Related papers: Inflection Point Quintessence
A scale-invariant universe can have a period of accelerated expansion at early times: inflation. We use a frame-invariant approach to calculate inflationary observables in a scale invariant theory of gravity involving two scalar fields -…
We investigate the dynamics of the recently proposed model of assisted inflation. In this model an arbitrary number of scalar fields with exponential potentials evolve towards an inflationary scaling solution, even if each of the individual…
We show that the accelerated expansion of the Universe can be viewed as a crossover phenomenon where the Newton constant and the Cosmological constant are actually scaling operators, dynamically evolving in the attraction basin of a…
Various scenarios of the initial inflation of the universe are distinguished by the choice of a scalar field {\em potential} $U(\phi)$ which simulates a {\it temporarily} non--vanishing {\em cosmological term}. Our new method, which…
The conditions under which cosmologies driven by time varying cosmological terms can be described by a scalar field coupled to a perfect fluid are discussed. An algorithm to reconstruct potentials dynamically and thermodynamically analogue…
We study the entanglement entropy resulting from tracing out local degrees of freedom of a quantum scalar field in an expanding universe. It is known that when field modes become superhorizon during inflation they evolve to increasingly…
In this paper, we investigate the role of scalar field potentials in the dynamical evolution of the Universe. A gravity theory with a non-minimally coupled scalar field with torsion in the geometrical action simulating effective dark energy…
A new model of nonlinear electrodynamics with a dimensional parameter $\beta$ coupled to gravity is considered. We show that an accelerated expansion of the universe takes place if the nonlinear electromagnetic field is the source of the…
A model for the Universe is proposed where it is considered as a mixture of scalar and matter fields. The particle production is due to an irreversible transfer of energy from the gravitational field to the matter field and represented by a…
Dynamical system analysis of a universe model which contains matter, radiation, and quintessence with exponential potential, $V \!(\phi)=V_{\!o} \, exp(-\alpha \kappa \phi) \,$, is studied in the light of recent observations and the…
To understand mechanisms leading to inflation and late acceleration of the Universe it is important to see how one or a set of quantum fields may evolve such that the classical energy-momentum tensor behave similar to a cosmological…
The ultimate fate of life in a universe with accelerated expansion is considered. Previous work showed that life cannot go on indefinitely in a universe dominated by a cosmological constant. In this paper we consider instead other models of…
We study the possibility to construct an observationally viable scenario where both early Inflation and the recently detected accelerated expansion of the universe can be explained by using a single scalar field associated with the Tachyon.…
Models where the accelerated expansion of our Universe is caused by a quintessence scalar field are reviewed. In the framework of high energy physics, the physical nature of this field is discussed and its interaction with ordinary matter…
The possibility of an expanding decelerating Universe in the distant future is investigated in the context of a quintessence scalar field cosmology. Such a conceivable evolution is tested against SNe Ia and $H(z)$ cosmic chronometers data,…
We construct the effective field theory of a perfect fluid in the early universe. Focusing on the case where the fluid has the equation of state of radiation, we show that it may lead to corrections to the background dynamics that can…
Inflection-point inflation is an interesting possibility to realize a successful slow-roll inflation when inflation is driven by a single scalar field with its initial value below the Planck mass ($\phi_I \lesssim M_{Pl}$). In order for a…
The implications of seven popular models of quintessence based on supergravity or M/string theory for the transition from a decelerating to an accelerating universe are explored. All seven potentials can mimic the LambdaCDM model at low…
We investigate the phase-space of a flat FRW universe including both a scalar field, $\phi,$ coupled to matter, and radiation. The model is inspired in scalar-tensor theories of gravity, and thus, related with $F(R)$ theories through…
We consider a noncommutative (NC) inflationary model with a homogeneous scalar field minimally coupled to gravity. The particular NC inflationary setting produces entirely new consequences. We first analyze the free field case and…