Related papers: Viscosity to entropy ratio at extremality
We give an explicit form of the classical entropy for four-dimensional static near-BPS-saturated black holes of generic N=2 superstring vacua. The expression is obtained by determining the leading corrections in the non-extremality…
We study general black-hole solutions of the low-energy string effective action in arbitrary dimensions using a general metric that can describe them all in a unified way both in the extreme and non-extreme cases. We calculate the mass,…
The thermodynamic and euclidean functional integral approaches to black hole entropy are discussed. The existence of some freedom in the definition of the entropy is pointed out and the possibility of a departure from the semiclassical…
We extract the shear viscosity to entropy density ratio \eta/s of cold fermionic atoms in the unitarity limit from experimental data on the damping of collective excitations. We find that near the critical temperature \eta/s is roughly…
In this note we show that the entropy of BPS, rotating, electrically charged AdS$_7 \times S^4$ black holes can be obtained by an extremization principle involving a particular combination of anomaly coefficients of the six-dimensional…
We study phases of five-dimensional three-charge black holes with a circle in their transverse space. In particular, when the black hole is localized on the circle we compute the corrections to the metric and corresponding thermodynamics in…
Based on a recent proposal for the volume inside a black hole, we calculate the entropy associated with this volume and show that such entropy is proportional to the surface area of the black hole. Together with the consideration of black…
We use the Kerr/CFT correspondence to calculate the entropy for all known extremal stationary and axisymmetric black holes. This is done with the help of two ansatzs that are general enough to cover all such known solutions. Considering…
We show explicitly, by using astrophysical data plus reasonable assumptions for the bulk viscosity in the cosmic fluid, how the magnitude of this viscosity may be high enough to drive the fluid from its position in the quintessence region…
The finiteness of black hole entropy suggest that spacetime is fundamentally discrete, and hints at an underlying relationship between geometry and "information". The foundation of this relationship is yet to be uncovered, but should…
Einstein-Maxwell-Gauss-Bonnet-axion theory in $4$-dimensional spacetime is investigated in this paper through a "Kaluza-Klein-like" process. Dual to systems at finite temperature with background magnetic field on three dimensions, the…
We study the Euler numbers and the entropies of the non-extremal intersecting D-branes in ten-dimensions. We use the surface gravity to constrain the compactification radii. We correctly obtain the integer valued Euler numbers for these…
We find the entropy of Kehagias-Sfetsos black hole in the deformed Ho\v{r}ava-Lifshitz gravity by using the first law of thermodynamics. When applying generalized uncertainty principle (GUP) to Schwarzschild black hole, the entropy…
We calculate the shear viscosity of strongly coupled field theories dual to Gauss-Bonnet gravity at zero temperature with nonzero chemical potential. We find that the ratio of the shear viscosity over the entropy density is $1/4\pi$, which…
In this paper we calculate the entropy of a thin spherical shell that contracts reversibly from infinity down to its event horizon. We find that, for a broad class of equations of state, the entropy of a non-extremal shell is one-quarter of…
The recent theory of 't Hooft [ Nucl. Phys. Suppl. {\bf 68}, 174 (1998)] models the black hole as a system endowed with an envelope of matter that obeys an equation of state in the form $ p=(\gamma -1)\rho$, and acts as a source in…
We study charged black hole solutions in 4-dimensional (4D) Einstein-Gauss-Bonnet-Maxwell theory to the linearized perturbation level. We first compute the shear viscosity to entropy density ratio. We then demonstrate how bulk causal…
We find a class of d=4, N=2 supergravity with $R^2$-interactions that admits exact BPS black holes. The prepotential contains quadratic, cubic and chiral curvature-squared terms. Black hole geometry realizes stretched horizon, and consists…
It is shown that adding hair like electric charge or angular momentum to the black hole decreases the amount of entropy emission. This motivates us to study the emission rate of entropy from black holes and conjecture a maximum limit (upper…
Suggested correspondence between a black hole and a highly excited elementary string is explored. Black hole entropy is calculated by computing the density of states for an open excited string. We identify the square root of oscillator…