Is there a particular conservation principle that necessitates that the outcoming photon pair has the same frequencies as the incoming photon pair? I'm thinking in particular of these Feynman-like ...
I am stuck at the beginning of a problem where I am given an interaction term that modifies the regular QED Lagrangian. It involves the interaction between a photon field and a massive vector boson: ...
I've been playing around writing some software to generate Feynman diagrams for QED, respecting the vertex "rules" described here, and avoiding creating isomorphic duplicates. So from a starter ...
A bit of background helps frame this question. The question itself is in the last sentence. For his PhD thesis, Richard Feynman and his thesis adviser John Archibald Wheeler devised an astonishingly ...
Does it make sense to introduce Faddeev–Popov ghost fields for abelian gauge field theories? Wikipedia says the coupling term in the Lagrangian "doesn't have any effect", but I don't really know ...
Here is a Feynman diagram showing the mutual annihilation of a bound state electron positron pair into two photons: Is the electric charge conserved at the point A (or B)? What is the "charge" of ...