Feynman Diagram 1

physicsquantum field theoryFeynman diagramspropagatorsGreen's functioneffective actioncetztikz

Basic Feynman diagram showing a dressed propagator (hatched vertex) connecting two external fields φₐ and φᵦ with incoming momentum p₁ and outgoing momentum p₂. The vertex represents the full momentum-dependent two-point Green's function G_k, which includes all quantum corrections. This is a fundamental building block for more complex quantum field theory calculations.