Gravitational collapse in anti de Sitter space
International Nuclear Information System (INIS)
Garfinkle, David
2004-01-01
A numerical and analytic treatment is presented here of the evolution of initial data of the kind that was conjectured by Hertog, Horowitz and Maeda to lead to a violation of cosmic censorship. That initial data is essentially a thick domain wall connecting two regions of anti de Sitter space. The evolution results in no violation of cosmic censorship, but rather the formation of a small black hole
International Nuclear Information System (INIS)
Liu, James T.; Sabra, W.A.
2005-01-01
The boundary stress tensor approach has proven extremely useful in defining mass and angular momentum in asymptotically anti-de Sitter spaces with CFT duals. An integral part of this method is the use of boundary counterterms to regulate the gravitational action and stress tensor. In the presence of matter, however, ambiguities may arise that are related to the addition of possible finite counterterms. We demonstrate this explicitly for R-charged black holes in AdS 5 , where introduction of a finite counterterm proportional to φ 2 is necessary to properly reproduce the expected mass/charge relation for the black holes
Green's function for anti--de Sitter space gravity
International Nuclear Information System (INIS)
Kleppe, G.
1994-01-01
We solve for the retarded Green's function for linearized gravity in a background with a negative cosmological constant, anti--de Sitter space. In this background, it is possible for a signal to reach spatial infinity in a finite time. Therefore the form of the Green's function depends on a choice of boundary condition at spatial infinity. We take as our condition that a signal which reaches infinity should be lost, not reflected back. We calculate the Green's function associated with this condition, and show that it reproduces the correct classical solution for a point mass at the origin, the anti--de Sitter--Schwarzschild solution
A fond farewell to anti De Sitter space
International Nuclear Information System (INIS)
Freedman, D.Z.
1986-01-01
Recent results on supersymmetry in a fixed Anti de Sitter (AdS) background geometry are summarized. These results include i) required modification of the generators of the O(3,2) isometry group in the AdS Wess-Zumino model, ii) the one-loop renormalization structure of this model, showing that the special 'naturalness' properties of flat space supersymmetry do not extend to AdS, and iii) a non-perturbative Lehmann spectral representation. Open problems suggested by recent work are emphasized. (author)
Fermion tunneling from anti-de Sitter spaces
International Nuclear Information System (INIS)
Chen, Deyou; Yang, Haitang; Zu, Xiaotao
2008-01-01
Kerner and Mann's recent research on the Hawking radiation of the spherically symmetric uncharged black hole shows that the Hawking temperature can be obtained by the fermion tunneling method. In this paper, we extend this work to the general case and view the Hawking radiations of the Reissner-Nordstroem black hole, Kerr black hole and Kerr-Newman black hole in anti-de Sitter spaces. The Hawking temperatures are recovered and are exactly the same as that obtained by other methods. (orig.)
Stable black strings in anti-de sitter space
International Nuclear Information System (INIS)
Hirayama, Takayuki
2002-01-01
In my talk I show a black string which is a foliation of anti-de Sitter (AdS) Schwarzschild black hole becomes classically stable if the size of black hole horizon is larger than the AdS radius even if the black string extends infinitely. I will also give a comment on the relation with the Gubser-Mitra conjecture. This talk is based on our paper (Phys. Rev. D64: 064010, 2001) which is a collaboration with Gungwon Kang
Penrose inequality in anti-de Sitter space
Husain, Viqar; Singh, Suprit
2017-11-01
For asymptotically flat spacetimes the Penrose inequality gives an initial data test for the weak cosmic censorship hypothesis. We give a formulation of this inequality for asymptotically anti-de Sitter (AAdS) spacetimes, and show that the inequality holds for time asymmetric data in spherical symmetry. Our analysis is motivated by the constant-negative-spatial-curvature form of the AdS black hole metric.
Some exact solutions for maximally symmetric topological defects in Anti de Sitter space
Alvarez, Orlando; Haddad, Matthew
2018-03-01
We obtain exact analytical solutions for a class of SO( l) Higgs field theories in a non-dynamic background n-dimensional anti de Sitter space. These finite transverse energy solutions are maximally symmetric p-dimensional topological defects where n = ( p + 1) + l. The radius of curvature of anti de Sitter space provides an extra length scale that allows us to study the equations of motion in a limit where the masses of the Higgs field and the massive vector bosons are both vanishing. We call this the double BPS limit. In anti de Sitter space, the equations of motion depend on both p and l. The exact analytical solutions are expressed in terms of standard special functions. The known exact analytical solutions are for kink-like defects ( p = 0 , 1 , 2 , . . . ; l = 1), vortex-like defects ( p = 1 , 2 , 3; l = 2), and the 't Hooft-Polyakov monopole ( p = 0; l = 3). A bonus is that the double BPS limit automatically gives a maximally symmetric classical glueball type solution. In certain cases where we did not find an analytic solution, we present numerical solutions to the equations of motion. The asymptotically exponentially increasing volume with distance of anti de Sitter space imposes different constraints than those found in the study of defects in Minkowski space.
Quantum corrections in thermal states of fermions on anti-de Sitter space-time
Ambruş, Victor E.; Winstanley, Elizabeth
2017-12-01
We study the energy density and pressure of a relativistic thermal gas of massless fermions on four-dimensional Minkowski and anti-de Sitter space-times using relativistic kinetic theory. The corresponding quantum field theory quantities are given by components of the renormalized expectation value of the stress-energy tensor operator acting on a thermal state. On Minkowski space-time, the renormalized vacuum expectation value of the stress-energy tensor is by definition zero, while on anti-de Sitter space-time the vacuum contribution to this expectation value is in general nonzero. We compare the properties of the vacuum and thermal expectation values of the energy density and pressure for massless fermions and discuss the circumstances in which the thermal contribution dominates over the vacuum one.
Free massless fermionic fields of arbitrary spin in d-dimensional anti-de Sitter space
Energy Technology Data Exchange (ETDEWEB)
Vasiliev, M A
1988-04-25
Free massless fermionic fields of arbitrary spins, corresponding to fully symmetric tensor-spinor irreducible representations of the flat little group SO(d-2), are described in d-dimensional anti-de Sitter space in terms of differential forms. Appropriate linearized higher-spin curvature 2-forms are found. Explicitly gauge invariant higher-spin actions are constructed in terms of these linearized curvatures.
Stability of black holes and solitons in Anti-de Sitter space-time
Energy Technology Data Exchange (ETDEWEB)
Hartmann, Betti
2014-06-15
The stability of black holes and solitons in d-dimensional Anti-de Sitter (AdS{sub d}) space-time against scalar field condensation is discussed. The resulting solutions are “hairy” black holes and solitons, respectively. In particular, we will discuss static black hole solutions with hyperbolic, flat and spherical horizon topology and emphasize that two different type of instabilities exist depending on whether the scalar field is charged or uncharged, respectively. We will also discuss the influence of Gauss-Bonnet curvature terms. The results have applications within the AdS/CFT correspondence and describe e.g. holographic insulator/conductor/superconductor phase transitions.
Heterotic non-linear sigma models with anti-de Sitter target spaces
International Nuclear Information System (INIS)
Michalogiorgakis, Georgios; Gubser, Steven S.
2006-01-01
We calculate the beta function of non-linear sigma models with S D+1 and AdS D+1 target spaces in a 1/D expansion up to order 1/D 2 and to all orders in α ' . This beta function encodes partial information about the spacetime effective action for the heterotic string to all orders in α ' . We argue that a zero of the beta function, corresponding to a worldsheet CFT with AdS D+1 target space, arises from competition between the one-loop and higher-loop terms, similarly to the bosonic and supersymmetric cases studied previously in [J.J. Friess, S.S. Gubser, Non-linear sigma models with anti-de Sitter target spaces, Nucl. Phys. B 750 (2006) 111-141]. Various critical exponents of the non-linear sigma model are calculated, and checks of the calculation are presented
Komar integrals in asymptotically anti-de Sitter space-times
International Nuclear Information System (INIS)
Magnon, A.
1985-01-01
Recently, boundary conditions governing the asymptotic behavior of the gravitational field in the presence of a negative cosmological constant have been introduced using Penrose's conformal techniques. The subsequent analysis has led to expressions of conserved quantities (associated with asymptotic symmetries) involving asymptotic Weyl curvature. On the other hand, if the underlying space-time is equipped with isometries, a generalization of the Komar integral which incorporates the cosmological constant is also available. Thus, in the presence of an isometry, one is faced with two apparently unrelated definitions. It is shown that these definitions agree. This coherence supports the choice of boundary conditions for asymptotically anti-de Sitter space-times and reinforces the definitions of conserved quantities
Null polygonal Wilson loops and minimal surfaces in Anti-de-Sitter space
International Nuclear Information System (INIS)
Alday, Luis F.; Maldacena, Juan
2009-01-01
We consider minimal surfaces in three dimensional anti-de-Sitter space that end at the AdS boundary on a polygon given by a sequence of null segments. The problem can be reduced to a certain generalized Sinh-Gordon equation and to SU(2) Hitchin equations. We describe in detail the mathematical problem that needs to be solved. This problem is mathematically the same as the one studied by Gaiotto, Moore and Neitzke in the context of the moduli space of certain supersymmetric theories. Using their results we can find the explicit answer for the area of a surface that ends on an eight-sided polygon. Via the gauge/gravity duality this can also be interpreted as a certain eight-gluon scattering amplitude at strong coupling. In addition, we give fairly explicit solutions for regular polygons.
