Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

N-point Green's function in QFT

  1. May 27, 2010 #1
    Something about N-point Green's function in QFT really troubles me......
    In the path-integral formalism,why will we introduce the N-point Green's function? I mean is it enough because we have calculated the 2-point green's function.
    And in the canonical formalism, it seems we can finish the calculation of transition amplitude only with the help of 2-point Green's function(Wick contraction)
    What are the differences?
  2. jcsd
  3. May 27, 2010 #2
    What is the equation satisfied by the 2-point Green's function in an interacting field theory?
  4. May 27, 2010 #3
    Using the pertubative expansion and the definition of N-point Green's function.Because of the pertubation,i can only calculate the 2-point Green's function.But i really can't find the eqution it satisfies.
  5. May 27, 2010 #4
    Funny, because it carries your name. :)
  6. May 28, 2010 #5
    Please correct me if I'm wrong, but when we renormalize the coupling constant, don't you need to calculate the 4point function?

    And in calculating the S matrix, you can get some N point function, which has to be reduced to 2 point functions using Wick's contraction, but with all sorts of symmetry factors which you use Feynman diagrams to account for?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook