In particular, note that the representation Δ of the orthochronous spin group is a unitary representation. In general, there are Clebsch–Gordan decompositions Δ Δ ⊗ ⊗ Δ Δ ¯ ¯ ≅ ≅ ⨁ ⨁ p = 0 k ( σ σ − − Γ Γ p ⊕ ⊕ σ σ + Γ Γ p ) .