B Are there Hadrons with more than three quarks?

[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?

 

[jerromyjon]

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.

 

[A. Neumaier]

See https://en.wikipedia.org/wiki/Pentaquark
It is probably a baryon-meson molecule. Of course there are also dodeca-quarks = alpha-particles, stable bound states of 12 quarks, or of two protons and two neutrons, and heavier nuclei.

 

[KBon]

Aight, I'll surely look it up. Thank you very much :) @jerromyjon @A. Neumeier

 

[mikeyork]

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.

 

[snorkack]

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...

 

[mfb]

Don't forget tetraquarks, also found by LHCb.

 

[snorkack]

How is a tetraquark verified to be that?

 

[mfb]

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.