Decoherence-Free Interface Dynamics III: Asymmetric Baryogenesis as a Topological Selection Effect at the Cosmic Cavitation Boundary

This paper presents a mechanical resolution to the cosmic baryon asymmetry problem (the observed dominance of matter over antimatter) by extending the framework of Decoherence-Free Interface Dynamics (Part I) and Thermo-Viscous Phase Boundaries (Part II). We demonstrate that the net baryon number density (N_B / N_γ ≈ 10⁻¹⁰) is not an ad-hoc initial condition or the product of microscopic CP-violating decay channels within interior spacetime. Instead, it is derived as a macroscopic, topological selection effect occurring at the expanding cosmic cavitation boundary (∂ℳ). By coupling the directional condensation vector n^μ across the zero-metric boundary (g_μν = 0 → g_μν ≠ 0) with the phase winding of the complex order parameter field Ψ, we show that matter (χ = +1) and antimatter (χ = -1) exhibit differential phase-matching efficiencies. Matter constructs a stable, phase-locked state inside the expanding metric, while antimatter suffers destructive interference at the interface and dissipates back into the spaceless continuum. The resulting Baryon-to-Photon ratio η_B is quantitatively linked to the interfacial energy density σ_∂ℳ and the expansion rate ȧ/a.