Hello,
I tried to find a general expression for a tensor integral using
Feyncalc. To test the result, I performed an especially easy
contraction where one can calculate the result by hand. Unfortunately
I reproduced the result only up to an additional summand of 1/2.
I then tried to find where I made a mistake. Finally I figured out
that there is obviously a problem with Feyncalc. Maybe it is related
to Bug #4, but it is somehow different.
Using the following mathematica code, the problem becomes obvious
already in this very simple case:
LoopFunc =
FVD[q, \[Mu]] FVD[q, \[Nu]]
FAD[{q, Subscript[m, 0]}, {q + Subscript[p, 1], Subscript[m, 1]}]
test1 =
OneLoop[q,
Contract[MTD[\[Mu], \[Nu]] LoopFunc ,
OneLoopSimplify -> False] ]
test2 = Contract[
MTD[\[Mu], \[Nu]] OneLoop[q, LoopFunc,
OneLoopSimplify -> False] ]
diff = PaVeReduce[(test1 - test2)]
Can you please comment on this. Maybe it is already known. Or you can
advice me, what I should not do using these functions since I do not
know why this problem occurs.
best regards,
Sascha
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