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Photon question.

  1. Nov 26, 2004 #1
    Its a simple and elementary question, i think. Since electromagnetism has both attractive and repulsive effects and the photon is the quanta of this EM force, then shouldn't there be 2 flavours of photons?

    Say, if and 2 electrons gets close each other, they exchange photons, which causes repulsion. But if an electron and positron get close, they too exchange the same photon but its attraction. Why?
  2. jcsd
  3. Nov 26, 2004 #2
    As a spin 1 particle (+ em wave transverse condition), you have 2 types of photons: the spin + and spin -.


  4. Nov 26, 2004 #3
    whoa, haven't thought of spin, but which spin is associated with which force (i mean attraction or repulsion)?
  5. Nov 30, 2004 #4
    I am not confident that spin fixes the problem because spin can be either way. Better see if there is some property of the wavefunction of the electrons/positrons/protons that accounts for it.
  6. Dec 2, 2004 #5
    2 electrons don't interact in the same way as an electron interacting with a positron. You can see this by looking at the tree diagrams for these interactions.
  7. Dec 2, 2004 #6
    That isn't quite the same thing. Those aren't two particles. They are the exact same particles, they are just in different states. Electrons can be in either of two spin states +1/2 and -1/2. But there are electrons and positrons (anti-electrons)

  8. Dec 2, 2004 #7
    Where is that published? I want a copy.
  9. Dec 7, 2004 #8
    Check any book on quantum field theory. When you calculate the amplitude for each process, whether it be electron electron, or electron positron interaction, you will see which diagrams contribute for each process.

    Peskin is the common textbook for QFT, so if it isn't an example, it is probably a problem.
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