>>11346787How to get the principle value of a complex contour integral when a singularity is on the contour path. In particular, in the context of many body solid state physics.
Makes no fucking sense, and I'm nearly done doing a phd in this field. I ask people how to do it, people that allegedly know how, and they can't even explain it to me.
You do some bullshit where you move the contour off the singularity. You either move it above or below it, but no one can explain how you choose (and it completely changes the value of the integral).
You want to know why feynman diagrams were such a revolutionary concept? Because they make it so we never have to compute shit like this again.