Inside and outside stories of black-branes in anti de Sitter space
International Nuclear Information System (INIS)
Hansen, Jakob; Lee, Bum-Hoon; Park, Chanyong; Yeom, Dong-han
2013-01-01
In this paper, we investigate the dynamics inside and outside of black-branes in anti de Sitter space by numerical simulations using double-null formalism. We prepare a charged planar matter shell which, due to a negative cosmological constant, collapses and dynamically forms a black-brane with an apparent horizon, a singularity and a Cauchy horizon. The gravitational collapse cannot form a naked overcharged black-brane and hence weak cosmic censorship is safe. Although mass inflation occurs, the effect is much milder than in the case of charged black holes; hence, strong cosmic censorship seems not to be safe. We observed the scalar field dynamics outside the horizon. There should remain a non-trivial scalar field combination—‘charge cloud’—between the horizon and the boundary. This can give some meaning in terms of the AdS/CFT correspondence. (paper)
Quantum groups, roots of unity and particles on quantized Anti-de Sitter space
International Nuclear Information System (INIS)
Steinacker, H.
1997-01-01
Quantum groups in general and the quantum Anti-de Sitter group U q (so(2,3)) in particular are studied from the point of view of quantum field theory. The author shows that if q is a suitable root of unity, there exist finite-dimensional, unitary representations corresponding to essentially all the classical one-particle representations with (half) integer spin, with the same structure at low energies as in the classical case. In the massless case for spin ≥ 1, open-quotes naiveclose quotes representations are unitarizable only after factoring out a subspace of open-quotes pure gaugesclose quotes, as classically. Unitary many-particle representations are defined, with the correct classical limit. Furthermore, the author identifies a remarkable element Q in the center of U q (g), which plays the role of a BRST operator in the case of U q (so(2,3)) at roots of unity, for any spin ≥ 1. The associated ghosts are an intrinsic part of the indecomposable representations. The author shows how to define an involution on algebras of creation and anihilation operators at roots of unity, in an example corresponding to non-identical particles. It is shown how nonabelian gauge fields appear naturally in this framework, without having to define connections on fiber bundles. Integration on Quantum Euclidean space and sphere and on Anti-de Sitter space is studied as well. The author gives a conjecture how Q can be used in general to analyze the structure of indecomposable representations, and to define a new, completely reducible associative (tensor) product of representations at roots of unity, which generalizes the standard open-quotes truncatedclose quotes tensor product as well as many-particle representations
Quantum groups, roots of unity and particles on quantized Anti-de Sitter space
Energy Technology Data Exchange (ETDEWEB)
Steinacker, Harold [Univ. of California, Berkeley, CA (United States). Dept. of Physics
1997-05-23
Quantum groups in general and the quantum Anti-de Sitter group U_{q}(so(2,3)) in particular are studied from the point of view of quantum field theory. The author shows that if q is a suitable root of unity, there exist finite-dimensional, unitary representations corresponding to essentially all the classical one-particle representations with (half) integer spin, with the same structure at low energies as in the classical case. In the massless case for spin ≥ 1, "naive" representations are unitarizable only after factoring out a subspace of "pure gauges", as classically. Unitary many-particle representations are defined, with the correct classical limit. Furthermore, the author identifies a remarkable element Q in the center of U_{q}(g), which plays the role of a BRST operator in the case of U_{q}(so(2,3)) at roots of unity, for any spin ≥ 1. The associated ghosts are an intrinsic part of the indecomposable representations. The author shows how to define an involution on algebras of creation and anihilation operators at roots of unity, in an example corresponding to non-identical particles. It is shown how nonabelian gauge fields appear naturally in this framework, without having to define connections on fiber bundles. Integration on Quantum Euclidean space and sphere and on Anti-de Sitter space is studied as well. The author gives a conjecture how Q can be used in general to analyze the structure of indecomposable representations, and to define a new, completely reducible associative (tensor) product of representations at roots of unity, which generalizes the standard "truncated" tensor product as well as many-particle representations.
Violating the Weak Cosmic Censorship Conjecture in Four-Dimensional Anti-de Sitter Space
Crisford, Toby; Santos, Jorge E.
2017-05-01
We consider time-dependent solutions of the Einstein-Maxwell equations using anti-de Sitter (AdS) boundary conditions, and provide the first counterexample to the weak cosmic censorship conjecture in four spacetime dimensions. Our counterexample is entirely formulated in the Poincaré patch of AdS. We claim that our results have important consequences for quantum gravity, most notably to the weak gravity conjecture.
Superfield approach to anti de Sitter supersymmetry
International Nuclear Information System (INIS)
Ivanov, E.A.
1979-01-01
A self-contained superfield approach to global supersymmetry in anti de Sitter space (OSp(1.4)) is developed. General transformation laws for OSp(1.4)-superfields are established, and all basic elements of the OSp(1.4)-covariant formalism in the real basis, such as covariant superfield derivatives, invariant integration measure over the superspace OSp(1.4)/O(1.3), etc., are explicitly given. The reducibility questions are analyzed and realizations of OSp(1.4) in the left- and right-handed chiral superspaces are found
FLAT TIME-LIKE SUBMANIFOLDS IN ANTI-DE SITTER SPACE H12n-1(-1)
Institute of Scientific and Technical Information of China (English)
ZUO DAFENG; CHEN QING; CHENG YI
2005-01-01
By using dressing actions of the Gn-1 1,1,n-1-system, the authors study geometric transformations for flat time-like n-submanifolds with flat, non-degenerate normal bun dle in anti-de Sitter space H1 2n-1(-1), where G1,1 n-1,n-1= O(2n - 2, 2)/O(n - 1, 1) ×O(n - 1, 1).
Noncommutative de Sitter and FRW spaces
International Nuclear Information System (INIS)
Burić, Maja; Madore, John
2015-01-01
Several versions of fuzzy four-dimensional de Sitter space are constructed using the noncommutative frame formalism. Although all noncommutative spacetimes which are found have commutative de Sitter metric as a classical limit, the algebras and the differential calculi which define them have many differences, which we derive and discuss
Generic cosmic-censorship violation in anti-de Sitter space.
Hertog, Thomas; Horowitz, Gary T; Maeda, Kengo
2004-04-02
We consider (four-dimensional) gravity coupled to a scalar field with potential V(phi). The potential satisfies the positive energy theorem for solutions that asymptotically tend to a negative local minimum. We show that for a large class of such potentials, there is an open set of smooth initial data that evolve to naked singularities. Hence cosmic censorship does not hold for certain reasonable matter theories in asymptotically anti-de Sitter spacetimes. The asymptotically flat case is more subtle. We suspect that potentials with a local Minkowski minimum may similarly lead to violations of cosmic censorship in asymptotically flat spacetimes, but we do not have definite results.
(Anti-)Evaporation of Schwarzschild-de Sitter Black Holes
Bousso, Raphael; Hawking, Stephen
1997-01-01
We study the quantum evolution of black holes immersed in a de Sitter background space. For black holes whose size is comparable to that of the cosmological horizon, this process differs significantly from the evaporation of asymptotically flat black holes. Our model includes the one-loop effective action in the s-wave and large N approximation. Black holes of the maximal mass are in equilibrium. Unexpectedly, we find that nearly maximal quantum Schwarzschild-de Sitter black holes anti-evapor...
Critical phenomena of regular black holes in anti-de Sitter space-time
Energy Technology Data Exchange (ETDEWEB)
Fan, Zhong-Ying [Peking University, Center for High Energy Physics, Beijing (China)
2017-04-15
In General Relativity, addressing coupling to a non-linear electromagnetic field, together with a negative cosmological constant, we obtain the general static spherical symmetric black hole solution with magnetic charges, which is asymptotic to anti-de Sitter (AdS) space-times. In particular, for a degenerate case the solution becomes a Hayward-AdS black hole, which is regular everywhere in the full space-time. The existence of such a regular black hole solution preserves the weak energy condition, while the strong energy condition is violated. We then derive the first law and the Smarr formula of the black hole solution. We further discuss its thermodynamic properties and study the critical phenomena in the extended phase space where the cosmological constant is treated as a thermodynamic variable as well as the parameter associated with the non-linear electrodynamics. We obtain many interesting results such as: the Maxwell equal area law in the P-V (or S-T) diagram is violated and consequently the critical point (T{sub *},P{sub *}) of the first order small-large black hole transition does not coincide with the inflection point (T{sub c},P{sub c}) of the isotherms; the Clapeyron equation describing the coexistence curve of the Van der Waals (vdW) fluid is no longer valid; the heat capacity at constant pressure is finite at the critical point; the various exponents near the critical point are also different from those of the vdW fluid. (orig.)
Toward de Sitter space from ten dimensions
Moritz, Jakob; Retolaza, Ander; Westphal, Alexander
2018-02-01
Using a 10D lift of nonperturbative volume stabilization in type IIB string theory, we study the limitations for obtaining de Sitter vacua. Based on this we find that the simplest Kachru, Kallosh, Linde, and Trivedi vacua with a single Kähler modulus stabilized by a gaugino condensate cannot be uplifted to de Sitter. Rather, the uplift flattens out due to stronger backreaction on the volume modulus than has previously been anticipated, resulting in vacua which are metastable and supersymmetry breaking, but that are always anti-de Sitter (AdS). However, we also show that setups such as racetrack stabilization can avoid this issue. In these models it is possible to obtain supersymmetric AdS vacua with a cosmological constant that can be tuned to zero while retaining finite moduli stabilization. In this regime, it seems that de Sitter uplifts are possible with negligible backreaction on the internal volume. We exhibit this behavior also from the 10D perspective.
