Positive-Energy Dirac Particles and Dark Matter

TL;DR

This paper explores the idea that particles described by Dirac's 1971 positive-energy wave equation could serve as dark matter candidates due to their non-interaction with electromagnetic fields and unique transformation properties.

Contribution

It proposes a novel candidate for dark matter based on Dirac particles and discusses their distinctive properties and potential implications for physics beyond the Standard Model.

Findings

Dirac particles do not interact with electromagnetic fields under minimal coupling.

They transform under an infinite-dimensional representation of the Lorentz group.

These properties suggest a new physics beyond the Standard Model.

Abstract

The relativistic positive-energy wave equation proposed by P. Dirac in 1971 is an old but largely forgotten subject. The purpose of this note is to speculate that particles described by this equation (called here Dirac particles) are natural candidates for the dark matter. The reasoning is based on a fact that the internal structure of such particles simply prohibits their interaction with electromagnetic fields (at least with the minimal coupling) which is exactly what is required for dark matter. Dirac particles have quite unusual properties. In particular, they are transformed by an infinite-dimensional representation of the homogeneous Lorentz group, which clearly distinguishes them from all known elementary particles described by finite-dimensional representations and hints to a physics beyond the Standard Model. To clarify the topic, a brief review of the main features of {the above-mentioned} Dirac equation is given.