Related papers: Dark Energy, Scalar-Tensor Gravity and Large Extra…
In this work we explore a model of the universe in which dark energy is modelled explicitely with both a dynamical quintessence field (with a double exponential self-interaction potential) and a cosmological constant. For a given region of…
We explore unification of dark matter and dark energy in a theory containing a scalar field of non-Lagrangian type, obtained by direct insertion of a kinetic term into the energy-momentum tensor. This scalar is different from quintessence,…
The generalized hybrid metric-Palatini theory of gravity admits a scalar-tensor representation in terms of two interacting scalar fields. We show that, upon an appropriate choice of the interaction potential, one of the scalar fields…
We present here some recent results concerning scalar-tensor Dark Energy models. These models are very interesting in many respects: they allow for a consistent phantom phase, the growth of matter perturbations is modified. Using a…
We investigate cosmology of massive electrodynamics and explore the possibility whether massive photon could provide an explanation of the dark energy. The action is given by the scalar-vector-tensor theory of gravity which is obtained by…
Recent observations suggest that the accelerated expansion of the Universe at late times is caused by a temporally changing dark energy component, rather than the constant one in the standard $\Lambda$CDM scenario. In this context…
Recently, attempts have been made to understand the apparent near coincidence of the present dark energy and matter energy in terms of a dynamical attractor-like solution for the evolution of a scalar field. In these models the field…
This talk is based on my work in collaboration with B. Boisseau, D. Polarski, and A.A. Starobinsky. The most natural and best-motivated alternatives to general relativity are the so-called "scalar-tensor" theories, in which the…
Although equivalent to general relativity, teleparallel gravity is conceptually speaking a completely different theory. In this theory, the gravitational field is described by torsion, not by curvature. By working in this context, a new…
We highlight a viable mechanism leading to the formation of dark energy structures on sub-horizon cosmological scales, starting from linear perturbations in scalar-tensor cosmologies. We show that the coupling of the dark energy scalar…
We investigate the connection between dark energy and fourth order gravity by analyzing the behavior of scalar perturbations around a Friedmann-Robertson-Walker background. The evolution equations for scalar perturbation are derived using…
In this Letter, we motivate the fact that couplings between a scalar field and the Standard Model with strengths $10^{-6}(m_\phi/{\rm eV})^{-1/4}$ relative to gravity yield the total measured cosmological dark matter abundance over a broad…
Scalar-tensor theories are studied in the context of cosmological evolution, where the expansion history of the Universe is reconstructed. It is considered quintessence/phantom models, where inflation and cosmic acceleration are reproduced.…
This talk presents a pedagogical discussion of how precision distance-redshift observations can map out the recent expansion history of the universe, including the present acceleration and the transition to matter dominated deceleration.…
Scalar fields with inverse power-law effective potentials may provide a negative pressure component to the energy density of the universe today, as required by cosmological observations. In order to be cosmologically relevant today, the…
The accelerated expansion of the universe is a rather established fact in cosmology and many different models have been proposed as a viable explanation. Many of these models are based on the standard general relativistic framework of…
In this paper, we consider a normal branch of the DGP cosmological model with a quintessence scalar field on the brane as the dark energy component. Using the dynamical system approach, we study the stability properties of the model. We…
In this work, we explore some cosmological implications of the model proposed by M. Visser in 1998. In his approach, Visser intends to take in account mass for the graviton by means of an additional bimetric tensor in the Einstein's field…
We explore the cosmic evolution of a scalar field which is identified with the four dimensional spacetime volume. Given a specific form for the Lagrangian of the scalar field, a new holographic dark energy model is present. The energy…
Can local fluctuations of a ``Quintessence'' scalar field play a dynamical role in the gravitational clustering and cosmic structure formation process? We address this question in the general framework of scalar-tensor theories of gravity.…