999 research outputs found
Near Horizon Extremal Geometry Perturbations: Dynamical Field Perturbations vs. Parametric Variations
In arXiv:1310.3727 we formulated and derived the three universal laws
governing Near Horizon Extremal Geometries (NHEG). In this work we focus on the
Entropy Perturbation Law (EPL) which, similarly to the first law of black hole
thermodynamics, relates perturbations of the charges labeling perturbations
around a given NHEG to the corresponding entropy perturbation. We show that
field perturbations governed by the linearized equations of motion and symmetry
conditions which we carefully specify, satisfy the EPL. We also show that these
perturbations are limited to those coming from difference of two NHEG solutions
(i.e. variations on the NHEG solution parameter space). Our analysis and
discussions shed light on the "no-dynamics" statements of arXiv:0906.2380 and
arXiv:0906.2376.Comment: 38 page
Crimean-congo hemorrhagic fever: Case series from a medical center in golestan province, Northeast of Iran (2004-2006)
Crimean-Congo hemorrhagic fever (CCHF) is a widely distributed lethal disease, worldwide. Humans are usually infected with CCHF virus through a tick bite or close contact with viral contaminated tissues or with blood of domestic animals or of infected patients. The present study reports six cases of CCHF, who were in contact with both infected tissues and blood from sheep. In some regions like Golestan province (North of Iran), clinician suspicion may have an important role in early diagnosis and treatment of the disease. Conservative therapy (intensive monitoring) and prescription of antiviral medication (Ribavirin) accompanied with corticosteroids, was useful at the early stage of CCHF
Wiggling Throat of Extremal Black Holes
We construct the classical phase space of geometries in the near-horizon
region of vacuum extremal black holes as announced in [arXiv:1503.07861].
Motivated by the uniqueness theorems for such solutions and for perturbations
around them, we build a family of metrics depending upon a single periodic
function defined on the torus spanned by the isometry directions. We
show that this set of metrics is equipped with a consistent symplectic
structure and hence defines a phase space. The phase space forms a
representation of an infinite dimensional algebra of so-called symplectic
symmetries. The symmetry algebra is an extension of the Virasoro algebra whose
central extension is the black hole entropy. We motivate the choice of
diffeomorphisms leading to the phase space and explicitly derive the symplectic
structure, the algebra of symplectic symmetries and the corresponding conserved
charges. We also discuss a formulation of these charges with a Liouville type
stress-tensor on the torus defined by the isometries and outline
possible future directions.Comment: 56 pages, 3 figure
Extremal Rotating Black Holes in the Near-Horizon Limit: Phase Space and Symmetry Algebra
We construct the NHEG phase space, the classical phase space of Near-Horizon
Extremal Geometries with fixed angular momenta and entropy, and with the
largest symmetry algebra. We focus on vacuum solutions to dimensional
Einstein gravity. Each element in the phase space is a geometry with
isometries which has vanishing and constant charges. We construct an on-shell vanishing symplectic
structure, which leads to an infinite set of symplectic symmetries. In four
spacetime dimensions, the phase space is unique and the symmetry algebra
consists of the familiar Virasoro algebra, while in dimensions the
symmetry algebra, the NHEG algebra, contains infinitely many Virasoro
subalgebras. The nontrivial central term of the algebra is proportional to the
black hole entropy. This phase space and in particular its symmetries might
serve as a basis for a semiclassical description of extremal rotating black
hole microstates.Comment: Published in PLB, 5 page
in generalized supergravity
We showed in previous work that for homogeneous Yang-Baxter (YB) deformations
of AdSS, the open string metric and coupling, and as a result the
closed string density , remain undeformed. In this work,
in addition to extending these results to the deformation associated with the
modified CYBE, or -deformation, we identify the Page forms as the open
string counterpart for RR fields and demonstrate case by case that the non-zero
Page forms remain invariant under YB deformations. We give a physical meaning
to the Killing vector of generalized supergravity and show for all YB
deformations: 1) appears as a current for center of mass motion on the
worldvolume of a D-branes probing the background, 2) is equal to the
divergence of the noncommutativity parameter, 3) exhibits "holographic"
behavior, where the radial component of vanishes at the AdS boundary, and
4) in pure spinor formalism is related to a certain state in the BRST
cohomology.Comment: 11 pages, 2 column; v2 references updated; v3 to appear in EPJ
p-p' System with B-field, Branes at Angles and Noncommutative Geometry
We study the generic system in the presence of constant NS
2-form field. We derive properties concerning with the
noncommutativity of D-brane worldvolume, the Green functions and the spectrum
of this system. In the zero slope limit, a large number of light states appear
as the lowest excitations in appropriate cases. We are able to relate the
energies of the lowest states after the GSO projection with the configurations
of branes at angles. Through analytic continuation, the system is compared with
the branes with relative motion.Comment: 21 pages, Latex. References regarding to section 3 and 4 added. Typos
correcte
Extensions of AdS_5 x S^5 and the Plane-wave Superalgebras and Their Realization in the Tiny Graviton Matrix Theory
In this paper we consider all consistent extensions of the AdS_5 x S^5
superalgebra, psu(2,2|4), to incorporate brane charges by introducing both
bosonic and fermionic (non)central extensions. We study the Inonu-Wigner
contraction of the extended psu(2,2|4) under the Penrose limit to obtain the
most general consistent extension of the plane-wave superalgebra and compare
these extensions with the possible BPS (flat or spherical) brane configurations
in the plane-wave background. We give an explicit realization of some of these
extensions in terms of the Tiny Graviton Matrix Theory (TGMT)[hep-th/0406214]
which is the 0+1 dimensional gauge theory conjectured to describe the DLCQ of
strings on the AdS_5 x S^5 and/or the plane-wave background.Comment: 27 pages, LaTe
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