Related papers: Dark Energy with Logarithmic Cosmological Fluid
We propose a new UV-complete dark energy model which is \underbar{\it neither} a cosmological constant nor a slowly rolling scalar field. Our dark energy is the flux of a top form in a hidden sector gauge theory similar to QCD. The top form…
Dark matter modeled as a classical scalar field that interacts only with gravity and with itself by a potential that is close to quartic at large field values and approaches a quadratic form when the field is small would be gravitationally…
We generalize quintom to include the tachyonic kinetic term along with the classical one. For such a model we obtain the expressions for energy density and pressure. For the spatially flat, homogeneous and isotropic Universe with…
Recently, the observed equation of state for dark energy appears to favor values below $-1$. The tendency implies that the nature of dark energy may be quite different from that of the cosmological constant. In view of the adjustment on the…
From a variational action with non-minimal coupling with a scalar field and classical scalar and fermionic interaction, cosmological field equations can be obtained. Imposing a FLRW metric the equations lead directly to a cosmological model…
Nearly seventy per cent of the energy density in the universe is unclustered and exerts negative pressure. This conclusion -- now supported by numerous observations -- poses the greatest challenge for theoretical physics today. I discuss…
Recent analyses from the DESI collaboration suggest that the dark energy density of the Universe may be decreasing with time, slowing the acceleration of the scale factor $a$. Typically these studies are performed assuming an ansatz for the…
Recent cosmological observations suggest that nearly seventy per cent of the energy density in the universe is unclustered and has negative pressure. Several conceptual issues related to the modeling of this component (`dark energy'), which…
It is widely assumed that the observed universe is accelerating due to the existence of a new fluid component called dark energy. In this article, the thermodynamics consequences of a nonzero chemical potential on the dark energy component…
The coupling between the dark components provides a new approach to mitigate the coincidence problem of cosmological standard model. In this paper, dark energy is treated as a fluid with a constant equation of state, whose coupling with…
The early cosmic inflation, when taken along with the recent observations that the universe is currently dominated by a low density vacuum energy, leads to at least two potential problems which modern cosmology must address. First, there is…
Since the discovery of the accelerated expansion of the Universe, the constraints on the equation of state $w_\text{DE}$ of dark energy, the stress-energy component responsible for the acceleration, have tightened significantly. These…
Following the holographic principle, which suggests that the energy density of dark energy may be proportional inversely to the area of the event horizon of the Universe, we have proposed a new energy density of dark energy through the…
We propose a dark energy density based on the Gauss-Bonnet 4-dimensional invariant and its modification. This model avoids the necessity of introducing the black hole limit to define the holographic density, since it can be considered as a…
Motivated by some recent speculative attempts to model the dark energy, scalar fields with negative kinetic energy coupled to gravity without a cosmological constant are considered. It is shown that in the presence of an ordinary fluid, any…
We present a new mechanism for cosmic acceleration consisting of a scalar field coupled to a triplet of classical U(1) gauge fields. The gauge fields are arranged in a homogeneous, isotropic configuration, with both electric- and…
We study the cosmological evolution of two coupled scalar fields with an arbitrary interaction term V_T(\phi,\vp) in the presence of a barotropic fluid, which can be matter or radiation. The force between the barotropic fluid and the scalar…
A cosmological model of dark energy interacting with dark matter and another general component of the universe is considered. The evolution equations for coincidence parameters r and s, which represent the ratios between the dark energy and…
We suggest a scalar model of dark energy with the SO(1,1) symmetry. The model may be reformulated in terms of a real scalar field $\Phi$ and the scale factor $a$ so that the Lagrangian may be decomposed as that of the real quintessence…
A cosmological constant fits all current dark energy data, but requires two extreme fine tunings, both of which are currently explained by anthropic arguments. Here we discuss anti-anthropic solutions to one of these problems: the cosmic…