Name: Frederik Orellana (email_not_shown)
Date: 04/16/03-03:14:56 PM Z

After thinking a bit about it, let me clarify:

GA is a way of quickly inputting Dirac matrices. The arguments of GA
should not be wrapped in LorentzIndex; this will be done automatically.

Thus the correct input is


which returns (in StandardForm)


as it should.

Again: FeynCalc does not deal with explicit (integer) Lorentz indices,
but if there is a real need for this kind of funtionality and someone is
willing to contribute the code, we will be happy to look at including it
in the distribution.


Frederik Orellana wrote:
> 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.
>>*Do You Yahoo!?*

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