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A One-loop diagrams of Delbruck scattering

  1. Feb 15, 2017 #1
    I would like to draw the one-loop diagrams for four photon Delbruck scattering amplitude in QED.

    Here are the three one-loop diagrams that contribute to the scattering amplitude.

    5207ddd525.png

    There are three more one-loop diagrams that contribute to the amplitude.
    However, I cannot find the other diagrams.

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    Here is my tabulation of how the external photons lines are connected using propagators. Here, ##p_1## and ##p_2## are the incoming momenta and ##k_1## and ##k_2## are the outgoing momenta and ##\leftrightarrow## represents a propagator.


    ##p_{1} \leftrightarrow p_{2} \qquad k_{1} \leftrightarrow k_{2} \qquad p_{1} \leftrightarrow k_{1} \qquad p_{2} \leftrightarrow k_{2}##

    ##p_{1} \leftrightarrow p_{2} \qquad k_{1} \leftrightarrow k_{2} \qquad p_{1} \leftrightarrow k_{2} \qquad p_{2} \leftrightarrow k_{1}##

    ##p_{1} \leftrightarrow k_{1} \qquad p_{2} \leftrightarrow k_{2} \qquad p_{1} \leftrightarrow k_{2} \qquad p_{2} \leftrightarrow k_{1}##

    This happens to exhaust all possible pairings of external photon lines with propagators. However, three more one-loop diagrams still remain. I know other three one-loop diagrams give the same amplitudes as those above. So, why should be treat the other three diagrams as distinct from the ones drawn above?
     
  2. jcsd
  3. Feb 23, 2017 #2
    Thanks for the thread! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post? The more details the better.
     
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