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Asymptotic freedom
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The strong force weakens at short distances.
The strong coupling weakens at high energy (short distance), so quarks behave almost free in high-energy collisions, but at larger distances it grows. Nobel Prize 2004.
Allows perturbative calculations at colliders.
Opposite of QED behaviour.
In more detail
Asymptotic freedom means the strong force becomes weaker at short distances or high energies. This allows quarks to behave almost freely inside protons when probed at high energy.
Real-world uses
- Asymptotic freedom explains results from deep inelastic scattering.
- It underpins predictions for high-energy collisions.
- Physicists explain why quarks behave almost freely inside protons at high energy, which was key to understanding deep inelastic scattering.
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Frequently asked questions
Who discovered asymptotic freedom?
David Gross, David Politzer and Frank Wilczek, who received the 2004 Nobel Prize.
Why does it matter?
It makes QCD calculable at high energies, where perturbation theory works.
Why does the strong force weaken at short range?
Gluons interact with each other, so at short distances the effective strong coupling becomes small.
Related topics in Particle Physics & Cosmology
Higgs boson · Standard Model · Colour charge and QCD · Confinement · Weak interaction · Electroweak unification