What question did this study set out to answer?

This research aims to address the tension between Cosmic Microwave Background measurements and weak lensing surveys by introducing a new model based on ECSK gravity.

February 2, 2026Open Access

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

Key Points

This research aims to address the tension between Cosmic Microwave Background measurements and weak lensing surveys by introducing a new model based on ECSK gravity.
Developed a phenomenological model using ECSK gravity to include primordial torsion.
Utilized CLASS Boltzmann code for power spectrum simulations.
Compensated a 16% damping of primordial power amplitude with a closed spatial geometry (Ωₖ = -0.009).
Verified compliance with BAO constraints from galaxy surveys.
Achieved S₈ = 0.759, effectively resolving the tension with KiDS/DES weak lensing data.
Retained standard sound horizon (rₛ = 147.1 Mpc) and expansion history (H₀ ≈ 67.4 km/s/Mpc).
Demonstrated that the mimic universe is statistically indistinguishable from ΛCDM regarding the Planck 2018 TT spectrum.

Abstract

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 (S₈ = 0. 759) while preserving the Sound Horizon (rₛ = 147. 1 Mpc). Methodology: Finalized the Torsion Damping factor at 16% (Aₛ multiplier = 0. 840) and Curvature at ₖ = -0. 009. Validation: Added "Physics Compliance Check" confirming no violation of expansion history or universe age. Plots: Added railₛwitchₘasterₚlot. 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.

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