Compact space-like hypersurfaces in de Sitter space
Lv, Jinchi
2005-01-01
We present some integral formulas for compact space-like hypersurfaces in de Sitter space and some equivalent characterizations for totally umbilical compact space-like hypersurfaces in de Sitter space in terms of mean curvature and higher-order mean curvatures.
More on asymptotically anti-de Sitter spaces in topologically massive gravity
International Nuclear Information System (INIS)
Henneaux, Marc; Martinez, Cristian; Troncoso, Ricardo
2010-01-01
Recently, the asymptotic behavior of three-dimensional anti-de Sitter (AdS) gravity with a topological mass term was investigated. Boundary conditions were given that were asymptotically invariant under the two dimensional conformal group and that included a falloff of the metric sufficiently slow to consistently allow pp-wave type of solutions. Now, pp waves can have two different chiralities. Above the chiral point and at the chiral point, however, only one chirality can be considered, namely, the chirality that has the milder behavior at infinity. The other chirality blows up faster than AdS and does not define an asymptotically AdS spacetime. By contrast, both chiralities are subdominant with respect to the asymptotic behavior of AdS spacetime below the chiral point. Nevertheless, the boundary conditions given in the earlier treatment only included one of the two chiralities (which could be either one) at a time. We investigate in this paper whether one can generalize these boundary conditions in order to consider simultaneously both chiralities below the chiral point. We show that this is not possible if one wants to keep the two-dimensional conformal group as asymptotic symmetry group. Hence, the boundary conditions given in the earlier treatment appear to be the best possible ones compatible with conformal symmetry. In the course of our investigations, we provide general formulas controlling the asymptotic charges for all values of the topological mass (not just below the chiral point).
Phase transitions in de Sitter space
Directory of Open Access Journals (Sweden)
Alexander Vilenkin
1983-10-01
Full Text Available An effective potential in de Sitter space is calculated for a model of two interacting scalar fields in one-loop approximation and in a self-consistent approximation which takes into account an infinite set of diagrams. Various approaches to renormalization in de Sitter space are discussed. The results are applied to analyze the phase transition in the Hawking-Moss version of the inflationary universe scenario. Requiring that inflation is sufficiently large, we derive constraints on the parameters of the model.
Krein Spaces in de Sitter Quantum Theories
Czech Academy of Sciences Publication Activity Database
Gazeau, J.P.; Siegl, Petr; Youssef, A.
2010-01-01
Roč. 6, - (2010), 011/1-011/23 ISSN 1815-0659 Institutional research plan: CEZ:AV0Z10480505 Keywords : de Sitter group * undecomposable representations * Krein spaces Subject RIV: BE - Theoretical Physics Impact factor: 0.856, year: 2010
Energy Technology Data Exchange (ETDEWEB)
Prasia, P.; Kuriakose, V.C. [Cochin University of Science and Technology, Department of Physics, Kochi (India)
2017-01-15
In this work we study the Quasi-Normal Modes (QNMs) under massless scalar perturbations and the thermodynamics of linearly charged BTZ black holes in massive gravity in the (Anti)de Sitter ((A)dS) space-time. It is found that the behavior of QNMs changes with the massive parameter of the graviton and also with the charge of the black hole. The thermodynamics of such black holes in the (A)dS space-time is also analyzed in detail. The behavior of specific heat with temperature for such black holes gives an indication of a phase transition that depends on the massive parameter of the graviton and also on the charge of the black hole. (orig.)
Schwinger effect in de Sitter space
Energy Technology Data Exchange (ETDEWEB)
Fröb, Markus B.; Garriga, Jaume [Departament de Física Fonamental i Institut de Ciències del Cosmos, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain); Kanno, Sugumi [Laboratory for Quantum Gravity and Strings and Astrophysics, Cosmology and Gravity Center, Department of Mathematics and Applied Mathematics, University of Cape Town, Private Bag, Rondebosch 7701 (South Africa); Sasaki, Misao; Tanaka, Takahiro [Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan); Soda, Jiro [Department of Physics, Kobe University, Kobe 657-8501 (Japan); Vilenkin, Alexander, E-mail: mfroeb@ffn.ub.edu, E-mail: jaume.garriga@ub.edu, E-mail: sugumi.kanno@uct.ac.za, E-mail: misao@yukawa.kyoto-u.ac.jp, E-mail: jiro@phys.sci.kobe-u.ac.jp, E-mail: tanaka@yukawa.kyoto-u.ac.jp, E-mail: vilenkin@cosmos.phy.tufts.edu [Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford, Massachusetts 02155 (United States)
2014-04-01
We consider Schwinger pair production in 1+1 dimensional de Sitter space, filled with a constant electric field E. This can be thought of as a model for describing false vacuum decay beyond the semiclassical approximation, where pairs of a quantum field φ of mass m and charge e play the role of vacuum bubbles. We find that the adiabatic ''in'' vacuum associated with the flat chart develops a space-like expectation value for the current J, which manifestly breaks the de Sitter invariance of the background fields. We derive a simple expression for J(E), showing that both ''upward'' and ''downward'' tunneling contribute to the build-up of the current. For heavy fields, with m{sup 2} >> eE,H{sup 2}, the current is exponentially suppressed, in agreement with the results of semiclassical instanton methods. Here, H is the inverse de Sitter radius. On the other hand, light fields with m || H lead to a phenomenon of infrared hyperconductivity, where a very small electric field mH∼
International Nuclear Information System (INIS)
Jiang Qingquan; Wu Shuangqing
2007-01-01
Robinson-Wilczek's recent work, which treats Hawking radiation as a compensating flux to cancel gravitational anomaly at the horizon of a Schwarzschild-type black hole, is extended to study Hawking radiation of rotating black holes in anti-de Sitter spaces, especially that in dragging coordinate system, via gauge and gravitational anomalies. The results show that in order to restore gauge invariance and general coordinate covariance at the quantum level in the effective field theory, the charge and energy flux by requiring to cancel gauge and gravitational anomalies at the horizon, must have a form equivalent to that of a (1+1)-dimensional blackbody radiation at Hawking temperature with an appropriate chemical potential
Mixed-symmetry fields in de Sitter space: a group theoretical glance
Energy Technology Data Exchange (ETDEWEB)
Basile, Thomas [Laboratoire de Mathématiques et Physique Théorique, Unité Mixte de Recherche 7350 du CNRS,Fédération de Recherche 2964 Denis Poisson, Université François Rabelais,Parc de Grandmont, 37200 Tours (France); Groupe de Mécanique et Gravitation, Service de Physique Théorique et Mathématique,Université de Mons - UMONS,20 Place du Parc, 7000 Mons, Belgique (Belgium); Bekaert, Xavier [Laboratoire de Mathématiques et Physique Théorique, Unité Mixte de Recherche 7350 du CNRS,Fédération de Recherche 2964 Denis Poisson, Université François Rabelais,Parc de Grandmont, 37200 Tours (France); B.W. Lee Center for Fields, Gravity and Strings, Institute for Basic Science,Daejeon (Korea, Republic of); Boulanger, Nicolas [Groupe de Mécanique et Gravitation, Service de Physique Théorique et Mathématique,Université de Mons - UMONS,20 Place du Parc, 7000 Mons, Belgique (Belgium)
2017-05-15
We derive the characters of all unitary irreducible representations of the (d+1)-dimensional de Sitter spacetime isometry algebra so(1,d+1), and propose a dictionary between those representations and massive or (partially) massless fields on de Sitter spacetime. We propose a way of taking the flat limit of representations in (anti-) de Sitter spaces in terms of these characters, and conjecture the spectrum resulting from taking the flat limit of mixed-symmetry fields in de Sitter spacetime. We identify the equivalent of the scalar singleton for the de Sitter (dS) spacetime.
Small Kerr-anti-de Sitter black holes are unstable
International Nuclear Information System (INIS)
Cardoso, Vitor; Dias, Oscar J.C.
2004-01-01
Superradiance in black hole spacetimes can trigger instabilities. Here we show that, due to superradiance, small Kerr-anti-de Sitter black holes are unstable. Our demonstration uses a matching procedure, in a long wavelength approximation
Discrete Torsion, (Anti) de Sitter D4-Brane and Tunneling
Singh, Abhishek K.; Pandey, P. K.; Singh, Sunita; Kar, Supriya
2014-06-01
We obtain quantum geometries on a vacuum created pair of a (DDbar)3-brane, at a Big Bang singularity, by a local two form on a D4-brane. In fact our analysis is provoked by an established phenomenon leading to a pair creation by a gauge field at a black hole horizon by Stephen Hawking in 1975. Importantly, the five dimensional microscopic black holes are described by an effective non-perturbative curvature underlying a discrete torsion in a second order formalism. In the case for a non-propagating torsion, the effective curvature reduces to Riemannian, which in a low energy limit may describe Einstein vacuum in the formalism. In particular, our analysis suggests that a non-trivial space begin with a hot de Sitter brane-Universe underlying a nucleation of a vacuum pair of (DDbar)-instanton at a Big Bang. A pair of instanton nucleats a D-particle which in turn combines with an anti D-particle to describe a D-string and so on. The nucleation of a pair of higher dimensional pair of brane/anti-brane from a lower dimensional pair may be viewed via an expansion of the brane-Universe upon time. It is in conformity with the conjecture of a branes within a brane presumably in presence of the non-zero modes of two form. Interestingly, we perform a thermal analysis underlying various emergent quantum de Sitter vacua on a D4-brane and argue for the plausible tunneling geometries underlying a thermal equilibrium. It is argued that a de Sitter Schwarzschild undergoes quantum tunneling to an AdS-brane Schwarzschild via Nariai and de Sitter topological black hole.
