Lecture
This lecture covers Quantum Electrodynamics (QED) calculations for electron-positron annihilation. It explains how to calculate cross sections using Feynman diagrams, matrix elements, and perturbation expansions. The lecture delves into the spin considerations, chiral states, and the Lorentz invariance of the matrix element. It concludes with discussions on the differential and total cross sections, angular dependencies, and the importance of chirality in QED interactions.