Hi,
I think there might be a bug about SetMandelstam in D Dimension.
In[5]:= $BreitMaison = True;
In[13]:= SetMandelstam[s, t, u, p1, p2, -k1, -k2, 0, 0, m, m];
In[17]:= Pair[Momentum[k1, -4 + D], Momentum[k1, -4 + D]]
Out[17]= m^2
Which should be 0.
In some gamma5 involved D-dimensional traces, there would lead wrong results:
In[16]:= test1 =
DiracTrace[(m + DiracGamma[Momentum[k2, D], D]).DiracGamma[
LorentzIndex[mu3, D],
D].(-m + DiracGamma[Momentum[k1, D], D]).DiracGamma[
5].(m + DiracGamma[Momentum[k1, D], D]).DiracGamma[
LorentzIndex[mu1, D],
D].(m + DiracGamma[Momentum[-k1 - k2, D], D]).DiracGamma[
LorentzIndex[mu3, D],
D].(-m + DiracGamma[Momentum[k2, D], D]).DiracGamma[5]] /.
DiracTrace -> Tr /. D -> 4
Out[16]= 0
In[15]:= test2 =
ChangeDimension[
DiracTrace[(m + DiracGamma[Momentum[k2, D], D]).DiracGamma[
LorentzIndex[mu3, D],
D].(-m + DiracGamma[Momentum[k1, D], D]).DiracGamma[
5].(m + DiracGamma[Momentum[k1, D], D]).DiracGamma[
LorentzIndex[mu1, D],
D].(m + DiracGamma[Momentum[-k1 - k2, D], D]).DiracGamma[
LorentzIndex[mu3, D],
D].(-m + DiracGamma[Momentum[k2, D], D]).DiracGamma[5]], 4] /.
DiracTrace -> Tr
Out[15]= -32 m^2 (m^2-s) Overscript[k1, _]^mu1
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