Name: Vladyslav Shtabovenko (email_not_shown)
Date: 12/16/14-12:29:58 PM Z


Here are the needed replacements for your code. I assume that you want
to specify some InsertionLevel (e.g. Classes), since otherwise the
vertices will remain very general.

Cheers,
Vladyslav

$FAVerbose = 0;
t = CreateTopologies[0, 2 -> 2];
ww = InsertFields[t, {F[3], -F[3]} -> {V[3], -V[3]},
    InsertionLevel -> {Classes}];
ampww = CreateFeynAmp[ww, Truncated -> False];
tmp2 = (Apply[List, ampww] /.
      FeynAmp[_, _,
        am_, ___] :> (am /. RelativeCF -> 1)) //. {DiracSpinor ->
      Spinor, FermionChain -> DOT, NonCommutative -> DOT,
     FourMomentum[Incoming, 1] -> p1, FourMomentum[Incoming, 2] -> p2,
     FourMomentum[Outgoing, 1] -> k1, FourMomentum[Outgoing, 2] -> k2,
     Index[Lorentz, x_] :>
      LorentzIndex[ToExpression["Lor" <> ToString[x]]],
     Index[Gluon, x_] :> SUNIndex[ToExpression["Glu" <> ToString[x]]],
     Index[Colour, x_] :> ToExpression["Col" <> ToString[x]],
     PolarizationVector[_, x_, y_] :> PolarizationVector[x, y],
     Conjugate[PolarizationVector][_, x_, y_] :>
      Conjugate[PolarizationVector[x, y]]
     };
enmomcon = k2 -> p2 + p1 - k1;
tmp3 = Explicit[Total[tmp2], Gauge -> (1 - \[Alpha]),
    Dimension -> 4] /. enmomcon

Cheers,
Vladyslav

On 16/12/14 11:59, Vladyslav Shtabovenko wrote:
> 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,
> Vladyslav
>
>
> 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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