Speaker
Description
We investigate the cosmological applications of new gravitational scalar-tensor theories and we
analyze them in the light of H0 tension. In these theories the Lagrangian contains the Ricci scalar
and its first and second derivatives in a specific combination that makes them free of ghosts, thus
corresponding to healthy bi-scalar extensions of general relativity. We examine two specific models,
and for particular choices of the model parameters we find that the effect of the additional terms is
negligible at high redshifts, obtaining a coincidence with ΛCDM cosmology, however as time passes
the deviation increases and thus at low redshifts the Hubble parameter acquires increased values
(H0 ≈ 74km/s/M pc) in a controlled way. The mechanism behind this behavior is the fact that the
effective dark-energy equation-of-state parameter exhibits phantom behavior, which implies faster
expansion, which is one of the sufficient conditions that are capable of alleviating the H0 tension.
Lastly, we confront the models with Cosmic Chronometer (CC) data showing full agreement within
1σ confidence level.
| sshreyabbanerjee@gmail.com | |
| Affiliation | Friedrich Alexander University, Germany |
