SISE[p]
can be used as input for -dimensional with -dimensional Lorentz vector and is transformed into PauliSigma[Momentum[p,D-4], D-4]
by FeynCalcInternal
.
[p] SISE
[p] // FCI // StandardForm
SISE
(*PauliSigma[Momentum[p, -4 + D], -4 + D]*)
[p, q, r, s] SISE
[p, q, r, s] // StandardForm
SISE
(*SISE[p] . SISE[q] . SISE[r] . SISE[s]*)