Phenomenological Measurement of Omega_m h^2 and H_0 from DESI DR2, Pantheon+, and CMB Shift Data

Abstract

A reproducible MCMC analysis of cosmological parameters (H_0, Omega_m h^2) using DESI DR2 baryon acoustic oscillation measurements, Pantheon+ Type Ia supernovae with full covariance, and CMB shift parameters. We measure H_0 = 69.91 +/- 0.71 km/s/Mpc and Omega_m h^2 = 0.14763 +/- 0.00126, with a 3.6 sigma deviation from Planck 2018 in the matter density. The pipeline is fully reproducible: all data files are downloaded from public sources, the MCMC chain is saved, and the analysis script is provided. This is a phenomenological measurement within standard flat LambdaCDM; no extended framework is assumed or tested. All code, data, and figures are openly available under CC BY 4.0.