# How do quarks keep themselves apart?

I was chatting with user Dan Yand regarding my recent question about colour charges, it was mentioned in the comment section that particles with colour charges attract each other like or unlike hence I would like to know how do quarks keep themselves apart? It can't be electromagnetic force because it is much weaker than strong force so how about exclusion principle similar to electron degeneracy pressure in compact star but that way it will become a gluon plasma soup?

• My first guess would be pauli exclusion principle, but I thought about it for about 30 seconds and don't have any calculations to offer. Dec 28 '18 at 5:21
• @InertialObserver: I'm picking up chromodynamics trying to understand what each symbol in the equation of Wilson Loop mean, now got to admit this is challenging! Dec 28 '18 at 5:27
• I do admit that Wilson Loops aren't a walk in the park Dec 28 '18 at 5:28

## 1 Answer

The attractive color force actually gets weaker as quarks get closer together. This is called asymptotic freedom, and it was discovered as a property of QCD in 1973. Since quarks become non-interacting at short distances, there is no need for a force to keep them apart.

The opposite is also true: the attractive color force stays strong as the quarks get arbitrarily far apart. It essentially approaches a constant value. This is called confinement.

• like opposite of gravity Dec 28 '18 at 6:19
• And also opposite to electrostatic attraction, which gets stronger when the separation decreases. Dec 28 '18 at 6:23
• colour confinement right? Dec 28 '18 at 6:26
• Confinement is the opposite of asymptotic freedom. Confinement happens at large distances. Asymptotic freedom happens at small distances. Dec 28 '18 at 6:29
• like an elastic string. This was the first application of string theory. Dec 28 '18 at 18:27