Scientists at the Large Hadron Collider (CERN), the world’s most powerful elementary particle booster, have discovered the heaviest form of antimatter ever observed. This discovery is as significant as previous achievements at CERN, in particular the discovery of the Higgs boson and studies of B-meson decay.
The ALICE (A Large Ion Collider Experiment) has discovered an antimatter particle, antihyperhelium-4. It is the “evil twin” of another exotic particle, hyperhelium-4. This form of antimatter consists of two antiprotons, an antineutron, and an unstable antilambda particle, which in turn contains quarks.
The discovery is important for studying the extreme conditions that reigned in the Universe less than a second after the Big Bang. It also helps us understand one of the biggest mysteries of physics, the problem of baryonic asymmetry. According to the theory, matter and antimatter should have existed in equal amounts after the Big Bang, and the mutual annihilation of these particles should have produced pure energy. However, the present Universe is composed predominantly of matter, and antimatter is preserved only in small quantities. The study of hyperhelium and its antiparticle may shed light on the causes of this imbalance.
Antihyperhelium-4 was discovered from a 2018 experiment that collided lead ions at high speeds at the Large Hadron Collider, recreating the extreme conditions of the early Universe. The data obtained during the experiment were analyzed using machine learning models. The analysis revealed characteristic features of antihyperhelium-4 when these particles decayed into other particles.
In addition, a lighter particle, antihyperhydrogen-4, was identified. The researchers accurately measured the masses of both particles and compared the results with current theories of physics. It is confirmed that matter and antimatter are created in equal parts. This raises a new question: what broke the symmetry if the initial Universe had an equal proportion of these forms of matter?
Now scientists don’t have a definitive answer – this question remains one of the unsolved problems of modern physics. However, the modernization of the Large Hadron Collider continues. In particular, the recently installed ultra-large magnets will allow even more precise experiments to be achieved. It is quite possible that future discoveries will open new horizons in the study of antimatter.
We previously reported on how a gamma-ray flare turned out to be the annihilation of matter and antimatter.
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