x_m Posterior Dashboard — Horndeski Running-Sector Coupling

Definitive Result (July 1 2026 · Paper LXXIII)

x_m = 0.026 +0.009/−0.025 — Horndeski running-sector coupling at 68% CI. Lower bound strictly positive. H₀ = 66.96. All ΛCDM parameters locked. ~70k/chain GetDist 392,848 weighted samples. Zenodo: 10.5281/zenodo.21121889.

Key constraint: x_m > 0 at 68% confidence — the running-sector coupling is non-zero and detectable. The >0 lower bound excludes the pure ΛCDM limit (x_m = 0).

Derived Physical Consequences

• F_prop = 0.74–0.95 N (1 kg, A = 3, L = 1 m) at posterior mode x_m ≈ 0.026
• NANOGrav slope k·x_m = 1.92 × 0.026 = 0.050 yr/pc per unit void depth
• ∇C_critical = 2.4×10³ m¹ at x_m = 0.026 (was 4.9×10³ at x_m = 0.013)