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Homework Help: Feynman diagram

  1. Jan 19, 2005 #1
    Is there a systematical way to count all the possible feynman diagram with vertices less than or equal to n......
     
  2. jcsd
  3. Jan 19, 2005 #2
    one more question.... see the attachment.... are these two feynman diagram the same?
     

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  4. Jan 19, 2005 #3

    dextercioby

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    They're not.There are the 2 (distinct) contributions to the Compton scattering of electrons (if i saw well,or positrons in the other case).

    To the first question:nope,in general u cannot tell how many distinct Feynman diagrams a QFT has in a certain order.U have to compute all possible unconnected Green functions,using the approximation for the generating functional.

    Daniel.
     
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