Related papers: Fermionic Tachyons as a Source of Dark Energy
The solution of the field equations of the conformal theory of gravitation with Dirac scalar field in Cartan-Weyl spacetime at the very early Universe is obtained. In this theory dark energy (describing by an effective cosmological…
Accelerated expansion of the Universe may result from an anti-frictional force that is self-consistently exerted on cold dark matter (CDM). Cosmic anti-friction is shown to give rise to an effective negative pressure of the cosmic medium.…
Many candidate models for dark energy are based on the existence of a classical scalar field. In the context of Quantum Field Theory (QFT), we briefly discus the condensation of such a field from a light quantum scalar field produced by…
The introduction of an interaction for dark energy to the standard cosmology offers a potential solution to the cosmic coincidence problem. We examine the conditions on the dark energy density that must be satisfied for this scenario to be…
Is Dark Energy justified as an alternative to the cosmological constant $\Lambda$ in order to explain the acceleration of the cosmic expansion ? It turns out that a straightforward dimensional analysis of Einstein equation provides us with…
We argue that the occurrence of late-time acceleration can conveniently be described by first-order general relativity covariantly coupled to fermions. Dark energy arises as a Bardeen-Cooper-Schrieffer condensate of fermions which forms in…
The accelerated expansion of the universe implies the existence of an energy contribution known as dark energy. Associated with the cosmological constant in the standard model of cosmology, the nature of this dark energy is still unknown.…
We show that the presence of a temporal electromagnetic field on cosmological scales generates an effective cosmological constant which can account for the accelerated expansion of the universe. Primordial electromagnetic quantum…
Accepting the Komar mass definition of a source with energy-momentum tensor $T_{\mu\nu}$, and using the thermodynamic pressure definition, we find a relaxed energy-momentum conservation law. Thereinafter, we study some cosmological…
Dark energy appears to be the dominant component of the physical Universe, yet there is no persuasive theoretical explanation for its existence or magnitude. The acceleration of the Universe is, along with dark matter, the observed…
This paper deals with dark and phantom energy in the tachyon and sub-quantum models for dark energy. We obtain that the simplest condition for such a regime to occur in these scenarios is that the scalar field be Wick rotated to imaginary…
To explain the acceleration of the cosmological expansion researchers have considered an unusual form of mass-energy generically called dark energy. Dark energy has a ratio of pressure over mass density which obeys $w=p/\rho <-1/3$. This…
Einstein's Field Equations have proven applicable across many scales, from black holes to cosmology. Even the mysterious Cosmological Constant found a physical interpretation in the so-called ``dark energy'' causing the accelerated cosmic…
We analyse dark energy models where self-interacting three-forms or phantom fields drive the accelerated expansion of the Universe. The dynamics of such models is often studied by rewriting the cosmological field equations in the form of a…
The discovery of cosmic acceleration has triggered a consistent body of theoretical work aimed at modeling its phenomenology and understanding its fundamental physical nature. In recent years, a powerful formalism that accomplishes both…
A new model for the universe filled with a generalized Chaplygin fluid is considered which unitarily describes as a single vacuum entity both a quintessence scalar field and a cosmological constant, so unifying the notion of dark energy.…
Recent observations from the DESI survey have reignited the debate on the true nature of dark energy, challenging the standard model of cosmology. The results suggest a preference for dynamical dark energy rather than a constant. Several…
It has been recently shown that tachyonic chameleon model of dark energy in which tachyon scalar field non-minimally coupled to the matter admits stable scaling attractor solution that could give rise to the late-time accelerated expansion…
We propose in this Letter a holographic model of tachyon dark energy. A connection between the tachyon scalar-field and the holographic dark energy is established, and accordingly, the potential of the holographic tachyon field is…
In this paper we introduce the fractional dark energy model, in which the accelerated expansion of the Universe is driven by a nonrelativistic gas (composed by either fermions or bosons) with a noncanonical kinetic term. The kinetic energy…