Interaction Lagrangians and coupling constans. Interaction representation for the time evolution of the state vector. S-matrix. Cross sections.Edit

Covariant perturbation theory. T-product and N-product of the field operators. Propagators. Wick's theorem.Edit

Interaction of fermions and bosons, Lint=-gψψ(φ+φ+). Feynman rules in coordinate and momentum space. Scattering of fermions. Non-relativistic limit. One boson exchange potential.Edit