Range of strong force as strength gets weaker.

Click For Summary

Discussion Overview

The discussion revolves around the implications of varying the strength of the strong force, particularly whether a weaker strong force could lead to an increased range of gluons from quarks and if it could resemble the electromagnetic force in terms of range. The scope includes theoretical considerations and conceptual clarifications related to quantum chromodynamics (QCD).

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that if the strength of the strong force is reduced, gluons could potentially range further from quarks, possibly resembling the electromagnetic force.
  • Another participant counters that while reducing the coupling strength may lead to larger QCD bound states, the strong force will always remain confining for any non-zero coupling, and the range will never reach infinity.
  • A participant questions the general belief regarding confinement in QCD, asking for proof and expressing skepticism about the coupling dependency of confinement.
  • Another reply indicates that while there may not be a first-principles proof of confinement being coupling-dependent, the phenomenological observation of confinement should hold across different coupling strengths.
  • One participant discusses the implications of massless quarks and dynamical chiral symmetry breaking, suggesting that a lower coupling in QCD leads to a change of scale rather than a fundamental change in confinement properties.
  • It is noted that while QCD remains confining regardless of the coupling chosen, making the coupling too weak could allow other interactions, such as electroweak interactions, to become significant.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between the strength of the strong force and confinement, with some asserting that confinement is a fundamental property of QCD, while others challenge this notion and seek further evidence. The discussion remains unresolved regarding the specifics of confinement and the effects of varying coupling strength.

Contextual Notes

Participants highlight the lack of definitive proofs regarding the coupling dependency of confinement and the implications of massless quarks on QCD dynamics. The discussion also touches on the potential interplay between strong force and other fundamental forces at varying coupling strengths.

Spinnor
Gold Member
Messages
2,231
Reaction score
419
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!
 
Physics news on Phys.org
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.
 
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.
 
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.
 
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.
 

Similar threads

Graduate How does the strong force loses its strength with distance?
  • · Replies 3 ·
Replies
3
Views
4K
Undergrad Strong and Weak Nuclear forces at long ranges
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad Question about gluons and nucleon binding
  • · Replies 5 ·
Replies
5
Views
2K
Graduate Size of a proton as a function of relative strength of color force?
  • · Replies 32 ·
2
Replies
32
Views
6K
High School Is the Strong Force Really Stronger Than the Electromagnetic Force?
  • · Replies 3 ·
Replies
3
Views
9K
Undergrad Why do the fundamental forces have different ranges?
  • · Replies 1 ·
Replies
1
Views
1K
Undergrad How Does Binding Energy Relate to Nucleon Distance in Atomic Nuclei?
  • · Replies 17 ·
Replies
17
Views
3K
Graduate My Confusion Regarding the Strong Force
  • · Replies 6 ·
Replies
6
Views
2K
Undergrad How does the strong force give nucleons most of their mass?
  • · Replies 17 ·
Replies
17
Views
4K
Graduate Decay through gravitional interaction
  • · Replies 8 ·
Replies
8
Views
2K