Holographic Energy Research Articles

Nuclear and Crystal State Aspects of Overlapping Holographic Phase Patterns

Holographic aspects of 2D Fresnel type memory patterns with 3D couplings and mutual diffractions are considered. Encoding topological charges and spin, the nonlinear interaction potentials are assigned to a shared holographic memory phase space with limited information storage density. Neutral intermediate structures arise in the overlap region. The neutralizing process is regarded as a generator of anti-charge around the topological monopole singularity and maps Coulomb/Kepler to oscillator potentials. The twistorial overlap pattern projects a quasiparticle into the orthogonal holographic extra dimension while providing for a massless and stereographic coupling (Gudermannian function). Basic interactions are: local strong between overlapping topological charges, weak by neutral intermediate quasiparticle overlap patterns, topological charge stereographic long-range interaction in 2D, and a weak long-range higher-dimensional interaction. It is conjectured that the mediating neutral patterns responsible for interaction and energy shifts behave like neutrons, neutrinos, photons, and quasiparticles in 2D crystals (graphene). A cluster of Z=4 partially overlapping topological charge memory patterns could explain the exceptional stability of Beryllium with 5 neutrons. Forcing special phase conditions this principle could act as a prototype for holographic energy releases/drives.

INTERACTING NON-MINIMALLY COUPLED CANONICAL, PHANTOM AND QUINTOM MODELS OF HOLOGRAPHIC DARK ENERGY IN NON-FLAT UNIVERSE

Motivated by our recent work,72 we generalize this work to the interacting non-flat case. Therefore in this paper we deal with canonical, phantom and quintom models, with various fields that are non-minimally coupled to gravity, within the framework of interacting holographic dark energy. We employ the holographic model of interacting dark energy to obtain the equation of state for the holographic energy density in non-flat (closed) universe enclosed by the event horizon measured from the sphere of horizon named L.

A holographic energy model

We suggest a holographic energy model in which the energy coming from spatial curvature, matter and radiation can be obtained by using the particle horizon for the infrared cut-off. We show the consistency between the holographic dark-energy model and the holographic energy model proposed in this paper. Then, we give a holographic description of the universe.

Holographic dark energy in Brans–Dicke cosmology with chameleon scalar field

We study a cosmological implication of holographic dark energy in the Brans–Dicke gravity. We employ the holographic model of dark energy to obtain the equation of state for the holographic energy density in non-flat (closed) universe enclosed by the event horizon measured from the sphere of horizon named L. Our analysis shows that one can obtain the phantom crossing scenario if the model parameter α (of order unity) is tuned accordingly. Moreover, this behavior is achieved by treating the Brans–Dicke scalar field as a Chameleon scalar field and taking a non-minimal coupling of the scalar field with matter. Hence one can generate phantom-like equation of state from a holographic dark energy model in non-flat universe in the Brans–Dicke cosmology framework.

RECONSTRUCTING THE POTENTIALS FOR THE QUINTESSENCE AND TACHYON DARK ENERGY, FROM THE HOLOGRAPHIC PRINCIPLE

We propose holographic quintessence and tachyon models of dark energy. The correspondence between the quintessence and tachyon energy densities with the holographic density allows the reconstruction of the potentials and the dynamics for the quintessence and tachyon fields, in the flat FRW background. The proposed infrared cutoff for the holographic energy density works for two cases of the constant α: for α < 1 we reconstruct the holographic quintessence model in the region before the ω = -1 crossing for the EoS parameter. The cosmological dynamics for α > 1 is also reconstructed for the holographic quintessence and tachyon models.

Interacting holographic dark energy in Brans–Dicke theory

We study cosmological application of interacting holographic energy density in the framework of Brans–Dicke cosmology. We obtain the equation of state and the deceleration parameter of the holographic dark energy in a non-flat universe. As system's IR cutoff we choose the radius of the event horizon measured on the sphere of the horizon, defined as L=ar(t). We find that the combination of Brans–Dicke field and holographic dark energy can accommodate wD=−1 crossing for the equation of state of noninteracting holographic dark energy. When an interaction between dark energy and dark matter is taken into account, the transition of wD to phantom regime can be more easily accounted for than when resort to the Einstein field equations is made.

