Related papers: Correspondence between dark energy quantum cosmolo…
We use general arguments to examine the energy scales for which a quantum coherent description of gravitating quantum energy units is necessary. The cosmological dark energy density is expected to decouple from the Friedman-Lemaitre energy…
The universe content is considered as a non-perfect fluid with bulk viscosity and can be described by a general equation of state (endowed some deviation from the conventionally assumed cosmic perfect fluid model). An explicitly bulk…
Brans--Dicke scalar--tensor theory provides a conformally coupling of the scalar field with gravity in Einstein's frame. This model is equivalent to an interacting quintessence in which dark matter is coupled to dark energy. This provides a…
We study the extent up to which the equivalence principle is obeyed in models of modified gravity and dark energy involving a single scalar degree of freedom. We focus on the effective field theories of dark energy describing the late time…
The semi-classical approach to the quantum geometrodynamical model is used for the description of the properties of the universe on extremely small spacetime scales. Quantum theory for a homogeneous, isotropic and closed universe is…
The Quantum Cosmology can be understand as the theory of an one object that is the Universe described in terms of fundamental mass groundstate of the free boson string, that is a tachyon - a hypothetical particle with negative mass square,…
We discuss a mechanism that induces a time-dependent vacuum energy on cosmological scales. It is based on the instability induced renormalization triggered by the low energy quantum fluctuations in a Universe with a positive cosmological…
We propose a relativistic model of dark matter reproducing at once the concordance cosmological model $\Lambda$-Cold-Dark-Matter ($\Lambda$-CDM) at cosmological scales, and the phenomenology of the modified Newtonian dynamics (MOND) at…
A cosmological scenario where dark matter interacts with a variable vacuum energy for a spatially flat Friedmann-Robertson-Walker space-time is proposed and analysed to show that with a linear equation of state and a particular interaction…
For a spatially Friedmann-Lema\^{\i}tre-Robertson-Walker cosmology, we propose a multi-scalar field gravitational model. Specifically, we consider a two-scalar field cosmological model in which the kinetic components of the scalar fields…
Within the framework of loop quantum cosmology, there exists a semi-classical regime where spacetime may be approximated in terms of a continuous manifold, but where the standard Friedmann equations of classical Einstein gravity receive…
The consideration of dark energy's quanta, required also by thermodynamics, introduces its chemical potential into the cosmological equations. Isolating its main contribution, we obtain solutions with dark energy decaying to matter or…
The Universe is modeled as a binary mixture whose constituents are described by a van der Waals fluid and by a dark energy density. The dark energy density is considered either as the quintessence or as the Chaplygin gas. The irreversible…
In cosmology based on general relativity, the universe is modeled as a fluid. The transition from the Einstein field equation to its large-scale (cosmological) version is thus analogous to the transition, for a system consisting of a large…
Requiring all massless elementary fields to have conformal scaling symmetry removes a conflict between gravitational theory and the quantum theory of elementary particles and fields. Extending this postulate to the scalar field of the Higgs…
The time variation of fundamental mass scales can have profound cosmological implications. We investigate a particular model of crossover quintessence which is compatible with all present cosmological observations. This model can also…
We analyze scalar field dark energy models minimally and non-minimally coupled to gravity, postulating that a Yukawa-like interacting term is \emph{in form} equivalent for general relativity, teleparallel and symmetric-teleparallel…
The consideration of dark energy's quanta, required also by thermodynamics, introduces its chemical potential into the cosmological equations. Isolating its main contribution, we obtain solutions with dark energy decaying to matter or…
We construct a viable cosmological model based on velocity diffusion of matter particles. In order to ensure the conservation of the total energy-momentum tensor in the presence of diffusion, we include a cosmological scalar field $\phi$…
Cosmological model based on metric of Fridmann-Robertson-Walker with permanent size and acceleration of time is considered. The problem of the dark matter is analyzed within this model .