Addressing the Majorana vs. Dirac Question Using Neutrino Decays

TL;DR

This paper discusses the challenge of distinguishing Majorana from Dirac neutrinos with ultra-relativistic neutrinos and proposes that studying angular distributions in heavy neutrino decays could provide a solution.

Contribution

It introduces a novel approach using non-relativistic neutrino decay angular distributions to determine the Majorana or Dirac nature of neutrinos.

Findings

Angular distributions differ significantly for Majorana vs. Dirac neutrinos.

Non-relativistic neutrino decays offer a promising method for identification.

Ultra-relativistic neutrinos are insufficient for this distinction.

Abstract

We explain why it is so hard to determine whether neutrinos are Majorana or Dirac particles as long as the only neutrinos we study are ultra-relativistic. We then show how non-relativistic neutrinos could help, and focus on the angular distributions in the decays of an as-yet-to-be-discovered heavy neutrino $N$. We find that these angular distributions could very well tell us whether neutrinos are Majorana or Dirac particles.