Recent content by guestspeaker

okay okay :) I was hoping for something immediately obvious from just the diagrams (like the -1 for fermion loop etc.)

The example in P&S is with t- and u-channel diagrams, for which the negative sign can come from a "heuristic" argument of antisymmetrization of the final states. But for Bhabha scattering, the diagrams are s- and t-channel... is there a similar heuristic argument without resorting to the Wick...

I cannot figure out why there is a relative sign difference between the two diagrams for bhabha scattering. Fermi statistics is at play here but I don't see how that affects the relative sign between 2 different diagrams...

I cannot figure out why there is a relative sign difference between the two diagrams for bhabha scattering. Fermi statistics is at play here but I don't see how that affects the relative sign between 2 different diagram...