Project Meridian Technical Summary

We present a self-contained technical summary of the Meridian framework, a unified approach to gravity, the Standard Model of particle physics, and dark energy constructed from a single spectral action principle evaluated on a specific warped product geometry. The framework begins from two inputs: a five-dimensional Randall-Sundrum orbifold (M₄ ×w (S¹/Z₂) ) warped with exponential factor A (y) = -k|y|, tensored with the Connes-Lott finite noncommutative spectral triple (AF = C ⊕ H ⊕ M₃ (C), HF, DF) ; and a smooth cutoff function f regulating the Chamseddine-Connes spectral action S = Trf (D²/Λ²) + ⟨Jψ, Dψ⟩. From these inputs, the Seeley-DeWitt heat kernel expansion yields: a cosmological constant sequestered via the Kaloper-Padilla mechanism (a₀), Einstein gravity with conformal scalar coupling ξ = 1/6 (a₂), and the full Standard Model gauge sector SU (3) C × SU (2) L × U (1) Y with Higgs mechanism and a bulk cuscuton scalar (a₄). The gauge group, fermion content, and Higgs field are derived from the algebra and its inner fluctuations, not postulated. The framework's principal novel results include: (1) a zero-free-parameter derivation of the weak mixing angle sin²θW from the topological resolution of Z₃ orbifold singularities, where the gauge coupling correction is shown to be necessarily topological through a four-zero uniqueness proof eliminating all perturbative mechanisms; (2) the identification of the cuscuton as the unique bulk scalar compatible with singularity-free self-tuning within the NCG spectral action, yielding a dark energy equation of state w₀ (ζ₀) = -1 + CKK/ζ₀ with predicted time variation wₐ ≈ 0; (3) a UV completion stack linking F-theory on del Pezzo surfaces through NCG through RS geometry to 4D effective theory, with each level constraining the next; and (4) growth-expansion decoupling as a falsifiable structural prediction — the cuscuton's zero dynamical degrees of freedom ensure that modifications to the expansion history do not propagate into the growth of large-scale structure. The framework produces twelve confirmed predictions (including αT = 0, normal neutrino mass ordering, gravitational wave speed, and perturbation theory quantities μ = Σ = 1, η = 0 exactly) and six pending predictions testable by DESI Y5, DUNE, LiteBIRD, and LISA. The decisive near-term falsification test is wₐ ≈ 0: significant time variation in the dark energy equation of state would exclude the cuscuton mechanism. Open problems include the Higgs mass (CCM prediction of 136-142 GeV vs. observed 125. 1 GeV, likely requiring full RG running from the asymptotic safety boundary condition), the determination of the cutoff function f from first principles, and the sterile neutrino dark matter mass spectrum.