Cosmology in new gravitational scalar-tensor theories

Abstract

We investigate the cosmological applications of new gravitational scalar-tensor theories, which are novel modifications of gravity possessing 2+2 propagating degrees of freedom, arising from a Lagrangian that includes the Ricci scalar and its first and second derivatives. Extracting the field equations we obtain an effective dark energy sector that consists of both extra scalar degrees of freedom, and we determine various observables. We analyze two specific models and we obtain a cosmological behavior in agreement with observations, i.e. transition from matter to dark energy era, with the onset of cosmic acceleration. Additionally, for a particular range of the model parameters, the equation-of-state parameter of the effective dark energy sector can exhibit the phantom-divide crossing. These features reveal the capabilities of these theories, since they arise solely from the novel, higher-derivative terms.

8 pages, 4 figures, version published in Phys. Rev. D

References in corpus (14)

• Dynamics of dark energy
• Unified cosmic history in modified gravity: from F(R) theory to Lorentz non-invariant models
• Covariant Galileon
• Modified f(R) gravity consistent with realistic cosmology: from matter dominated epoch to dark energy universe
• Healthy theories beyond Horndeski
• Generalized Galileons: All scalar models whose curved background extensions maintain second-order field equations and stress tensors
• Exploring gravitational theories beyond Horndeski
• Construction of cosmologically viable f(G) gravity models
• Unifying framework for scalar-tensor theories of gravity
• Bi-galileon theory I: motivation and formulation
• Black Holes in Bi-scalar Extensions of Horndeski Theories
• Hamiltonian analysis of spatially covariant gravity
• Fourth order Weyl gravity
• Gravitational scalar-tensor theory

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