Researchers have detected traces of antimatter in cosmic rays, potentially pointing to the existence of a new class of undiscovered particles called WIMPs (Weakly Interacting Massive Particles) that could make up dark matter. This discovery has reignited the search for these elusive particles, which have long been theorized but never directly observed. The findings suggest that WIMPs may be even more exotic than previously thought, challenging our understanding of the standard model of particle physics.
The Antimatter Clue
A Rust Buster for Dark Matter: One of the greatest riddles in contemporary cosmology is that over 85% of the matter in the world is unobservable. We know it is there but have as yet been unable to see it. A new paper published in the Journal of Cosmology and Astroparticle Physics attempts to study antimatter in cosmic rays as a potential signal for WIMPs, along with other methods.
Antimatter has the opposite electrical charge to regular matter. Matter and antimatter mutually annihilate when they come into contact with an explosion of energy. This is true because the ordinary matter in the universe clearly dominates over antimatter. Thus the detection of antihelium nuclei in cosmic rays by the AMS-02 experiment onboard the International Space Station came as a surprise and was a thrilling discovery.
The Elusive Quest for WIMPs
That makes WIMPs a natural candidate for dark matter, and they’ve been considered a leading one for quite some time. A few years ago, scientists were hopeful that the first hard evidence for WIMPs would come to light in a matter of years. But we first have to throw out whole classes of such ideas, based on recent research showing that some features of their emissions wouldn’t be detectable.
Rather, the discovery of an antihelium nuclei has given a second life to WIMPs. According to the theory, when two WIMP particles collide, they can annihilate one another and create both types of particles. The AMS-02 data on this so-called “antihelium” nuclei are significantly more plentiful than had been anticipated, which could indicate that WIMP annihilation is taking place. The researchers also note that the antihelium-4 nuclei seen are especially baffling, as they are far heavier and less common than anyone thought possible in WIMP models. That implies the particles responsible would be even more “exotic,” than the hypothetical WIMPs we’ve conjured up until now.
Exploring the frontier of particle physics
The finding of these weird antihelium nuclei in cosmic rays represents a big challenge to our understanding, not only of particle physics, but also the nature of dark matter. This could mean that the standard model of particle physics, after 40 years in which it has successfully predicted particles and interactions at CERN up to the discovery of the Higgs boson, may need to be extended or changed.
In the most optimistic models, the amount of detected Coherent interaction could be explained by WIMP annihilation, but even then it couldn´t account for Coherent (or not?) antihelium-4. The fact is that this would involve a “discipline” of a particle (or class) far stranger than the WIMPs raised until then, or in technical jargon even more exotic. More detailed observations will be needed to further explore this phenomenon and its consequences for the elusive nature of dark matter.
And this curiosity could foreshadow dark matter discovery yet to come, one of many new themes in a long tale that began when the search for dark matter began. The truth, however, is that the more we learn about the universe, we make once-unanticipated discoveries that test our current foundation for what does and does not categorize the basic components of reality.
