On the nature of the neutrino

TL;DR

This paper demonstrates that under the assumption of a massive Dirac field, neutrinos can be rotated into their antiparticles, leading to the conclusion that neutrinos are necessarily Majorana particles.

Contribution

It provides a theoretical proof that neutrinos must be Majorana particles if described by a massive Dirac field operator.

Findings

Neutrino and antineutrino states can be rotated into each other.

Neutrinos must be Majorana particles under the given assumptions.

Abstract

Assuming that one neutrino type with definite mass is described by a massive Dirac field operator, it is shown that the physical one-particle states for particles and antiparticles can be rotated to each other, irrespective of their helicity. This result is used to prove that the neutrino must necessarily be a Majorana particle.