Wave Ψ n {\displaystyle \Psi _{n}} is set of two functions Ψ n ≡ { A → ( t , x → ) : R 4 → R n , φ ( t , x → ) : R 4 → R } {\displaystyle \Psi _{n}\equiv \{{\vec {A}}(t,{\vec {x}}):\mathbb {R} ^{4}\rightarrow \mathbb {R} ^{n},\varphi (t,{\vec {x}}):\mathbb {R} ^{4}\rightarrow \mathbb {R} \}} .
Wave function Ψ n ( t , x → ) : R 4 → R n {\displaystyle \Psi _{n}(t,{\vec {x}}):\mathbb {R} ^{4}\rightarrow \mathbb {R} ^{n}} is function defined as