Range of strong force as strength gets weaker.

In summary, the conversation discusses the possibility of weakening the strong force and its effect on the range of the force and the behavior of QCD bound states. While it is believed by many physicists that the strong force will remain confining even with a weaker coupling, there is no proof of this. However, it is generally accepted that the presence of confinement cannot be coupling-dependent, and thus it should still apply to an identical theory with a different coupling. Furthermore, it is noted that QCD with massless quarks can still exhibit confinement and dynamical chiral symmetry breaking, but with a change in scale. The main concern is that with a weaker coupling, other interactions such as the electroweak force may become more significant.
  • #1
Spinnor
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Say we can set the strength of the strong force weaker, can the glouns then range further and further from a quark? Can we eventually get the strong force to look like the electromagnetic force as far as the range of the force is concerned?

Thanks for any help!
 
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  • #2
Sort of. And, no. For any non-zero QCD coupling, the strong force will be confining. But, as you turn down the coupling strength, the QCD bound states will tend to get physically larger. And, if you turn down the coupling strength far enough, fragmentation of QCD states becomes exponentially suppressed. With a sufficiently weak strong force you could, in principle, get macroscopic bound states. However, the range would never get to infinity.
 
  • #3
Parlyne said:
...For any nonzero QCD coupling, the strong force will be confining...

Hmmm?? I think you express a general belief by a majority of the physicists, but I have never seen a proof of it. Can you refer me to an article where this is proven.
 
  • #4
fermi said:
Hmmm?? I think you express a general belief by a majority of the physicists, but I have never seen a proof of it. Can you refer me to an article where this is proven.

So far as I know, there is no first-principles proof of this. However, my impression was that the presence of confinement can't be coupling-dependent. So, given that the strong force is seen phenomenologically to be confining, that should continue to apply to an identical theory no matter where you set its coupling.
 
  • #5
If you forget about absolute mass scales from current quark masses, you still get dynamical chiral symmetry breaking and the generation of a scale from a growing of the perturbative coupling at long distances. Another way to say it, setting a lower coupling in QCD with massless quarks merely amounts to a change of scale : the coupling takes arbitrarily low values at high energies.

You can obtain confinement and dynamical chiral symmetry breaking with massless quarks for instance in instanton models of the vacuum.

At any rate, I think it is not controversial that QCD itself will still be confining whichever coupling you choose at a given scale. You just get a larger proton. But the issue is that if you make the coupling too weak, other interactions (electroweak) might become important.
 

1. What is the range of the strong force as its strength gets weaker?

The range of the strong force is approximately 10^-15 meters when its strength is at its maximum. As the strength of the strong force decreases, its range also decreases.

2. How does the range of the strong force change as its strength decreases?

As the strength of the strong force decreases, its range decreases as well. This is because the strong force is only able to act within a certain distance, and as its strength decreases, it is less able to extend its reach.

3. What is the relationship between the strength and range of the strong force?

The strength and range of the strong force are inversely proportional. This means that as the strength of the strong force decreases, its range also decreases.

4. Can the range of the strong force ever be greater than 10^-15 meters?

No, the range of the strong force is limited to 10^-15 meters even at its maximum strength. This is due to the nature of the strong force and its interaction with other particles.

5. How does the range of the strong force compare to other fundamental forces?

The range of the strong force is much smaller than the range of the other fundamental forces, such as the electromagnetic force and the weak force. This is because the strong force is only responsible for interactions between particles within the nucleus of an atom, while the other forces act over longer distances.

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