PauliEta[I] represents a two-component Pauli spinor
\eta_C, while
PauliEtaC[-I] stands for \eta_C^{\dagger }.
PauliEtaC[I]\eta _c
PauliEtaC[-I]\eta _c^{\dagger }
```mathematica PauliEtaC[-I] . SIS[p] . PauliXi[I]
% // ComplexConjugate
```mathematica
\eta _c^{\dagger }.\left(\bar{\sigma }\cdot \overline{p}\right).\xi
\xi ^{\dagger }.\left(\bar{\sigma }\cdot \overline{p}\right).\eta _c