126084815
Entropy of quantum field in toroidal black hole without brick wall
The calculation of the brick-wall model gives the entropy as two terms: one is proportional to the horizon area and the other is a constant. Then they renormalized the entropy by introducing the Newton’s constant and the entropy correction arising from the higher curvature effective gravitational action. Finally, they got the renormalized entropy whose leading term is proportional to the horizon area of the black hole and the others is precisely the one-loop correction arising from the higher curvature terms of the gravitational action. Their work confirmed the suggestion by Susskind and Uglum [25] that these divergences have the correct form to be absorbed in the Bekenstein–Hawking formula as a renormalization of Newton’s constant.
122100665
Modified de Broglie-Bohm approach to the Schwarzschild black hole
A modified de Broglie?Bohm approach is generalized to the Schwarzschild black hole. By using this method, the quantum potential and the quantum trajectories of the black hole are investigated. And we find that the linear combination of two particular solutions of the black hole wavefunction is not physical although each of them is physical, if we think that the quantum gravity should reduce into its corresponding classical counterpart in which the gravity vanishes. It seems to confirm the argument, given by Alwis and MacIntire, that a possible resolution on the quantum gravity is to give up the superposition principle.
119513098
Thermodynamical properties of apparent horizon in warped DGP braneworld
In this paper we first obtain Friedmann equations for the (n - I)-dimensional brane embedded in the (n +1)-dimensional bulk, with intrinsic curvature term of the brane included in the action (DGP model). Then, we show that one can always rewrite the Friedmann equations in the form of the first law of thermodynamics, dE = T dS + W d V, at apparent horizon on the brane, regardless of whether there is the intrinsic curvature term on the brane or a cosmological constant in the bulk. Using the first law, we extract the entropy expression of the apparent horizon on the brane. We also show that in the case without the intrinsic curvature term, the entropy expressions are the same by using the apparent horizon on the brane and by using the bulk geometry. When the intrinsic curvature appears, the entropy of apparent horizon on the brane has two parts, one pail follows the n-climensional area formula on the brane, and the other part is the same as the entropy in the case without the intrinsic curvature term. As an interesting result, in the warped DGP model, the entropy expression in the bulk and on the brane are not the same. This is reasonable, since in this model gravity on the brane has two parts, one induced from the (n + I)-dimensional bulk gravity and the other due to the intrinsic curvature term on the brane. (c) 2007 Elsevier B.V. All rights reserved.
119282988
Dynamics of an interacting dark energy model in Einstein and loop quantum cosmology
We investigate the background dynamics when dark energy is coupled to dark matter in the Universe described by Einstein cosmology and loop quantum cosmology. We introduce a new general form of dark sector coupling, which presents a more complicated dynamical phase space. Differences in the phase space in obtaining the accelerated scaling attractor in Einstein cosmology and loop quantum cosmology are disclosed.
8468193
Modification to the power spectrum in the brane world inflation driven by the bulk inflaton
We compute the cosmological perturbations generated in the brane world inflation driven by the bulk inflaton. Different from the model in which inflation is a brane effect, we exhibit the modification of the power spectrum of scalar perturbations due to the existence of a fifth dimension. With the change of the initial vacuum, we investigate the dependence of the correction of the power spectrum on the choice of the vacuum.
120889836
QUANTUM CORRECTIONS TO THE ENTROPY OF EXTREME REISSNER–NORDSTRÖM BLACK HOLES
Using brick wall model, the first quantum corrections to the extreme Reissner–Nordstrom black hole entropy due to scalar field as well as electromagnetic field have been calculated. Different quantum entropy values have been obtained for two different kinds of extreme black holes.
119418069
Quasinormal behavior of massless scalar field perturbation in Reissner-Nordstrom anti-de Sitter spacetimes
We present a comprehensive study of the massless scalar field perturbation in the Reissner-Nordstroem anti-de Sitter (RNAdS) space-time and compute its quasinormal modes (QNM). For the lowest lying mode, we confirm and extend the dependence of the QNM frequencies on the black hole charge obtained in previous works. In near extreme limit, under the scalar perturbation we find that the imaginary part of the frequency tends to zero, which is consistent with the previous conjecture based on electromagnetic and axial gravitational perturbations. For the extreme value of the charge, the asymptotic field decay is dominated by a power-law tail, which shows that the extreme black hole can still be stable to scalar perturbations. We also study the higher overtones for the RNAdS black hole and find large variations of QNM frequencies with the overtone number and black hole charge. The nontrivial dependence of frequencies on the angular index l is also discussed.