arXiv subjects

Burkhard Kleihaus

Publications and source records attributed to Burkhard Kleihaus.

At least 109 records · Page 6Linked to original sources

arXiv2010

On the Bekenstein-Hawking area law for black objects with conical singularities

We argue that, when working with the appropriate set of thermodynamical variables, the Bekenstein-Hawking law still holds for asymptotically flat black objects with conical singularities. The mass-energy which enters the first law of thermodynamics does not, however, coincide with the ADM mass; it differs from the latter by the energy associated with the conical singularity, as seen by an asymptotic, static observer. These statements are supported by a number of examples: the Bach-Weyl (double-Schwarzschild) solution, its dihole generalisation in Einstein-Maxwell theory and the five dimensional static black ring.

gr-qc↗

arXiv2010

Rotating Electroweak Sphaleron-Antisphaleron Systems

At finite weak mixing angle the sphaleron solution of Weinberg-Salam theory can be endowed with angular momentum proportional to the electric charge. Here we show, that this holds also for sphaleron-antisphaleron systems such as pairs, chains and vortex rings. We also address the equilibrium conditions for these solutions.

hep-th↗

arXiv2009

Generalized Weyl solutions in d=5 Einstein-Gauss-Bonnet theory: the static black ring

We argue that the Weyl coordinates and the rod-structure employed to construct static axisymmetric solutions in higher dimensional Einstein gravity can be generalized to the Einstein-Gauss-Bonnet theory. As a concrete application of the general formalism, we present numerical evidence for the existence of static black ring solutions in Einstein-Gauss-Bonnet theory in five spacetime dimensions. They approach asymptotically the Minkowski background and are supported against collapse by a conical singularity in the form of a disk. An interesting feature of these solutions is that the Gauss-Bonnet term reduces the conical excess of the static black rings. Analogous to the Einstein-Gauss-Bonnet black strings, for a given mass the static black rings exist up to a maximal value of the Gauss-Bonnet coupling constant $α'$. Moreover, in the limit of large ring radius, the suitably rescaled black ring maximal value of $α'$ and the black string maximal value of $α'$ agree.

gr-qc↗

arXiv2009

Harrison transformation and charged black objects in Kaluza-Klein theory

We generate charged black brane solutions in $D-$dimensions in a theory of gravity coupled to a dilaton and an antisymmetric form, by using a Harrison-type transformation. The seed vacuum solutions that we use correspond to uplifted Kaluza-Klein black strings and black holes in $(D-p)$-dimensions. A generalization of the Marolf-Mann quasilocal formalism to the Kaluza-Klein theory is also presented, the global charges of the black objects being computed in this way. We argue that the thermodynamics of the charged solutions can be derived from that of the vacuum configurations. Our results show that all charged Kaluza-Klein solutions constructed by means of Harrison transformations are thermodynamically unstable in a grand canonical ensemble. The general formalism is applied to the case of nonuniform black strings and caged black hole solutions in $D=5, 6$ Einstein-Maxwell-dilaton gravity, whose geometrical properties and thermodynamics are discussed. We argue that the topology changing transition scenario, which was previously proposed in the vacuum case, also holds in this case. Spinning generalizations of the charged black strings are constructed in six dimensions in the slowly rotating limit. We find that the gyromagnetic ratio of these solutions possesses a nontrivial dependence on the nonuniformity parameter.

hep-th↗

arXiv2009

$d\geq 5$ static black holes with $S^2\times S^{d-4}$ event horizon topology

We present numerical evidence for the existence of new black hole solutions in $d\geq 6$ spacetime dimensions. They approach asymptotically the Minkowski background and have an event horizon topology $S^2\times S^{d-4}$. These static solutions share the basic properties of the nonrotating black rings in five dimensions, in particular the presence of a conical singularity.

hep-th↗

arXiv2009

Charged Boson Stars and Black Holes

We consider boson stars and black holes in scalar electrodynamics with a V-shaped scalar potential. The boson stars come in two types, having either ball-like or shell-like charge density. We analyze the properties of these solutions and determine their domains of existence. When mass and charge become equal, the space-times develop a throat. The shell-like solutions need not be globally regular, but may possess a horizon. The space-times then consist of a Schwarzschild-type black hole in the interior, surrounded by a shell of charged matter, and thus a Reissner-Nordstroem-type space-time in the exterior. These solutions violate black hole uniqueness. The mass of the black hole solutions is related to the mass of the regular shell-like solutions by a mass formula of the type first obtained within the isolated horizon framework.

gr-qc↗

arXiv2008

Electroweak Sphalerons with Spin and Charge

We show that, at finite weak mixing angle the sphaleron solution of Weinberg-Salam theory can be endowed with angular momentum proportional to the electric charge. Carrying baryon number 1/2 these sphalerons with spin and charge may contribute to baryon number violating processes.