DENSITY PERTURBATIONS IN DECAYING HOLOGRAPHIC DARK ENERGY MODELS

We study cosmological perturbations in the context of an interacting dark energy model, where the holographic dark energy with IR cutoff decays into the cold dark matter (CDM). For this purpose, we introduce three IR cutoffs of Hubble horizon, particle horizon, and future event horizon. Here we present small perturbations under the case that effective equation of state (EOS: ωeff) for the holographic energy density is determined to be the same negative constant as that for the CDM. Such new matter productions tend to dilute the density perturbations of CDM (matter contrast). For a decelerating universe of ωeff> -1/3, the matter contrast is growing as the universe evolves, while for an accelerating universe of ωeff< -1/3, the matter contrast is decaying, irrespective of the choice of IR cutoff. This shows clearly that the acceleration suppresses the growing of the density perturbations at the early universe.

Interacting Holographic Dark Energy in the Scalar Gauss–Bonnet Gravity

We study cosmological application of interacting holographic dark energy density in the scalar Gauss–Bonnet framework. We employ the interacting holographic model of dark energy to obtain the equation of state for the interacting holographic energy density in a spatially flat universe. Our calculations show that taking ΩΛ = 0.73 for the present time, it is possible to have wΛeff crossing –1. This implies that one can generate a phantom-like equation of state from the interacting holographic dark energy model in flat universe in the scalar Gauss–Bonnet cosmology framework. Then we reconstruct the potential of the scalar field.

Origin of holographic dark energy models

We investigate the origin of holographic dark energy models which were recently proposed to explain the dark energy-dominated universe. For this purpose, we introduce the spacetime foam uncertainty of δ l ⩾ l p α l α − 1 . It was argued that the case of α = 2 / 3 could describe the dark energy with infinite statistics, while the case of α = 1 / 2 can describe the ordinary matter with Bose–Fermi statistics. However, two cases may lead to the holographic energy density if the latter recovers from the geometric mean of UV and IR scales. Hence the dark energy with infinite statistics based on the entropy bound is not an ingredient for deriving the holographic dark energy model. Furthermore, it is shown that the agegraphic dark energy models are the holographic dark energy model with different IR length scales.

Holographic cosmological models on the braneworld

In this Letter we have studied a closed universe which a holographic energy on the brane whose energy density is described by ρ(H)=3c2H2 and we obtain an equation for the Hubble parameter. This equation gave us different physical behavior depending if c2>1 or c2<1 against of the sign of the brane tension.

HOLOGRAPHIC MODIFIED GRAVITY

In this paper, we investigate cosmological application of holographic dark energy density in the modified gravity framework. We employ the holographic model of dark energy to obtain the equation of state for the holographic energy density in a spatially flat universe. Our calculation shows that, taking ΩΛ = 0.73 for the present time, it is possible to have wΛ crossing -1. This implies that one can generate a phantom-like equation of state from a holographic dark energy model in flat universe in the modified gravity cosmology framework. Also, we develop a reconstruction scheme for the modified gravity with f(R) action.

Holography in three-dimensional Kerr–de Sitter space with a gravitational Chern–Simons term

The holographic description of the three-dimensional Kerr–de Sitter space with a gravitational Chern–Simons term is studied, in the context of dS/CFT correspondence. The space has only one (cosmological) event horizon and its mass and angular momentum are identified from the holographic energy–momentum tensor at the asymptotic infinity. The thermodynamic entropy of the cosmological horizon is computed directly from the first law of thermodynamics, with the conventional Hawking temperature, and it is found that the usual Gibbons–Hawking entropy is modified. It is remarked that, due to the gravitational Chern–Simons term, (a) the results go beyond the analytic continuation from AdS, (b) the maximum-mass/N-bound conjecture may be violated and (c) the three-dimensional cosmology is chiral. A statistical mechanical computation of the entropy, from a Cardy-like formula for a dual CFT at the asymptotic boundary, is discussed. Some remarks on the technical differences in the Chern–Simons energy–momentum tensor, from the literature, are also made.

Gauge theory duals of cosmological backgrounds and their energy momentum tensors

We revisit type IIB supergravity backgrounds with null and spacelike singularities with natural gauge theory duals proposed in [S. R. Das, J. Michelson, K. Narayan, and S. P. Trivedi, Phys. Rev. D 74, 026002 (2006)] and [S. R. Das, J. Michelson, K. Narayan, and S. P. Trivedi, Phys. Rev. D 75, 026002 (2007)]. We show that for these backgrounds there are always choices of the boundaries of these deformed ${\mathrm{AdS}}_{5}\ifmmode\times\else\texttimes\fi{}{S}^{5}$ space-times, such that the dual gauge theories live on flat metrics and have space-time dependent couplings. We present a new time dependent solution of this kind where the effective string coupling is always bounded and vanishes at a spacelike singularity in the bulk, and the space-time becomes ${\mathrm{AdS}}_{5}\ifmmode\times\else\texttimes\fi{}{S}^{5}$ at early and late times. The holographic energy momentum tensor calculated with a choice of flat boundary is shown to vanish for null backgrounds and to be generically nonzero for time dependent backgrounds.

