Scalar-tensor theories of gravity, neutrino physics, and the H0 tension
Abstract
We use Planck 2018 data to constrain the simplest models of scalar-tensor theories
characterized by a coupling to the Ricci scalar of the type F(σ)R with F(σ) = N2
pl + ξσ2
.
We update our results with previous Planck and BAO data releases obtaining the tightest
constraints to date on the coupling parameters, that is ξ < 5.5 × 10−4
for Npl = 0 (induced
gravity or equivalently extended Jordan-Brans-Dicke) and (Npl
√
8πG) − 1 < 1.8 × 10−5
for
ξ = −1/6 (conformal coupling), both at 95% CL. Because of a modified expansion history
after radiation-matter equality compared to the ΛCDM model, all these dynamical models
accommodate a higher value for H0 and therefore alleviate the tension between Planck/BAO
and distance-ladder measurement from SNe Ia data from 4.4σ at best to 2.7-3.2σ with CMB
alone and 3.5-3.6σ including BAO data.