CoreLumen Cosmology V : Late-Time Condensate and Cosmic Acceleration

This work presents the fifth and final paper of the CoreLumenCosmology series. Following the radiation-dominated stage developed inCoreLumen Cosmology IV, the universe eventually enters amatter-dominated phase during which large-scale structureformation becomes efficient. Within the CoreLumen framework the vacuum is described by acondensate order parameter Ψ = ρ e^{iθ}. Although the condensate sector remains subdominant during mostof the matter era, its relative contribution to the cosmicenergy density gradually increases as the matter densitydilutes through cosmic expansion. The late-time resurgence of the condensate generates aneffective dark-energy component of the form ρ_DE = ρ_∞ + α H^2 M_Pl^2. This contribution drives the transition from matter-dominateddeceleration to accelerated cosmic expansion. The framework predicts a late-time cosmological evolutionthat remains close to the ΛCDM expansion history whileallowing mild dynamical deviations in the Hubble expansionrate, the effective dark-energy equation of state, and thegrowth of large-scale structure. This paper completes the foundational CoreLumen cosmologysequence, which describes the full cosmic evolution: condensate vacuum → inflation → primordial perturbations →reheating → radiation era → matter era → late-timeaccelerated expansion.