Everything you see around consists ofelementary particles - quarks and leptons, which can be combined with the formation of larger particles, such as protons or atoms. But this is not limited to: these subatomic particles can also be connected in an exotic way, which we have never seen. The CERN LHCb collaboration has announced the discovery of new particles, which are called pentaquarks. The results of their work can help us discover the many mysteries of quark theory, the most important part of the Standard Model.
At the LHC they found pentaquarks: what is it?
Quarks were first proposed for explanation.the oddities of new particles found in cosmic rays and during experiments at colliders in the middle of the 20th century. This growing "zoo" apparently fundamental particles caused confusion in the ranks of physicists who adore simplicity and order - and do not like to produce the basic principles. The famous Italian physicist Enrico Fermi noticed the mood of his colleagues and said the following: "Young man, if I could remember the names of all these particles, I would be a nerd."
Fortunately, in the 1960s, an American physicistMurray Gell-Mann observed patterns in the zoo of particles, similar to those noted by Dmitri Mendeleev, making up a periodic table of chemical elements. Just as the periodic table implies the existence of things that are smaller than atoms, the Gell-Man theory suggested the existence of a new class of fundamental particles. Particle physicists were ultimately able to explain that the hundreds of particles in a zoo are made up of a much smaller number of truly fundamental particles, called quarks.
There are six types of quarks in the Standard Model -lower, upper, strange, enchanted, beautiful and true. They also have satellites in the form of antimatter - it is believed that each particle has a version of antimatter, almost identical to it, but with an opposite charge. Quarks and antiquarks are combined with the creation of particles known as hadrons.
According to the Gell-Mann model, there are two wideHadron class. One of the particles consists of three quarks — baryons (which include protons and neutrons making up atomic nuclei) —and other particles consisting of a quark and an antiquark, that is, mesons.
Until recently, baryons and mesons werethe only types of hadrons that were observed experimentally. But in the 1960s, Gell-Mann also discovered the possibility of more exotic combinations of quarks, such as tetraquark (two quarks and two antiquark) and pentaquarks (four quarks and one antiquark).
In 2014, the LHCb, where one of the fourgiant experiments at the Large Hadron Collider at CERN, published results showing that particle Z (4430) + was a tetraquark. This generated a stream of interest in new exotic hadrons. Then, in 2015, LHCb announced the discovery of the first ever pentaquark, which added an entirely new class of particles to the family of hadrons.
Results presented by LHCb todayexpand after the first discovery of pentaquarks by detecting additional such particles. This was made possible thanks to the flow of new data recorded during the second launch of the Large Hadron Collider. Lyming Zhang, a professor at Tsinghua University in Beijing and one of the physicists who conducted the measurements, says that "we now have ten times more data than in 2015, which allows us to see more interesting and thinner structures than before." When Leaming and his colleagues investigated the original pentaquark, discovered in 2015, they were surprised to learn that it was divided into two parts. The original pentaquark consisted of two separate pentaquark particles, which had masses so similar that they were taken as one particle.
But two pentaquars for the price of one are notall the interesting news. LHCb also found a third pentaquark with a mass smaller than the first two. All three pentaquars consist of one lower quark, two upper, enchanted quark and enchanted antiquark.
The big question is this: What is the exact internal structure of these pentaquarks? One of the options is that they really consist of five quarks, mixed evenly in a single hadron. Another possibility is that pentaquarks are actually a baryon and a meson, which stick together to form a weakly bound molecule, just as protons and neutrons are bound together inside an atomic nucleus.
Tomash Skvarnitsky, a professor of physics at SyracuseThe university in New York, which also worked on the measurement, said that the new state has "a mass that gives clues about the internal structure of pentaquarks." The most likely option is that these pentaquarks are baryon-meson molecules, he adds. To be absolutely sure, physicists will need to conduct additional experiments, as well as develop a theory. This means that the history of pentaquarks is far from complete.
These results finish the week of incredibleLHCb ads, including the discovery of a new type of matter and antimatter asymmetry. The LHC has not yet detected any particles that go beyond the Standard Model, which could help explain riddles such as dark matter, an invisible and unknown substance that makes up most of the matter in the Universe.
However, these exciting measurements showthat much remains to be learned about the particles and forces of the Standard Model. Perhaps our best chance to find answers to the big questions facing fundamental physics lies in a more detailed study of particles that we already know about, and not in the discovery of new ones. In any case, much remains to be discovered.
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