A periodic oscillatory parametrisation of H(z): fits to DESI DR1 and DR2, comparison with w0waCDM, and mock-catalogue validation

We present the Concentric Orbital Cosmological Model (COCM), an extension of LCDM in which the observable universe is a ring R_n in Keplerian orbit around a cosmological focus C_0, interpreted as a dynamic p-brane in a higher-dimensional bulk. The orbit imprints a periodic multiplicative modulation on the expansion rate H(z). We fit this model to H(z) data from DESI DR1+BAO (n=24) and DESI DR2+BAO (n=14) combined with cosmic chronometers, and compare it directly against w0waCDM. Key results: (1) COCM improves over LCDM with Delta_chi2=10.1 (p=0.018) in DR1 and Delta_chi2=194.6 in DR2.(2) COCM outperforms w0waCDM by Delta_chi2=87.7.(3) COCM+w0wa improves over w0wa alone by Delta_chi2=126.1 (p<0.0001): the two signals are statistically independent.(4) Bootstrap significance rises from 1.2-sigma (DR1) to 1.7-sigma (DR2).(5) MCMC analysis gives A0=0.177+/-0.019 in COCM+w0wa at 9.4-sigma (68% CI: [0.158, 0.193]).(6) The modulation naturally accounts for ~87% of the Hubble tension (4.86 of 5.6 km/s/Mpc) without additional free parameters. This is the fifth paper in the COCM research programme. Related works:P1: DOI 10.5281/zenodo.19950582P2: DOI 10.5281/zenodo.19991607P3: DOI 10.5281/zenodo.20090596P4: DOI 10.5281/zenodo.20096465NT: DOI 10.5281/zenodo.20104113 v4 (May 2026): Complete revision. Added mock catalogue test (N=300, p<0.0033), residuals comparison figure, zero-mean parametrisation correction, structured limitations section, explicit confirmation/falsification criteria for DESI DR3 and Euclid DR1. Survey timelines updated to May 2026. Final editorial pass. Scientific results unchanged. v5 (May 2026): Bayesian evidence via nested sampling (Appendix A, ΔlogZ=0.4 consistent with p=0.049). CMB perturbative compatibility demonstrated numerically (Δl<0.1, 1943 cycles). Added citations: Skilling 2004, Speagle 2020, Kass-Raftery 1995, Calderon et al. 2025, Planck 2020. Editorial compression. All scientific conclusions unchanged.