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Will two particles never touch each other?

  1. Jul 1, 2015 #1
    i found that in the 3 W-W exhange of 4-fermion interaction of weak decay of Neturon beta-decay process and also this happens in scattering process,is there will be a gap or a channel between two particles?

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  3. Jul 1, 2015 #2


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    What do you mean by a "gap"? This is a quantum process and the Feynman diagram is a pictorial representation of a term in a mathematical expansion. It should not be viewed as a pictograph of what is going on in terms of classical particles because particles are not classical at the quantum level.
  4. Jul 1, 2015 #3


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    More explicitly: you should not view a Feynman diagram as a "position versus time" diagram.
  5. Jul 1, 2015 #4
    but I Seen from the particle physics textbook,it called the "gap" as a channel.
  6. Jul 1, 2015 #5


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    There is no gap. You can rearrange the lines arbitrarily (as long as the connections stay the same) and physics does not change, this is just the most convenient way to graph it.

    "Channel" refers to a specific Feynman diagram or a class of Feynman diagrams.

    The concept of touching does not make sense for elementary particles. They do not have a size, and they do not have an exact position.
  7. Jul 1, 2015 #6
    thanks for letting me know that there is no"touch" in particles in the classical pysics,otherwise my mind is going to be blowed up,coz I am just a starter and an amtateur,so maybe I will have more questions.But I really get confused why ?there is really no channel or gap between two particles when they collided?
  8. Jul 2, 2015 #7
    my assumption for understanding the 3-W exchange in 4-Fermman inmteraction is that if an particle crashed onto the front of another particle,it will be pushed backwards for some distance,and it will be reflected and remain the same horinzontal level direcrion;but if a particle crashed onto the back (or the inner space)of another particle ,it will be pushed inwards and but goes opposite direction


    Last edited: Jul 2, 2015
  9. Jul 2, 2015 #8
    actually what is another way to understand this ?the above post is just my own special thinking about 3-w exchnage in 4-fermmann diagram
  10. Jul 2, 2015 #9
    thanks a lot!
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