HDGXL: Temporal Memory Suppression of Late-Time Structure Growth — Code and Data

This repository contains the complete numerical implementation, data, and analysis pipeline for the paper "History-Dependent Gravity: Temporal Memory Suppression of Late-Time Structure Growth". History-Dependent Gravity (HDG) is a modified gravity framework based on nonlocal temporal memory effects characterized by a spectral density ρ (μ). In the critical regime ρ (μ) = const, the theory develops a marginal infrared fixed point leading to logarithmic suppression of structure growth: δ (a) ∝ ln (a/a*) ². The repository includes: • Core HDG module (hdgcore. py) with growth equation solver• 2D and 3D Metropolis-Hastings MCMC samplers• Robustness tests (profile likelihood, Planck-fixed σ₈, Ωₘ variation) • Publication-quality figure generators• Low-redshift fσ₈ data compilation (6dFGS, BOSS, DES, eBOSS) Key results: • Transition scale: a* = 0. 165 (+0. 234, -0. 096) 68% C. L. • σ₈ = 0. 784 (+0. 122, -0. 104) • Ωₘ = 0. 274 (+0. 067, -0. 048) • χ² improvement vs Planck-fixed ΛCDM: Δχ² ≈ 54. 8 The code is fully reproducible and can be used to test HDG predictions against additional datasets or extend the analysis with covariance matrices and joint CMB+BAO+weak lensing inference. Companion paper: arXiv: XXXX. XXXXX (to be updated after arXiv submission)