The Nature of the Neutrino (Dirac/Majorana) and Double Beta Decay with or without Neutrinos

TL;DR

This paper reviews the historical research on whether neutrinos are Dirac or Majorana particles and discusses the processes of double beta decay with or without neutrinos.

Contribution

It provides a comprehensive overview of the fundamental problem of neutrino nature and the related double beta decay processes, highlighting key developments and open questions.

Findings

Neutrinoless double beta decay is a crucial process to determine neutrino nature.

Majorana neutrinos could lead to observable neutrinoless double beta decay.

The history of research shows ongoing efforts to detect and understand these phenomena.

Abstract

The history of research associated with the fundamental problem of the nature of massive neutrinos, which can be Dirac particles or Majorana fermions, and the related processes of neutrinoless double beta decay, $(A,Z)\rightarrow (A,Z+2) + e^- + e^-$, and two neutrino double beta decay, $(A,Z)\rightarrow (A,Z+2) + e^- + e^- + \bar{\nu_e} + \bar{\nu_e}$, is reviewed.