If one inserts Eq.(14) into (13) and brings the free Dirac operator (15) to the right of the matrix hyperbolic functions and uses standard gamma matrix commutators and anticommutators and cosh 2 ⁡ ⁡ Δ Δ − − sinh 2 ⁡ ⁡ Δ Δ = 1 one arrives at ( ∂ ∂ μ μ = ∂ ∂ / ∂ ∂ x μ μ ) , ( G γ γ 1 ⋅ ⋅ P 2 − − E 1 β β 1 + M 1 − − G i 2 Σ Σ 2 ⋅ ⋅ ∂ ∂ ( L β β 2 − − G β β 1 ) γ γ 52 ) ψ ψ = 0 ,