相关论文: Extended quintessence and the primordial helium ab…
We reanalyze a new quintessence scenario in a brane world model, assuming that a quintessence scalar field is confined in our 3-dimensional brane world. We study three typical quintessence models : (1) an inverse-power-law potential, (2) an…
A generic feature of cosmic quintessence models is the possibility of significant energy density in the scalar field during the radiation dominated epoch. This possibility is even greater if the quintessence field begins in a…
There is a tension between observed Helium abundance and the prediction of the standard Big Bang Nucleosynthesis. We show that non-minimally quintessence model may help to reduce this tension between theory and observation.
We discuss BBN in the presence of a non-minimally coupled quintessence model. In some of these models, the gravitational constant and cosmic expansion rate are smaller than standard model predicts. The Helium abundance is then smaller,…
We propose a new quintessence scenario in the brane cosmology, assuming that a quintessence field $Q$ is confined in our 3-dimensional brane world. With a potential $V(Q)= \mu^{\alpha+4} Q^{-\alpha}~(\alpha\geq 2)$, we find that the density…
We discuss the phenomenological model in which the potential energy of the quintessence field depends linearly on the energy density of the spatial curvature. We find that the pressure of the scalar field takes a different form when the…
We investigate the possibility of replacing the cosmological constant with gradual condensation of a scalar field produced during the decay of a superheavy dark matter. The advantage of this class of models to the ordinary quintessence is…
The main aim of this paper is to analyse minimally-coupled scalar-fields -- quintessence and phantom -- as the main candidates to explain the accelerated expansion of the universe and compare its observables to current cosmological…
We reconstruct the shape of the primordial power spectrum of curvature perturbations in extended cosmological models, including addition of massive neutrinos, extra relativistic species or varying primordial helium abundance, from the…
In the general context of scalar-tensor theories, we consider a model in which a scalar field coupled to the Ricci scalar in the gravitational sector of the Lagrangian, is also playing the role of an ``Extended Quintessence'' field,…
An introductory review of the early evolution of the Universe relevant to the primordial synthesis of the light nuclides deuterium, helium-3, helium-4 and lithium-7. The predictions of the element abundances in the "standard", hot, big bang…
Ultralight scalar dark matter can interact with all massive Standard Model particles through a universal coupling. Such a coupling modifies the Standard Model particle masses and affects the dynamics of Big Bang Nucleosynthesis. We model…
The recent observations of type Ia supernovae strongly support that the universe is accelerating now and decelerated in the recent past. By assuming a general relation between the quintessence potential and the quintessence kinetic energy,…
We present new upper and lower bounds to the primordial abundances of deuterium and helium-3 based on observational data from the solar system and the interstellar medium. Independent of any model for the primordial production of the…
In this comment, we show explicitly that the phenomenological model in which the quintessence field depends linearly on the energy density of the spatial curvature can provide acceleration for the universe, contrary to recent claims it…
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…
We examine a quintessence model with a modified exponential potential given by $V(\phi) = V_0(1+e^{-\lambda \phi})$. Unlike quintessence with a standard exponential potential, our model can yield an acceptable accelerated expansion at late…
The presence of a dynamical scalar field in the early universe could significantly affect the `freeze-out' time of particle species. In particular, it was recently shown that an enhancement of the relic abundance of neutralinos can be…
In the past years 'quintessence' models have been considered which can produce the accelerated expansion in the universe suggested by recent astronomical observations. One of the key differences between quintessence and a cosmological…
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…