12,317 research outputs found
First Law of Black Rings Thermodynamics in Higher Dimensional Dilaton Gravity with p + 1 Strength Forms
We derive the first law of black rings thermodynamics in n-dimensional
Einstein dilaton gravity with additional (p+1)-form field strength being the
simplest generalization of five-dimensional theory containing a stationary
black ring solution with dipole charge. It was done by means of choosing any
cross section of the event horizon to the future of the bifurcation surface.Comment: 6 pages, to be published in Phys.Rev.D1
Non-Abelian pp-waves in D=4 supergravity theories
The non-Abelian plane waves, first found in flat spacetime by Coleman and
subsequently generalized to give pp-waves in Einstein-Yang-Mills theory, are
shown to be 1/2 supersymmetric solutions of a wide variety of N=1 supergravity
theories coupled to scalar and vector multiplets, including the theory of SU(2)
Yang-Mills coupled to an axion \sigma and dilaton \phi recently obtained as the
reduction to four-dimensions of the six-dimensional Salam-Sezgin model. In this
latter case they provide the most general supersymmetric solution. Passing to
the Riemannian formulation of this theory we show that the most general
supersymmetric solution may be constructed starting from a self-dual Yang-Mills
connection on a self-dual metric and solving a Poisson equation for e^\phi. We
also present the generalization of these solutions to non-Abelian AdS pp-waves
which allow a negative cosmological constant and preserve 1/4 of supersymmetry.Comment: Latex, 1+12 page
Moduli, Scalar Charges, and the First Law of Black Hole Thermodynamics
We show that under variation of moduli fields the first law of black
hole thermodynamics becomes , where are the scalar charges. We also show
that the ADM mass is extremized at fixed , , when the moduli
fields take the fixed value which depend only on electric
and magnetic charges. It follows that the least mass of any black hole with
fixed conserved electric and magnetic charges is given by the mass of the
double-extreme black hole with these charges. Our work allows us to interpret
the previously established result that for all extreme black holes the moduli
fields at the horizon take a value depending only
on the electric and magnetic conserved charges: is such
that the scalar charges .Comment: 3 pages, no figures, more detailed versio
Multi-black holes and instantons in effective string theory
The effective action for string theory which takes into account non-minimal
coupling of moduli admits multi-black hole solutions. The euclidean
continuation of these solutions can be interpreted as an instanton mediating
the splitting and recombination of the throat of extremal magnetically charged
black holes.Comment: 10 pages, plain Te
Non-asymptotically flat, non-AdS dilaton black holes
We show that previously known non-asymptotically flat static black hole
solutions of Einstein-Maxwell-dilaton theory may be obtained as near-horizon
limits of asymptotically flat black holes. Specializing to the case of the
dilaton coupling constant , we generate from the
non-asymptotically flat magnetostatic or electrostatic black holes two classes
of rotating dyonic black hole solutions. The rotating dyonic black holes of the
``magnetic'' class are dimensional reductions of the five-dimensional
Myers-Perry black holes relative to one of the azimuthal angles, while those of
the ``electric'' class are twisted dimensional reductions of rotating dyonic
Rasheed black strings. We compute the quasi-local mass and angular momentum of
our rotating dyonic black holes, and show that they satisfy the first law of
black hole thermodynamics, as well as a generalized Smarr formula. We also
discuss the construction of non-asymptotically flat multi-extreme black hole
configurations.Comment: Minor corrections. 2 references added. To appear in Physical Review
Integrable Cosmological Models From Higher Dimensional Einstein Equations
We consider the cosmological models for the higher dimensional spacetime
which includes the curvatures of our space as well as the curvatures of the
internal space. We find that the condition for the integrability of the
cosmological equations is that the total space-time dimensions are D=10 or D=11
which is exactly the conditions for superstrings or M-theory. We obtain
analytic solutions with generic initial conditions in the four dimensional
Einstein frame and study the accelerating universe when both our space and the
internal space have negative curvatures.Comment: 10 pages, 2 figures, added reference, corrected typos(v2),
explanation improved and references and acknowledgments added, accepted for
publication in PRD(v3
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