**Next message:**V. Shtabovenko: "Re: Feyncalc refuses to expand LC"**Previous message:**Vladyslav Shtabovenko: "Re: A bug with FCE[Eps]?"**Maybe in reply to:**purnendu@tnp.saha.ernet.in: "A question"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ]**Mail actions:**[ respond to this message ] [ mail a new topic ]

*> Dear Prffesior,
*

*> I am a research-fellow at a physics institute of India,
*

*> working on "Finite Temperature Field Theory",and "QGP phenomenology".
*

*> I am trying to use Feyncalc for my calculations but facing some problems.
*

*> Let me explain them.
*

*> At finite temperature the propagators and the vertices
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*> loses the simple Lorentz invariant structure and acquires an admixture
*

*> of both spatial and temporal components. Therefore, to perform these
*

*> calculations the programe should be able to recognige both the zeroth
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*> and spatial components of a four-vector and know should be able to do
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*> calculations with DiracGamma[0] and Diracgamma[i],i=1,2,3 explicitly.
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*> Can such things be done with feynCalc? Plese let me know.
*

*> Sincerly
*

*>
*

*> Purnendu
*

More than 16 years after the original question, the answer is yes, with FeynCalc 9.3 (aka the current development version) this will be possible.

For example (TGA[] is gamma^0, CGA[i] is gamma^i)

Tr[CGA[i].CGA[j]] (i.e. the trace of two Dirac matrices with Cartesian indices)

yields

-4 CartesianPair[CartesianIndex[i], CartesianIndex[j]]

where CartesianPair[CartesianIndex[i], CartesianIndex[j]] signifies a Kronecker delta

Then

DiracSimplify[TGA[].TGA[]]

yields 1, since gamma^0 gamma^0 =1, while

DiracSimplify[CGA[i, j, i, j]] (i.e. g^i g^j g^i g^j

gives -3

This still needs some testing, performance improvements and a proper documentation,

but this is a work in progress to be completed soon.

Cheers,

Vladyslav

**Next message:**V. Shtabovenko: "Re: Feyncalc refuses to expand LC"**Previous message:**Vladyslav Shtabovenko: "Re: A bug with FCE[Eps]?"**Maybe in reply to:**purnendu@tnp.saha.ernet.in: "A question"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ]**Mail actions:**[ respond to this message ] [ mail a new topic ]

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