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Identical particles and feynman diagrams

  1. Aug 25, 2014 #1
    In Introduction to QFT (peskin) 4.5, he writes:

    The computation for M, of course, will be quite different when identical particles are present.

    However, I have finished reading the first part of the book and found no special treatment for identical particles. Can anybody tell me how to compute M if identical particles are present?
  2. jcsd
  3. Aug 25, 2014 #2


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    There is a combinatorial factor you must divide by when computing the amplitude for a scattering process involving identical particles. It's in the Feynman rules so look in the index for the section on them.
  4. Aug 25, 2014 #3
    But that's not about computing M matrix. So basically there's nothing special for identical particles?
  5. Aug 25, 2014 #4


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    Different Feynman diagrams contribute if the particles are identical. For example, electron-muon scattering has only one diagram at tree level (t-channel photon exchange), but electron-electron scattering has two (t-channel and u-channel photon exchange).
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