Discrete Torsion, (Anti) de Sitter D4-Brane and Tunneling
International Nuclear Information System (INIS)
Singh, Abhishek K.; Pandey, P.K.; Singh, Sunita; Kar, Supriya
2014-01-01
We obtain quantum geometries on a vacuum created pair of a (DD ¯ ) 3 -brane, at a Big Bang singularity, by a local two form on a D 4 -brane. In fact our analysis is provoked by an established phenomenon leading to a pair creation by a gauge field at a black hole horizon by Stephen Hawking in 1975. Importantly, the five dimensional microscopic black holes are described by an effective non-perturbative curvature underlying a discrete torsion in a second order formalism. In the case for a non-propagating torsion, the effective curvature reduces to Riemannian, which in a low energy limit may describe Einstein vacuum in the formalism. In particular, our analysis suggests that a non-trivial space begin with a hot de Sitter brane-Universe underlying a nucleation of a vacuum pair of (DD ¯ )-instanton at a Big Bang. A pair of instanton nucleats a D-particle which in turn combines with an anti D-particle to describe a D-string and so on. The nucleation of a pair of higher dimensional pair of brane/anti-brane from a lower dimensional pair may be viewed via an expansion of the brane-Universe upon time. It is in conformity with the conjecture of a branes within a brane presumably in presence of the non-zero modes of two form. Interestingly, we perform a thermal analysis underlying various emergent quantum de Sitter vacua on a D 4 -brane and argue for the plausible tunneling geometries underlying a thermal equilibrium. It is argued that a de Sitter Schwarzschild undergoes quantum tunneling to an AdS-brane Schwarzschild via Nariai and de Sitter topological black hole
The zero mass limit of Kerr and Kerr-(anti-)de-Sitter space-times: exact solutions and wormholes
Birkandan, T.; Hortaçsu, M.
2018-03-01
Heun-type exact solutions emerge for both the radial and the angular equations for the case of a scalar particle coupled to the zero mass limit of both the Kerr and Kerr-(anti)de-Sitter spacetime. Since any type D metric has Heun-type solutions, it is interesting that this property is retained in the zero mass case. This work further refutes the claims that M going to zero limit of the Kerr metric is both locally and globally the same as the Minkowski metric.
Gravitational collapse in asymptotically anti-de Sitter or de Sitter backgrounds
International Nuclear Information System (INIS)
Madhav, T. Arun; Goswami, Rituparno; Joshi, Pankaj S.
2005-01-01
We study here the gravitational collapse of a matter cloud with a nonvanishing tangential pressure in the presence of a nonzero cosmological term Λ. It is investigated how Λ modifies the dynamics of the collapsing cloud and whether it affects the cosmic censorship. Conditions for bounce and singularity formation are derived. It is seen that when the tangential pressure vanishes, the bounce and singularity conditions reduce to the dust case studied earlier. The collapsing interior is matched to an exterior which is asymptotically de Sitter or anti-de Sitter, depending on the sign of the cosmological constant. The junction conditions for matching the cloud to the exterior are specified. The effect of Λ on apparent horizons is studied in some detail and the nature of central singularity is analyzed. The visibility of singularity and implications for the cosmic censorship conjecture are discussed. It is shown that for a nonvanishing cosmological constant, both black hole and naked singularities do form as collapse end states in spacetimes which are asymptotically de Sitter or anti-de Sitter
Mass, entropy, and holography in asymptotically de Sitter spaces
International Nuclear Information System (INIS)
Balasubramanian, Vijay; Boer, Jan de; Minic, Djordje
2002-01-01
We propose a novel prescription for computing the boundary stress tensor and charges of asymptotically de Sitter (dS) spacetimes from data at early or late time infinity. If there is a holographic dual to dS spaces, defined analogously to the AdS/conformal field theory correspondence, our methods compute the (Euclidean) stress tensor of the dual. We compute the masses of Schwarzschild-de Sitter black holes in four and five dimensions, and the masses and angular momenta of Kerr-de Sitter spaces in three dimensions. All these spaces are less massive than de Sitter space, a fact which we use to qualitatively and quantitatively relate de Sitter entropy to the degeneracy of possible dual field theories. Our results in general dimensions lead to a conjecture: Any asymptotically de Sitter spacetime with mass greater than de Sitter space has a cosmological singularity. Finally, if a dual to de Sitter space exists, the trace of our stress tensor computes the renormalized group (RG) equation of the dual field theory. Cosmological time evolution corresponds to RG evolution in the dual. The RG evolution of the c function is then related to changes in accessible degrees of freedom in an expanding universe
Fuzzy Euclidean wormholes in de Sitter space
Energy Technology Data Exchange (ETDEWEB)
Chen, Pisin; Hu, Yao-Chieh; Yeom, Dong-han, E-mail: pisinchen@phys.ntu.edu.tw, E-mail: r04244003@ntu.edu.tw, E-mail: innocent.yeom@gmail.com [Leung Center for Cosmology and Particle Astrophysics, National Taiwan University, Taipei 10617, Taiwan (China)
2017-07-01
We investigate Euclidean wormholes in Einstein gravity with a massless scalar field in de Sitter space. Euclidean wormholes are possible due to the analytic continuation of the time as well as complexification of fields, where we need to impose the classicality after the Wick-rotation to the Lorentzian signatures. For some parameters, wormholes are preferred than Hawking-Moss instantons, and hence wormholes can be more fundamental than Hawking-Moss type instantons. Euclidean wormholes can be interpreted in three ways: (1) classical big bounce, (2) either tunneling from a small to a large universe or a creation of a collapsing and an expanding universe from nothing, and (3) either a transition from a contracting to a bouncing phase or a creation of two expanding universes from nothing. These various interpretations shed some light on challenges of singularities. In addition, these will help to understand tensions between various kinds of quantum gravity theories.
Topology and isometries of the de Sitter space-time
International Nuclear Information System (INIS)
Mitskevich, N.V.; Senin, Yu.E.
1982-01-01
Spaces with a constant four-dimensional curvature, which are locally isometric to the de Sitter space-time but differing from it in topology are considered. The de Sitter spaces are considered in coordinates fitted at best for introduction of topology for three cross sections: S 3 , S 1 x S 2 , S 1 x S 2 x S 3 . It is shown that the de Sitter space-time covered by the family of layers, each of them is topologically identical, may be covered by another family of topologically identical layers. But layers in these families will have different topology
Strong cosmic censorship in de Sitter space
Dias, Oscar J. C.; Eperon, Felicity C.; Reall, Harvey S.; Santos, Jorge E.
2018-05-01
Recent work indicates that the strong cosmic censorship hypothesis is violated by nearly extremal Reissner-Nordström-de Sitter black holes. It was argued that perturbations of such a black hole decay sufficiently rapidly that the perturbed spacetime can be extended across the Cauchy horizon as a weak solution of the equations of motion. In this paper we consider the case of Kerr-de Sitter black holes. We find that, for any nonextremal value of the black hole parameters, there are quasinormal modes which decay sufficiently slowly to ensure that strong cosmic censorship is respected. Our analysis covers both scalar field and linearized gravitational perturbations.
A Static Solution of Yang-Mills Equation on Anti-de Sitter Space
International Nuclear Information System (INIS)
Chen Li; Ren Xinan
2009-01-01
Since product metric on AdS space has played a very important role in Lorentz version of AdS/CFT correspondence, the Yang-Mills equation on AdS space with this metric is considered and a static solution is obtained in this paper, which helps to understand the AdS/CFT correspondence of Yang-Mills fields. (general)
Gravity mediated Dark Matter models in the de Sitter space
Vancea, Ion V.
2018-01-01
In this paper, we generalize the simplified Dark Matter models with graviton mediator to the curved space-time, in particular to the de Sitter space. We obtain the generating functional of the Green's functions in the Euclidean de Sitter space for the covariant free gravitons. We determine the generating functional of the interacting theory between Dark Matter particles and the covariant gravitons. Also, we calculate explicitly the 2-point and 3-point interacting Green's functions for the sym...
The large dimension limit of a small black hole instability in anti-de Sitter space
Herzog, Christopher P.; Kim, Youngshin
2018-02-01
We study the dynamics of a black hole in an asymptotically AdS d × S d space-time in the limit of a large number of dimensions, d → ∞. Such a black hole is known to become dynamically unstable below a critical radius. We derive the dispersion relation for the quasinormal mode that governs this instability in an expansion in 1 /d. We also provide a full nonlinear analysis of the instability at leading order in 1 /d. We find solutions that resemble the lumpy black spots and black belts previously constructed numerically for small d, breaking the SO( d + 1) rotational symmetry of the sphere down to SO( d). We are also able to follow the time evolution of the instability. Due possibly to limitations in our analysis, our time dependent simulations do not settle down to stationary solutions. This work has relevance for strongly interacting gauge theories; through the AdS/CFT correspondence, the special case d = 5 corresponds to maximally supersymmetric Yang-Mills theory on a spatial S 3 in the microcanonical ensemble and in a strong coupling and large number of colors limit.
Principle of space existence and De Sitter metric
International Nuclear Information System (INIS)
Mal'tsev, V.K.
