Dear Paulina,
many thanks. I found the issue and already fixed it in the
repository. So please reinstall the package.
Perhaps I should have guessed that Majorana fermions
are involved. Those are something that was added only not
so long ago, so such glitches still may exist.
BTW, since your expression is mostly made of scalar coefficients
that are irrelevant for the Dirac algebra, you can help FeynCalc
by isolating those from the very beginning. This way the calculation
of traces proceeds much faster:
amp2 = Collect2[DotSimplify[amp],
Join[FeynCalc`Package`DiracHeadsList,
FeynCalc`Package`TensorArgsList], IsolateNames -> KK]
(*Check*)
FreeQ[FRH[amp],
Join[FeynCalc`Package`DiracHeadsList,
FeynCalc`Package`TensorArgsList]]
ampSquared =
DiracSimplify[amp2*ComplexConjugate[amp2] // FermionSpinSum]
ampSquared // FRH
Usually this trick doesn't work so well when polarization vectors
and SU(N) matrices are involved, but your amplitude is structurally
simple enough, so it pays off well.
Cheers,
Vladyslav
Am 27.07.20 um 22:08 schrieb Paulina Knees:
> PS: I get the error message when I run
> ampSquared = DiracSimplify[
> amplitud *ComplexConjugate[amplitud] // FermionSpinSum]
>
> Thank you!
>
> Cheers,
>
> Paulina
>
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