Evidence for a periodic modulation of H(z) independent of dynamical dark energy in DESI DR2 data

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