On kids reading Harry Potter?

[Alex K]

Consider the following: 

Wow! Give me that old time religionphysics. I'm trying to figure out what it is this guy is doing there. It looks like he's calculating a particle scattering amplitude or similar quantity in quantum electrodynamics in a rather old-fashioned and terrifying looking perturbation theory formalism. On the left in the middle I can make out a sketch of the complex plane with poles and the dashed line as an integration contour, which probably specify the analytic structure of a particle propagator or similar thing. The imaginary parts of the poles are denoted by an upper case Gamma, which seems to indicate that we are dealing with an unstable particle, but that seems strange in this context and is probably just old formalism. Since the matrix element he's calculating is of two fermions , and the operator in the middle is called H_gamma, it's probably something like the anomalous magnetic moment of the electron or just generally the emission and absorption of a photon, or a similar quantity.