LHCb discovers a new tetraquark state

  • A
  • Thread starter Wrichik Basu
  • Start date
  • Tags
    Lhcb State
  • Featured
In summary, the LHCb collaboration has reported the discovery of a new type of tetraquark. The data shows that the structure is resonant and has a mass just above the predicted masses of states composed of four charm quarks. There is still some uncertainty surrounding the status of lattice QCD results on these tetraquarks, but it appears that they are still a matter of debate.
  • #1
Wrichik Basu
Science Advisor
Insights Author
Gold Member
2,111
2,691
In a recent paper submitted by the LHCb collaboration at arXiv, they have reported a tetraquark state composed of charm quarks and antiquarks. The statistical significance of the data is more than 5σ.

The abstract:
Using proton-proton collision data at centre-of-mass energies of √s=7, 8 and 13TeV recorded by the LHCb experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 9fb−1, the invariant mass spectrum of J/ψ pairs is studied. A narrow structure around 6.9GeV/c2 matching the lineshape of a resonance and a broad structure just above twice the J/ψ mass are observed. The deviation of the data from nonresonant J/ψ-pair production is above five standard deviations in the mass region between 6.2 and 7.4GeV/c2, covering predicted masses of states composed of four charm quarks. The mass and natural width of the narrow X(6900) structure are measured assuming a Breit--Wigner lineshape.

An article on this paper:
https://www.symmetrymagazine.org/article/lhcb-discovers-a-new-type-of-tetraquark

A tweet by the LHCb collaboration:
 
Last edited:
  • Like
Likes vanhees71 and BvU
Physics news on Phys.org
  • #2
Interesting. How many other tetraquark states are known? A quick look at the tetraquark page on wiki didn't give me any conclusive answers.
 
  • #3
That depends on who you ask.
Z(4430) is well established.
Zc(3900) looks like a tetraquark, too.
Then there are the three older LHCb candidates, X(4274), X(4500) and X(4700)
Now there is X(6900), which looks like (charm, charm, anticharm, anticharm) object.
There is also X(3872), which doesn't fit into the traditional models and might be a tetraquark.

There are a few more candidates where it's unclear if they exist - or if their existence is clear it's unclear if they are tetraquarks (or similar).
 
  • Like
  • Informative
Likes dlgoff, DifferentialGalois, ohwilleke and 3 others
  • #4
The a0(980) and f0(980) are almost certainly tetraquarks. This goes back to a 1975 paper by Ken Johnson and Bob Jaffe.
 
  • Like
Likes vanhees71 and Drakkith
  • #5
There are definitional issues concerning what counts as a tetraquark too, which complicate the business of making a definitive list.

In sensu stricto a tetraquark is a hadron in which all quarks involved are bound directly to each other via gluon mediated strong force interactions.

But, sometimes a "meson molecule" , is also called a tetraquark in the less strict sense. In this example, if it is not a "true" tetraquark, it could be two charmonium mesons bound to each other by something akin to the residual strong force mediated mostly by pions that binds nucleons in an atomic nucleus to each other.

Experimentally distinguishing between the two possibilities is a subtle matter, even if you can agree that a bound structure is made of four valence quarks of particular types.
 
  • Like
Likes Wrichik Basu and Drakkith
  • #6
What is the status of lattice QCD results on these tetraquarks?
 
  • #7
Lots of papers, no consensus.
 
  • Like
Likes vanhees71

1. What is LHCb and what is its significance in the discovery of a new tetraquark state?

LHCb stands for Large Hadron Collider beauty experiment and it is a particle physics experiment located at the Large Hadron Collider (LHC) at CERN. LHCb is designed to study the properties of particles containing beauty or charm quarks. Its significance in the discovery of a new tetraquark state lies in its ability to produce and study these particles at high energies, providing valuable insights into the fundamental building blocks of matter.

2. What is a tetraquark state and why is its discovery important?

A tetraquark state is a type of exotic particle made up of four quarks (two quarks and two antiquarks) bound together by the strong nuclear force. Its discovery is important because it adds to our understanding of the Standard Model of particle physics and could potentially lead to the discovery of new particles and interactions beyond the Standard Model.

3. How did LHCb discover this new tetraquark state?

LHCb discovered the new tetraquark state by analyzing data from proton-proton collisions at the LHC. They observed an excess of events that could not be explained by known particles, leading to the discovery of a new particle with a mass of approximately 6.9 GeV/c².

4. What are the potential implications of this discovery?

This discovery could have several implications in the field of particle physics. It could provide new insights into the strong nuclear force and how it binds quarks together. It could also help us understand the nature of dark matter, as some theories suggest that dark matter could be made up of exotic particles like tetraquarks.

5. What further research is needed to fully understand this new tetraquark state?

Further research is needed to confirm the existence of this new tetraquark state and to study its properties in more detail. This could involve conducting more experiments at the LHC or using other particle accelerators. Theoretical models will also be developed and tested to better understand the nature of this new particle and its role in the Standard Model.

Similar threads

  • High Energy, Nuclear, Particle Physics
Replies
7
Views
997
  • High Energy, Nuclear, Particle Physics
2
Replies
41
Views
8K
  • High Energy, Nuclear, Particle Physics
Replies
8
Views
3K
Replies
1
Views
1K
  • High Energy, Nuclear, Particle Physics
Replies
11
Views
1K
  • Beyond the Standard Models
2
Replies
39
Views
4K
  • Other Physics Topics
Replies
4
Views
3K
  • Special and General Relativity
2
Replies
38
Views
43K
  • MATLAB, Maple, Mathematica, LaTeX
Replies
8
Views
3K
Back
Top