FeynCalc manual (development version)

FeynAmpDenominatorExplicit

FeynAmpDenominatorExplicit[exp] changes each occurrence of PropagatorDenominator[a,b] in exp into 1/(SPD[a,a]-b^2) and replaces FeynAmpDenominator by Identity.

See also

Overview, FeynAmpDenominator, PropagatorDenominator.

Examples

FAD[{q, m}, {q - p, 0}] 
 
FeynAmpDenominatorExplicit[%] 
 
% // FCE // StandardForm

1(q2m2).(qp)2\frac{1}{\left(q^2-m^2\right).(q-p)^2}

1(q2m2)(2(pq)+p2+q2)\frac{1}{\left(q^2-m^2\right) \left(-2 (p\cdot q)+p^2+q^2\right)}

1(m2+SPD[q,q])(SPD[p,p]2  SPD[p,q]+SPD[q,q])\frac{1}{\left(-m^2+\text{SPD}[q,q]\right) (\text{SPD}[p,p]-2 \;\text{SPD}[p,q]+\text{SPD}[q,q])}

Notice that you should never apply FeynAmpDenominatorExplicit to loop integrals. Denominators in a proper loop integral should be written as FeynAmpDenominators. Otherwise, the given integral is assumed to have no denominators and consequently set to zero as being scaleless.

TID[FVD[q, mu] FAD[{q, m}, {q - p, 0}], q]

(m2+p2)pmu2p2q2.((qp)2m2)pmu2p2(q2m2)\frac{\left(m^2+p^2\right) p^{\text{mu}}}{2 p^2 q^2.\left((q-p)^2-m^2\right)}-\frac{p^{\text{mu}}}{2 p^2 \left(q^2-m^2\right)}

TID[FeynAmpDenominatorExplicit[FVD[q, mu] FAD[{q, m}, {q - p, 0}]], q]

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