CETΩ: Reproducible numerical pipeline for late-time background modifications of cosmology

This repository contains a minimal, fully reproducible numerical pipeline used to generate the results presented in the accompanying manuscript “A late–time informational modification of the cosmological background and the Hubble tension”. The pipeline implements the CETΩ framework as a purely late–time, background-level modification of the cosmological expansion history, leaving recombination physics, the sound horizon, and linear perturbations unchanged by construction. The modification is implemented directly in the background routines of CAMB, without introducing new propagating degrees of freedom or altering the Einstein–Boltzmann equations. The pipeline produces: background expansion curves H(z)H(z), BAO distance observables and an effective BAO–inferred Hubble constant, consistency checks with CMB low-ℓℓ temperature anisotropies (ISW regime), growth observables fσ8(z)fσ8(z) and comparison with representative RSD measurements, profile likelihood scans for the CETΩ deformation parameter. All figures and numerical consistency checks reported in the manuscript can be reproduced by running the provided scripts.The pipeline is intended for transparency and reproducibility purposes and is not optimized for large-scale parameter inference or full MCMC analyses. Cosmology Dark energy Hubble tension Late-time cosmology BAO CMB CAMB Numerical pipeline Reproducibility