The results of the study were presented at the CERN seminar on July 5, 2022. The discovery concerns a new type of pentaquark and two tetraquarks. They will help physicists better understand how quarks bind to complex particles.

Opening details

Quarks are fundamental and fundamental particles of matter. Simply put, everything is made up of them. They are classified into six types: lower, higher, strange, magical, beautiful, and real. They often combine in groups of two and three to form hadrons – for example, protons and neutrons, which in turn make up the atomic nucleus.

In some cases, four and five quarks, known as tetraquarks and pentaquarks, respectively, can also combine. These exotic hadrons were predicted by theorists about 60 years ago, at the same time as ordinary hadrons, but were detected relatively recently by collider and other experiments in the last 20 years. Most of the exotic hadrons discovered in the last two decades are exactly tetraquarks or pentaquarks.

Discoveries announced today by the LHCb collaboration include new types of exotic hadrons.

• first type pentaquarkconsists of a magic quark and a magic antiquark, as well as up, down, and strange quarks. It is the first pentaquark found to contain a strange quark.
• The second type is doubly charged. tetraquark. It consists of a magic quark, a strange antiquark, and an up and down antiquark.
• Found another one next to it. tetraquark, similar to the previous one, but without an electrical charge. This is claimed to be the first pair of tetraquarks discovered by physicists.

A pair of tetraquarks discovered by scientists / Photo by CERN

The more analysis we do, the more exotic hadron species we find. We are witnessing a similar period of discovery to the 1950s, when the hadron “zoo of particles” began to be discovered, eventually leading to the quark model of ordinary hadrons in the 1960s. We create a “Particle Zoo 2.0”,
Says Niels Tuning from the LHCb team.

Some theoretical models describe exotic hadrons as discrete units of tightly bound quarks, while other models consider them as standard pairs of hadrons bound in a molecular structure. Therefore, finding new types of tetraquarks and pentaquarks and measuring their properties will help theorists develop a unified model of exotic hadrons and understand whether these particles are one, the other, or both.