2,642 research outputs found

    Einstein-Yang-Mills-Chern-Simons solutions in D=2n+1 dimensions

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    We investigate finite energy solutions of the Einstein--Yang-Mills--Chern-Simons system in odd spacetime dimensions, D=2n+1, with n>1. Our configurations are static and spherically symmetric, approaching at infinity a Minkowski spacetime background. In contrast with the Abelian case, the contribution of the Chern-Simons term is nontrivial already in the static, spherically symmetric limit. Both globally regular, particle-like solutions and black holes are constructed numerically for several values of D. These solutions carry a nonzero electric charge and have finite mass. For globally regular solutions, the value of the electric charge is fixed by the Chern-Simons coupling constant. The black holes can be thought as non-linear superpositions of Reissner-Nordstrom and non-Abelian configurations. A systematic discussion of the solutions is given for D=5, in which case the Reissner-Nordstrom black hole becomes unstable and develops non-Abelian hair. We show that some of these non-Abelian configurations are stable under linear, spherically symmetric perturbations. A detailed discussion of an exact D=5 solution describing extremal black holes and solitons is also provided.Comment: 34 pages, 14 figures; v2: misprints corrected and references adde

    Instantonic dyons of Yang-Mills--Chern-Simons models in d=2n+1 dimensions, n>2

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    We investigate finite energy solutions of Yang-Mills--Chern-Simons systems in odd spacetime dimensions, d=2n+1, with n>2. This can be carried out systematically for all n, but the cases n=3,4 corresponding to a 7,8 dimensional spacetime are treated concretely. These are static and spherically symmetric configurations, defined in a flat Minkowski background. The value of the electric charge is fixed by the Chern-Simons coupling constant.Comment: 15 pages, 4 figure

    Stable black hole solutions with non-Abelian fields

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    We construct finite mass, asymptotically flat black hole solutions in d=4 Einstein-Yang-Mills theory augmented with higher order curvature terms of the gauge field. They possess non-Abelian hair in addition to Coulomb electric charge, and, below some non-zero critical temperature, they are thermodynamically preferred over the Reissner-Nordstrom solution. Our results indicate the existence of hairy non-Abelian black holes which are stable under linear, spherically symmetric perturbations.Comment: 8 pages, 3 figure

    Asymptotically flat, stable black hole solutions in Einstein--Yang-Mills--Chern-Simons theory

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    We construct finite mass, asymptotically flat black hole solutions in d=5 Einstein--Yang-Mills--Chern-Simons theory. Our results indicate the existence of a second order phase transition between Reissner-Nordstrom solutions and the non-Abelian black holes which generically are thermodynamically preferred. Some of the non-Abelian configurations are also stable under linear, spherically symmetric perturbations. In addition a solution in closed form describing an extremal black hole with non-Abelian hair is found for a special value of the Chern-Simons coupling constant.Comment: 9 pages, 3 figure

    Nonabelian solutions in N=4, D=5 gauged supergravity

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    We consider static, nonabelian solutions in N=4, D=5 Romans' gauged supergravity model. Numerical arguments are presented for the existence of asymptotically anti-de Sitter configurations in the N=4+N=4^+ version of the theory, with a dilaton potential presenting a stationary point. Considering the version of the theory with a Liouville dilaton potential, we look for configurations with unusual topology. A new exact solution is presented, and a counterterm method is proposed to compute the mass and action.Comment: 15 pages, 4 figure

    On a Petrov-type D homogeneous solution

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    We present a new two-parameter family of solutions of Einstein gravity with negative cosmological constant in 2+1 dimensions. These solutions are obtained by squashing the anti-de Sitter geometry along one direction and posses four Killing vectors. Global properties as well as the four dimensional generalization are discussed, followed by the investigation of the geodesic motion. A simple global embedding of these spaces as the intersection of four quadratic surfaces in a seven dimensional space is obtained. We argue also that these geometries describe the boundary of a four dimensional nutty-bubble solution and are relevant in the context of AdS/CFT correspondence.Comment: 20 pages, TeX fil

    AdS5_5 rotating non-Abelian black holes

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    We present arguments for the existence of charged, rotating black holes with equal magnitude angular momenta in d=5d=5 Einstein-Yang-Mills theory with negative cosmological constant. These solutions posses a regular horizon of spherical topology and approach asymptotically the Anti-de Sitter spacetime background. The black hole solutions have also an electric charge and a nonvanishing magnetic flux through the sphere at infinity. Different from the static case, no regular solution with a nonvanishing angular momenta is found for a vanishing event horizon radius.Comment: 14 pages, 7 figure

    Positive surgical margins in nephron-sparing surgery; the great unknown

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    There is a currently a general trend towards organ-preserving surgery, and urology is no exception. Specifically, nephron-sparing surgery (NSS) has gained general acceptance for T1a renal cell carcinoma (guidelines recommendations). Moreover T1b, T2 and even T3 stage tumors have been included on the nephron sparing list at some centers. An unresolved issue is that of positive surgical margins (PSM), not only their detection but also the implications for follow up and treatment. This paper highlights data available on risk factors for PSM, their clinical relevance, and possible therapeutic consequences. From the surgeon’s viewpoint, NSS is a daring and risky surgical procedure. Urological guidelines stress the importance of NSS, and thus the trend is moving in that direction. Unresolved, however, is the problem of PSM. Trifecta, MIC, and pentafecta are applicable concepts which attempt to define the optimal endpoint of NSS, but further elaboration is necessary. Specifically, research needs to focus less on the concept of definitive margins and more on their identification and avoidance. Although some studies suggest that PSMs do not influence overall survival rate, the basic idea of preserving tissue that is not cancerous leads to further medical, social, and psychological considerations
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