FAD
is the FeynCalc external form of
FeynAmpDenominator
and denotes an inverse propagator.
FAD[q, q-p, ...]
is .
FAD[{q1,m}, {q1-p,m}, q2, ...]
is .
Translation into FeynCalc internal form is performed by
FeynCalcInternal
.
Overview, FAD, FCE, FCI, FeynAmpDenominator, FeynAmpDenominatorSimplify, PropagatorDenominator.
[q, p - q] FAD
[p, {p - q, m}] FAD
[{p, 0, 2}, {p - q, m, 3}] FAD
[q, p - q] // FCI // StandardForm
FAD
(*FeynAmpDenominator[PropagatorDenominator[Momentum[q, D], 0], PropagatorDenominator[Momentum[p, D] - Momentum[q, D], 0]]*)
[p] FAD[p - q] // FeynAmpDenominatorCombine[#, FCE -> True] & // StandardForm
FAD
(*FAD[p, p - q]*)