1,872 research outputs found

    Super black hole as spinning particle: Supersymmetric baglike core

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    We consider particlelike solutions to supergravity based on the Kerr-Newman black hole (BH) solution. The BH singularity is regularized by means of a phase transition to a new vacuum state near the core region confining a dual gauge field. Supersymmetric BPS-saturated domain wall model is suggested which can provide this phase transition and formation the stable charged superconducting core. For spinning particle the core takes the form of thin, relativistically rotaiting disk.Comment: 9 pages, Latex, plenary talks given at the School-Workshop Praha-Spin-2001 (Prague,July 15-28,2001) and at the XXIV International Workshop on Fundamental Problems of HEP and Field Theory (IHEP, June 2001, Protvino

    The GEMS Approach to Stationary Motions in the Spherically Symmetric Spacetimes

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    We generalize the work of Deser and Levin on the unified description of Hawking radiation and Unruh effect to general stationary motions in spherically symmetric black holes. We have also matched the chemical potential term of the thermal spectrum of the two sides for uncharged black holes.Comment: Latex file, 12 pages, no figure; v2: typos fixed; v3: minor corrections, final version published in JHE

    Involvement of the agmatinergic system in the depressive-like phenotype of the Crtc1 knockout mouse model of depression.

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    Recent studies implicate the arginine-decarboxylation product agmatine in mood regulation. Agmatine has antidepressant properties in rodent models of depression, and agmatinase (Agmat), the agmatine-degrading enzyme, is upregulated in the brains of mood disorder patients. We have previously shown that mice lacking CREB-regulated transcription coactivator 1 (CRTC1) associate behavioral and molecular depressive-like endophenotypes, as well as blunted responses to classical antidepressants. Here, the molecular basis of the behavioral phenotype of Crtc1(-/-) mice was further examined using microarray gene expression profiling that revealed an upregulation of Agmat in the cortex of Crtc1(-/-) mice. Quantitative polymerase chain reaction and western blot analyses confirmed Agmat upregulation in the Crtc1(-/-) prefrontal cortex (PFC) and hippocampus, which were further demonstrated by confocal immunofluorescence microscopy to comprise an increased number of Agmat-expressing cells, notably parvalbumin- and somatostatin-positive interneurons. Acute agmatine and ketamine treatments comparably improved the depressive-like behavior of male and female Crtc1(-/-) mice in the forced swim test, suggesting that exogenous agmatine has a rapid antidepressant effect through the compensation of agmatine deficit because of upregulated Agmat. Agmatine rapidly increased brain-derived neurotrophic factor (BDNF) levels only in the PFC of wild-type (WT) females, and decreased eukaryotic elongation factor 2 (eEF2) phosphorylation in the PFC of male and female WT mice, indicating that agmatine might be a fast-acting antidepressant with N-methyl-D-aspartate (NMDA) receptor antagonist properties. Collectively, these findings implicate Agmat in the depressive-like phenotype of Crtc1(-/-) mice, refine current understanding of the agmatinergic system in the brain and highlight its putative role in major depression

    Production, Collection and Utilization of Very Long-Lived Heavy Charged Leptons

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    If a fourth generation of leptons exists, both the neutrino and its charged partner must be heavier than 45 GeV. We suppose that the neutrino is the heavier of the two, and that a global or discrete symmetry prohibits intergenerational mixing. In that case, non-renormalizable Planck scale interactions will induce a very small mixing; dimension five interactions will lead to a lifetime for the heavy charged lepton of O(1100)O(1-100) years. Production of such particles is discussed, and it is shown that a few thousands can be produced and collected at a linear collider. The possible uses of these heavy leptons is also briefly discussed.Comment: 9 pages Late

