Lepton Number Violation and `Diracness' of massive neutrinos composed of Majorana states

TL;DR

This paper explores how Majorana neutrinos can exhibit lepton number violation or mimic Dirac neutrinos, emphasizing the importance of combined low and high energy studies to understand neutrino properties and potential new physics.

Contribution

It demonstrates the correlation between lepton number violation and neutrino parameters, highlighting the need to consider non-degenerate masses and flavor mixing in heavy neutrino searches.

Findings

Lepton number violation strength correlates with CP-phases and flavor mixings.

Superpositions of Majorana states can mimic Dirac neutrinos.

Non-degenerate heavy neutrino scenarios are essential for new physics searches.

Abstract

Majorana neutrinos naturally lead to a Lepton Number Violation (LNV). A superposition of Majorana states can mimic Dirac-type neutrinos, leading to its conservation (LNC). We demonstrate on the example of specific observables related to high and low energy processes how a strength of LNV correlates with neutrino parameters such as CP-phases, flavor mixings, mass ratios. We stress the coaction between low and high energy studies for putting phenomenological models to a quantitative test. Secondly, we conclude that in order to fully study the role of heavy neutrinos in search for New Physics (NP) signals, a departure from trivial scenarios assuming degeneracy in mass and no flavor mixing or CP-phases becomes necessary for a proper physical analysis.