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

[Cody Livengood]

TL;DR Summary

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

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

 

[Vanadium 50]

You posted this in classical physics. What strong force do you mean?

 

[vanhees71]

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

 

[Dale]

You posted this in classical physics.

I have moved it to HEP

 

[Drakkith]

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

Yes, there have been trillions of observed collisions at various colliders around the world over the past 70 years or so that support the idea that the strong force either grows or remains constant with distance.

Trillions. This isn't hyperbole or exaggeration.

 

[Cody Livengood]

You posted this in classical physics. What strong force do you mean?

Is there more than one? What are my options?

 

[vanhees71]

Yes, there have been trillions of observed collisions at various colliders around the world over the past 70 years or so that support the idea that the strong force either grows or remains constant with distance.

Trillions. This isn't hyperbole or exaggeration.

Well, QCD is only about 50 years old ;-)). It's of course right, that it is very well established nowadays by all experiments ever made.

 

[Cody Livengood]

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

That's a lot of text to read. Help me out. What experiment showed this and how did it show it?

 

[Dale]

Is there more than one? What are my options?

There is the residual strong force. This is the strong force that holds a nucleus together. There is also the strong interaction or color force. This is the strong force that holds a quark together. From context I think that you mean the second one.

 

[malawi_glenn]

That's a lot of text to read. Help me out. What experiment showed this and how did it show it?

Is this also for your school project? Seems to me you want others to do the work for you

 

[Cody Livengood]

Yes, there have been trillions of observed collisions at various colliders around the world over the past 70 years or so that support the idea that the strong force either grows or remains constant with distance.

Trillions. This isn't hyperbole or exaggeration.

How do those observations show that? What physical action did particles make in the experiment to demonstrate this?

 

[vanhees71]

That's precisely told in this article from "Review of Particle Physics". That's why I posted this link. It's the most convenient way to find the state-of-the-art experimental (as well as theoretical results) in HEP physics. On top it's even totally for free. You can even order hard copies of the review as well as the very handy particle-data booklet.

 

[vanhees71]

Is this also for your school project? Seems to me you want others to do the work for you

Well, the Particle Data Group already has done this work for you!

 

[malawi_glenn]

Well, the Particle Data Group already has done this work for you!

PDG is cheat mode!

 

[Cody Livengood]

Is this also for your school project? Seems to me you want others to do the work for you

It's not for school. It's a personal project. I just need a few more questions answered and I should be done with it. And if you're already familiar with what the text says, it's quicker to just ask you to sum it up than to spend the next hour reading something that may or may not actually include the answer I'm looking for.

 

[malawi_glenn]

It's not for school. It's a personal project. I just need a few more questions answered and I should be done with it. And if you're already familiar with what the text says, it's quicker to just ask you to sum it up than to spend the next hour reading something that may or may not actually include the answer I'm looking for.

In the other thread you said you are not doing this for fun?

 

[Drakkith]

Well, QCD is only about 50 years old ;-)). It's of course right, that it is very well established nowadays by all experiments ever made.

Eh, I estimated.

How do those observations show that? What physical action did particles make in the experiment to demonstrate this?

They decayed into jets of particles exactly as predicted by the theory (Quantum Chromodynamics) that says that the strong force doesn't decrease in strength with distance.

If the strong force DID drop off with distance then all sorts of things would be different from what we observe.

 

[Dale]

It doesn't really matter why they are doing this project. This is not a homework-like question so it is on-topic. At the same time, if you want to answer with a solid reference then that is fine.

 

[malawi_glenn]

It doesn't really matter why they are doing this project. This is not a homework-like question so it is on-topic. At the same time, if you want to answer with a solid reference then that is fine.

It would be helpful to know what the OPs own knowledge is and what the ultimate goal is in order to help as best as possible.

 

[Cody Livengood]

In the other thread you said you are not doing this for fun?

Yes, my personal project isn't being done for fun. I've been working at it for over seven years now. I'm doing it to change what the scientific community believes, not for no reason.

 

[Dale]

It would be helpful to know what the OPs own knowledge is and what the ultimate goal is in order to help as best as possible.

Agreed, their background level would be useful, but we don't need to pry into their project.

 

[malawi_glenn]

Yes, my personal project isn't being done for fun. I've been working at it for over seven years now. I'm doing it to change what the scientific community believes, not for no reason.

So it is work on a personal theory?

 

[Dale]

Yes, my personal project isn't being done for fun. I've been working at it for over seven years now. I'm doing it to change what the scientific community believes, not for no reason.

