214 research outputs found
Finite action, holographic conformal anomaly and quantum brane-worlds in d5 gauged supergravity
We report our recent results concerning d5 gauged supergravity (dilatonic
gravity) considered on AdS background. The finite action on such background as
well as d4 holographic conformal anomaly (via AdS/CFT correspondence) are
found. In such formalism the bulk potential is kept to be arbitrary, dilaton
dependent function. Holographic RG in such theory is briefly discussed. d5 AdS
brane-world Universe induced by quantum effects of brane CFT is constructed.
Such brane is spherical, hyperbolic or flat one. Hence, the possibility of
quantum creation of inflationary brane-world Universe is shown.Comment: Proceedings of Londrina conference, April 2000, to appea
Quantum bounds for gravitational de Sitter entropy and the Cardy-Verlinde formula
We analyze different types of quantum corrections to the Cardy-Verlinde
entropy formula in a Friedmann-Robertson-Walker universe and in an (anti)-de
Sitter space. In all cases we show that quantum corrections can be represented
by an effective cosmological constant which is then used to redefine the
parameters entering the Cardy-Verlinde formula so that it becomes valid also
with quantum corrections, a fact that we interpret as a further indication of
its universality. A proposed relation between Cardy-Verlinde formula and the
ADM Hamiltonian constraint is given.Comment: LaTeX file, 15 pages, reference is adde
Induced wormholes due to quantum effects of spherically reduced matter in large N approximation
Using one-loop effective action in large N and s-wave approximation we
discuss the possibility to induce primordial wormholes at the early Universe.
An analytical solution is found for self-consistent primordial wormhole with
constant radius. Numerical study gives the wormhole solution with increasing
throat radius and increasing red-shift function. There is also some indication
to the possibility of a topological phase transition.Comment: LaTeX file, 2 eps figures, 9 pages, few misprints are corrected,
numerics are change
Unified approach to study quantum properties of primordial black holes, wormholes and of quantum cosmology
We review the anomaly induced effective action for dilaton coupled spinors
and scalars in large N and s-wave approximation. It may be applied to study the
following fundamental problems: construction of quantum corrected black holes
(BHs), inducing of primordial wormholes in the early Universe (this effect is
confirmed) and the solution of initial singularity problem. The recently
discovered anti-evaporation of multiple horizon BHs is discussed. The existance
of such primordial BHs may be interpreted as SUSY manifestation. Quantum
corrections to BHs thermodynamics maybe also discussed within such scheme.Comment: LaTeX file and two eps files, to appear in MPLA, Brief Review
Acausality in Gowdy spacetimes
We present a parametrization of and Gowdy cosmological
models which allows us to study both types of topologies simultaneously. We
show that there exists a coordinate system in which the general solution of the
linear polarized special case (with both topologies) has exactly the same
functional dependence. This unified parametrization is used to investigate the
existence of Cauchy horizons at the cosmological singularities, leading to a
violation of the strong cosmic censorship conjecture. Our results indicate that
the only acausal spacetimes are described by the Kantowski-Sachs and the
Kerr-Gowdy metrics.Comment: Typos corrected, 10 pages. Dedicated to Michael P. Ryan on the
occasion of his 60-th birthda
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