Key Takeaways

Sample Definition And Size

This paper is a theoretical overview and does not involve an empirical sample or quantitative study population. It reviews various proposed dark matter candidates from the literature, including axions, inert Higgs doublet, sterile neutrinos, supersymmetric particles, and Kaluza–Klein particles. No sample size is applicable.

Study Type

The paper is a theoretical review or overview article summarizing and discussing various dark matter candidate models and recent developments in cosmic-ray antimatter observations as potential indirect evidence.

Conflicts Of Interest

No conflicts of interest are declared in the abstract or metadata available.

Results Summary

The paper discusses multiple dark matter candidates—axions, inert Higgs doublet, sterile neutrinos, supersymmetric particles, and Kaluza–Klein particles—and highlights that recent cosmic-ray antimatter results have made dark matter explanations particularly compelling. It addresses challenges to these explanations, proposes possible solutions, and emphasizes the importance of forthcoming measurements. It suggests that if dark matter is indeed responsible, it could open a new field of physics characterized by unusual but plausible mass and interaction properties. No specific statistical results (e.g., p-values, effect sizes) are provided.

Abstract

An overview is given of various dark matter candidates. Among the many\nsuggestions given in the literature, axions, inert Higgs doublet, sterile\nneutrinos, supersymmetric particles and Kaluza-Klein particles are discussed.\nThe situation has recently become very interesting with new results on\nantimatter in the cosmic rays having dark matter as one of the leading possible\nexplanations. Problems of this explanation and possible solutions are\ndiscussed, and the importance of new measurements is emphasized. If the\nexplanation is indeed dark matter, a whole new field of physics, with unusual\nalthough not impossible mass and interaction properties may soon open itself to\ndiscovery.\n

Referenced In

StarTalk Show Notes

2 months ago

StarTalk

Season 17, Episode 16: Dark Matter Candidates Explained

Hey StarTalkers! Season 17, episode 16 had Neil and Chuck discussed the “dark” universe with Professor Katherine Freese.

A fan question called on Professor Freese to run-through the leading candidates for the unknown source of gravity known as dark matter:

Dark Universe Decoded with Katherine Freese - StarTalk Radio

(from 33:30)

She names three key candidates: WIMPs, axions and primordial black holes. But what are they? And why do we think they could make up dark matter?

WIMPs

These Weakly-Interacting Massive Particles are probably the most well-known dark matter candidate.

The “weakly-interacting” part isn’t an insult. They literally interact with ordinary matter through the weak force. A 2024 paper explains that in the energetic, early universe, weakly-interacting particles were created thermally and frequently interacted with normal matter.

But as the universe expanded and cooled, the interactions stopped and left behind a “relic” of now basically inert particles. This relic would be pretty close to the amount of dark matter we see today.

Many particles could be WIMPs, including neutrinos, supersymmetric particles (like the neutralino) and the inert Higgs doublet. Beyond the fact that some dark matter is probably neutrinos, we aren’t too sure.

Axions

Understanding axions fully would require a whole post, but the basics are easy enough to get. In order to solve an outstanding problem in particle physics, two physicists proposed a new symmetry, which can be spontaneously broken. Just as the Higgs Boson is the particle associated with the breaking of electroweak symmetry, the axion is the particle associated with the breaking of this symmetry.

The major issue with this is that axions barely have mass, so we’d need a lot of them to account for dark matter.

Primordial Black Holes

In the early universe, it may have been possible for much lighter black holes to form than today. One with the mass of Earth, for instance, would be about the size of an American dime. These tiny, primordial black holes could be zipping around the universe today and make up a substantial portion of dark matter.

There are limitations on their size – Hawking radiation would have “evaporated” tiny ones already, for instance – but LIGO’s detection of gravitational waves from merging black holes has reignited interest.

Read Full Post

Created: Mar 18, 2026