1990-01-01
The selection principle for the solutions of the Einstein equations suggested in a series of papers implies the existence of space (g ik ≠ 0) only in the presence of matter (T ik ≠0). This selection principle (principle of space existence, in the Markov terminology) implies, in the general case, the absence of the cosmological solution with the De Sitter metric. On the other hand, the De Sitter metric is necessary for describing both inflation and deflation periods of the Universe. It is shown that the De Sitter metric is also allowed by the selection principle under discussion if the metric experiences the evolution into the Friedmann metric
Bartz, Sean P.; Jacobson, Theodore
2018-04-01
The phase transition from hadronic matter to chirally symmetric quark-gluon plasma is expected to be a rapid crossover at zero quark chemical potential (μ ), becoming first order at some finite value of μ , indicating the presence of a critical point. Using a three-flavor soft-wall model of anti-de Sitter/QCD, we investigate the effect of varying the light and strange quark masses on the order of the chiral phase transition. At zero quark chemical potential, we reproduce the Columbia Plot, which summarizes the results of lattice QCD and other holographic models. We then extend this holographic model to examine the effects of finite quark chemical potential. We find that the the chemical potential does not affect the critical line that separates first-order from rapid crossover transitions. This excludes the possibility of a critical point in this model, suggesting that a different setup is necessary to reproduce all the features of the QCD phase diagram.
Asymptotically anti-de Sitter spacetimes in topologically massive gravity
International Nuclear Information System (INIS)
Henneaux, Marc; Martinez, Cristian; Troncoso, Ricardo
2009-01-01
We consider asymptotically anti-de Sitter spacetimes in three-dimensional topologically massive gravity with a negative cosmological constant, for all values of the mass parameter μ (μ≠0). We provide consistent boundary conditions that accommodate the recent solutions considered in the literature, which may have a slower falloff than the one relevant for general relativity. These conditions are such that the asymptotic symmetry is in all cases the conformal group, in the sense that they are invariant under asymptotic conformal transformations and that the corresponding Virasoro generators are finite. It is found that, at the chiral point |μl|=1 (where l is the anti-de Sitter radius), allowing for logarithmic terms (absent for general relativity) in the asymptotic behavior of the metric makes both sets of Virasoro generators nonzero even though one of the central charges vanishes.
On electric field in anti-de Sitter spacetime
Energy Technology Data Exchange (ETDEWEB)
Cheong, Lee Yen, E-mail: lee-yencheong@petronas.com.my, E-mail: chewxy01813@gmail.com, E-mail: dennis.ling@petronas.com.my; Yan, Chew Xiao, E-mail: lee-yencheong@petronas.com.my, E-mail: chewxy01813@gmail.com, E-mail: dennis.ling@petronas.com.my; Ching, Dennis Ling Chuan, E-mail: lee-yencheong@petronas.com.my, E-mail: chewxy01813@gmail.com, E-mail: dennis.ling@petronas.com.my [Department of Fundamental and Applied Sciences, Universiti Teknologi Petronas, Bandar Seri Iskandar, Tronoh 31750, Perak (Malaysia)
2014-10-24
In this paper we calculate the electromagnetic field produced using retarded Green's function in Anti-de Sitter spacetime (AdS). Since this spacetime is non-globally hyperbolic and has no Cauchy surface, we only consider the field originated from a charge moving along its geodesic in the region consists of points covered by future null geodesic of the charge.
Hybridizing the Skyrmion with an Anti-de-Sitter bag
International Nuclear Information System (INIS)
Rosu, H.
1992-02-01
We discuss a phenomenological model of the nucleon in which a small Anti-de-Sitter bag is placed into the Skyrmion configuration. Such a bag has a timelike boundary and allows naturally the Cheshire Cat Principle. Very important in this model is the membrane of the bag, the 3-dimensional manifold S 1 xS 2 , in which topological techniques will come into play. (author). 63 refs
Quantum physics of an elementary system in de Sitter space
International Nuclear Information System (INIS)
Rabeie, A.
2012-01-01
We present the coherent states of a scalar massive particle on 1+3-de Sitter space. These states are vectors in Hilbert space, and they are labeled by points in the associated phase space. To do this, we use the fact that the phase space of a scalar massive particle on 1+3-de Sitter space is a cotangent bundle T * (S 3 ) which is isomorphic with the complex sphere S C 3 . Then by using the heat kernel on '' S C 3 '' that was presented by Hall-Mitchell, we construct our coherent states. At the end, by these states we quantize the classical kinetic energy on de Sitter space. (orig.)
Analogies between Kruskal space and de Sitter space
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Rindler, W.
1986-01-01
Kruskal space is the analytical completion of Schwarzschild space and it consists of two outside and two inside Schwarzchild regions. Under suppression of the two angular coordinates, this space is usually diagrammed in terms of the Kruskal coordinates, μ,upsilon, much like Minkowski space is in terms of x, y. In particular, radial light paths correspond to +- 45 0 lines, the hyperbolas of μ/sup 2/ - upsilon/sup 2/ = a/sup 2/ represent uniformly accelerated particles (these being at rest in outer Schwarzschild space), and Lorentz transformations in μ, upsilon map the space into itself. Hermann Weyl first gave the analytic completion of de Sitter space as a hyper-hyperboloid μ/sub 1//sup 2/ + μ/sub 2//sup 2/ + μ/sub 3//sup 2/ + μ/sub 4//sup 2/ - upsilon/sup 2/ = a/sup 2/ in five-dimensional Minkowski space, which also contains two outside inside de Sitter regions. In a Weyl diagram, μ/sub 3/ and μ/sub 4/ are suppressed. There are many analogies: Lorentz transformations in μ/sub i/, upsilon map Weyl space into itself, the +- 45 0 generators are light paths, timelike plane hyperbolic sections are uniformly accelerated particles, and the horizon structure relative to each free worldline is analogous to the absolute horizon structure in Kruskal space
Discrete symmetries for spinor field in de Sitter space
International Nuclear Information System (INIS)
Moradi, S.; Rouhani, S.; Takook, M.V.
2005-01-01
Discrete symmetries, parity, time reversal, antipodal, and charge conjugation transformations for spinor field in de Sitter space, are presented in the ambient space notation, i.e., in a coordinate independent way. The PT and PCT transformations are also discussed in this notation. The five-current density is studied and their transformation under the discrete symmetries is discussed
Noronha, Jorge; Gyulassy, Miklos; Torrieri, Giorgio
2009-03-13
We show that far zone Mach and diffusion wake "holograms" produced by supersonic strings in anti-de Sitter space/conformal field theory (AdS/CFT) correspondence do not lead to observable conical angular correlations in the strict N_{c}-->infinity supergravity limit if Cooper-Frye hadronization is assumed. However, a special nonequilibrium "neck" zone near the jet is shown to produce an apparent sonic boom azimuthal angle distribution that is roughly independent of the heavy quark's velocity. Our results indicate that a measurement of the dependence of the away-side correlations on the velocity of associated identified heavy quark jets at the BNL Relativistic Heavy Ion Collider and CERN LHC will provide a direct test of the nonperturbative dynamics involved in the coupling between jets and the strongly coupled quark-gluon plasma implied by AdS/CFT correspondence.
International Nuclear Information System (INIS)
Noronha, Jorge; Gyulassy, Miklos; Torrieri, Giorgio
2009-01-01
We show that far zone Mach and diffusion wake 'holograms' produced by supersonic strings in anti-de Sitter space/conformal field theory (AdS/CFT) correspondence do not lead to observable conical angular correlations in the strict N c →∞ supergravity limit if Cooper-Frye hadronization is assumed. However, a special nonequilibrium 'neck' zone near the jet is shown to produce an apparent sonic boom azimuthal angle distribution that is roughly independent of the heavy quark's velocity. Our results indicate that a measurement of the dependence of the away-side correlations on the velocity of associated identified heavy quark jets at the BNL Relativistic Heavy Ion Collider and CERN LHC will provide a direct test of the nonperturbative dynamics involved in the coupling between jets and the strongly coupled quark-gluon plasma implied by AdS/CFT correspondence
Hawking radiation from black holes in de Sitter spaces
International Nuclear Information System (INIS)
Jiang Qingquan
2007-01-01
Recently, Hawking radiation has been treated, by Robinson and Wilczek (2005 Phys. Rev. Lett. 95 011303), as a compensating flux of the energy-momentum tensor required to cancel a gravitational anomaly at the event horizon (EH) of a Schwarzschild-type black hole. In this paper, motivated by this work, Hawking radiation from the event horizon (EH) and the de Sitter cosmological horizon (CH) of black holes in de Sitter spaces, specifically including the purely de Sitter black hole and the static, spherically symmetric Schwarzschild-de Sitter black hole as well as the rotating Kerr-de Sitter black hole, have been studied by anomalies. The results show that the gauge-current and energy-momentum tensor fluxes, required to restore gauge invariance and general coordinate covariance at the EH and the CH, are precisely equal to those of Hawking radiation from the EH and the CH, respectively. It should be noted that gauge and gravitational anomalies taking place at the CH arise from the fact that the effective field theory is formulated inside the CH to integrate out the classically irrelevant outgoing modes at the CH, which are different from those at the black hole horizon
Kerr–anti-de Sitter/de Sitter black hole in perfect fluid dark matter background
Xu, Zhaoyi; Hou, Xian; Wang, Jiancheng
2018-06-01
We obtain the Kerr–anti-de-sitter (Kerr–AdS) and Kerr–de-sitter (Kerr–dS) black hole (BH) solutions to the Einstein field equation in the perfect fluid dark matter background using the Newman–Janis method and Mathematica package. We discuss in detail the black hole properties and obtain the following main results: (i) From the horizon equation g rr = 0, we derive the relation between the perfect fluid dark matter parameter α and the cosmological constant Λ when the cosmological horizon exists. For , we find that α is in the range for and for . For positive cosmological constant Λ (Kerr–AdS BH), decreases if , and increases if . For negative cosmological constant (Kerr–dS BH), increases if and decreases if ; (ii) An ergosphere exists between the event horizon and the outer static limit surface. The size of the ergosphere evolves oppositely for and , while decreasing with the increasing . When there is sufficient dark matter around the black hole, the black hole spacetime changes remarkably; (iii) The singularity of these black holes is the same as that of rotational black holes. In addition, we study the geodesic motion using the Hamilton–Jacobi formalism and find that when α is in the above ranges for , stable orbits exist. Furthermore, the rotational velocity of the black hole in the equatorial plane has different behaviour for different α and the black hole spin a. It is asymptotically flat and independent of α if while is asymptotically flat only when α is close to zero if . We anticipate that Kerr–Ads/dS black holes could exist in the universe and our future work will focus on the observational effects of the perfect fluid dark matter on these black holes.
