Name: D. Azevedo Date: 02/11/20-05:12:23 PM Z


Hello,

I am having problems running a notebook I have written in FC v9.2 (Mathematica 10) within a PC with FC v9.3 (Mathematica 12).

I have generated tadpole diagrams using FeynArts and I want to have the amplitude expression in FeynCalc form, for that I use:

 amps = FCFAConvert[CreateFeynAmp[DiagTadpolesBigH],
      IncomingMomenta -> {p}, LoopMomenta -> {q},
     UndoChiralSplittings -> True, SMP -> True, DropSumOver -> True,
     ChangeDimension -> 4 - \[Epsilon]] /.
    PropagatorDenominator[x_, y_] :>
     FeynAmpDenominator[PropagatorDenominator[x, y]] /. paramsubs //
  Contract

But it doesn’t accept the dimension change, it says

ChangeDimension::failmsg: Error! ChangeDimension has encountered a fatal problem and must abort the computation. The problem reads: Unsupported choice of dimension!

If I choose just \[Epsilon] then it doesn’t give me any error but it seems the dimention becomes undefined. Also I need to change
 
PropagatorDenominator[x_, y_] :>
     FeynAmpDenominator[PropagatorDenominator[x, y]]

to

PropagatorDenominator[x_, y_] :>
     FeynAmpDenominator[PropagatorDenominator[Momentum[x,4-\[Epsilon]], y]]

for the propagator to behave “normally”.

Is there any change in this regard with the change of version of FC?

Cheers,
Duarte