The first tetrawark with dual beauty – CERN physicists have discovered the most durable combination of four quarks to date

A special attraction: physicists first discovered a tetraquark made from two heavier beautiful quarks and two lighter antiqueworks – the first representative of a completely new class of four quark particles. These double-weight tetraguarks have long been regarded as standard representatives of perhaps exotic quark combinations. The discovery of one of these particles in the Large Hadron Conflict (LHC) at CERN opens up new opportunities for research in this fascinating form.

In the normal case, like the protons and neutrons of the nucleus, quarks generally occur in three combinations. There are also short-lived missions made by Quark and AntiWork. So much for classic inventory. In recent years, however, physicists have discovered other attractive combinations of quarks in particle accelerators. Four, For Or even Six quarks.

First double weight tetraquark

Now the particle is in development at the zoo: physicists The big Hadron collision (LHC) research center CERN finds first representative of new class of four quark particles⁺) These particles, made up of two heavy and two light quarks, were proposed in the 1980s, but were not discovered later. They are considered to be the best candidates for stable hadrons despite their attractive combination of quarks.

Such a Tcc⁺-Tetrawark is now discovered by CERN researchers. This particle accelerator arises from proton collisions in the LHC and is detected on the basis of a significant “hump” in the mass distribution of the captured particles in the LHCb detector. “Tetraquark de Mason manifests itself as a narrow peak in the mass spectrum,” the physicists describe the signal.

According to the researchers, the statistical significance is more than 20 level deviations – thus one speaks of a discovery in particle physics above the threshold of five sigma.

Double Glamor (s)

The newly discovered Tetrawark features two heavier exotic quarks, Up Antivark and Down Antivark. This means that it is not only the first double weight four quark particle — it is the first tetra quark with two exotic quarks without compensating for the exotic antiquarks. Physicists point out that such a particle has a double “open beauty” – just as it has a double size beauty (s).

For a long time, it was not clear whether such particles even existed, as did other tetraworks, that they were fused together by a strong nuclear force. “This week’s long-awaited discovery now shows such a Tcc⁺-Tetrawark exists and can prove its signature experimentally, “said physicists of the LHCb collaboration at the European Society’s High Energy Physics Conference on July 29, 2021.

More durable than all other exotic creatures

More exciting: According to physicists, the new Tetrawark lived longer than all known exotic hotspots. Hatrons are all passing particles Strong nuclear power Conducted together. The mass of tetraquark is slightly less than the value of its decomposition material – each of the two D mesons has a heavier glamorous quark and a lighter antiquework.

The energy in the bonded quadruple state is slightly higher than the energy of the decaying material and is a sign of relatively high stability. “What this means is that this tetraquark decomposes into two D-missions with even stronger contact, but it occurs more slowly and less intensely than other exotic hotspots,” explains Ivan Poliakov, an LHCb researcher at the University of Syracuse. The new particle confirms that the class of twice as heavy TetraWorks is indeed particularly stable.

New insights into exotic hotspots

The invention of the new Tetrawark now allows one to make the first decisions about the next. However, with the current performance of the LHC, this heavy hydron has not yet been detected and is very rare, Poliakov explains.

Its lighter relative, the double “beautiful” tetraquark, is particularly easy to detect, and it is very useful for research. “The new Tcc⁺-Tetrawark is an attractive subject for further research. Because its decomposition involves only easily detectable particles, “says the LHCb team.” It enables greater accuracy in determining mass and rigorous tests for existing theoretical models. “EPS-HEP 2021))

QUELLO: CERN, LHCb Collaboration

4. August 2021

– Natja Bodybreaker