Name: Vladyslav Shtabovenko (email_not_shown)
Date: 12/16/14-11:59:30 AM Z

Hi Ralph,

FeynArts and FeynCalc are two different projects developed by different
people, so there is no 100% comptability between the two. For practical
purposes one always needs to convert the FeynArts output into something
FeynCalc can work with.

Have a look at the examples, for more details

https://github.com/FeynCalc/feyncalc/tree/master/FeynCalc/fcexamples/QED

Since you are using FeynCalc 8.2, you don't need to apply to
FCPrepareFAAmp and specify Transversality->True in PolarizationVector.
Those are things that came with FeynCalc 9 that is still under devlopment.

Also, have a look at the corresponding wiki page:

https://github.com/FeynCalc/feyncalc/wiki/FeynArts#fatofc

Cheers,

On 15/12/14 20:12, Ralph wrote:
> Thanks for the suggestion Vladyslav, turns out FeynArtsDirectory was set to ./FeynArts-3.7/&#65533; and after I changed it seems to load ok. Is it possible for FC to process the output of FA so that traces are contracted etc? I tried the following:
>
> t = CreateTopologies[0, 2 -> 2];&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;
> ww = InsertFields[t, {F[3], -F[3]} -> {V[3], -V[3]}];&#65533;&#65533;&#65533;
> ampww = CreateFeynAmp[ww, Truncated -> False];&#65533;&#65533;
> tmp2 = Apply[List, ampww] /.
> FeynAmp[_, _, am_, _] :> (am /. RelativeCF -> 1) /.
> Polarization[a_, b_, _] :> Polarization[a, b]
> enmomcon = k2 -> p2 + p1 - k1;
> tmp3 = Explicit[Plus @@ tmp2, Gauge -> (1 - \[Alpha]),
> Dimension -> 4] /. enmomcon&#65533;&#65533;&#65533;
>
> Calc[tmp3]
>
> But all the gamma matrices etc are still uncontracted. Is there something else I should do, or is it not possible to convert the CreateFeynAmp output into the type of analytical expression you can usually get in FC?
>

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