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Hi,

if I enter

Tr1a = Tr[GS[P1].GS[P2].GS[P3].GA[i].(1 - GA[5])];

Tr2a = Tr[GS[Q1].GS[Q2].GS[Q3].GA[i].(1 - GA[5])];

Tr3a = Tr[

GS[P1].GS[P2].GS[P3].GA[i].GS[Q1].GS[Q2].GS[Q3].GA[i].(1 - GA[5])];

then

Result = Simplify[Contract[Tr1a.Tr2a + 2 Tr3a]] // Schouten

indeed returns zero.

Cheers,

Vladyslav

Am 03.08.2014 20:38, schrieb Nikita Belyaev:

*> Good day,
*

*> I've tried to calculate some matrix elements and I've faced with a bug.
*

*> As an example I can provide the following calculation.
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*> Here are the well-known formula to calculate some trace combinations (FeynCalc syntaxis):
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*>
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*> Tr1a = Tr[P1.P2.P3.GA[i].(1 - GA[5])];
*

*> Tr2a = Tr[Q1.Q2.Q3.GA[i].(1 - GA[5])];
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*> Tr3a = Tr[P1.P2.P3.GA[i].Q1.Q2.Q3.GA[i].(1 - GA[5])];
*

*>
*

*> Result = FullSimplify[Contract[Tr1a.Tr2a + 2 Tr3a]];
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*>
*

*> P1,...,Q1,... are dirac slashed values.
*

*>
*

*> Result should be zero, but in FeynCalc there is a bug with calculating of Tr[P1.P2.P3.GA[i].Q1.Q2.Q3.GA[i].GA[5]) term. The result contsins wrong imaginary combination of Levi-Civita symbols (there are 15 terms instead of 6), real part is zero.
*

*> So what is the reason for that?
*

*> I can provide any files you might need.
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*>
*

*> P.S. FeynCalc 8.2.0, Mathematica 9
*

*>
*

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