The ΛCDM model has been remarkably successful in describing the evolution of the universe. However, it faces notable challenges, such as
the Hubble tension, a discrepancy between the estimated value of the
Hubble constant H0 inferred from Cosmic Microwave Background
measurements under the assumption of ΛCDM and that obtained from local
measurements. In this talk, i will present how scalar-tensor and
bi-scalar-tensor theories can alleviate this tension. To address this
issue, we investigate scalar-tensor models with shift-symmetric friction
term, showing that they can reduce the effective Newton’s constant at
intermediate times, leading to an increased H₀ value. Additionally, we
examine bi-scalar-tensor theories, where the phantom behavior of the
effective dark-energy equation-of-state parameter plays a crucial role
in resolving the tension. These findings highlight the potential of
modified gravity theories to provide viable alternatives to the ΛCDM
paradigm while maintaining theoretical consistency and observational
viability.