Is there an experiment that shows strong force grows with distance?

In summary: Okay, so let's summarize the conversation. In summary, the strong force has been observed through trillions of collisions at various colliders over the past 70 years, supporting the idea that it either grows or remains constant with distance. This is confirmed by the "running coupling" of QCD, as shown in the Review of Particle Physics. The strong force is composed of the residual strong force, which holds a nucleus together, and the strong interaction or color force, which holds a quark together. The Particle Data Group has compiled all the necessary information on this topic. The observations of particles decaying into jets exactly as predicted by the theory of Quantum Chromodynamics further support the idea that the strong force does not decrease in strength with distance. Overall
  • #36
Drakkith said:
It's called color confinement. Wikipedia has an article on it if your interested. Have you heard of it before?
Yes, I've heard of it, and I've already read the entire Wikipedia page on color confinement, but that would be a good place to point to if I hadn't. Thank you.
 
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  • #37
Cody Livengood said:
I'm one class away from being halfway done with my physics degree
Must be a very good university that teaches QFT already then (usually a year 4 course) and is failing misarable at explaining the scientific method and not making their students threw out their own non-scientific theories.

Anyway
vanhees71 said:
The "running coupling" of QCD can be measured and agrees pretty well with the predictions of the theory:

https://pdg.lbl.gov/2022/web/viewer.html?file=../reviews/rpp2022-rev-qcd.pdf#chapter.9
You should read chapter 9.4

Dale said:
the main experimental observation that leads us to believe that the color force grows with distance is the absence of free quarks.
and results from deep inelastic scattering, showing that at high energy scales (small distances), quarks are basically free particles. So combing these two results, we can infer that the strength of the interaction between quarks goes like this
1660578251476.png

(from that PDG article)

Running of coupling constant is a general QFT phenomena, that the strength of the interaction varies with distance (energy scale) is not only for QCD.

For the electromagnetic force (QED), the behaviour is different. There the strength of the interaction becomes larger and larger for smaller distances (higher energy scales) and weaker at larger distances (Coulombs law). Are you familiar with electric screening of the nuclei in atomic physics? In an atom, the electrons in the outer "shells" is subjected to a weaker electric force than the inner shell electrons. Not only because they are farther out, but also because the inner electrons are "screening" the electric charge of the nucleus.

Here is an heuristic analogy of that in QFTs. All particles are surronded by a "cloud" of virtual particles, which in some sense is working like the electron shells around a nuclei in an atom. At higher energies (shorter distances) you get closer to the "real" particle. For QCD, it actually turns out that because the gluons can interact with themselves (and the fact that there are just the right amount of quarks, the formula can be found here https://en.wikipedia.org/wiki/Beta_function_(physics) ) the sign of this screening effect is opposite that of QED.
1660579428773.png

Of course, what I wrote above are just fancy words. One have to do the actual QFT calculations. And a result of such calculations is that coupling constants vary with the energy scale of the interaction (Nobel prize 2004). You mentioned that you were quite familiar with QFT in another thread, so it should be within your reach to perform and understand such calculations yourself.

What one does experimentally is to observe and measure the rate of certain events, like number of jets. Then you compare the experimentally measured rate with what your model would yield as a theoretical rate with a) constant interaction strength and b) varying interaction strength .

And it turns out that a) sucks at explaining data and that b) is what describe data best. Furthermore, if you insert precisely the energy scale dependence of the interaction strength as it is predicted by QCD, you get an extremely good fit. Now there are of course some subtleties here, otherwise it would not require hundreds of particle physicists with a phd to make these experiements and calculations (though the basics are accesible to master students). But roughly speaking, this is what you do, i.e. the scientific method.
 
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  • #38
Cody Livengood said:
It's not a coincidence, but I don't think we can really discuss my theory here.
You're right, you can't. Still, it would have been more, I dunno, honest, to have told us in the beginning rather than pretending you're "just asking questions" rather than having an axe to grind.
 
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  • #39
Vanadium 50 said:
You're right, you can't. Still, it would have been more, I dunno, honest, to have told us in the beginning rather than pretending you're "just asking questions" rather than having an axe to grind.
And now he is gone.
 
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  • #40
malawi_glenn said:
And now he is gone.
For now.

A shame your nice message on antiscreening was wasted.
 
  • #41
Vanadium 50 said:
For now.

A shame your nice message on antiscreening was wasted.
It might have been wasted on the OP, but it wasn't wasted. As very much a non-expert for this topic, I certainly appreciated it and found it informative.
 
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  • #42
Dale said:
It might have been wasted on the OP, but it wasn't wasted. As very much a non-expert for this topic, I certainly appreciated it and found it informative.
There are some nice analogies for QED with dielectric media and QCD with paramagnetic media as well.

Vanadium 50 said:
A shame your nice message on antiscreening was wasted.
Let's hope OP read anyway, even though blocked. And that he changes his mind regarding... well everything that has to do with natural science. We had a dude who was doing his phd in experimental hadron physics in my division. He never finished, but is instead "working" with cold fusion and other related topics. Oh well.
 
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