TC[p]
is the temporal component of a 4-vector and is transformed into TemporalPair[TemporalMomentum[p], ExplicitLorentzIndex[0]]
by FeynCalcInternal
.
Overview, TemporalPair, TemporalMomentum, FCClearScalarProducts.
[p] TC
p^0
[p - q] TC
(p-q)^0
[TC[p]] // StandardForm
FCI
(*TemporalPair[ExplicitLorentzIndex[0], TemporalMomentum[p]]*)
ExpandScalarProduct
is used to expand momenta in TC
[TC[p - q]] ExpandScalarProduct
p^0-q^0
[TC[p - q]] // StandardForm
ExpandScalarProduct
(*TemporalPair[ExplicitLorentzIndex[0], TemporalMomentum[p]] - TemporalPair[ExplicitLorentzIndex[0], TemporalMomentum[q]]*)