Hello,
I am doing 1-loop calculations,I have written a model and loaded it in FeynArts and painted the amplitudes and constructed feynarts amplitude with no problem but when I use FormCalc's command CalcFeynAmp[...........,PaVeReduce->True] it does not do it's job and merely prints sum of integrals over propagators.something like this:(I have included a part of it as it is too big)

Amp[{{S[1], k[1], ms, {X}}} -> {{S[1], k[2], ms, {X}}}][-1/(
16 \[Pi]^4)
I (g^2 ("g"[Lor1, Lor2]^2 FAPropagatorDenominator[q1, 0] +
q1[Lor2] ((-q1)[Lor1] + q1[Lor1] (
SequenceForm["xi",
Subscript[
FeynArts`V[Gen3]]])) "g"[Lor1, Lor2] FAPropagatorDenominator[q1,
0]^2 + FAPropagatorDenominator[q1, ms Sqrt[SequenceForm["xi",
Subscript[
FeynArts`S[Gen3]]]]]))]

but when I use for example SM model which is built in to FeynArts everything is fine and I get a fine output like this:(again a part of it as it is big)

-(1/(MW2 \[Pi] SW2))
Alfa (1/4 (A0[Mf2[2, Gen3]] +
ms^2 B0i[bb1, ms^2, Mf2[2, Gen3], Mf2[2, Gen3]]) Mf2[2,
Gen3] + 1/
2 B0i[bb0, ms^2, Mf2[2, Gen3], Mf2[2, Gen3]] Mf2[2, Gen3]^2 +
3/4 ((A0[Mf2[3, Gen3]] +
ms^2 B0i[bb1, ms^2, Mf2[3, Gen3], Mf2[3, Gen3]]) Mf2[3,
Gen3] + (A0[Mf2[4, Gen3]] +
ms^2 B0i[bb1, ms^2, Mf2[4, Gen3], Mf2[4, Gen3]]) Mf2[4,
Gen3]) +
3/2 (B0i[bb0, ms^2, Mf2[3, Gen3], Mf2[3, Gen3]] Mf2[3, Gen3]^2 +
B0i[bb0, ms^2, Mf2[4, Gen3], Mf2[4, Gen3]] Mf2[4,
Gen3]^2)) SumOver[Gen3, 3]

I will be thankful if you help me with what might have gone wrong.Thank you in advance.

Regards.

Hi,

that looks strange. If other SARAH generated models work with your setup of FeynArts/FormCalc, I would guess that this is a naming conflict: names of fields or parameters used in your model are identical to variables in FA or FC.

Cheers,
Florian