The CFT dual of AdS gravity with torsion

We consider the Mielke–Baekler model of three-dimensional AdS gravity with torsion, which has gravitational and translational Chern–Simons terms in addition to the usual Einstein–Hilbert action with cosmological constant. It is shown that the topological nature of the model leads to a finite Fefferman–Graham expansion. We derive the holographic stress tensor and the associated Ward identities and show that, due to the asymmetry of the left- and right-moving central charges, a Lorentz anomaly appears in the dual conformal field theory. Both the consistent and the covariant Weyl and Lorentz anomaly are determined, and the Wess–Zumino consistency conditions for the former are verified. Moreover we consider the most general solution with flat boundary geometry, which describes left- and right-moving gravitational waves on AdS3 with torsion, and show that in this case the holographic energy–momentum tensor is given by the wave profiles. The anomalous transformation laws of the wave profiles under diffeomorphisms preserving the asymptotic form of the bulk solution yield the central charges of the dual CFT and confirm the results that appeared earlier on in the literature. Finally we comment on some points concerning the microstate counting for the Riemann–Cartan black hole.

The shear viscosity of the non-commutative plasma

We compute the shear viscosity of the non-commutative N = 4 super Yang-Mills quantum field theory at strong coupling using the dual supergravity background. Special interest derives from the fact that the background presents an intrinsic anisotropy in space through the distinction of commutative and non-commutative directions. Despite this anisotropy the analysis exhibits the ubiquitous result η/s = 1/4π for two different shear channels. In order to derive this result, we show that the boundary energy momentum tensor must couple to the open string metric. As a byproduct we compute the renormalised holographic energy momentum tensor and show that it coincides with one in the commutative theory.

Black hole and holographic dark energy

We discuss the connection between black hole and holographic dark energy. We examine the issue of the equation of state (EOS) for holographic energy density as a candidate for the dark energy carefully. This is closely related to the EOS for black hole, because the holographic dark energy comes from the black hole energy density. In order to derive the EOS of a black hole, we may use its dual (quantum) systems. Finally, a regular black hole without the singularity is introduced to describe an accelerating universe inside the cosmological horizon. Inspired by this, we show that the holographic energy density with the cosmological horizon as the IR cutoff leads to the dark energy-dominated universe with ωΛ=−1.

Non-flat universe and interacting dark energy model

For non-flat universe of k≠0, we investigate a model of the interacting holographic dark energy with cold dark matter (CDM). There exists a mixture of two components arisen from decaying of the holographic dark energy into CDM. In this case we use the effective equations of state (ωΛeff,ωmeff) instead of the native equations of state (ωΛ,ωm). Consequently, we show that interacting holographic energy models in non-flat universe cannot accommodate a transition from the dark energy to the phantom regime.

The holographic dark energy in non-flat Brans–Dicke cosmology

In this Letter we study cosmological application of holographic dark energy density in the Brans–Dicke framework. We employ the holographic model of dark energy to obtain the equation of state for the holographic energy density in non-flat (closed) universe enclosed by the event horizon measured from the sphere of horizon named L . Our calculation shows, taking Ω Λ = 0.73 for the present time, the lower bound of w Λ is −0.9. Therefore it is impossible to have w Λ crossing −1. This implies that one cannot generate phantom-like equation of state from a holographic dark energy model in non-flat universe in the Brans–Dicke cosmology framework. On the other hand, we suggest a correspondence between the holographic dark energy scenario in flat universe and the phantom dark energy model in framework of Brans–Dicke theory with potential.

Bulk–brane interaction and holographic dark energy

Abstract In this Letter we consider the bulk–brane interaction to obtain the equation of state for the holographic energy density in non-flat universe enclosed by the event horizon measured from the sphere of horizon named L. We assume that the cold dark matter energy density on the brane is conserved, but the holographic dark energy density on the brane is not conserved due to brane–bulk energy exchange. Our calculation shows, taking Ω Λ = 0.73 for the present time, the lower bound of w Λ eff is −0.9. This implies that one cannot generate phantom-like equation of state from an interacting holographic dark energy model in non-flat universe.

Interacting holographic dark energy model in non-flat universe

We employ the holographic model of interacting dark energy to obtain the equation of state for the holographic energy density in non-flat (closed) universe enclosed by the event horizon measured from the sphere of horizon named L.