Signal of neutrinoless double beta decay, neutrino spectrum and oscillation scenarios

TL;DR

This paper analyzes how neutrino oscillation parameters and mass spectra influence the potential observation of neutrinoless double beta decay, providing a unified framework to interpret experimental constraints and theoretical scenarios.

Contribution

It introduces a unitarity triangle representation to relate neutrinoless double beta decay bounds with neutrino oscillation data and spectrum assumptions.

Findings

Constraints on decay rates depend on oscillation parameters and neutrino mass hierarchy.

The unitarity triangle clarifies when decay signals are suppressed or detectable.

Different neutrino spectra impact the prospects for observing neutrinoless double beta decay.

Abstract

The lower and upper bounds on the neutrinoless double beta (0nu-2beta) decay rate are obtained, as functions of the parameters of neutrino oscillations and of the lightest neutrino mass. The constraints on these parameters from the search for the 0nu-2beta transition, as well as from the interpretation of solar and atmospheric neutrino data in terms of oscillations, can be conveniently represented in one unitarity triangle. This representation helps to clarify the cases when the 0nu-2beta rate is small; the crucial dependence on the scenarios assumed for solar neutrino oscillations and on the neutrino spectrum is emphasized. We consider hierarchical and non-hierarchical neutrino spectra, and discuss their interest in view of future searches of the 0nu-2beta decay.