GA[mu]
can be used as input for a 4-dimensional and is transformed into DiracGamma[LorentzIndex[mu]]
by FeynCalcInternal (=FCI).
GA[mu , nu , ...]
is a short form for GA[mu].GA[nu]
.
Overview, DiracGamma, GAD, GS.
[\[Mu]] GA
[\[Mu], \[Nu]] - GA[\[Nu], \[Mu]] GA
StandardForm[FCI[GA[\[Mu]]]]
(*DiracGamma[LorentzIndex[\[Mu]]]*)
[\[Mu], \[Nu], \[Rho], \[Sigma]] GA
StandardForm[GA[\[Mu], \[Nu], \[Rho], \[Sigma]]]
(*GA[\[Mu]] . GA[\[Nu]] . GA[\[Rho]] . GA[\[Sigma]]*)
[\[Alpha]] . (GS[p] + m) . GA[\[Beta]] GA