Related papers: The Scalar-Tensor Inflationary Cosmology
We propose a novel scenario in which scalar perturbations, that seed the large scale structure of the Universe, are generated without relying on a scalar field (the inflaton). In this framework, inflation is driven by a de Sitter space-time…
We propose a model for cosmic inflation which is based on an effective description of strongly interacting, nonsupersymmetric matter within the framework of dynamical Abelian projection and centerization. The underlying gauge symmetry is…
We investigate the inflationary expansion of the universe induced by higher curvature corrections in M-theory. The inflationary evolution of the geometry is discussed in ref.[1], thus we succeed to analyse metric perturbations around the…
We study the scalar sector of the Two Measures Field Theory (TMT) model in the context of cosmological dynamics. The scalar sector includes the inflaton \phi and the Higgs \upsilon fields. The model possesses gauge and scale invariance. The…
We construct a model of quintessential inflation in Palatini $R^2$ gravity employing a scalar field with a simple exponential potential and coupled to gravity with a running non-minimal coupling. At early times, the field acts as the…
The cosmological constant (term) is the simplest way, presently known, to illustrate the accelerating expansion of the universe. However, because of/despite its simple appearance, there is much confusion surrounding its essence. Theorists…
We present a cosmological model arising from a gravitational theory with an infinite tower of higher-order curvature invariants that can reproduce the entire evolution of the Universe: from inflation to late-time acceleration, without…
For the models of inflation driven by the potential energy of an inflaton field $\phi$, the covariant Galileon Lagrangian $(\partial\phi)^2\Box \phi$ generally works to slow down the evolution of the field. On the other hand, if the…
WE analyse the universe inflation when the source of gravity is electromagnetic fields obeying nonlinear electrodynamics with two parameters and without singularities. The cosmology of the universe with stochastic magnetic fields is…
We investigate the inflation of Universe in a model of four dimensional dilatonic gravity with a massive dilaton field $\Phi$. The dilaton plays simultaneously the roles of an inflation field and a quintessence field. It yields a sequential…
In this paper, we explore the equivalence between two theories, namely f(R) and scalar-tensor theories of gravity. We use this equivalence to explore several f(R) toy models focusing on the inflation epoch of the early universe. The study…
Inflation with tunneling from a false to a true vacuum becomes viable in the presence of a scalar field that slows down the initial de Sitter phase. As a by-product this field also sets dynamically the value of the Newton constant observed…
Here, cosmology is obtained from the variable gravitational constant $ G \propto \phi^{-2}$ with $ \phi(x) $ being a scalar and its fluctuations around the ground state. The gravitational action contains Einstein-Hilbert like term with…
In the present paper we study warm inflationary universe models in the context of a polytropic gas. We derive the characteristics of this model in slow-roll approximation and develop our model in two cases, 1- For a constant dissipative…
The nature of the scalar field responsible for the cosmological inflation, the \qo{inflaton}, is found to be rooted in the most fundamental concept of the Weyl's differential geometry: the parallel displacement of vectors in curved…
We develop a quantum-cosmological framework in which the inflationary potential emerges from the structure of the wave function of the universe rather than being postulated. Starting from the Wheeler-DeWitt equation for a flat…
We present an inflationary universe model which utilizes two coupled real scalar fields. The inflation field $\phi$ experiences a first order phase transition and its potential dominates the energy density of the Universe during the…
We analyze solutions to Friedmann-Robertson-Walker cosmologies in Brans-Dicke theory, where a scalar field is coupled to gravity. Matter is modelled by a $\gamma$-law perfect fluid, including false-vacuum energy as a special case. Through a…
A weakly coupled scalar field $\Phi$ with a simple exponential potential $V=M_P^4\exp(-\lambda\Phi/M_P)$ where $M_P$ is the reduced Planck mass, and $\lambda > 2$, has an attractor solution in a radiation or matter dominated universe in…
A huge value of cosmological constant characteristic for the particle physics and the inflation of early Universe are inherently related to each other: one can construct a fine-tuned superpotential, which produces a flat potential of…