Showing papers by "Rong-Gen Cai published in 2001"
TL;DR: In this article, the authors show that the Cardy-Verlinde formula holds for AdS black holes with AdS asymptotics, but a proper internal energy, which corresponds to the mass of supersymmetric backgrounds, must be subtracted from the total energy.
Abstract: In a recent paper by E. Verlinde, hep-th/0008140, an interesting formula has been put forward, which relates the entropy of a conformal formal field in arbitrary dimensions to its total energy and Casimir energy. This formula has been shown to hold for the conformal field theories that have anti{endash}de Sitter (AdS) duals in the cases of AdS Schwarzschild black holes and AdS Kerr black holes. In this paper we further check this formula with various black holes with AdS asymptotics. For the hyperbolic AdS black holes, the Cardy-Verlinde formula is found to hold if we choose the ''massless'' black hole as the ground state, but in this case, the Casimir energy is negative. For the AdS Reissner-Nordstro''m black holes in arbitrary dimensions and charged black holes in D=5, D=4, and D=7 maximally supersymmetric gauged supergravities, the Cardy-Verlinde formula holds as well, but a proper internal energy, which corresponds to the mass of supersymmetric backgrounds, must be subtracted from the total energy. We fail to rewrite the entropy of corresponding conformal field theories in terms of the Cardy-Verlinde formula for the AdS black holes in Lovelock gravity.
111 citations
TL;DR: In this paper, a brane universe is investigated in the domain-wall black hole background, where the tension term of the brane is equal to the surface counterterm, and a Cardy-Verlinde-like formula is found, which relates the entropy density of the QFT to its energy density.
Abstract: We. consider a class of domain-wall black hole solutions in dilaton gravity with a Liouville-type dilaton potential. Using the surface counterterm. approach we calculate the stress-energy tensor of quantum field theory QFT) corresponding to the domain-wall black hole in the domain-wall-QFT correspondence. A brane universe is investigated in the domain-wall black hole background. When the tension term of the brane is equal to the surface counterterm, we find that the equation of motion of the brane can be mapped to the standard form of Friedmann-Robertson-Walker equations, but with a varying gravitational constant on the brane. A Cardy-Verlinde-like formula is found, which relates the entropy density of the QFT to its energy density. At the moment when the brane crosses the black hole horizon of the back.-round, the Cardy-Verlinde-like formula coincides with the Friedmann equation of the brane universe, and the Hubble entropy bound is saturated by the entropy of domain-wall black holes.
72 citations
TL;DR: In this article, the authors investigate the propagation of photons in the back ground of electromagnetic field, up to the leading order of the noncommutativity parameter, and show that the velocity of photons can be larger than the speed of light when the propagating direction of photons is perpendicular to the direction of background magnetic field.
46 citations
TL;DR: In this article, the authors discuss the question of whether the entropy of cosmological horizon in some asymptotically de Sitter spaces can be described by the Cardy-Verlinde formula.
Abstract: In this paper we discuss the question of whether the entropy of cosmological horizon in some asymptotically de Sitter spaces can be described by the Cardy-Verlinde formula, which is supposed to be an entropy formula of conformal field theory in any dimension. For the Schwarzschild-de Sitter solution, although the gravitational mass is always negative (in the sense of the prescription in hep-th/0110108 to calculate the conserved charges of asymptotically de Sitter spaces), we find that indeed the entropy of cosmological horizon can be given by using naively the Cardy-Verlinde formula. The entropy of pure de Sitter spaces can also be expressed by the Cardy-Verlinde formula. For the topological de Sitter solutions, which have a cosmological horizon and a naked singularity, the Cardy-Verlinde formula also works well. Our result is in favour of the dS/CFT correspondence.
14 citations
TL;DR: In this article, the authors obtained supergravity duals of decoupled theories in (5+1) dimensions corresponding to noncommutative open string (NCOS) theory, open D-string (OD1) theory and open D5-brane (OD5) theory.
