CERN physicists working with the LHCb detector have found the first possible differences between matter and antimatter, explaining why there is almost no antimatter in the modern Universe, according to an article published in the journal Nature Physics.
It is believed that in the first moments after the Big Bang there was an equal amount of matter and antimatter. Today the world is filled with matter, and this fact is a physical mystery, since the particles of matter and antimatter should have destroyed each other at the moment they appeared in the quark "soup" of the future Universe. Therefore, the question arises - where did the antimatter "disappear" and why the Universe exists.
Today scientists are trying to find an answer to this question in two ways - by simulating the conditions that existed during the Big Bang, including using particle accelerators, and also by comparing the fundamental properties of matter and antimatter. Over the past 50 years, no significant differences in their properties have been found, which is why many physicists began to look for exotic answers to the mystery of the disappearance of antimatter in the process of the expansion of the Universe and in the properties of the "God particle", the Higgs boson.
Nicola Neri of the University of Milan (Italy) and his colleagues in the LHCb collaboration, including dozens of Russian physicists, claim the possible discovery of such differences in the behavior of matter and antimatter in the data collected by the LHCb instrument during the first season of the Large Hadron Collider after restarting it in May 2015.
The scientists' attention was attracted by the oddities in the decays of the so-called lambda baryons - superheavy particles consisting of two light quarks and one heavy quark. In some rare cases, these particles decay into four parts - three pi-mesons and one proton, and in other, even more rare cases - into two kaons, a pi-meson and a proton.
The nature and frequency of these decays, as scientists note, should be approximately the same for particles and antiparticles, however, experimental data from the LHC show that the "pattern" of the movement of decay products in some cases differed by 10-20% from the generally accepted picture of the Standard Model of physics in those cases where anti-lambda baryons decayed. This asymmetry, according to physicists, indicates a similar asymmetry in strength in the properties of particles involved in the decay process.
So far, this observation is not a discovery - physicists have managed to record only six thousand cases of decay of lambda baryons according to these scenarios, and the confidence level of this discovery is 3.3 sigma (0.1% of the probability of a coincidence or measurement error). In particle physics, only those observations that reach a 5 sigma level of confidence are considered a discovery, and therefore, so far, the calculations of Neri and his colleagues are only a serious hint of a discovery.
On the other hand, according to the journal Symmetry, scientists promise to soon post updated measurement results, built taking into account the data that LHCb and the entire Large Hadron Collider conducted from January to November last year. If these initial data are confirmed, then it will be possible to say that scientists are really close to solving one of the main mysteries of the Universe, associated with the existence of mankind in particular and all matter in general.
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“We have proven that we are on the cusp of amazing discoveries. Our detector is so sensitive that we can now begin a systematic search for the asymmetry of matter and antimatter in other heavy baryons. Our capabilities will expand even further with the update of the detector in 2018,”concludes Neri.