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 ΩΛ=0.73 for the present time, the lower bound of wΛ is −0.9. Therefore it is impossible to have wΛ 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.
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.
Here we obtain the new four-dimensional black hole solutions to the Einstein-power-Maxwell-dilaton gravity theory. We solve the coupled scalar, electromagnetic, and gravitational field equations in a ...static and spherically symmetric geometry and show that dilatonic potential, as the solution to the scalar field equation, can be written as a generalized Liouville potential. We obtain three classes of novel charged dilaton black hole solutions, in the presence of power law nonlinear electrodynamics, which are asymptotically nonflat and non-anti-de Sitter. Then we calculate the conserved and thermodynamic quantities from geometrical and thermodynamical approaches, separately. Since the results of these two alternative approaches are identical, one can argue that the first law of black hole thermodynamics is valid for all of the new black hole solutions. We study thermodynamic stability or phase transition of the black holes using the canonical ensemble method. The points of type-1 and type-2 phase transitions and the ranges at which the black holes remain stable are indicated by considering the heat capacity of the black hole solutions. The global stability of the black holes is studied through the grand canonical ensemble method. Regarding the Gibbs free energy of the black holes, we find the points of Hawking-Page phase transition and ranges of the horizon radii at which the black holes are globally stable.
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 ΩΛ=0.73 for the present time, the lower bound of wΛeff 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.
We study some aspects of a class of non-AdS holography where the 3D bulk gravity is given by generalized minimal massive gravity (GMMG). We consider the spacelike warped
A
d
S
3
(
W
A
d
S
3
) black ...hole solution of this model where the 2d dual boundary theory is the warped conformal field theory (WFCT). The charge algebra of the isometries in the bulk and the charge algebra of the vacuum symmetries at the boundary are compatible and this is an evidence for the duality conjecture. Further evidence for this duality is the equality of entanglement entropy and modular Hamiltonian on both sides of the duality. So we consider the modular Hamiltonian for the single interval at the boundary in associated to the modular flow generators of the vacuum. We calculate the gravitational charge in associated to the asymptotic Killing vectors that preserve the metric boundary conditions. Assuming the first law of the entanglement entropy to be true, we introduce the matching conditions between the variables in two side of the duality and we find equality of the modular Hamiltonian variations and the gravitational charge variations in two sides of the duality. According to the results of the present paper we can say with more sure that the dual theory of the warped
AdS
3 black hole solution of GMMG is a Warped CFT.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Previously we have studied the Generalized Minimal Massive Gravity (GMMG) in asymptotically
A
d
S
3
background, and have shown that the theory is free of negative-energy bulk modes. Also we have ...shown GMMG avoids the aforementioned “bulk-boundary unitarity clash”. Here instead of
A
d
S
3
space we consider asymptotically flat space, and study this model in the flat limit. The dual field theory of GMMG in the flat limit is a
B
M
S
3
invariant field theory, dubbed (BMSFT) and we have BMS algebra asymptotically instead of Virasoro algebra. In fact here we present an evidence for this claim. Entanglement entropy of GMMG is calculated in the background in the flat null infinity. Our evidence for mentioned claim is the result for entanglement entropy in filed theory side and in the bulk (in the gravity side). At first using Cardy formula and Rindler transformation, we calculate entanglement entropy of BMSFT in three different cases. Zero temperature on the plane and on the cylinder, and non-zero temperature case. Then we obtain the entanglement entropy in the bulk. Our results in gravity side are exactly in agreement with field theory calculations.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this paper we study the Generalized Minimal Massive Gravity (GMMG) in asymptotically AdS3 background. The generalized minimal massive gravity theory is realized by adding the CS deformation term, ...the higher derivative deformation term, and an extra term to pure Einstein gravity with a negative cosmological constant. We study the linearized excitations around the AdS3 background and find that at special point (tricritical) in parameter space the two massive graviton solutions become massless and they are replaced by two solutions with logarithmic and logarithmic-squared boundary behavior. So it is natural to propose that GMMG model could also provide a holographic description for a 3-rank Logarithmic Conformal Field Theory (LCFT). We calculate the energy of the linearized gravitons in AdS3 background, and show that the theory is free of negative-energy bulk modes. Then we obtain the central charges of the CFT dual explicitly and show GMMG also avoids the aforementioned “bulk-boundary unitarity clash”. After that we show that General Zwei–Dreibein Gravity (GZDG) model can reduce to GMMG model. Finally by a Hamiltonian analysis we show that the GMMG model has no Boulware–Deser ghosts and this model propagates only two physical modes.
In this Letter we consider a correspondence between the holographic dark energy density and Chaplygin gas energy density in FRW universe. Then we reconstruct the potential and the dynamics of the ...scalar field which describe the Chaplygin cosmology.
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.
Interacting holographic phantom Setare, M.R.
The European physical journal. C, Particles and fields,
05/2007, Letnik:
50, Številka:
4
Journal Article
Recenzirano
Odprti dostop
In this paper we consider the holographic model of interacting dark energy in non-flat universe. With the choice of c≤0.84, the interacting holographic dark energy can be described by a phantom ...scalar field. Then we show this phantomic description of the holographic dark energy with c≤0.84 and reconstruct the potential of the phantom scalar field.
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