Related papers: Accelerated expansion and matter creation
We propose that dark energy in the form of a scalar field could effectively couple to dark matter inhomogeneities. Through this coupling energy could be transferred to/from the scalar field, which could possibly enter an accelerated regime.…
It is a puzzle why the densities of dark matter and dark energy are nearly equal today when they scale so differently during the expansion of the universe. This conundrum may be solved if there is a coupling between the two dark sectors. In…
Subject of our study it is the accelerated expansion of the large scale universe, where a varying ghost dark energy can take the role of the dark energy. The model of the varying ghost dark energy considered in this work it is a…
Non-conservation of dark matter can lead to late-time cosmic acceleration. This mechanism is known as the matter creation theory and this replaces the need of dark energy and modified gravity theories. We consider a two-fluid system…
Although the cosmic concordance cosmology is quite successful in fitting data, fine tuning and coincidence problems apparently weaken it. We review several possibilities to ease its problems, by considering various kinds of dynamical Dark…
In this paper we review in detail a number of approaches that have been adopted to try and explain the remarkable observation of our accelerating Universe. In particular we discuss the arguments for and recent progress made towards…
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 discuss a model of non perturbative decay of dark energy into hot and cold dark matter. This model provides a mechanism from the field theory to realize the energy transfer from dark energy into dark matter, which is the requirement to…
Explanations of the late-time cosmic acceleration within the framework of general relativity are plagued by difficulties. General relativistic models are mostly based on a dark energy field with fine-tuned, unnatural properties. There is a…
The existence of dark matter and dark energy in cosmology is implied by various observations, however, they are still unclear because they have not been directly detected. In this Letter, an unified model of dark energy and dark matter that…
While there is plentiful evidence in all fronts of experimental cosmology for the existence of a non-vanishing dark energy (DE) density \rho_D in the Universe, we are still far away from having a fundamental understanding of its ultimate…
A web of interlocking observations has established that the expansion of the Universe is speeding up and not slowing, revealing the presence of some form of repulsive gravity. Within the context of general relativity the cause of cosmic…
The origin of accelerating expansion of the Universe is one the biggest conundrum of fundamental physics. In this paper we review vacuum energy issues as the origin of accelerating expansion - generally called dark energy - and give an…
Using a model for an ideal fluid with a variable number of particles, a phenomenological description of the processes of particle production in strong external fields is investigated. The conformal invariance of the creation law is shown,…
Theoretical results on a conventional approach to the dark energy (DE) concept are reviewed and discussed. According to them, there is absolutely no need for a novel DE component in the Universe, provided that the associated matter-energy…
Dark energy is an elusive concept, which has been introduced two decades ago in order to make the acceleration of the universe a comprehensible phenomenon. However, the nature of this energy is far from being understood, both from a…
In an undulant universe, cosmic expansion is characterized by alternating periods of acceleration and deceleration. We examine cosmologies in which the dark-energy equation of state varies periodically with the number of e-foldings of the…
If the equation of state for "dark energy" varies periodically, the expansion of the Universe may have undergone alternating eras of acceleration and deceleration. We examine a specific form that survives existing observational tests, does…
The acceleration of the cosmic expansion is a fundamental challenge to standard models of particle physics and cosmology. The new physics of dark energy may lie in the nature of gravity, the quantum vacuum, or extra dimensions. I give a…
The standard model of particle physics is marvelously successful. However, it is obviously not a complete or final theory. I shall argue here that the structure of the standard model gives some quite concrete, compelling hints regarding…