Non-minimally Coupled Running Curvaton for DESI-motivated Dynamical Dark Energy

Abstract

Recent DESI BAO data combined with CMB and supernova measurements suggest a dynamical dark energy that can cross the phantom divide. We show that introducing a non-minimal coupling $\xi {\chi }^{2}R$ to the running-curvaton framework allows a single field to drive early-universe curvature perturbations and late-time phantom-crossing cosmic acceleration without ghost instabilities. Using MCMC background likelihoods with DESI DR2 BAO, Pantheon+ SNe, and a reduced CMB prior, we constrain the cosmological parameters: $H_0=67.88_{-0.61}^{+0.53}\mathrm{km}{\mathrm{s}}^{-1}\mathrm{Mp}{\mathrm{c}}^{-1}$, ${\Omega }_m=0.3072_{-0.0054}^{+0.0059}$, $w_0=-0.922_{-0.063}^{+0.055}$, and $w_a=-0.205_{-0.182}^{+0.173}$. Parameter degeneracies leave the coupling constants weakly constrained, highlighting the need for full perturbation-level analysis using CMB spectra and lensing.

To be published by EPJC