Scalar-Tensor Gravity and DESI 2024 BAO data

Understand

We discuss the implications of the DESI 2024 BAO data on scalar-tensor models of gravity.

• We consider four representative models: induced gravity (IG, equivalent to Jordan-Brans-Dicke), where we either fix today's value of the effective gravitational constant on cosmological scales to the Newton's constant or allow them to differ, Jordan-Brans-Dicke supplemented with a Galileon term (BDG), and early modified gravity (EMG) with a conformal coupling.
• In this way it is possible to investigate how different modified gravity models compare with each other when confronted with DESI 2024 BAO data.
• Compared to previous analyses, for all of these models, the combination of Planck and DESI data favors a larger value of the key parameter of the theory, such as the nonminimal coupling to gravity or the Galileon term, leading also to a larger value of $H_0$, due to the known degeneracy between these parameters.