Relaxation-Driven Cyclic Cosmology (RDCC) v29.0 - Minimal Extension of ΛCDM / Bounce EFT Framework

Relaxation-Driven Cyclic Cosmology (RDCC) v29.0 presents a minimal, CPT-symmetric and nonsingular extension of LambdaCDM in which the thermodynamic arrow of time, dark matter abundance, baryon asymmetry, primordial perturbations, and cosmic bounce dynamics all arise from a single structural principle: the global CPT symmetry of the quantum state. The minimal realization of this symmetry enforces a two-sector Hilbert-space factorization, with the visible and mirror sectors interacting only through gravity. A single infrared relaxation parameter, alpha ~ 10^-2, generated by the leading Planck-suppressed operator T^{mu nu}_+ T^-_{mu nu} / M_*^2, governs all observable deviations from LambdaCDM. This parameter is not free: it emerges naturally as a loop-suppressed coefficient and as an infrared fixed point of the renormalization-group flow. The same alpha controls the primordial spectral tilt, the contribution to Delta N_eff, the dark-matter-to-baryon ratio, the damping of isocurvature modes, percent-level corrections to f*sigma_8(z), and the amplitude of the LISA-band stochastic gravitational-wave background. RDCC v29.0 includes several major improvements and new components: - Fully restructured Section 4 (Bounce Dynamics) with new subsections on the origin of the modified Friedmann equation and the dynamical stability of the cuscuton-induced bounce. - A complete overhaul of Section 7 (Cosmological Perturbations), including a refined entropic mechanism, a detailed delta-N formalism treatment, and a new summary linking early- and late-time observables. - A strengthened Section 8 (Primordial Gravitational Waves) with a clear derivation of logarithmic oscillations, two-sector interference, and alpha-scaling. - Updated forecasts for Euclid and large-scale structure (Section 10) with improved clarity and correlation structure. - A refined LISA prediction section (Section 11) emphasizing multi-cycle enhancement and observational prospects. - A new Section 14: "Limitations and Open Questions", providing a transparent and reviewer-friendly discussion of open theoretical and numerical challenges. - Numerous stylistic, structural, and conceptual improvements across the manuscript, ensuring internal consistency and publication-ready clarity. RDCC offers a unified and radiatively natural explanation for several persistent puzzles in cosmology, with falsifiability built into its core. The next generation of observations, including CMB-S4, DESI, SKA, and LISA, will decisively test the multi-observable signature pattern predicted by the model. Related documents and the full RDCC ecosystem are available via Zenodo:https://zenodo.org/records/18204087 Michael [email protected]