SISD[p]
can be used as input for -dimensional with -dimensional Lorentz vector and is transformed into PauliSigma[Momentum[p,D],D-1]
by FeynCalcInternal
.
[p] SISD
[p] // FCI // StandardForm
SISD
(*PauliSigma[Momentum[p, D], -1 + D]*)
[p, q, r, s] SISD
[p, q, r, s] // StandardForm
SISD
(*SISD[p] . SISD[q] . SISD[r] . SISD[s]*)
[q] . (SISD[p] + m) . SISD[q] SISD