FeynCalc does not deal with explicit Lorentz indices. In fact,
LorentzIndex[0], LorentzIndex[1], ... get replaced with
ExplicitLorentzIndex[0], ExplicitLorentzIndex[1], ... immediately.
DiracSimplify[GA[ExplicitLorentzIndex[0],ExplicitLorentzIndex[0]] should
then not return 4. It should be left unevaluated. This should be fixed.
I will look at it. Thanks for reporting it.
If you need to work with explicit Lorentz indices, you are more than
welcome to contribute code to facilitate this.
Cheers, Frederik
Zhiwei Huang wrote:
> I don't know how to input a single gamma matrix such as \gamma^0,
> \gamma^1 and so on. In physics, the square of \gamma^0 satisfies
> (\gamma^0)^2 = 1. However, if I input "GA[LorentzIndex[0]]", I find that
> "DiracSimplify[GA[LorentzIndex[0],LorentzIndex[0]]" is equal to 4, and
> if I input "GA[0]", I find that "DiracSimplify[GA[0,0]" is equal to
> "DiracGamma(0).DiracGamma(0)", which is not I expect.
> Why I can not conduct \gammma^0 like \gamma^5? We can see that
> "DiracSimplify[GA[5, 5]]" is exactly equal to 1! It's wonderful.
> I want to find a command for \gamma^0 matrix which works like the
> \gamma^5 case. But I can not find the way. So I really want to get help
> from you.
>
>
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