相关论文: Null Branes in Curved Backgrounds

We present two new classes of magnetic brane solutions in Einstein-Maxwell-Gauss-Bonnet gravity with a negative cosmological constant. The first class of solutions yields an $(n+1)$-dimensional spacetime with a longitudinal magnetic field…

An application of the Newman-Penrose dyad formalism for description of tensionless (null) string dynamics in 4D Minkowski spacetime is studied in a background of antisymmetric fields. We present a special class of background antisymmetric…

Nonlinear equations of $p$-branes in $D=(2p+1)$-dimensional Minkowski space are discussed. Presented are new exact solutions for a set of spinning $p$-branes with $p=2,3,...,(D-1)/2$ and the Abelian symmetries $U(1)\times U(1)\times...…

In the context of brane cosmology, a scenario where our universe is a 3+1-dimensional surface (the ``brane'') embedded in a five-dimensional spacetime (the ``bulk''), we study geometries for which the brane is anisotropic - more…

We study gravitational perturbations in the Randall-Sundrum two-brane background with scalar-curvature terms in the action for the branes, allowing for positive as well as negative bulk gravitational constant. In the zero-mode…

The supersymmetry arises in certain theories of fermions coupled to gauge fields and gravity in a spacetime of 11 dimensions. The dynamical brane background has mainly been studied for the class of purely bosonic solutions only, but recent…

We consider type IIB (p,q) 5-branes in constant non-zero background tensor potentials, or equivalently, with finite constant field strength on the brane. At linear level, zero-modes are introduced and the physical degrees of freedom are…

Spherically symmetric space-times provide many examples for interesting black hole solutions, which classically are all singular. Following a general program, space-like singularities in spherically symmetric quantum geometry, as well as…

We point out several subtleties arising in brane-world scenarios of cosmological constant cancellation. We show that solutions with curvature singularities are inconsistent, unless the contribution to the effective four-dimentional…

We consider a model for tensionless (null) p-branes with N=1 global supersymmetry in 10-dimensional Minkowski space-time. We give an action for the model and show that it is reparametrization and kappa-invariant. We also find some solutions…

The existence and stability closed timelike curves in a Bonnor-Ward spacetime without torsion line singularities is shown by exhibiting particular examples.

In this paper we obtain supersymmetric brane-like configurations in the vacuum of N=4 gauged $SU(2)\times SU(2)$ supergravity theory in four spacetime dimensions. Almost all of these vacuum solutions preserve either half or one quarter of…

We describe static, brane--like, solutions to vacuum Einstein's equations in D = n + m + 2 dimensional spacetime with m \ge 2 and n \ge 1. These solutions have positive ADM mass but no horizon. The curvature invariants are finite everywhere…

A theorem, giving necessary and sufficient condition for naked singularity formation in spherically symmetric non static spacetimes under hypotheses of physical acceptability, is formulated and proved. The theorem relates existence of…

The null string's equations of motion and constraints in the Kerr spacetime are given. We assume a generic ansatz for the null strings in the Kerr spacetime and we present the resulting solutions in quadratures. Some specific string…

An intense study of the relationship between certain quantum theories of gravity realized on curved backgrounds and suitable gauge theories, has been originated by a remarkable conjecture put forward by Maldacena almost one year ago. Among…

A model with brane-localized curvature terms in a warped background is proposed. The model is based on the Randall-Sundrum solution for the background metric and possesses some interesting features, in particular, the radion field is absent…

We consider a semi-classical approximation to the dynamics of a point particle in a noncommutative space. In this approximation, the noncommutativity of space coordinates is described by a Poisson bracket. For linear Poisson brackets, the…

We construct a kinematical analogue of superluminal travel in the ``warped'' space-times curved by gravitation, in the form of ``super-phononic'' travel in the effective space-times of perfect nonrelativistic fluids. These warp-field…

We study the motion of neutral and charged spinning bodies in curved space-time in the test-particle limit. We construct equations of motion using a closed covariant Poisson-Dirac bracket formulation which allows for different choices of…