Scalar-tensor cosmological models

Abstract

We analyze the qualitative behaviors of scalar-tensor cosmologies with an arbitrary monotonic !( ) function. In particular, we are interested on scalartensor theories distinguishable at early epochs from General Relativity (GR) but leading to predictions compatible with solar-system experiments. After extending the method developed by Lorentz-Petzold and Barrow, we establish the conditions required for convergence towards GR at t ! 1. Then, we obtain all the asymptotic analytical solutions at early times which are possible in the framework of these theories. The subsequent qualitative evolution, from these asymptotic solutions until their later convergence towards GR, has been then analyzed by means of numerical computations. From this analysis, we have been able to establish a classi cation of the di erent qualitative behaviors of scalar-tensor cosmological models with an arbitrary monotonic !( ) function. PACS number(s): 04.50.+h, 04.80.+z, 98.80.Cq, 98.80.Hw Typeset using REVT E X 1

Behavior of cosmological models with varyingG

“…Theory 1 has been studied previously by Serna and Alimi [45], Comer et al [46], Barrow [52], and Garcia-Bellido and Quiros [54]. Serna and Alimi [45] paid particular attention to the radiation eras of these models, extending their treatment to allow 2ω + 3 < 0, leading to φ-dominated initial conditions.…”

“…Serna and Alimi [45] paid particular attention to the radiation eras of these models, extending their treatment to allow 2ω + 3 < 0, leading to φ-dominated initial conditions. Their analysis dealt mainly with the early-time behaviour of the models, we shall examine in detail the late-time approach to GR.…”

“…In particular, they found the first dust solutions for scalar-tensor theories more general than BD together with a wide range of new inflationary solutions. Recently, the techniques introduced by Barrow and Mimoso have been used to study the asymptotic behaviour of isotropic and anisotropic cosmological models in scalar-tensor theories [45,46]. The anisotropic case has also been studied by Mimoso and Wands [47].…”

Dark Matter and Dark Energy from Gravitational Symmetry Breaking

“…(7) are almost the same than those of the usual tensor-scalar case ( [14,15]), but in this case the source term is the sum of θ and ordinary matter contributions T m µν + T θ µν . The Klein-Gordon equation for the scalar field Φ, however, is modified due to the violation of the WEP and writes down…”

Qualitative Properties of Scalar-Tensor Theories of Gravity

“…This work was further generalized by Mimosa and Wands (1995b) to various special anisotropic Bianchi models for both BDT and scalar-tensor theories with a particular form for ω(φ); both exact solutions were obtained and the asymptotic limits of the solutions, including their possible isotropization, were studied. The qualitative properties of both isotropic and special anisotropic scalar-tensor theory models was also studied by Serna and Alimi (1996). Isotropization and inflation in anisotropic scalar-tensor theories was discussed earlier by Pimentel and Stein-Schabes (1989).…”