Good luck with that. We can help with what the scientific community believes and why, but we cannot discuss unpublished personal theories here. So stick with questions about standard theories and avoid pushing your own theories. Most of us have already inferred that this is exactly what you are doing, hence the general tone of the responses.

 

[PeroK]

It's not for school. It's a personal project. I just need a few more questions answered and I should be done with it. And if you're already familiar with what the text says, it's quicker to just ask you to sum it up than to spend the next hour reading something that may or may not actually include the answer I'm looking for.

The strong force (QCD) is something of a package, IMO. You have a theoretical infrastructure of quarks, gluons, colour charge, isospin and rules for the way these interoperate and out comes a theory that predicts what will happen in various high-energy experiments. It's difficult or impossible to isolate these components (e.g. a quark) and indeed some of the rules prevent isolation (e.g. colour confinement).

All you can do, really, is test the theoretical package. QCD produces accurate predictions. In a way that's all you can say.

Moreover, I don't think the concept of existence is really very important in physics. All that matters is that something is a useful concept. One example is the classical electromagnetic field. It doesn't matter whether you say it really exists or not. All that matters is that it is a useful concept that is part of the model for classical electromagnetism and that theory works in its domain of applicability.

 

[Drakkith]

My reason for asking the question is irrelevant to the question itself. But if you must know what my knowledge level is, I'm one class away from being halfway done with my physics degree and I work for Boeing's Defense, Space and Security division.

You aren't by chance an author, are you?

 

[malawi_glenn]

Agreed, their background level would be useful, but we don't need to pry into their project.

Its up to them if they want to reply. I just think its good to know what they are going to do with that knowledge. It is for sci fi novel, is it for a lego diorama, or just out of sheer interest

 

[Cody Livengood]

You aren't by chance an author, are you?

Yes. A quick Googling of my name and you could find that out.

 

[Drakkith]

Yes. A quick Googling of my name and you could find that out.

That's exactly what I did, but I figured I'd ask in case it was merely a coincidence that you have the same name as the author of a book that claims that they have a theory of everything that makes more sense than much of science.

 

[Dale]

I am by FAR not the expert on this topic, but assuming that you are talking about the color force, the one responsible for holding protons and neutrons together, the main experimental observation that leads us to believe that the color force grows with distance is the absence of free quarks.

Btw, given your background, the reference posted should be something that you can read and understand.

 

[Cody Livengood]

That's exactly what I did, but I figured I'd ask in case it was merely a coincidence that you have the same name as the author of a book that claims that they have a theory of everything that makes more sense than much of science.

It's not a coincidence, but I don't think we can really discuss my theory here.

 

[berkeman]

It's not a coincidence, but I don't think we can really discuss my theory here.

Correct. But is is being discussed currently in the Mentor forums...

 

[Cody Livengood]

I am by FAR not the expert on this topic, but assuming that you are talking about the color force, the one responsible for holding protons and neutrons together, the main experimental observation that leads us to believe that the color force grows with distance is the absence of free quarks.

Btw, given your background, the reference posted should be something that you can read and understand.

Yes, I can read and understand it.

Correct. But is is being discussed currently in the Mentor forums...

That's alright with me. I'm new to Physics Forums, but if you believe you know of any reason why it can't be true or have anything you want me to clarify, there are less public ways of contacting me where we can discuss it if anyone has any desire to do so. Thanks.

 

[Motore]

Because of this:

I've been working at it for over seven years now.

there should be no:

That's a lot of text to read.

excuses.

 

[Cody Livengood]

I am by FAR not the expert on this topic, but assuming that you are talking about the color force, the one responsible for holding protons and neutrons together, the main experimental observation that leads us to believe that the color force grows with distance is the absence of free quarks.

Btw, given your background, the reference posted should be something that you can read and understand.

The answer that it is because of the "absence of free quarks" is more along the lines of the answer I was looking for. That's something that's actually physical. Thank you.

 

[Drakkith]

The answer that it is because of the "absence of free quarks" is more along the lines of the answer I was looking for. That's something that's actually physical. Thank you.

It's called color confinement. Wikipedia has an article on it if your interested. Have you heard of it before?

 

[Cody Livengood]

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.

 

[malawi_glenn]

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

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

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

(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.

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.

 

[Vanadium 50]

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.

 

[malawi_glenn]

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.

 

[Vanadium 50]

And now he is gone.

For now.

A shame your nice message on antiscreening was wasted.

 

[Dale]

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.

 

[malawi_glenn]

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.

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.