Abstract: It is well-known that (N, M) 5-branes of type IIB supergravity form a non-threshold bound state with (N', M') strings called the (F, D1, NS5, D5) bound state where the strings lie along one of the spatial directions of the 5-branes (hep-th/9905056). By taking low energy limits in appropriate ways on this supergravity configuration, we obtain the supergravity duals of various decoupled theories in (5+1) dimensions corresponding to noncommutative open string (NCOS) theory, open D-string (OD1) theory and open D5-brane (OD5) theory. We then study the SL(2; Z) transformation properties of these theories. We show that when the asymptotic value of the axion (chi(o)) is rational (for which chi(o) can be put to zero), NCOS theory is always related to OD1 theory by strong-weak or S-duality symmetry. We also discuss the self-duality conjecture (hep-th/0006062) of both NCOS and OD1 theories. On the other hand, when chi(o) is irrational, we find that SL(2; Z) duality on NCOS theory gives another NCOS theory with different values of the parameters, but for OD1 theory SL(2; Z) duality always gives an NCOS theory. SL(2; Z) transformation on OD5 theory reveals that it gives rise to Little String Theory (LST) when chi(o) = rational, but it gives another OD5 theory with different values of the parameters when chi(o) is irrational.
8 citations
TL;DR: In this paper, it was shown that the entropy of cosmological horizon in the Schwarzschild-de Sitter solution can be expressed in a form of the Cardy-Verlinde formula, if one adopts the prescription to compute the gravitational mass from data at early or late time infinity of de Sitter space.
Abstract: We continue the study of thermodynamics of black holes in de Sitter spaces. In a previous paper (hep-th/0111093), we have shown that the entropy of cosmological horizon in the Schwarzschild-de Sitter solution and topological de Sitter solution can be expressed in a form of the Cardy-Verlinde formula, if one adopts the prescription to compute the gravitational mass from data at early or late time infinity of de Sitter space. However, this definition of gravitational mass cannot give a similar expression like the Cardy-Verlinde formula for the entropy associated with the horizon of black holes in de Sitter spaces. In this paper, we first generalize the previous discussion to the case of Reissner-Nordstrom-de Sitter and Kerr-de Sitter solutions. Furthermore, we find that the entropy of black hole horizon can also be rewritten in terms of the Cardy-Verlinde formula for these black holes in de Sitter spaces, if we use the definition due to Abbott and Deser for conserved charges in asymptotically de Sitter spaces. We discuss the implication of our result. In addition, we give the first law of de Sitter black hole mechanics.
5 citations
TL;DR: In this article, the supergravity duals of decoupled theories in (5+1) dimensions corresponding to noncommutative open string (NCOS) theory, open D-string (OD1) theory and open D5-brane (OD5) theory were obtained.
Abstract: It is well-known that ($N$, $M$) 5-branes of type IIB supergravity form a non-threshold bound state with ($N'$, $M'$) strings called the (F, D1, NS5, D5) bound state where the strings lie along one of the spatial directions of the 5-branes (hep-th/9905056). By taking low energy limits in appropriate ways on this supergravity configuration, we obtain the supergravity duals of various decoupled theories in (5+1) dimensions corresponding to noncommutative open string (NCOS) theory, open D-string (OD1) theory and open D5-brane (OD5) theory. We then study the $SL(2, Z)$ transformation properties of these theories. We show that when the asymptotic value of the axion ($\chi_0$) is rational (for which $\chi_0$ can be put to zero), NCOS theory is always related to OD1 theory by strong-weak or S-duality symmetry. We also discuss the self-duality conjecture (hep-th/0006062) of both NCOS and OD1 theories. On the other hand, when $\chi_0$ is irrational, we find that $SL(2, Z)$ duality on NCOS theory gives another NCOS theory with different values of the parameters, but for OD1 theory $SL(2,Z)$ duality always gives an NCOS theory. $SL(2, Z)$ transformation on OD5 theory reveals that it gives rise to Little String Theory (LST) when $\chi_0$ = rational, but it gives another OD5 theory with different values of the parameters when $\chi_0$ is irrational.
3 citations
TL;DR: In this paper, the authors investigate the propagation of photons in the background of an electromagnetic field, up to the leading order of the noncommutativity parameter, and show that the velocity of photons can be larger than the speed of light when the propagating direction of photons is perpendicular to the direction of background magnetic field.
Abstract: With the help of the Seiberg-Witten map, one can obtain an effective action of a deformed QED from a noncommutative QED. Starting from the deformed QED, we investigate the propagation of photons in the background of electromagnetic field, up to the leading order of the noncommutativity parameter. In our setting (both the electric and magnetic fields are parallel to the coordinate axis $x^1$ and the nonvanishing component of the noncommutativity parameter is $\theta^{23}$), we find that the electric field has no effect on the propagation of photons, but the velocity of photons can be larger than the speed of light ($c=1$) when the propagating direction of photons is perpendicular to the direction of background magnetic field, while the light-cone condition does not change when the propagating direction is parallel to the background magnetic field. The causality associated with the superluminal photons is discussed briefly.
3 citations