Two arXiv studies examine whether late-time cosmological anomalies can be explained by interactions within the dark sector rather than by evolving dark energy. One analysis reports that deviations from the standard ΛCDM model seen in recent DESI baryon acoustic oscillation measurements can be matched, without introducing a time-varying dark-energy equation of state, by interacting dark energy frameworks (including coupled quintessence and coupled fluid models). It finds robust evidence for non-zero dark-sector interactions at the 3–5σ level when simultaneously fitting CMB data (Planck, ACT, SPT), DESI BAO, and supernova data, including a DES-Dovekie recalibration. The reported preference persists even after that supernova recalibration, which is described as weakening dynamical dark-energy evidence, and the interacting models are said to provide fits to low- and high-redshift data comparable to or better than a CPL dynamical dark-energy parametrization.
A second study constrains a phenomenological interacting dark energy (ξIDE) model using DESI BAO from DR1 and DR2, cosmic chronometers, compressed CMB likelihoods, and three Type Ia supernova compilations (Pantheon+, DES-Dovekie, Union3). It finds only weak indications of non-zero interactions: the interaction-related combination ξ is close to its ΛCDM expectation, Bayesian evidence favors ΛCDM, and the strongest dataset combination yields ξ+3wX = −0.035 ± 0.023 (about 1.52σ from the non-interacting limit).
