BCT Appendix App-L208-mu: Isotropic Hopf Coherence Length — μ_scale = φ²×(σ₀/skew)^(√2−1)

The Bessel node separation parameter μ_scale in the BCT Bessel Asset Pricing Model is derived from the Ginzburg-Landau coherence length of the OHC condensate. The isotropic Hopf coupling Ω = σ₀/skew plays the role of inverse reduced temperature. BCT formula: μ_scale = φ²×Ω^(√2−1), where φ² = 2.618 (D4 bare coherence length) and √2−1 = 0.414 (BCT critical exponent, Tsirelson identity). Prefactor within 1.4% of φ² on 152 real trading days. BCT Prediction #257. Status: CONJECTURE. Zero free parameters.