1,048 research outputs found
On the Existence of Soliton and Hairy Black Hole Solutions of su(N) Einstein-Yang-Mills Theory with a Negative Cosmological Constant
We study the existence of soliton and black hole solutions of four-dimensional EinsteinâYangâMills theory with a negative cosmological constant. We prove the existence of non-trivial solutions for any integer N, with N â 1 gauge field degrees of freedom. In particular, we prove the existence of solutions in which all the gauge field functions have no zeros. For fixed values of the parameters (at the origin or event horizon, as applicable) defining the soliton or black hole solutions, if the magnitude of the cosmological constant is sufficiently large, then the gauge field functions all have no zeros. These latter solutions are of special interest because at least some of them will be linearly stable
On the existence of dyons and dyonic black holes in Einstein-Yang-Mills theory
We study dyonic soliton and black hole solutions of the
Einstein-Yang-Mills equations in asymptotically anti-de Sitter space. We prove
the existence of non-trivial dyonic soliton and black hole solutions in a
neighbourhood of the trivial solution. For these solutions the magnetic gauge
field function has no zeros and we conjecture that at least some of these
non-trivial solutions will be stable. The global existence proof uses local
existence results and a non-linear perturbation argument based on the (Banach
space) implicit function theorem.Comment: 23 pages, 2 figures. Minor revisions; references adde
Characterizing asymptotically anti-de Sitter black holes with abundant stable gauge field hair
In the light of the "no-hair" conjecture, we revisit stable black holes in
su(N) Einstein-Yang-Mills theory with a negative cosmological constant. These
black holes are endowed with copious amounts of gauge field hair, and we
address the question of whether these black holes can be uniquely characterized
by their mass and a set of global non-Abelian charges defined far from the
black hole. For the su(3) case, we present numerical evidence that stable black
hole configurations are fixed by their mass and two non-Abelian charges. For
general N, we argue that the mass and N-1 non-Abelian charges are sufficient to
characterize large stable black holes, in keeping with the spirit of the
"no-hair" conjecture, at least in the limit of very large magnitude
cosmological constant and for a subspace containing stable black holes (and
possibly some unstable ones as well).Comment: 33 pages, 13 figures, minor change
Different populations of RNA polymerase II in living mammalian cells
RNA polymerase II is responsible for transcription of most eukaryotic genes, but, despite exhaustive analysis, little is known about how it transcribes natural templates in vivo. We studied polymerase dynamics in living Chinese hamster ovary cells using an established line that expresses the largest (catalytic) subunit of the polymerase (RPB1) tagged with the green fluorescent protein (GFP). Genetic complementation has shown this tagged polymerase to be fully functional. Fluorescence loss in photobleaching (FLIP) reveals the existence of at least three kinetic populations of tagged polymerase: a large rapidly-exchanging population, a small fraction resistant to 5,6-dichloro-1-ÎČ-D-ribofuranosylbenzimidazole (DRB) but sensitive to a different inhibitor of transcription (i.e. heat shock), and a third fraction sensitive to both inhibitors. Quantitative immunoblotting shows the largest fraction to be the inactive hypophosphorylated form of the polymerase (i.e. IIA). Results are consistent with the second (DRB-insensitive but heat-shock-sensitive) fraction being bound but not engaged, while the third (sensitive to both DRB and heat shock) is the elongating hyperphosphorylated form (i.e. IIO)
Autonomous control of underground mining vehicles using reactive navigation
Describes how many of the navigation techniques developed by the robotics research community over the last decade may be applied to a class of underground mining vehicles (LHDs and haul trucks). We review the current state-of-the-art in this area and conclude that there are essentially two basic methods of navigation applicable. We describe an implementation of a reactive navigation system on a 30 tonne LHD which has achieved full-speed operation at a production mine
Geon black holes and quantum field theory
Black hole spacetimes that are topological geons in the sense of Sorkin can
be constructed by taking a quotient of a stationary black hole that has a
bifurcate Killing horizon. We discuss the geometric properties of these geon
black holes and the Hawking-Unruh effect on them. We in particular show how
correlations in the Hawking-Unruh effect reveal to an exterior observer
features of the geometry that are classically confined to the regions behind
the horizons.Comment: 11 pages. Talk given at the First Mediterranean Conference on
Classical and Quantum Gravity, Kolymbari (Crete, Greece), September 2009.
Dedicated to Rafael Sorkin. v2: typesetting bug fixe
Instability of a four-dimensional de Sitter black hole with a conformally coupled scalar field
We study the stability of new neutral and electrically charged
four-dimensional black hole solutions of Einstein's equations with a positive
cosmological constant and conformally coupled scalar field. The neutral black
holes are always unstable. The charged black holes are also shown analytically
to be unstable for the vast majority of the parameter space of solutions, and
we argue using numerical techniques that the configurations corresponding to
the remainder of the parameter space are also unstable.Comment: revtex4, 8 pages, 4 figures, minor changes, accepted for publication
in Phys. Rev.
On the linear stability of solitons and hairy black holes with a negative cosmological constant: the odd-parity sector
Using a recently developed perturbation formalism based on curvature
quantities, we investigate the linear stability of black holes and solitons
with Yang-Mills hair and a negative cosmological constant. We show that those
solutions which have no linear instabilities under odd- and even- parity
spherically symmetric perturbations remain stable under odd-parity, linear,
non-spherically symmetric perturbations.Comment: 26 pages, 1 figur
Gravitating sphalerons and sphaleron black holes in asymptotically anti-de Sitter spacetime
Numerical arguments are presented for the existence of spherically symmetric
regular and black hole solutions of the EYMH equations with a negative
cosmological constant. These solutions approach asymptotically the anti-de
Sitter spacetime. The main properties of the solutions and the differences with
respect to the asymptotically flat case are discussed. The instability of the
gravitating sphaleron solutions is also proven.Comment: 30 pages, LaTeX, 8 Encapsulated PostScript figure
Production and evaporation of Planck scale black holes at the LHC
We review the phenomenology of mini black holes at colliders in light of the latest data from the LHC. By improving the conventional production cross-section, we show that the current non-observation of black hole signals can be explained in terms of quantum gravity effects. In the most optimistic case, black hole production could take place at a scale slightly above the LHC design energy. We also analyse possible new signatures of quantum-corrected Planck-scale black holes: in contrast to the semiclassical scenario the emission would take place in terms of soft particles mostly on the brane
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