Are there Hadrons with more than three quarks?

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Discussion Overview

The discussion centers on the existence of hadrons containing more than three quarks, exploring various types of hadrons such as pentaquarks, tetraquarks, and hexaquarks. Participants examine theoretical implications, experimental evidence, and the nature of these exotic states within the context of particle physics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants note that traditional hadrons include mesons (quark-antiquark pairs) and baryons (three quarks), questioning the existence of hadrons with more than three quarks.
  • There is mention of recent claims regarding the discovery of pentaquark hadrons at the LHC, which involve five quarks, although details are limited.
  • One participant references the concept of dodeca-quarks, suggesting they could be stable bound states of 12 quarks or configurations involving protons and neutrons.
  • Discussion includes the observation that in meson-baryon scattering, resonances are typically seen only for three-quark systems, raising questions about the existence of exotic states like four-quark combinations.
  • The orthodeuteron is identified as a known hexaquark, with questions raised about the existence of other bound hexaquarks, while some configurations like diproton and dineutron are noted to be unbound.
  • Participants highlight the discovery of tetraquarks by LHCb and inquire about the verification methods for such states.
  • Specific decay patterns of the Z(4430) are discussed, suggesting it contains a combination of quarks that supports the tetraquark hypothesis.

Areas of Agreement / Disagreement

Participants express a range of views on the existence and nature of hadrons with more than three quarks, with no consensus reached on the verification or classification of these exotic states.

Contextual Notes

Limitations include the lack of definitive experimental evidence for certain exotic states and the dependence on theoretical models for understanding the interactions and properties of these hadrons.

KBon
As far as I know there are Mesons (quark-Antiquark pair) and Baryons (three quarks). But are there Hadrons which contain more than 3 Quarks?
 
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Hi and welcome to PF!
There has been a lot of hype lately that the LHC discovered penta-quark hadrons but I don't know much about it, other than there are 5 quarks involved.
 
Aight, I'll surely look it up. Thank you very much :) @jerromyjon @A. Neumeier
 
In meson-baryon scattering, ## q\bar{q} + qqq##, one typically sees resonances (short-lived particles) only for ##qqq## systems, where one ##q## annihilates with the ##\bar{q}##. States such as ##qqqq\bar{q}## where there is no ##q## able to annihilate the ##\bar{q}## are called exotic and no such resonances have been verified. This is most easily seen in ##K^+p## scattering.
 
The only well-known hexaquark is orthodeuteron, and it behaves strongly as a bound system of two separate nucleons.
Paradeuteron, diproton and dineutron are confirmed to be unbound.
Are there any other hexaquarks that are bound?
With 5 quarks participating in baryons, there are a lot of combinations to check...
 
How is a tetraquark verified to be that?
 
Z(4430) decays to ## J/\psi \,\pi^\pm##, and based on its mass it cannot have a b quark, so it has to have ##c \bar c## in it. It also has a charge, so it needs at least two more quarks.
 

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