Name: V. Shtabovenko (email_not_shown)
Date: 01/18/18-10:34:21 AM Z

Try this:

\$BreitMaison = True;

Deno[k_, m_] := FAD[{k, m}, Dimension -> D]
dm[mu_] := GA[mu, Dimension -> D]
dm[5] := DiracMatrix[5]
ds[p_] := DiracSlash[p, Dimension -> D]
ds2[p_] := DiracGamma[Momentum[p, D], D]
fprop[p_, m_] := ds[p] + m
fv[p_, mu_] := FourVector[p, mu, Dimension -> D]
po2[p_] := Pair[Momentum[p], Momentum[p]]
mt[mu_, nu_] := MetricTensor[mu, nu, Dimension -> D]

ampF1 := Contract[
GaugeP[k, MZ, a, b].ffZ[b].FermiP[p + k, mf].ffZ[a]]
ampW1 := (-1) Tr[FermiP[k, mf].ffW[nu].FermiP[k + p, mfp].ffW[mu]]

TID[ampF1, k]

TID[ampF1, k, UsePaVeBasis -> True, ToPaVe -> True]

Cheers,

Am 18.01.2018 um 16:55 schrieb Duarte:
> Sure;
> I start by making some definitions:
>
> (* ----------- Definitions ----------- *)
> Deno[k_,m_]:=FeynAmpDenominator[PropagatorDenominator[k,m]]
> dm[mu_]:=DiracMatrix[mu,Dimension->d]
> dm[5]:=DiracMatrix[5]
> ds[p_]:=DiracSlash[p,Dimension->d]
> ds2[p_]:=DiracGamma[Momentum[p]]
> fprop[p_,m_]:=ds[p] + m
> fv[p_,mu_]:=FourVector[p,mu,Dimension->d]
> po2[p_]:=Pair[Momentum[p], Momentum[p]]
> mt[mu_,nu_]:=MetricTensor[mu,nu,Dimension->d]
>
> Then, I write some Feynman rules:
>
> (* ----------- Feynman Rules ----------- *)
> GaugeP[k_,m_,mu_,nu_]:= (-I) Deno[k,m] mt[mu,nu]
> FermiP[p_,m_]:= I fprop[p,m] Deno[p,m]
> ffZ[mu_]:= (-I) g/cw dm[mu] (gv - ga dm[5])
> ffW[mu_]:= (-I) g/Sqrt[2] dm[mu] (1-dm[5])/2
>
> Finally, the amplitudes:
>
> (* ----------- Amplitudes ----------- *)
> ampF1:= Contract[GaugeP[k,MZ,a,b] . ffZ[b] . FermiP[p+k,mf] . ffZ[a]]
> ampW1:= (-1) Tr[FermiP[k,mf] . ffW[nu] . FermiP[k+p,mfp] . ffW[mu]]
>
> The first problem I mentioned shows up when I try to compute
> OneLoop[k,ampF1] (this means I was incorrect; the problem is not
> in the Contract itself, but in the the attempt to use OneLoop to
> the contracted structure). Here's what I get:
>
> In[21]:= OneLoop[k, ampF1]
>
> During evaluation of In[21]:= DiracTrick::failmsg: Error! DiracTrick
> has encountered a fatal problem and must abort the computation. The
> problem reads: Incorrect combination of dimensions and g^5 scheme!
>
> Out[21]= \$Aborted
>
> The second problem shows up when I try to compute ampW1 (it means it's
> a trace problem, not a loop problem). Here's what I get:
>
> In[22]:= ampW1
>
> During evaluation of In[22]:= DiracTrace::failmsg: Error! DiracTrace
> has encountered a fatal problem and must abort the computation. The
> problem reads: Irregular trace structure in
>
> During evaluation of In[22]:= (g^2
> [Gamma]^mu \[Gamma]^nu.(\[Gamma]\[CenterDot](k+p)+mfp).(1-
> Overscript[\[Gamma], _]^5)))/(8 (k^2-mf^2) ((k+p)^2-mfp^2))
>
> Out[22]= \$Aborted
>
> Thanks again,
> Duarte
>
>
>

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