Phase Transitions for Flat Anti - de Sitter Black Holes
International Nuclear Information System (INIS)
Surya, Sumati; Schleich, Kristin; Witt, Donald M.
2001-01-01
We reexamine the thermodynamics of anti - de Sitter (adS) black holes with Ricci flat horizons using the adS soliton as the thermal background. We find that there is a phase transition which is dependent not only on the temperature but also on the black hole area, which is an independent parameter. As in the spherical adS black hole, this phase transition is related via the adS/conformal-field-theory correspondence to a confinement-deconfinement transition in the large-N gauge theory on the conformal boundary at infinity
Instability of charged anti-de Sitter black holes
International Nuclear Information System (INIS)
Gwak, Bogeun; Lee, Bum-Hoon; Ro, Daeho
2016-01-01
We have studied the instability of charged anti-de Sitter black holes in four- or higher-dimensions under fragmentation. The unstable black holes under fragmentation can be broken into two black holes. Instability depends not only on the mass and charge of the black hole but also on the ratio between the fragmented black hole and its predecessor. We have found that the near extremal black holes are unstable, and Schwarzschild-AdS black holes are stable. These are qualitatively similar to black holes in four dimensions and higher. The detailed instabilities are numerically investigated.
Cosmic censorship of rotating Anti-de Sitter black hole
Energy Technology Data Exchange (ETDEWEB)
Gwak, Bogeun; Lee, Bum-Hoon, E-mail: rasenis@sogang.ac.kr, E-mail: bhl@sogang.ac.kr [Center for Quantum Spacetime, Sogang University, Seoul 04107 (Korea, Republic of)
2016-02-01
We test the validity of cosmic censorship in the rotating anti-de Sitter black hole. For this purpose, we investigate whether the extremal black hole can be overspun by the particle absorption. The particle absorption will change the mass and angular momentum of the black hole, which is analyzed using the Hamilton-Jacobi equations consistent with the laws of thermodynamics. We have found that the mass of the extremal black hole increases more than the angular momentum. Therefore, the outer horizon of the black hole still exists, and cosmic censorship is valid.
Cosmic censorship of rotating Anti-de Sitter black hole
International Nuclear Information System (INIS)
Gwak, Bogeun; Lee, Bum-Hoon
2016-01-01
We test the validity of cosmic censorship in the rotating anti-de Sitter black hole. For this purpose, we investigate whether the extremal black hole can be overspun by the particle absorption. The particle absorption will change the mass and angular momentum of the black hole, which is analyzed using the Hamilton-Jacobi equations consistent with the laws of thermodynamics. We have found that the mass of the extremal black hole increases more than the angular momentum. Therefore, the outer horizon of the black hole still exists, and cosmic censorship is valid
Poisson's equation in de Sitter space-time
Energy Technology Data Exchange (ETDEWEB)
Pessa, E [Rome Univ. (Italy). Ist. di Matematica
1980-11-01
Based on a suitable generalization of Poisson's equation for de Sitter space-time the form of gravitation's law in 'projective relativity' is examined; it is found that, in the interior case, a small difference with the customary Newtonian law arises. This difference, of a repulsive character, can be very important in cosmological problems.
Revisiting the conformal invariance of the scalar field: From Minkowski space to de Sitter space
International Nuclear Information System (INIS)
Huguet, E.; Queva, J.; Renaud, J.
2008-01-01
In this article, we clarify the link between the conformal (i.e. Weyl) correspondence from the Minkowski space to the de Sitter space and the conformal [i.e. SO(2,d)] invariance of the conformal scalar field on both spaces. We exhibit the realization on de Sitter space of the massless scalar representation of SO(2,d). It is obtained from the corresponding representation in Minkowski space through an intertwining operator inherited from the Weyl relation between the two spaces. The de Sitter representation is written in a form which allows one to take the point of view of a Minkowskian observer who sees the effect of curvature through additional terms
Linearized curvatures for auxiliary fields in the de Sitter space
Energy Technology Data Exchange (ETDEWEB)
Vasiliev, M A
1988-09-19
New consistent linearized curvatures in the de Sitter space are constructed. The sequence of actions, describing bosonic and fermionic gauge auxiliary fields, is found based on these curvatures. The proposed actions are parametrized by two integer parameters, n greater than or equal to 0 and m greater than or equal to 0. The simplest case n=m=0 corresponds in the flat limit to the auxiliary fields of 'new minimal' supergravity. The hamiltonian formulation is developed for the auxiliary fields suggested; hamiltonians and first- and second-class constraints are constructed. Using these results, it is shown that the systems of fields proposed possess no dynamical degrees of freedom in de Sitter and flat spaces. In addition the hamiltonian formalism is analysed for some free dynamical systems based on linearized higher-spin curvatures introduced previously.
Supersymmetry of anti-de Sitter black holes
International Nuclear Information System (INIS)
Caldarelli, Marco M.; Klemm, Dietmar
1999-01-01
We examine supersymmetry of four-dimensional asymptotically anti-de Sitter (AdS) dyonic black holes in the context of gauged N = 2 supergravity. Our calculations concentrate on black holes with unusual topology and their rotating generalizations, but we also reconsider the spherical rotating dyonic Ker-Newman-AdS black hole, whose supersymmetry properties have previously been investigated by Kostelecky and Perry within another approach. We find that in the case of spherical, toroidal or cylindrical event horizon topology, the black holes must rotate in order to preserve some supersymmetry; the non-rotating supersymmetric configurations representing naked singularities. However, we show that this is no more true for black holes whose event horizons are Riemann surfaces of genus g > 1, where we find a non-rotating extremal solitonic black hole carrying magnetic charge and permitting one Killing spinor. For the non-rotating supersymmetric configurations of various topologies, all Killing spinors are explicitly constructed
Flow equation, conformal symmetry, and anti-de Sitter geometry
Aoki, Sinya; Yokoyama, Shuichi
2018-03-01
We argue that the anti-de Sitter (AdS) geometry in d+1 dimensions naturally emerges from an arbitrary conformal field theory in d dimensions using the free flow equation. We first show that an induced metric defined from the flowed field generally corresponds to the quantum information metric, called the Bures or Helstrom metric, if the flowed field is normalized appropriately. We next verify that the induced metric computed explicitly with the free flow equation always becomes the AdS metric when the theory is conformal. We finally prove that the conformal symmetry in d dimensions converts to the AdS isometry in d+1 dimensions after d-dimensional quantum averaging. This guarantees the emergence of AdS geometry without explicit calculation.
Covariant fields on anti-de Sitter spacetimes
Cotăescu, Ion I.
2018-02-01
The covariant free fields of any spin on anti-de Sitter (AdS) spacetimes are studied, pointing out that these transform under isometries according to covariant representations (CRs) of the AdS isometry group, induced by those of the Lorentz group. Applying the method of ladder operators, it is shown that the CRs with unique spin are equivalent with discrete unitary irreducible representations (UIRs) of positive energy of the universal covering group of the isometry one. The action of the Casimir operators is studied finding how the weights of these representations (reps.) may depend on the mass and spin of the covariant field. The conclusion is that on AdS spacetime, one cannot formulate a universal mass condition as in special relativity.
Stability of black holes in de Sitter space
International Nuclear Information System (INIS)
Mellor, F.; Moss, I.
1990-01-01
The theory of black-hole perturbations is extended to charged black holes in de Sitter space. These spacetimes have wormholes connecting different asymptotic regions. It appears that, at least in some cases, these holes are stable even at the Cauchy horizon. It follows that they violate cosmic censorship and an observer could in principle travel through the black hole to another universe. The stability of these spacetimes also implies the existence of a cosmological ''no hair'' theorem
ADM Mass for Asymptotically de Sitter Space-Time
International Nuclear Information System (INIS)
Huang Shiming; Yue Ruihong; Jia Dongyan
2010-01-01
In this paper, an ADM mass formula for asymptotically de Sitter(dS) space-time is derived from the energy-momentum tensor. We take the vacuum dS space as the background and investigate the ADM mass of the (d + 3)-dimensional sphere-symmetric space with a positive cosmological constant, and find that the ADM mass of asymptotically dS space is based on the ADM mass of Schwarzschild field and the cosmological background brings some small mass contribution as well. (general)
Kinematics of a relativistic particle with de Sitter momentum space
International Nuclear Information System (INIS)
Arzano, Michele; Kowalski-Glikman, Jerzy
2011-01-01
We discuss kinematical properties of a free relativistic particle with deformed phase space in which momentum space is given by (a submanifold of) de Sitter space. We provide a detailed derivation of the action, Hamiltonian structure and equations of motion for such a free particle. We study the action of deformed relativistic symmetries on the phase space and derive explicit formulae for the action of the deformed Poincare group. Finally we provide a discussion on parametrization of the particle worldlines stressing analogies and differences with ordinary relativistic kinematics.
