Section outline

    • Feynman rules: identical particles in final state; sum on final states; average on initial states.
    • Feynman rules for toy scalar theory. Interaction as exchange of mediator particle.
    • Charge conservation and gauge symmetry.
    • QED Feynman diagrams.
    • e+e- anihilation in a muon pair.
    • Hydrogen levels, fine and hyperfine structure, Lamb shift, [Lamb-Retherford experiment]
    • Positronium, level structure, decay channels.
    • Alpha QED evolution with energy.