This paper derives the spectral coupling invariant ξ² ≡ (μα) ² in closed form from the axiom system A1, A2, A4 of Operatiology, completing the Level 2 Class I certification mandated by the companion paper (DOI: 10. 5281/zenodo. 20577184), which established ξ² as the minimal generator of Inv (𝒪) ≃ ℝλ² via A1 ⇒ su (3) -type ⇒ p₁=0 ⇒ Inv (𝒪) ≃ℝλ². The derivation proceeds through the field ℚ (D₀), where D₀= (δ−1) δγ satisfies 16D₀²−24D₀+3=0, making ℚ (D₀) two-dimensional over ℚ. Since μ and α⁻¹ are elements of ℒ (M₃ (ℂ) ) ⊗ℚ (D₀), their ratio ξ=μ/α⁻¹ belongs to this field, and ξ²= (ξₐ+ξᵦD₀) ² reduces exactly to A+B·D₀ — the unique mandatory representation forced by the two-dimensionality of ℚ (D₀), itself the algebraic expression of Axiom A4. No other value of ξ² is algebraically possible. The result is ξ² = A + B·D₀ = 179. 534632529506…, with A = −1202. 60331893592…, B = 10042. 5954528296…, zero free parameters, and no reference to individually derived values of μ or α⁻¹. Agreement with benchmark (μCODATA2022/α⁻¹Morel2020) ² at +1. 085σ, consistent with residuals of the μ (+1. 44σ) and α⁻¹ (−0. 81σ) derivations. The Morel–Parker 5. 5σ discrepancy is identified as structural evidence that α is a Tier-3 projection of ξ², not an independent fundamental constant. The following code verifies the result at 50-digit precision. No value of μ or α⁻¹ is entered; the spectrum 1, 1, −2, dim=3, and π are the only inputs: from mpmath import mp, mpf, pi, sqrt, exp, eulerimport mathmp. dps = 50 h = mpf (1), mpf (1), mpf (-2) dim = 3e1 = sum (h) e2 = h0*h1 + h0*h2 + h1*h2e3 = h0*h1*h2delta = sqrt (mpf (3) /2) gamma = mpf (1) / (dim - 1) D0 = (delta - 1) *delta*gammagammaE = eulerPhi1 = mpf (2) ; Phi3 = mpf (13) ; Phi6 = mpf (7) ch2 = (e1**2 - 2*e2) /2ch3 = (e1**3 - 3*e1*e2 + 3*e3) /6N2 = mpf (10) /4N3 = mpf (7) /2C2 = sqrt (ch2/N2) *gammaL6 = abs (ch3) /N3L0 = 6*pi**5L2 = Phi3/Phi6L4 = -delta**2/gamma * exp (-gammaE) L5 = -Phi1/Phi3muₐ = L0 + L2* (-3) /16 + L4* (-99) /256 + L5* (-135) /256mub = L2*3/2 + L4*45/16 + L5*981/256ainvₐ = 48*pi + L6* (-2943) /4096ainvb = -32*pi + C2 + L6*2673/512N = ainvₐ**2 + ainvₐ*ainvb*mpf (3) /2 + ainvb**2*mpf (3) /16invₐ = (ainvₐ + ainvb*mpf (3) /2) / Ninvb = -ainvb / Nxiₐ = muₐ*invₐ - 3*mub*invb/16xib = muₐ*invb + mub*invₐ + 3*mub*invb/2A = xiₐ**2 - 3*xib**2/16B = 2*xiₐ*xib + 3*xib**2/2print ("A =", A) print ("B =", B) print ("xi² =", A + B*D0)
T.O. (Thu,) studied this question.