Three-dimensional black hole from a stringy anti endash de Sitter background
International Nuclear Information System (INIS)
Hjelmeland, S.E.
1997-01-01
A new black hole solution in 2+1 dimensions is found by taking cosmic strings as part of the vacuum structure of the anti endash de Sitter space-time. The solution has a structure that in many ways is similar to that of the Reissner-Nordstroem solution. With a vanishing cosmological constant, a space-time with a black hole of infinite extension appears with the inner horizon playing the role of a cosmological event horizon. The timelike and null geodesics are discussed. In particular it is shown that photons may follow conic sections. copyright 1997 The American Physical Society
Discrete Torsion, (Anti) de Sitter D{sub 4}-Brane and Tunneling
Energy Technology Data Exchange (ETDEWEB)
Singh, Abhishek K.; Pandey, P.K.; Singh, Sunita; Kar, Supriya, E-mail: skkar@physics.du.ac.in
2014-06-15
We obtain quantum geometries on a vacuum created pair of a (DD{sup ¯}){sub 3}-brane, at a Big Bang singularity, by a local two form on a D{sub 4}-brane. In fact our analysis is provoked by an established phenomenon leading to a pair creation by a gauge field at a black hole horizon by Stephen Hawking in 1975. Importantly, the five dimensional microscopic black holes are described by an effective non-perturbative curvature underlying a discrete torsion in a second order formalism. In the case for a non-propagating torsion, the effective curvature reduces to Riemannian, which in a low energy limit may describe Einstein vacuum in the formalism. In particular, our analysis suggests that a non-trivial space begin with a hot de Sitter brane-Universe underlying a nucleation of a vacuum pair of (DD{sup ¯})-instanton at a Big Bang. A pair of instanton nucleats a D-particle which in turn combines with an anti D-particle to describe a D-string and so on. The nucleation of a pair of higher dimensional pair of brane/anti-brane from a lower dimensional pair may be viewed via an expansion of the brane-Universe upon time. It is in conformity with the conjecture of a branes within a brane presumably in presence of the non-zero modes of two form. Interestingly, we perform a thermal analysis underlying various emergent quantum de Sitter vacua on a D{sub 4}-brane and argue for the plausible tunneling geometries underlying a thermal equilibrium. It is argued that a de Sitter Schwarzschild undergoes quantum tunneling to an AdS-brane Schwarzschild via Nariai and de Sitter topological black hole.
Integral-spin fields on (3+2)-de Sitter space
International Nuclear Information System (INIS)
Gazeau, J.; Hans, M.
1988-01-01
Nowadays, (3+2)-de Sitter (or anti-de Sitter space) appears as a very attractive possibility at several levels of theoretical physics. The Wigner definition of an elementary system as associated to a unitary irreducible representation of the Poincare group may be extended to the de Sitter group SO(3,2) [or ∼(SO(3,2))] without great difficulty. The constant curvature, as small as it can be, is a natural candidate to play the role of a regularization parameter with respect to the flat-space limit. Massless particles in (3+2)-de Sitter theory are composite (singletons). On the other hand, supergravity theories necessitate a (large) constant curvature. The content of this paper is group theoretical. It attempts to continue the ''a la Wigner'' program for SO(3,2), already largely broached by Fronsdal. Three recurrence formulas are presented. They permit one to build up the carrier states for representations with arbitrary integral spin. Two of them are valid for the ''massive'' representations whereas the third one is applicable to the indecomposable massless representations. In addition, other presumably indecomposable, though nonphysical, representations are studied, in relation to the existence of ''generalized'' gauge fields and divergences. The recurrence formulas also allow one to build up the invariant two-point functions or homogeneous propagators
International Nuclear Information System (INIS)
Cvetic, Mirjam; Nojiri, Shin'ichi; Odintsov, S.D.
2002-01-01
We investigate the charged Schwarzschild-anti-de Sitter (SAdS) BH thermodynamics in 5d Einstein-Gauss-Bonnet gravity with electromagnetic field. The Hawking-Page phase transitions between SAdS BH and pure AdS space are studied. The corresponding phase diagrams (with critical line defined by GB term coefficient and electric charge) are drawn. The possibility to account for higher derivative Maxwell terms is mentioned. In frames of proposed dS/CFT correspondence it is demonstrated that brane gravity maybe localized similarly to AdS/CFT. SdS BH thermodynamics in 5d Einstein and Einstein-Gauss-Bonnet gravity is considered. The corresponding (complicated) surface counterterms are found and used to get the conserved BH mass, free energy and entropy. The interesting feature of higher derivative gravity is the possibility for negative (or zero) SdS (or SAdS) BH entropy which depends on the parameters of higher derivative terms. We speculate that the appearance of negative entropy may indicate a new type instability where a transition between SdS (SAdS) BH with negative entropy to SAdS (SdS) BH with positive entropy would occur
de Sitter Space in Non-Critical String Theory
Energy Technology Data Exchange (ETDEWEB)
Silverstein, Eva M
2002-08-13
Supercritical string theories in D > 10 dimensions with no moduli are described, generalizing the asymmetric orientifold construction of one of the authors [1]. By taking the number of dimensions to be large and turning on fluxes, dilaton potentials are generated with nontrivial minima at arbitrarily small cosmological constant and D-dimensional string coupling, separated by a barrier from a flat-space linear dilaton region, but possibly suffering from strong coupling problems. The general issue of the decay of a de Sitter vacuum to flat space is discussed. For relatively small barriers, such decays are described by gravitational instantons. It is shown that for a sufficiently large potential barrier, the bubble wall crosses the horizon. At the same time the instanton decay time exceeds the Poincare recurrence time. It is argued that the inclusion of such instantons is neither physically meaningful nor consistent with basic principles such as causality. This raises the possibility that such de Sitter vacua are effectively stable. In the case of the supercritical flux models, decays to the linear dilaton region can be forbidden by such large barriers, but decays to lower flux vacua including AdS minima nevertheless proceed consistently with this criterion. These models provide concrete examples in which cosmological constant reduction by flux relaxation can be explored.
Geometrothermodynamics for black holes and de Sitter space
Kurihara, Yoshimasa
2018-02-01
A general method to extract thermodynamic quantities from solutions of the Einstein equation is developed. In 1994, Wald established that the entropy of a black hole could be identified as a Noether charge associated with a Killing vector of a global space-time (pseudo-Riemann) manifold. We reconstruct Wald's method using geometrical language, e.g., via differential forms defined on the local space-time (Minkowski) manifold. Concurrently, the abstract thermodynamics are also reconstructed using geometrical terminology, which is parallel to general relativity. The correspondence between the thermodynamics and general relativity can be seen clearly by comparing the two expressions. This comparison requires a modification of Wald's method. The new method is applied to Schwarzschild, Kerr, and Kerr-Newman black holes and de Sitter space. The results are consistent with previous results obtained using various independent methods. This strongly supports the validity of the area theorem for black holes.
Real forms of complex quantum anti-de-Sitter algebra Uq(Sp(4;C)) and their contraction schemes
International Nuclear Information System (INIS)
Lukierski, J.; Nowicki, A.; Ruegg, H.
1991-01-01
We describe four types of inner involutions of the Cartan-Weyl basis providing (for vertical strokeqvertical stroke=1 and q real) three types of real quantum Lie algebras: U q (O(3, 2)) (quantum D=4 anti-de-Sitter), U q (O(4, 1)) (quantum D=4 de-Sitter) and U q (O(5)). We give also two types of inner involutions of the Cartan-Chevalley basis of U q (Sp(4; C)) which cannot be extended to inner involutions of the Cartan-Weyl basis. We outline twelve contraction schemes for quantum D=4 anti-de-Sitter algebra. All these contractions provide four commuting translation generators, but only two (one for vertical strokeqvertical stroke=1, the second for q real) lead to the quantum Poincare algebra with an undeformed space rotation O(3) subalgebra. (orig.)
Surviving in a metastable de Sitter space-time
International Nuclear Information System (INIS)
Kashyap, Sitender Pratap; Mondal, Swapnamay; Sen, Ashoke; Verma, Mritunjay
2015-01-01
In a metastable de Sitter space any object has a finite life expectancy beyond which it undergoes vacuum decay. However, by spreading into different parts of the universe which will fall out of causal contact of each other in future, a civilization can increase its collective life expectancy, defined as the average time after which the last settlement disappears due to vacuum decay. We study in detail the collective life expectancy of two comoving objects in de Sitter space as a function of the initial separation, the horizon radius and the vacuum decay rate. We find that even with a modest initial separation, the collective life expectancy can reach a value close to the maximum possible value of 1.5 times that of the individual object if the decay rate is less than 1% of the expansion rate. Our analysis can be generalized to any number of objects, general trajectories not necessarily at rest in the comoving coordinates and general FRW space-time. As part of our analysis we find that in the current state of the universe dominated by matter and cosmological constant, the vacuum decay rate is increasing as a function of time due to accelerated expansion of the volume of the past light cone. Present decay rate is about 3.7 times larger than the average decay rate in the past and the final decay rate in the cosmological constant dominated epoch will be about 56 times larger than the average decay rate in the past. This considerably weakens the lower bound on the half-life of our universe based on its current age.
