Rail-Switch Torsion V5: Degeneracy Breaking of the S8 Tension

Abstract

V5: Degeneracy Breaking of the S8 Tension via Torsion-Induced Amplitude Damping in a Closed Geometry

The statistical tension between the Cosmic Microwave Background (CMB) measurements of the universe's clumpiness (S₈) and those from weak lensing surveys remains one of the most significant challenges in modern cosmology. Standard attempts to resolve this tension often result in a degraded fit to the CMB power spectrum or a violation of the Baryon Acoustic Oscillation (BAO) sound horizon (rₛ).

This work presents a phenomenological model based on Einstein-Cartan-Sciama-Kibble (ECSK) gravity, where primordial torsion manifests as a mechanism for amplitude damping. Using the CLASS Boltzmann code, we demonstrate that a 16% damping of the primordial power amplitude (Aₛ), when compensated by a closed spatial geometry (Ωₖ = -0.009), creates a "mimic" universe that is statistically indistinguishable from ΛCDM regarding the Planck 2018 TT spectrum (Δχ² < 1.0).

However, this degeneracy is broken in the late-time matter power spectrum, yielding a value of S₈ = 0.759, effectively resolving the tension with KiDS/DES weak lensing data. Crucially, this mechanism preserves the standard sound horizon (rₛ = 147.1 Mpc) and expansion history (H₀ ≈ 67.4 km/s/Mpc), satisfying constraints from BOSS/DESI galaxy surveys.

Included in this dataset:

• Scientific Letter: A 4-page summary of the methodology and results.

• Source Code: The Jupyter Notebook used to generate the CLASS simulations (Python wrapper).

• Master Plot: High-resolution comparison of the CMB and Matter Power Spectra.

• Major Result: Successfully identified the parameter space that resolves the S8 Tension ($S_8 = 0.759$) while preserving the Sound Horizon ($r_s = 147.1$ Mpc).

• Methodology: Finalized the Torsion Damping factor at 16% ($A_s$ multiplier = 0.840) and Curvature at $\Omega_k = -0.009$.

• Validation: Added "Physics Compliance Check" confirming no violation of expansion history or universe age.

• Plots: Added rail_switch_master_plot.png demonstrating the CMB degeneracy and P(k) suppression.

Keywords: ECSK Gravity, Big Bounce, Spacetime Torsion, Cosmology, General Relativity, Black Hole Information Paradox, Citizen Science.