Could This Unusual Antimatter Detection on the ISS Reveal New Physics?
Unofficial reports of 10 antihelium nuclei striking the International Space Station (ISS) have inspired theoretical physicists to explore beyond our current models. The unusual nature of the antihelium shower has prompted researchers to treat the event like a rainstorm in a desert.
In a recently published analysis, scientists from the Perimeter Institute for Theoretical Physics in Canada and Johns Hopkins University in the US propose that physics beyond the Standard Model may be at play, possibly involving dark matter.
Since 2011, the Alpha Magnetic Spectrometer (AMS-02) on the ISS has recorded over 200 billion cosmic ray events. While most were ordinary particles, ten of them appeared atypical, consisting of pairs of antiprotons bound with one or two antineutrons.
Every fundamental particle of ‘ordinary’ matter, such as electrons and quarks, has an antiparticle with the same properties but opposite charge. Antiparticles should have been produced in equal amounts as particles during the Big Bang, annihilating each other and leaving behind a glow of gamma rays. However, the predominance of matter in the Universe suggests a discrepancy in this balance.
Though antimatter can be produced in particle colliders on Earth, natural high-energy events can also create antiprotons and antineutrons, some of which reach Earth. The reported AMS-02 detections involved antihelium nuclei, which would have required slow-moving antiparticles to bond. For each antihelium-4 nucleus (with two antineutrons), there were two antihelium-3 nuclei (with one antineutron), an unexpected ratio given established physics, which predicts a ratio of 10,000 to one.
This anomaly suggests the particles were slow-moving before being ejected, possibly originating from an unknown particle’s decay, potentially linked to dark matter. Alternatively, an incredibly hot, rapidly expanding plasma could have produced the observed antihelium ratios. Such events, though unobserved, might occur during dark matter collisions involving sufficient quantities of antiquarks.
Another hypothesis involves ‘dark dwarfs,’ hypothetical objects made of dark photons, dark electrons, and dark neutrons. These could potentially create the conditions to emit antihelium in the observed ratios.
Both models are speculative and involve complex dynamics, leaving much room for discussion. Dark matter itself remains unconfirmed as a material phenomenon. However, exploring these ideas might lead to new discoveries that could explain unexpected measurements.
With another six years of operation, the AMS-02 may collect more data, offering further insights into the origins of this strange antihelium shower. It may reveal an unknown process creating antimatter atoms in space, challenging our understanding of the Universe.
Source: Could This Unusual Antimatter Detection on the ISS Reveal New Physics?
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