Executive Summary : | The standard Λ Cold Dark Matter model, based on Einstein's General Relativity, provides a reasonable interpretation of astrophysical and cosmological observations. However, the model is plagued by several issues, including growing discordance between measurements of cosmological parameters and the Hubble tension, which has become a severe crisis. The Hubble tension, which is the disagreement in the value of the Hubble constant H₀, has been observed in ∼ 5σ+ tension with late-time direct local measurements by the sH0Es team. The existence of dark matter has been inferred by galactic rotation curves, gravitational lensing, and angular power spectrum of the CMB anisotropies. However, another ∼ 3σ discordance is observed between the CMB and large-scale structure (Lss) experiments, known as the clustering (s₈) tension. A complete cosmological model should not be plagued by such discrepancies, and a promising scenario for alleviating this crisis in cosmology has yet to be found. The project aims to look for promising models through modifications to late-time or early-time physics or the theory of gravity consistent with observations from indirect measurements. |