Name: Vladyslav Shtabovenko Date: 11/25/14-06:37:12 PM Z
Hi,
if the Levi-Civita tensors are contracted at least in one index,
FeynCalc can convert that to a bunch of metric tensors via Contract,
e.g.
LC[a][p1, p2, p3] LC[b][p4, p5, p6] // Contract
If this is not the case in your computation, it would be helpful
if you could post your final result to see where the problem is.
In the code you posted so far I don’t see any epsilon tensors.
Cheers,
Vladyslav
On 24/11/14 09:31, Lingxiao Xu wrote:
> Hi developers,
>
> I’m calculating the process “e-(R),e+(L)->w+w-“, the mass of
electron and anitelectron is neglected, “R” and “L” represent
helicity.
> The square of reduced matrix element obtained just cantain the
contraction of LeviCivita tensor and momentums, how can I simplify the
result further to get rid of the LeviCivita tensor in the final results
?
> Thanks for help.
> Cheers!
>
> Lingxiao
>
> Here is part of my code, it might be helpful to solve my problem.
“fnuL,faL,fzL” represent the amplitudes of t-channel diagram with
neutino propagator, s-channel diagram with photon propagator, s-channel
diagram with Z propagator respectively.
>
>
> flistL = List[fnuL, faL, fzL]
> fliststarL = {fnuLs, faLs, fzLs} =
> ComplexConjugate /@ {fnuL, faL,
> fzL} /. {\[Mu] -> \[Mu]s, \[Nu] ->
\[Nu]s, \[Epsilon] -> \
> \[Epsilon]s, \[Omega] -> \[Omega]s} //
Explicit
> Lsq = Table[0, {i, 1, 3}, {j, 1, 3}];
>
> Do[
> Lsq[[i, j]] =
> 1/4 FermionSpinSum[
> PolarizationSum[\[Mu], \[Mu]s,
> p3] PolarizationSum[\[Nu], \[Nu]s, p4]
flistL[[
> i]] fliststarL[[j]] // Expand] /.
DiracTrace -> TR //
> Contract // Simplify;
> Print[i, j, “: “, Lsq[[i, j]]], {i, 1, 3},
{j, 1, 3}
> ]
>
>