Name: James Date: 05/11/16-01:50:57 AM Z
Hello,
I am trying to use FeynArts -> FeynCalc -> Tarcer to compute some
2-loop self
energy integrals. However, I find that the ToTFI function won’t deal
with terms in
the numerator which contain an internal loop momentum. I see this when
trying to
convert complicated FeynArts output, and I can reproduce the problem
with a
simple example, which I copy below.
-——————
dm[mu_] := DiracMatrix[mu, Dimension -> 4]
dm[5] := DiracMatrix[5]
ds[p_] := DiracSlash[p]
SetOptions[DiracSlash, Dimension -> 4, FeynCalcInternal ->
True];
num := C dm[mu].(ds[k] -
M).dm[mu].(ds[k] - ds[q] - M).
dm[nu].(ds[q] - M).dm[nu]
amp := FeynAmpDenominator[PropagatorDenominator[k - p, M],
PropagatorDenominator[k, mw], PropagatorDenominator[k -
q, M],
PropagatorDenominator[q, M], PropagatorDenominator[q -
p, mw]] //
Contract // FCI
tfiamp := ToTFI[DiracSimplify[num SPC[amp, k, q]],
k, q, p]
tfiamp
-———————-
The output I get is half made up of nice integrals terms like F and V
and so on, but
the rest is basically just the original input, for all the terms which
contain an internal
momentum (slashed) in the numerator. Is there something I am
fundamentally
doing wrong with the input? I am unsure because the ToTFI instructions
don’t have
an example where there is a dot product of internal momentum and a gamma
matrix
like this in the numerator. If I can find the problem in this example
then it should
help with also converting the FeynArts output.
Thanks,
James