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Confinement
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Quarks are never seen in isolation.
Pulling quarks apart stretches a flux tube whose energy grows with distance until it creates a new quark–antiquark pair, so isolated quarks are never seen.
Separating a quark and antiquark produces jets of hadrons.
Proven only numerically (lattice QCD).
In more detail
Confinement means that quarks and gluons cannot be isolated; they are always bound within colour-neutral hadrons. Attempts to separate them create new quark-antiquark pairs instead.
Real-world uses
- Confinement explains why only hadrons are observed in experiments.
- It shapes the physics of protons and neutrons.
- Physicists explain why no free quarks are found in experiments, since they always appear in colourless hadrons.
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Frequently asked questions
What happens if you pull quarks apart?
The energy in the field creates new quark pairs, producing more hadrons.
Is confinement proven?
It is supported by lattice QCD calculations and by the absence of free quarks.
What happens if you pull two quarks apart?
The energy in the strong field creates new quark pairs, so you get new hadrons rather than isolated quarks.
Related topics in Particle Physics & Cosmology
Standard Model · Colour charge and QCD · Asymptotic freedom · Weak interaction · Electroweak unification · Conservation laws in particles