pp. 1310

Author(s):

Amina Khatun ◽

Adam Smetana ◽

Fedor Šimkovic

Keyword(s):

Standard Model ◽

Beta Decay ◽

Neutrinoless Double Beta Decay ◽

Majorana Neutrino ◽

Double Beta Decay ◽

Unitary Matrix ◽

Neutrino Mixing ◽

Dirac Neutrino ◽

The Standard Model ◽

Majorana Neutrino Mass

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.

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What Is Matter According to Particle Physics, and Why Try to Observe Its Creation in a Lab?

Universe ◽

10.3390/universe7030061 ◽

2021 ◽

Vol 7 (3) ◽

pp. 61

Author(s):

Francesco Vissani

Keyword(s):

Standard Model ◽

Conservation Laws ◽

Beta Decay ◽

Particle Physics ◽

Neutrinoless Double Beta Decay ◽

Lepton Number ◽

Double Beta Decay ◽

Nuclear Process ◽

The Standard Model ◽

Technical Considerations

The standard model of elementary interactions has long qualified as a theory of matter, in which the postulated conservation laws (one baryonic and three leptonic) acquire theoretical meaning. However, recent observations of lepton number violations—neutrino oscillations—demonstrate its incompleteness. We discuss why these considerations suggest the correctness of Ettore Majorana’s ideas on the nature of neutrino mass and add further interest to the search for an ultra-rare nuclear process in which two particles of matter (electrons) are created, commonly called neutrinoless double beta decay. The approach of the discussion is mainly historical, and its character is introductory. Some technical considerations, which highlight the usefulness of Majorana’s representation of gamma matrices, are presented in the appendix.

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