•The three-vertex Feynman rule

The QED lagrangian:

lag = ArgumentsSupply[Lagrangian[QED[1]], x, RenormalizationState[0]]

-1/4 (∂ _ μ A^(0 ) _ ν^ó  - ∂ _ ν A^(0 ) _ μ^ó ) . (∂ _ μ A^(0 ) _ ν^ó  - ∂ _ ν A^(0 ) _ μ^ó ) + Overscript[ψ^(0 ), _] . γ^μ . (e^(0 ) A^(0 ) _ μ . ψ^(0 ) + i ∂ _ μ ψ^(0 ) _ ó ^ó ) - Overscript[ψ^(0 ), _] . ψ^(0 ) m _ ψ^(ó  0 )

Calculation of the Feynman rule with FeynCalc:

fields = {QuantumField[Particle[Electron, RenormalizationState[0]]][p1], QuantumField[DiracBar[Particle[Electron, RenormalizationState[0]]]][p2], QuantumField[Particle[Photon, RenormalizationState[0]], LorentzIndex[μ3]][p3]}

{ψ^(0 ), Overscript[ψ^(0 ), _], A^(0 ) _ μ _ 3}

melsimplified = Simplify[FeynRule[lag, fields]]

i e^(0 ) γ^μ _ 3

Converted by Mathematica  (July 10, 2003)