Strong force as exchange of mesons, or of quark and antiquark

  • #1
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Main Question or Discussion Point

The (residual) strong force between nucleons can be desribed as

- The exchange of a meson (from a nucleon to the other), as in picture b)
- The exchange of a quark and an antiquark: in picture a) one nucleon "gives" a quark and receive an antiquark and it's the opposite for the other

2mK5f.png


I do no see how these two description are consistent with each other since in picture b) the meson (a quark + an antiquark) goes from one nucleon to the other, while in a) there is an exchange. So are these two interpretation equivalent? The nucleon that gives the quark also gives the antiquark (and therefore a meson) or receives it instead?
 

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Answers and Replies

  • #2
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Same thing. You don't have an actual time axis anyway in these diagrams, only initial and final states.

Here is your meson going from left to right in the left diagram:

meson.png
 

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  • #3
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Same thing. You don't have an actual time axis anyway in these diagrams, only initial and final states.

Here is your meson going from left to right in the left diagram:

View attachment 227384
Thanks for the answer.

But there is actually a time axis and it is vertical (going from down to up). I'm aware that antiparticles move backwards in time (in the picture it moves downward a bit) but the fact is that it moves from left to right "in space".

Is this wrong? So actually (besides moving backwards in time) the direction in space indicated by the arrow in the feynman diagram should be reversed for an antiparticle?
 
  • #4
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I'm aware that antiparticles move backwards in time
No they don't.
 
  • #5
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But there is actually a time axis and it is vertical (going from down to up).
The only meaningful times in a Feynman diagram are the initial and final states. Everything inside doesn't have a time ordering, and in fact you have to consider all times for all vertices for calculating such a diagram.
 

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