MaVaN neutrino-dark energy coupling fits DESI DR2 BAO but yields no decisive Bayesian edge over flat LCDM
Preprint examines three MaVaN dark-energy models against DESI DR2 and auxiliary probes; coupling remains allowed but Bayesian evidence does not favor any variant over LCDM. Neutrino mass bounds span 0.06-0.3 eV and depend strongly on supernova sample. Results highlight need for next-generation BAO and lensing data to resolve parameter degeneracies.
The analysis derives background equations for constant-w, exponential-potential, and CPL-type cases, then samples posteriors with emcee against DESI DR2 BAO, compressed Planck, and one supernova compilation at a time. H0 and Omega_m0 shift primarily with the chosen supernova sample, reproducing the pattern seen in other DESI DR2 studies. Non-zero coupling values appear in some chains but change sign or magnitude with prior choice and model parameterization.
Bayesian evidence ratios versus flat LCDM are inconclusive across all three cases, indicating that current data lack the leverage to favor dynamical neutrino mass over a cosmological constant. Neutrino mass upper bounds vary by nearly a factor of five depending on which supernova catalog anchors the fit, underscoring the dominant role of low-redshift distance-ladder systematics.
Future DESI year-3 and year-5 releases, combined with tighter CMB lensing and DESI full-shape analyses, will shrink the coupling posterior volume by a factor of two to three. Only then can the models be subjected to a decisive evidence test rather than the present suggestive but non-preferred status.
Sharma et al.: DESI DR3 full-shape analysis will exclude |beta| > 0.1 at 95% CL within 18 months if the coupling signal remains below current noise floor.
Sources (2)
- [1]Primary Source(https://arxiv.org/abs/2609.25090)
- [2]Supporting Source(https://arxiv.org/abs/2404.03002)