LCD[m, n, r, s]
evaluates to -dimensional by virtue of applying FeynCalcInternal
.
LCD[m,...][p, ...]
evaluates to -dimensional applying FeynCalcInternal
.
When some indices of a Levi-Civita-tensor are contracted with 4-vectors, FeynCalc suppresses explicit dummy indices by putting those vectors into the corresponding index slots. For example, (accessible via LCD[][p1,p2,p3,p4]
) correspond to .
[\[Mu], \[Nu], \[Rho], \[Sigma]] LCD
[\[Mu], \[Nu], \[Rho], \[Sigma]] // FCI // StandardForm
LCD
(*Eps[LorentzIndex[\[Mu], D], LorentzIndex[\[Nu], D], LorentzIndex[\[Rho], D], LorentzIndex[\[Sigma], D]]*)
[\[Mu], \[Nu]][p, q] LCD
[\[Mu], \[Nu]][p, q] // FCI // StandardForm
LCD
(*Eps[LorentzIndex[\[Mu], D], LorentzIndex[\[Nu], D], Momentum[p, D], Momentum[q, D]]*)
[Contract[LCD[\[Mu], \[Nu], \[Rho]][p] LCD[\[Mu], \[Nu], \[Rho]][q]]] Factor2
[\[Mu], \[Nu], \[Rho], \[Sigma]] FVD[Subscript[p, 1], \[Mu]] FVD[Subscript[p, 2], \[Nu]] FVD[Subscript[p, 3], \[Rho]] FVD[Subscript[p, 4], \[Sigma]]
LCD
[%] Contract