    Gauge fixing and the Hamiltonian for cylindrical spacetimes

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    We introduce a complete gauge fixing for cylindrical spacetimes in vacuo that, in principle, do not contain the axis of symmetry. By cylindrically symmetric we understand spacetimes that possess two commuting spacelike Killing vectors, one of them rotational and the other one translational. The result of our gauge fixing is a constraint-free model whose phase space has four field-like degrees of freedom and that depends on three constant parameters. Two of these constants determine the global angular momentum and the linear momentum in the axis direction, while the third parameter is related with the behavior of the metric around the axis. We derive the explicit expression of the metric in terms of the physical degrees of freedom, calculate the reduced equations of motion and obtain the Hamiltonian that generates the reduced dynamics. We also find upper and lower bounds for this reduced Hamiltonian that provides the energy per unit length contained in the system. In addition, we show that the reduced formalism constructed is well defined and consistent at least when the linear momentum in the axis direction vanishes. Furthermore, in that case we prove that there exists an infinite number of solutions in which all physical fields are constant both in the surroundings of the axis and at sufficiently large distances from it. If the global angular momentum is different from zero, the isometry group of these solutions is generally not orthogonally transitive. Such solutions generalize the metric of a spinning cosmic string in the region where no closed timelike curves are present.Comment: 12 pages, accepted for publication in Physical Review

    Gluon self-energy in a two-flavor color superconductor

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    The energy and momentum dependence of the gluon self-energy is investigated in a color superconductor with two flavors of massless quarks. The presence of a color-superconducting quark-quark condensate modifies the gluon self-energy for energies which are of the order of the gap parameter. For gluon energies much larger than the gap, the self-energy assumes the form given by the standard hard-dense loop approximation. It is shown that this modification of the gluon self-energy does not affect the magnitude of the gap to leading and subleading order in the weak-coupling limit.Comment: 21 pages, 6 figures, RevTeX, aps and epsfig style files require

    F-term strings in the Bogomol'nyi limit are also BPS states

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    We derive the Bogomol'nyi equations for supersymmetric Abelian F-term cosmic strings in four-dimensional flat space and show that, contrary to recent statements in the literature, they are BPS states in the Bogomol'nyi limit, but the partial breaking of supersymmetry is from N=2. The second supersymmetry is not obvious in the N=1 formalism, so we give it explicitly in components and in terms of a different set of N=1 chiral superfields. We also discuss the appearance of a second supersymmetry in D-term models, and the relation to N=2 F-term models. The analysis sheds light on an apparent paradox raised by the recent observation that D-term strings remain BPS when coupled to N=1 supergravity, whereas F-term strings break the supersymmetry completely, even in the Bogomol'nyi limit. Finally, we comment on their semilocal extensions and their relevance to cosmology.Comment: 11 pages; References added, minor corrections, matches published versio

    Cooper pair dispersion relation for weak to strong coupling

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    Cooper pairing in two dimensions is analyzed with a set of renormalized equations to determine its binding energy for any fermion number density and all coupling assuming a generic pairwise residual interfermion interaction. \ Also considered are Cooper pairs (CPs) with nonzero center-of-mass momentum (CMM)--usually neglected in BCS theory--and their binding energy is expanded analytically in powers of the CMM up to quadratic terms. A Fermi-sea-dependent {\it linear} term in the CMM dominates the pair excitation energy in weak coupling (also called the BCS regime) while the more familiar quadratic term prevails in strong coupling (the Bose regime). The crossover, though strictly unrelated to BCS theory {\it per se,} is studied numerically as it is expected to play a central role in a model of superconductivity as a Bose-Einstein condensation of CPs where the transition temperature vanishes for all dimensionality d2d\leq 2 for quadratic dispersion, but is {\it nonzero} for all d1d\geq 1 for linear dispersion.Comment: 11 pages plus 3 figures, revised version accepted in Physical Review

    Tracking Black Holes in Numerical Relativity

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    This work addresses and solves the problem of generically tracking black hole event horizons in computational simulation of black hole interactions. Solutions of the hyperbolic eikonal equation, solved on a curved spacetime manifold containing black hole sources, are employed in development of a robust tracking method capable of continuously monitoring arbitrary changes of topology in the event horizon, as well as arbitrary numbers of gravitational sources. The method makes use of continuous families of level set viscosity solutions of the eikonal equation with identification of the black hole event horizon obtained by the signature feature of discontinuity formation in the eikonal's solution. The method is employed in the analysis of the event horizon for the asymmetric merger in a binary black hole system. In this first such three dimensional analysis, we establish both qualitative and quantitative physics for the asymmetric collision; including: 1. Bounds on the topology of the throat connecting the holes following merger, 2. Time of merger, and 3. Continuous accounting for the surface of section areas of the black hole sources.Comment: 14 pages, 16 figure
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