Interaction by Particle Exchange and QED

This lecture covers the computation of decay and scattering processes rates, focusing on Lorentz invariant Matrix Element, interaction by particle exchange, and introduction to Feynman diagrams. It explains the perturbation expansion for transition matrix elements, the classical and quantum field theory pictures of forces, and the Feynman rules for Quantum Electrodynamics (QED). The lecture also delves into the concept of virtual particles, Feynman diagrams representing time-orderings, and the Feynman rules for QED, including basic rules, vertex factors, and matrix element calculations.