Unified Dynamic Vacuum Theory - Repair

Abstract UDVT-R proposes a temporary reduction in photon propagation speed near cosmological recombination, described by a Gaussian function of the logarithmic scale factor, f(a) = 1 − β exp[︂− ln2 (a/a ⋆) 2 σ2 ]︂, with benchmark parameters β = 0.1753, σ = 0.7, a⋆ = 1/1101. Within an assumed effective photon-baryon description, the modified sound speed reduces the sound horizon. A smaller sound horizon could permit a higher inferred Hubble constant while approximately preserving the observed angular acoustic scale. This interpretation is conditional on an unchanged background expansion and a consistent treatment of photon interactions, atomic physics, and recombination. Prior monographs reported a target sound-horizon ratio of approximately 0.9208, not a validated Boltzmann-code prediction. Photon-diffusion estimates were schematic. Neither an observational likelihood analysis nor numerical posterior samples are supplied. This revised manuscript separates established algebra, imposed assumptions, illustrative calculations, and unresolved physics. The central outstanding requirement is a self-consistent derivation of the background, perturbation, and collision equations, followed by comparison with cosmological observations. Scientific status. A phenomenological proposal with analytically checkable properties and an outstanding theoretical and observational validation programme. This manuscript does not establish a proven theory, a completed cosmological simulation, or a demonstrated resolution of the Hubble tension.