**Next message:**Vladyslav Shtabovenko: "Re: On the Function FCPrepareFAAmp"**Previous message:**Naser Ahmadiniaz: "Re: Can Feyncalc do calculations in Euclidean Metrics?"**In reply to:**Naser Ahmadiniaz: "Re: Can Feyncalc do calculations in Euclidean Metrics?"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ]**Mail actions:**[ respond to this message ] [ mail a new topic ]

Hi,

sorry for the late reply.

I'm afraid that there is no straight-forward way to change the sign of

the anticommutation relation everywhere. The reason is that in most

cases FeynCalc doesn't apply the anticommutation relation directly, but

rather uses known formulas to simplify different chains of Dirac

matrices (see e.g. Veltman's Gammatrica).

To have DiracSimplify and DiracTrace work with Euclidean matrices with

any reasonable performance, one would need to rederive all those

formulas with the different metric (which possibly someone has already

did) and reimplement them again. This is of course not impossible, but

would reqire quite some work and testing.

You can always do some tricks to make FeynCalc work in your way, e.g.

multiplying each Dirac matrix with an I to have {i g^mu, i g^nu} = - 2

eta^munu, but then you still need to be very careful with Gamma 5 and

the Levi-Civita tensor.

Cheers,

Vladyslav

Am 26.01.2016 um 02:27 schrieb Naser Ahmadiniaz:

*> Hi,
*

*>
*

*> I am using FeynCalc package in Mathematica to calculate some complicated Traces, but I think the default convention for the anticommutator of two Gamma matrices in this package is with positive a sign on the right-hand side as
*

*>
*

*> ${\gamma^\mu,\gamma^\nu}=+2\eta^{\mu\nu}$
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*>
*

*> I would like to change this convention to the one with a negative sign, i.e
*

*>
*

*> ${\gamma^\mu,\gamma^\nu}=-2\eta^{\mu\nu}$
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*>
*

*> how can I do that once for all?
*

*>
*

*> Thanks,
*

*> Naser
*

*>
*

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