Moscow. September 3rd. INTERFAX.RU – The LHCb Collaboration (CERN, European Organization for Nuclear Research), which also includes Novosibirsk physicists, has specified the parameters of a new particle discovered in the summer of 2021 – an exotic tetraquark, the Budker Institute of Nuclear Physics (INP, Novosibirsk) reported.
“The exotic tetraquark Tcc + stands out among its brethren and represents a new form of matter. It is the only doubly charmed tetraquark known to science, that is, it contains two charmed quarks at once, but does not have charmed antiquarks in its composition,” the press release says.
The particle has a positive charge (+1) and a mass of approximately 3.875 GeV.
Scientists called this particle a long-lived record holder: “its life time, according to updated data, is 100-5000 times longer than particles with a similar mass.”
It also turned out that the doubly charmed tetraquark is a large object, roughly the size of a uranium atom.
The researchers also managed to establish some quantum numbers of the new particle and work out hypotheses about its internal structure.
Quantum numbers, whole or fractional, characterize elementary particles in a quantum system. The fundamental quantum numbers are total angular momentum, spatial parity, and isotopic spin.
Scientists have to clarify the quantum numbers of a tetraquark and establish all the final states (sets of particles) into which it decays, after which it will be given a final name, but the new particle does not fit into the nomenclature of the Standard Model – a kind of Periodic Table of the microworld.
A tetraquark is an exotic elementary particle, a hadron, made up of two quarks and two antiquarks. Exotic tetraquarks are called because it was originally believed that hadrons can consist of either a quark-antiquark pair (such a hadron is called a meson), or of three quarks (in this case, a hadron is called a baryon; baryons are, for example, a proton or neutron).
LHCb (Large Hadron Collider beauty experiment) is one of the detectors of the Large Hadron Collider; in total, 62 new elementary particles have been discovered at the LHC since the start of the collider.
Five employees of the INP and Novosibirsk State University are participating in the LHCb experiment.
A quark is a fundamental particle that is not observed in a free state, but is part of strongly interacting particles such as protons and neutrons. Quarks are structureless, pointlike particles. Enchanted are quarks with a positive charge equal to two-thirds of the elementary electric charge and a mass of 1.25 GeV, they occupy the third place in mass among quarks.