Recent content by GQuinta

  1. G

    Graduate Problem with Wick's theorem at first order

    Hey there, first post here! I've been struggling with a detail in Second Quantization which I really need to clear out of my head. If I expand the S-matrix of a theory with an interaction Hamiltonian H_I(x) then I have S - 1= \int^{+\infty}_{-\infty} d^4 x H_I(x) +...