Alleviating cosmological tensions with a hybrid dark sector

We investigate a cosmological model inspired by hybrid inflation, where two scalar fields representing dark energy (DE) and dark matter (DM) interact through a coupling that is proportional to the DE scalar field 1/�. The strength of the coupling is governed solely by the initial condition of the scalar field, ��, which parametrizes deviations from the standard Λ cold dark matter (Λ⁢CDM) model. In this model, the scalar field tracks the behavior of DM during matter domination until it transitions to DE while the DM component decays quicker than standard CDM during matter domination, and is therefore different from some interacting DM-DE models which behave like phantom dark energy. Using Planck 2018 CMB data, Dark Energy Spectroscopic Instrument baryonic acoustic oscillations measurements and Pantheon+supernova observations, we find that the model allows for an increase in �0 that can help reduce the Hubble tension. In addition, we find that higher values of the coupling parameter are correlated with lower values of ��, and a mild decrease of the weak-lensing parameter �8, potentially relevant to address the �8 tension. Bayesian model comparison, however, reveals inconclusive results for most datasets, unless S⁢�0⁡ES data are included, in which case a moderate evidence in favor of the hybrid model is found.