Beta Phase: Square45 is currently in beta testing. Expect some features or content to be incomplete or missing.
45

Feynman Rules

A set of rules for calculating QED amplitudes based on Feynman diagrams, linking diagrams to mathematical expressions for scattering probabilities.
📜

The statement of the theorem

The scattering amplitude M\mathcal{M} is calculated by summing contributions from all connected diagrams D\mathcal{D}. The rules define the components: M=∑D(Vertex Factor)×(∏internal linesPropagator)×(∏external linesExternal Field Factors)\mathcal{M} = \sum_{\mathcal{D}} \left( \text{Vertex Factor} \right) \times \left( \prod_{\text{internal lines}} \text{Propagator} \right) \times \left( \prod_{\text{external lines}} \text{External Field Factors} \right) Specifically, the vertex factor is −ieγμ-i e \gamma^{\mu}, the fermion propagator is iγ⋅(p−m)\frac{i}{\gamma \cdot (p - m)}, and the photon propagator is −igμνq2+iϵ\frac{-i g_{\mu\nu}}{q^2 + i\epsilon}.
Source: Wikipedia