arXiv subjects
Publications and source records attributed to Y. Leblanc.
The microcanonical treatment of black holes as opposed to the canonical formulation is reviewed and some major differences are displayed. In particular the decay rates are compared in the two different pictures.
The thermodynamical description of black holes is reviewed and critiqued. We present an alternative, microcanonical description of black holes and discuss the major differences. In particular the decay rates of black holes are compared in the two different pictures.
The Bekenstein-Hawking ``entropy'' of a Kerr-Newman dilaton black hole is computed in a perturbative expansion in the charge-to-mass ratio. The most probable configuration for a gas of such black holes is analyzed in the microcanonical formalism and it is argued that it does not satisfy the equipartition principle but a bootstrap condition. It is also suggested that the present results are further support for an interpretation of black holes as excitations of extended objects.
In this paper we analyze the perturbations of the Kerr-Newman dilatonic black hole background. For this purpose we perform a double expansion in both the background electric charge and the wave parameters of the relevant quantities in the Newman-Penrose formalism. We then display the gravitational, dilatonic and electromagnetic equations, which reproduce the static solution (at zero order in the wave parameter) and the corresponding wave equations in the Kerr background (at first order in the wave parameter and zero order in the electric charge). At higher orders in the electric charge one encounters corrections to the propagations of waves induced by the presence of a non-vanishing dilaton. An explicit computation is carried out for the electromagnetic waves up to the asymptotic form of the Maxwell field perturbations produced by the interaction with dilatonic waves. A simple physical model is proposed which could make these perturbations relevant to the detection of radiation coming from the region of space near a black hole.
This work describes new perturbative solutions to the classical, four-dimensional Kerr--Newman dilaton black hole field equations. Our solutions do not require the black hole to be slowly rotating. The unperturbed solution is taken to be the ordinary Kerr solution, and the perturbation parameter is effectively the square of the charge-to-mass ratio $(Q/M)^2$ of the Kerr--Newman black hole. We have uncovered a new, exact conjugation (mirror) symmetry for the theory, which maps the small coupling sector to the strong coupling sector ($ϕ\to -ϕ$). We also calculate the gyromagnetic ratio of the black hole.
Within the context of the recently formulated classical gauge theory of relativistic p-branes minimally coupled to general relativity in D-dimensional spacetimes, we obtain solutions of the field equations which describe black objects. Explicit solutions are found for two cases: D > p+1 (true p-branes) and D = p+1 (p-bags).
We review briefly the thermodynamical interpretation of black hole physics and discuss the problems and inconsistencies in this approach. We provide an alternative interpretation of black holes as quantum objects and investigate the statistical mechanics of a gas of such objects in the microcanonical ensemble. We argue that the theory of black holes has the conformal properties of duality and satisfaction of the statistical bootstrap condition. We show in the context of mean field theory that the thermal vacuum is the false vacuum for a black hole and define a microcanonical vacuum which leads to a number density characteristic of pure states for the Hawking radiation.
Canonical quantization of local field theories is classical black hole spacetimes with a single horizon leads to a particle number density with a thermal distribution in equilibrium at the Hawking temperature. A complete treatment including non-local quantum gravity effects has shown however that the full "thermal vacuum" of the theory is the false vacuum. In this work we find the true vacuum consistent with the complete semiclassical analysis of quantum black holes. The theory is described by a "microcanonical" quantum field theory with fixed energy E = M, the mass of the black hole. Considerations making use of the microcanonical density matrix as well as the idempotency condition show that particles in black hole backgrounds are described by pure states, unlike the canonical formulation.
Two types of semiclassical calculations have been used to study quantum effects in black hole backgrounds, the WKB and the mean field approaches. In this work we systematically reconstruct the logical implications of both methods on quantum black hole physics and provide the link between these two approaches. Our conclusions completely support our previous findings based solely on the WKB method: quantum black holes are effectively p-brane excitations and, consequently, no information loss paradox exists in this problem.
We consider modifications to general relativity by the non-local (classical and quantum) string effects for the case of a D-dimensional Scwarzschild black hole. The classical non-local effects do not alter the spacetime topology (the horizon remains unshifted, at least perturbatively). We suggest a simple analytic continuation of the perturbative result into the non-perturbative domain, which eliminates the black hole singularity at the origin and yields an ultraviolet-finite theory of quantum gravity. We investigate the quantum non- local effects (including massive modes) and argue that the inclusion of these back reactions resolves the problem of the thermal spectrum in the semi- classical approach of field quantization in a black hole background, through the bootstrap condition. The density of states for both the quantum and thermal interpretation of the WKB formula are finally shown to differ quant- itatively when including the non-local effects.
Non-local (alpha prime) corrections to Schwarzschild black holes are shown to invalidate the thermodynamical interpretation of black holes. In particular, the canonical and Bekenstein-Hawking temperatures are not equal. The particle number density of fields quantized in the (alpha prime modified) black hole background is no longer thermal. In the non-perturbative region (alpha prime going to infinity or mass going to zero), an analytic continuation to the number density is shown to vanish exponentially.
We consider modifications to general relativity due to non-local string effects by using perturbation theory about the 4-dimensional Schwarzschild black hole metric. In keeping with our interpretation in previous works of black holes as quantum p-branes we investigate non-local effects due to a critical bosonic string compactified down to 4 dimensions. We show that non-local effects do not alter the spacetime topology (at least perturbatively), but they do lead to violations of the area law of black hole thermodynamics and to Hawking's first law of black hole thermodynamics. We also consider a simple analytic continuation of our perturbaive result into the non-perturbative region, which yields an ultraviolet-finite theory of quantum gravity. The Hawking temperature goes to zero in the non-perturbative region (zero string tension parameter), which is consistent with the view that Planck-size physics is quantum mechanical.
We treat the horizons of charged, dilaton black extended objects as quantum mechanical objects. We show that the S matrix for such an object can be written in terms of a p-brane-like action. The requirements of unitarity of the S matrix and positivity of the p-brane tension equivalent severely restrict the number of space-time dimensions and the allowed values of the dilaton parameter a. Generally, black objects transform at the extremal limit into p-branes.
We extend the considerations of a previous paper on black hole statistical mechanics to the case of black extended objects such as black strings and black membranes in 10-dimensional space-time. We obtain a general expression for the Euclidean action of quantum black p-branes and derive their corresponding degeneracy of states. The statistical mechanics of a gas of black p-branes is then analyzed in the microcanonical ensemble. As in the case of black holes, the equilibrium state is not thermal and the stable configuration is the one for which a single black object carries most of the energy. Again, neutral black p-branes obey the bootstrap condition and it is then possible to argue that their scattering amplitudes satisfy crossing symmetry. Finally, arguments identifying quantum black p-branes with ordinary quantum branes of different dimensionality are presented.
We extend a previous calculation which treated Schwarschild black hole horizons as quantum mechanical objects to the case of a charged, dilaton black hole. We show that for a unique value of the dilaton parameter `a', which is determined by the condition of unitarity of the S matrix, black holes transform at the extremal limit into strings.
We analyze the statistical mechanics of a gas of neutral and charged black holes. The microcanonical ensemble is the only possible approach to this system, and the equilibrium configuration is the one for which most of the energy is carried by a single black hole. Schwarzschild black holes are found to obey the statistical bootstrap condition. In all cases, the microcanonical temperature is identical to the Hawking temperature of the most massive black hole in the gas. U(1) charges in general break the bootstrap property. The problems of black hole decay and of quantum coherence are also addressed.