FeynAmp

Description

FeynAmp[q, amp] is the head of a Feynman amplitude. amp denotes the analytical expression for the amplitude and q is the integration variable. FeynAmp[q1, q2, amp] denotes a two-loop amplitude.

FeynAmp has no functional properties and serves just as a head. There are however special typesetting rules attached.

See also:  Amplitudes.

Examples

This is a 1-loop gluon self-energy amplitude (ignoring factors of (2 π)).

FeynAmp[q, 
      GV[p, μ, a,  q - p, α, c,  -q, β, e] GP[
          p - q,  α, c,  ρ, d] 
        GV[-p, ν, b,  p - q, ρ, d,  q, σ, f] GP[
          q,  β, e,  σ, f]]

This is a generic 2-loop amplitude.

FeynAmp[(Subscript[q, 1]), (Subscript[q, 2]), anyexpression]