An Updated Constraint on the Effective Field Theory of Dark Energy

Abstract The effective field theory of dark energy (EFTofDE) provides a systematic and model-independent framework to study dark energy (DE) and modified gravity (MG) with one additional scalar degree of freedom. It can describe the known models such as Quintessence, k-essence, DGP, f ( R ), and Horndeski theories. In this work, we update constraints on EFTofDE by utilizing the most up-to-date public data including the Baryon Acoustic Oscillations (DESI DR2), CMB (Planck 2018 and ACT DR6), SNIa (DESY5), weak lensing (DESY3) and full-shape galaxy power (BOSS DR12). We find with the ΛCDM background, general relativity (GR) is favored by the data, while with the w 0 w a CDM background, slight modification to GR is favored, but still consistent with GR within 1.5 σ . We also find the significance level for dynamical DE is greatly reduced within EFTofDE compared to within GR, indicating the degeneracy between dynamical DE and MG.