Defining the antisymmetric s u ( 2 ) -valued objects σ σ μ μ ν ν as σ σ i j = ϵ ϵ i j k T k , σ σ i 4 = − − σ σ 4 i = T i , where Greek indices run from 1 to 4, Latin indices run from 1 to 3, and T i is a basis of s u ( 2 ) satisfying [ T i , T j ] = − − ϵ ϵ i j k T k . Then A μ μ = σ σ μ μ ν ν ∂ ∂ ν ν ρ ρ ρ ρ = σ σ μ μ ν ν ∂ ∂ ν ν log ⁡ ⁡ ( ρ ρ ) is a solution as long as ρ ρ : R 4 → → R is harmonic.