GFAD[{{{x, s}, n}, ...]
denotes a generic propagator given by , where x
can be an arbitrary expression. For brevity one can also use shorter forms such as GFAD[{x, n}, ...]
, GFAD[{x}, ...]
or GFAD[x, ...]
.
If s is not explicitly specified, then its value is determined by the option EtaSign
, which has the default value +1
.
If n
is not explicitly specified, then the default value 1
is assumed. Translation into FeynCalc internal form is performed by FeynCalcInternal
, where a GFAD
is encoded using the special head GenericPropagatorDenominator
.
[2 z SPD[p1, q] SPD[p2, q] + x SPD[p1, p2]]
GFAD
[%]
FeynAmpDenominatorExplicit
% // FCE // StandardForm