Three new particles have been discovered at the Large Hadron Collider. They are “exotic”. But why are they considered unusual?
What is the difference between matter and antimatter? To find out, it is necessary in particular to study a type of elementary particle: quarks. beauty. This is precisely the objective of the LHCb collaboration, based at the Large Hadron Collider. If the particle accelerator has just gone to record power, it did not wait for its upgrade to bring new data.
As revealed by CERN, during a seminar held on July 5, 2022, three exotic particles have recently been discovered. These are three new configurations of quarks. But what does that mean exactly?
An unusual mix of flavors
In quantum physics, flavors don’t have the same implication as they do in your kitchen. They designate a set of characteristics, including the electrical charge. Thus, there are six different quarks for six flavors: down quark, up quark, strange quark, beauty quark, charm quark, truth quark.
These different quarks combine in pairs or trios to form composite particles called hadrons. In short, the elementary particles which are the quarks are like distinct bricks which are assembled. But sometimes the assembly is more complex than expected, by four or by five quarks. This then forms so-called “exotic” hadrons, because they are out of the ordinary.
It is for this reason that the new particles recently detected at the Large Hadron Collider are not trivial. Except that they have, in addition, additional features:
- A “pentaquark” (5 quarks) composed of a charm quark and a charm antiquark, and an up quark, a down quark and a strange quark. It is quite simply the first pentaquark discovered to contain a strange quark.
- A “tetraquark” (4 quarks) doubly electrically charged. He was observed with his neutral counterpart “, which forms a total of two new tetraquarks. ” This is the first observation of a pair of tetraquarks explains CERN.
These findings are all the more significant because of their statistical significance. The statistical certainty of an observation, in physics, is based on the standard deviation: an observation is considered certain at 5 standard deviations. The pentaquark is 15 standard deviations away, the first tetraquark is 6.5 standard deviations away, and the second tetraquark is 8 standard deviations away.
The “particle zoo 2.0”
The discovery of exotic hadrons is not unprecedented. In 2021, a particle with a “double dose of charm” was unearthed. But this has accelerated markedly in recent years, as particle accelerators work at full speed.
” The more analyzes we perform, the more types of exotic hadrons we find explains, on the CERN site, Niels Tuning, who coordinates the LHCb experiment. ” We are currently living a era of discovery similar to that which we experienced in the 1950s, when we began to discover a veritable ‘zoo of particles’ – in this case hadrons. »
It is on the basis of this particle zoo discovered in the 1950s that so much is known today about classical hadrons and their model. All recent discoveries of exotic hadrons are forging, according to Niels Tuning, a ” particle zoo 2.0 “. There is currently no established model, strictly speaking, on exotic hadrons. These new findings take us there, while obviously advancing knowledge of hadrons and quarks more generally.
