Physicists working on the international LHCb experiment have re-analyzed data obtained during
The first of these is the pentaquark, which containsa strange quark enters. This is the first known hadron, consisting of five particles with a strange quark. It was discovered during the "decay" of negatively charged B mesons.
Possible structures of a pentaquark, which consists of a charm quark and a charmed antiquark, as well as up, down and strange quarks. Image: CERN
The second new species is a tetraquark with a doubleelectric charge. It is an open charm tetraquark, consisting of a charm quark, a strange antiquark, an up antiquark, and a down antiquark. Together with him, the researchers discovered his neutral counterpart. Both hadrons were found in the analysis of joint decays of positively charged and neutral B-mesons. Physicists note that this is the first time a pair of tetraquarks has been observed.
A pair of tetraquarks. Image: CERN
Quarks are the elementary particles that make upmatter. The standard theory describes six kinds of quarks: up, down, strange, charm, charm, and true. In addition, each quark has its own antiparticle, the antiquark. As a rule, quarks do not exist separately, but are combined in groups of two and three, forming hadrons, for example, protons and neutrons.
In addition to the well-known hadrons, consisting oftwo and three particles, there are more complex subatomic elements - exotic hadrons, which include four (tetraquarks) or five (pentaquarks) particles. They were theoretically predicted along with ordinary hadrons, but scientists have been able to observe them only in the last 20 years. At the LHC, physicists have already discovered many such particles, but discoveries continue.
The researchers note that the discovery of newtypes of exotic hadrons will help create a unified theory that will describe all kinds of such subatomic elements. They expect new discoveries from the third run of the LHC.
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