Momentum exchange of virtual pions


by gildomar
Tags: exchange, momentum, pions, virtual
gildomar
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#1
Dec16-13, 07:05 PM
P: 60
I know that the strong force is viewed as the exchange of virtual pions between two nucleons, with the mass and range of them confirmed by the energy-time uncertainty principle. But if the momentum of the pion is transferred from one nucleon to the other in the interaction, wouldn't that give an equivalent repulsive force between them instead of an attractive one?
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ChrisVer
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#2
Dec16-13, 07:16 PM
P: 368
http://www.physicsforums.com/showthread.php?t=726749
gildomar
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#3
Dec16-13, 07:43 PM
P: 60
Thanks; guess I didn't look far enough back in the past topics.

K^2
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#4
Dec17-13, 06:45 AM
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Momentum exchange of virtual pions


Virtual pion exchange is just one of the contributions. It's the dominant effect, but there are other things going on. Nucleons can exchange gluons directly, as well as exchange other mesons. Pions happen to be the lightest of mesons and not restricted by confinement, so they end up being better mediators for nuclear forces, but not the only ones there.
ChrisVer
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#5
Dec17-13, 06:56 AM
P: 368
gluons don't exist in the nuclei level due to confinement, so that's why in fact (effectively) you get the puons.
The main quarks you can make your "effective particle" consist of, are up and down, because I think (from the deep inelastic scattering on protons) we already know that strange is not favorable at all...it's almost not existing in the sea particles...
RGevo
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#6
Dec17-13, 10:02 AM
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How can you draw any strong interaction without involving gluons?
Bill_K
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#7
Dec17-13, 10:29 AM
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Quote Quote by K^2 View Post
Virtual pion exchange is just one of the contributions. It's the dominant effect, but there are other things going on. Nucleons can exchange gluons directly, as well as exchange other mesons. Pions happen to be the lightest of mesons and not restricted by confinement, so they end up being better mediators for nuclear forces, but not the only ones there.
From http://www.phy.ohiou.edu/~elster/lec..._2.pdf‎:

Fortunately, at distances larger than the nucleon extension, which dominate nuclear physics phenomena, color confinement dictates that nucleons can only interact by exchanging colorless objects, i.e. just mesons. Only at smaller distances, at which the two nucleons overlap, genuinely new processes may occur involving explicit quark-gluon exchange. Due to the repulsive core on the NN interaction, however, both nucleons do not come very close to each other unless the scattering energy is very high. Thus, there is good reason to believe these processes not to dominate the NN interaction for energies relevant in nuclear physics.
K^2
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#8
Dec18-13, 02:59 AM
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That's precisely what I said. Pions dominate interaction because they are not confined. Other processes are non-dominant either due to confinement or higher masses of mediator particles. Where's the problem?
Bill_K
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#9
Dec18-13, 03:31 AM
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Quote Quote by K^2 View Post
That's precisely what I said. Pions dominate interaction because they are not confined. Other processes are non-dominant either due to confinement or higher masses of mediator particles. Where's the problem?
Please don't take offense when someone agrees with you.


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