hep-ph↗

arXiv2008

Sphalerons, Antisphalerons and Vortex Rings

We present new classical solutions of Weinberg-Salam theory in the limit of vanishing Weinberg angle. In these static axially symmetric solutions, the Higgs field vanishes either on isolated points on the symmetry axis, or on rings centered around the symmetry axis. The solutions represent systems of sphalerons, antisphalerons, and vortex rings.

hep-th↗

arXiv2008

Gravitating Sphaleron-Antisphaleron Systems

We present new classical solutions of Einstein-Yang-Mills-Higgs theory, representing gravitating sphaleron-antisphaleron pair, chain and vortex ring solutions. In these static axially symmetric solutions, the Higgs field vanishes on isolated points on the symmetry axis, or on rings centered around the symmetry axis. We compare these solutions to gravitating monopole-antimonopole systems, associating monopole-antimonopole pairs with sphalerons.

gr-qc↗

arXiv2007

Rotating Boson Stars and Q-Balls II: Negative Parity and Ergoregions

We construct axially symmetric, rotating boson stars with positive and negative parity. Their flat space limits represent spinning Q-balls. $Q$-balls and boson stars exist only in a limited frequency range. The coupling to gravity gives rise to a spiral-like frequency dependence of the mass and charge of boson stars. We analyze the properties of these solutions. In particular, we discuss the presence of ergoregions in boson stars, and determine their domains of existence.

gr-qc↗

arXiv2007

Rotating Black Holes in Higher Dimensions

The properties of higher-dimensional black holes can differ significantly from those of black holes in four dimensions, since neither the uniqueness theorem, nor the staticity theorem or the topological censorship theorem generalize to higher dimensions. We first discuss black holes of Einstein-Maxwell theory and Einstein-Maxwell-Chern-Simons theory with spherical horizon topology. Here new types of stationary black holes are encountered. We then discuss nonuniform black strings and present evidence for a horizon topology changing transition.

hep-th↗

arXiv2007

Interior of Nonuniform Black Strings

We consider nonuniform black strings inside their event horizon. We present numerical evidence, that the singularity touches the horizon as the horizon topology changing transition is reached.

hep-th↗

arXiv2007

Nonabelian solutions in a Melvin magnetic universe

We show the existence of D=4 nonabelian solutions approaching asymptotically a dilatonic Melvin spacetime background. An exact solution generalizing the Chamseddine-Volkov soliton for a nonzero external U(1) magnetic field is also reported.

hep-th↗

arXiv2007

Gravitating Dyons with Large Electric Charge

We consider non-Abelian dyons in Einstein-Yang-Mills-Higgs theory. The dyons are spherically symmetric with unit magnetic charge. For large values of the electric charge the dyons approach limiting solutions, related to the Penney solutions of Einstein-Maxwell-scalar theory.

gr-qc↗

arXiv2007

Rotating nonuniform black string solutions

We explore via linearized perturbation theory the Gregory-Laflamme instability of rotating black strings with equal magnitude angular momenta. Our results indicate that the Gregory-Laflamme instability persists up to extremality for all even dimensions between six and fourteen. We construct rotating nonuniform black strings with two equal magnitude angular momenta in six dimensions. We see a first indication for the occurrence of a topology changing transition, associated with such rotating nonuniform black strings. Charged nonuniform black string configurations in heterotic string theory are also constructed by employing a solution generation technique.

hep-th↗

arXiv2007

Stationary Dyonic Regular and Black Hole Solutions

We consider globally regular and black hole solutions in SU(2) Einstein-Yang-Mills-Higgs theory, coupled to a dilaton field. The basic solutions represent magnetic monopoles, monopole-antimonopole systems or black holes with monopole or dipole hair. When the globally regular solutions carry additionally electric charge, an angular momentum density results, except in the simplest spherically symmetric case. We evaluate the global charges of the solutions and their effective action, and analyze their dependence on the gravitational coupling strength. We show, that in the presence of a dilaton field, the black hole solutions satisfy a generalized Smarr type mass formula.

gr-qc↗

arXiv2006

Spinning Gravitating Skyrmions

We investigate self-gravitating rotating solutions in the Einstein-Skyrme theory. These solutions are globally regular and asymptotically flat. We present a new kind of solutions with zero baryon number, which possess neither a flat limit nor a static limit.

gr-qc↗

arXiv2006

New nonuniform black string solutions

We present nonuniform vacuum black strings in five and six spacetime dimensions. The conserved charges and the action of these solutions are computed by employing a quasilocal formalism. We find qualitative agreement of the physical properties of nonuniform black strings in five and six dimensions. Our results offer further evidence that the black hole and the black string branches merge at a topology changing transition. We generate black string solutions of the Einstein-Maxwell-dilaton theory by using a Harrison transformation. We argue that the basic features of these solutions can be derived from those of the vacuum black string configurations.

hep-th↗