Physicists once again found no difference between matter and antimatter

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Physicists once again found no difference between matter and antimatter
Physicists once again found no difference between matter and antimatter
Anonim

Physicists from the ALPHA project, which is based at CERN, presented the first data on measurements of the fine structure of the spectrum of antimatter particles, from which one can draw conclusions about the structure of its quantum energy levels. In this, it turned out to be similar to ordinary matter, scientists write in an article published by the scientific journal Nature.

"The discovery of any discrepancies in the properties of matter and antimatter will literally shake the foundation of the Standard Model. These measurements helped us realize our long-held dream and study some aspects of the interaction of antimatter with the surrounding space, including measuring the shift of its lower energy levels," commented on the results of the work ALPHA official representative Jeffrey Hangst.

Cosmologists suggest that in the Universe in the first moments of its life, matter and antimatter were approximately equal. All chemical and physical properties of their particles, with the exception of the charge, should have been the same - unless, of course, the Standard Model is incomplete or erroneous (this theory describes most of the interactions of all elementary particles known to science today).

However, this contradicts the very existence of reality, since all particles of matter and antimatter had to destroy each other, colliding and mutually annihilating in the first moments after the Big Bang. Therefore, scientists have been arguing for many decades and wondering why there is practically no antimatter in the observable Universe.

Many physicists believe that the answer to this riddle lies in the slightest differences in the properties, behavior and structure of the particles of antimatter and matter. Scientists have recently found many hints that such discrepancies may exist, for example, in the masses of protons and antiprotons. However, physicists have not yet confirmed any of them.

Hangst and his colleagues have been trying to find them for many years using the ALPHA-2 instrument, a special magnetic trap for positrons and antiprotons that forces them to combine and form single antimatter atoms. The first measurements of this kind, which scientists carried out in 2012, 2016 and 2018, showed that there is no difference in how light excites electrons and positrons in atoms of antimatter and matter.

Secrets of antimatter

In a new series of experiments, CERN scientists have measured the so-called Lamb shift for antimatter for the first time. This is what scientists call small differences in where two specific energy levels within the atom, 2s and 2p, are located. According to the theory, their position should coincide, but in reality this is not so - they turn out to be shifted relative to each other.

The existence of this gap is due to the fact that particles of matter and antimatter constantly interact at the quantum level with pairs of virtual particles and antiparticles, which are continuously born and disappear in the void of vacuum. Traces of this can be seen in the so-called "fine structure" of the atom, a set of narrow bands in the spectrum into which theoretically predicted energy levels split.

Project ALPHA first studied the structure of this set of lines by passing 90,000 antihydrogen atoms through a powerful magnetic field, then irradiating them with an ultraviolet laser and watching how their spectrum changed as a result. Scientists used this data to calculate the Lamb shift of antimatter and compare it with a similar parameter for hydrogen.

On the whole, the obtained values coincided with measurements for ordinary matter and with the results of theoretical calculations, which took into account quantum effects. As Hangst emphasizes, these data are still preliminary, but even now we can say that measurements of the constant structure cannot deviate from the predictions of the theory by more than 2%, and the Lamb shift by more than 11%.

In the near future, ALPHA members plan to carry out more accurate measurements by cooling the antihydrogen atoms to temperatures close to absolute zero. These observations, scientists hope, will finally confirm that the values of the Lamb shift for matter and antimatter are the same, and that they will help physicists accurately measure the radius of the antiproton.

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