Construction and Cosmological Validation of Coherential Dark Energy

We construct a dark energy action motivated by the hypothesis that dark energy is the macroscopic residue of universal quantum decoherence. Starting from an ontological framework (Radial Coherential Dynamics, RCD) in which a scalar field C ∈ (0,1] represents a coarse-grained coherence order parameter, we derive the most general homogeneous action in FRW spacetime and subject all candidate kinetic terms K(C) and potentials V(C) to a systematic filter pipeline requiring domain consistency, structural irreversibility, ghost freedom, and falsifiability. Of four candidate pairs, only one survives all filters: P2 = (K=1, V_B), where V_B(C) = μ⁴(1 − exp(−β(1−C))) with β ≈ 22 ≈ α⁻¹³ and α ≈ 1.3 × 10⁻⁴ is the proposed universal decoherence rate. Self-consistent numerical integration in FRW reveals a cosmological attractor with Ω_DE ≈ 0.70 and C_today ≈ 0.80, emergent irreversibility without time-asymmetric terms in the Lagrangian, and an equation of state w₀ ≈ −0.987 (thawing quintessence) for initial conditions C₀ 0.90. The microphysics defining C and fixing (α, β) belongs to a fundamental program; it is not required for the internal consistency of the cosmological regime validated here. ---