Surviving in a metastable de Sitter space-time
Energy Technology Data Exchange (ETDEWEB)
Kashyap, Sitender Pratap; Mondal, Swapnamay [Harish-Chandra Research Institute,Chhatnag Road, Jhusi, Allahabad 211019 (India); Sen, Ashoke [Harish-Chandra Research Institute,Chhatnag Road, Jhusi, Allahabad 211019 (India); School of Physics, Korea Institute for Advanced Study,Seoul 130-722 (Korea, Republic of); Verma, Mritunjay [Harish-Chandra Research Institute,Chhatnag Road, Jhusi, Allahabad 211019 (India); International Centre for Theoretical Sciences,Malleshwaram, Bengaluru 560 012 (India)
2015-09-21
In a metastable de Sitter space any object has a finite life expectancy beyond which it undergoes vacuum decay. However, by spreading into different parts of the universe which will fall out of causal contact of each other in future, a civilization can increase its collective life expectancy, defined as the average time after which the last settlement disappears due to vacuum decay. We study in detail the collective life expectancy of two comoving objects in de Sitter space as a function of the initial separation, the horizon radius and the vacuum decay rate. We find that even with a modest initial separation, the collective life expectancy can reach a value close to the maximum possible value of 1.5 times that of the individual object if the decay rate is less than 1% of the expansion rate. Our analysis can be generalized to any number of objects, general trajectories not necessarily at rest in the comoving coordinates and general FRW space-time. As part of our analysis we find that in the current state of the universe dominated by matter and cosmological constant, the vacuum decay rate is increasing as a function of time due to accelerated expansion of the volume of the past light cone. Present decay rate is about 3.7 times larger than the average decay rate in the past and the final decay rate in the cosmological constant dominated epoch will be about 56 times larger than the average decay rate in the past. This considerably weakens the lower bound on the half-life of our universe based on its current age.
Relationship between five-dimensional black holes and de Sitter spaces
International Nuclear Information System (INIS)
Myung, Y S
2004-01-01
We study a close relationship between the topological anti-de Sitter (TAdS) black holes and topological de Sitter (TdS) spaces including the Schwarzschild-de Sitter (SdS) black hole in five dimensions. We show that all thermal properties of the TdS spaces can be found from those of the TAdS black holes by replacing k by -k. Also we find that all thermal information for the cosmological horizon of the SdS black hole is obtained from either the hyperbolic-AdS black hole or the Schwarzschild-TdS space by substituting m with -m. For this purpose we calculate thermal quantities of bulk (Euclidean) conformal field theory (ECFT) and moving domain wall by using the A(dS)/(E)CFT correspondences. Further, we compute logarithmic corrections to the Bekenstein-Hawking entropy, Cardy-Verlinde formula and Friedmann equation due to thermal fluctuations. It implies that in the thermal relation between the TdS spaces and TAdS black holes, the cosmological horizon plays the same role as the horizon of TAdS black holes. Finally we note that the dS/ECFT correspondence is valid for the TdS spaces in conjunction with the AdS/CFT correspondence for the TAdS black holes
De Sitter space in gauge/gravity duality
Directory of Open Access Journals (Sweden)
Lilia Anguelova
2015-10-01
Full Text Available We investigate gauge/gravity duality for gauge theories in de Sitter space. More precisely, we study a five-dimensional consistent truncation of type IIB supergravity, which encompasses a wide variety of gravity duals of strongly coupled gauge theories, including the Maldacena–Nunez solution and its walking deformations. We find several solutions of the 5d theory with dS4 spacetime and nontrivial profiles for (some of the scalars along the fifth (radial direction. In the process, we prove that one of the equations of motion becomes dependent on the others, for nontrivial warp factor. This dependence reduces the number of field equations and, thus, turns out to be crucial for the existence of solutions with (AdS4 spacetime. Finally, we comment on the implications of our dS4 solutions for building gravity duals of Glueball Inflation.
Distortion of Schwarzschild-anti-de Sitter black holes to black strings
International Nuclear Information System (INIS)
Tomimatsu, Akira
2005-01-01
Motivated by the existence of black holes with various topologies in four-dimensional spacetimes with a negative cosmological constant, we study axisymmetric static solutions describing any large distortions of Schwarzschild-anti-de Sitter black holes parametrized by the mass m. Under the approximation such that m is much larger than the anti-de Sitter radius, it is found that a cylindrically symmetric black string is obtained as a special limit of distorted spherical black holes. Such a prolonged distortion of the event horizon connecting a Schwarzschild-anti-de Sitter black hole to a black string is allowed without violating both the usual black hole thermodynamics and the hoop conjecture for the horizon circumference
Infinitesimal conformal closed transformations of de Sitter and Robertson-Walker cosmological spaces
International Nuclear Information System (INIS)
Sakoto, Moussa
1976-01-01
The infinitesimal conformal closed transfromations of de Sitter and Robertson-Walker cosmological spaces are determined and an interesting property of the current lines for Robertson-Walker spaces is given [fr
de Sitter space from dilatino condensates in massive IIA supergravity
Souères, Bertrand; Tsimpis, Dimitrios
2018-02-01
We use the superspace formulation of (massive) IIA supergravity to obtain the explicit form of the dilatino terms, and we find that the quartic-dilatino term is positive. The theory admits a ten-dimensional de Sitter solution, obtained by assuming a nonvanishing quartic-dilatino condensate which generates a positive cosmological constant. Moreover, in the presence of dilatino condensates, the theory admits formal four-dimensional de Sitter solutions of the form d S4×M6, where M6 is a six-dimensional Kähler-Einstein manifold of positive scalar curvature.
Conformal use of retarded Green's functions for the Maxwell field in de Sitter space
International Nuclear Information System (INIS)
Faci, S.; Huguet, E.; Renaud, J.
2011-01-01
We propose a new propagation formula for the Maxwell field in de Sitter space which exploits the conformal invariance of this field together with a conformal gauge condition. This formula allows to determine the classical electromagnetic field in the de Sitter space from given currents and initial data. It only uses the Green's function of the massless Minkowskian scalar field. This leads to drastic simplifications in practical calculations. We apply this formula to the classical problem of the two charges of opposite signs at rest at the North and South Poles of the de Sitter space.
Vacuum states for gravitons field in de Sitter space
Bamba, Kazuharu; Rahbardehghan, Surena; Pejhan, Hamed
2017-11-01
In this paper, considering the linearized Einstein equation with a two-parameter family of linear covariant gauges in de Sitter spacetime, we examine possible vacuum states for the gravitons field with respect to invariance under the de Sitter group S O0(1 ,4 ) . Our calculations explicitly reveal that there exists no natural de Sitter-invariant vacuum state (the Euclidean or Bunch-Davies state) for the gravitons field. Indeed, on the foundation of a rigorous group-theoretical reasoning, we prove that if one insists on full covariance as well as causality for the theory, one has to give up the positivity requirement of the inner product. However, one may still look for states with as much symmetry as possible, more precisely, a restrictive version of covariance by considering the gravitons field and the associated vacuum state which are, respectively, covariant and invariant with respect to some maximal subgroup of the full de Sitter group. In this regard, we treat the S O (4 ) case and find a family of S O (4 )-invariant states. The associated S O (4 )-covariant quantum field is given, as well.
Toldo, C.
2014-01-01
This thesis is devoted to the analysis of asymptotically Anti-de Sitter (AdS) black holes arising as solutions of theories of gauged Supergravity in four spacetime dimensions. After a brief recap of the main features of gauged supergravity, the first part of the thesis deals with the explicit
Asymptotic behavior and Hamiltonian analysis of anti-de Sitter gravity coupled to scalar fields
International Nuclear Information System (INIS)
Henneaux, Marc; Martinez, Cristian; Troncoso, Ricardo; Zanelli, Jorge
2007-01-01
We examine anti-de Sitter gravity minimally coupled to a self-interacting scalar field in D>=4 dimensions when the mass of the scalar field is in the range m * 2 = 2 * 2 +l -2 . Here, l is the AdS radius, and m * 2 is the Breitenlohner-Freedman mass. We show that even though the scalar field generically has a slow fall-off at infinity which back reacts on the metric so as to modify its standard asymptotic behavior, one can still formulate asymptotic conditions (i) that are anti-de Sitter invariant; and (ii) that allows the construction of well-defined and finite Hamiltonian generators for all elements of the anti-de Sitter algebra. This requires imposing a functional relationship on the coefficients a, b that control the two independent terms in the asymptotic expansion of the scalar field. The anti-de Sitter charges are found to involve a scalar field contribution. Subtleties associated with the self-interactions of the scalar field as well as its gravitational back reaction, not discussed in previous treatments, are explicitly analyzed. In particular, it is shown that the fields develop extra logarithmic branches for specific values of the scalar field mass (in addition to the known logarithmic branch at the B-F bound)
Thermodynamic stability of asymptotically anti-de Sitter rotating black holes in higher dimensions
International Nuclear Information System (INIS)
Dolan, Brian P
2014-01-01
Conditions for thermodynamic stability of asymptotically anti-de Sitter (AdS) rotating black holes in D-dimensions are determined. Local thermodynamic stability requires not only positivity conditions on the specific heat and the moment of inertia tensor but it is also necessary that the adiabatic compressibility be positive. It is shown that, in the absence of a cosmological constant, neither rotation nor charge is sufficient to ensure full local thermodynamic stability of a black hole. Thermodynamic stability properties of AdS Myers–Perry black holes are investigated for both singly spinning and multi-spinning black holes. Simple expressions are obtained for the specific heat and moment of inertia tensor in any dimension. An analytic expression is obtained for the boundary of the region of parameter space in which such space-times are thermodynamically stable. (paper)
Massless Interacting Scalar Fields in de Sitter space
López Nacir, Diana
2016-10-28
We present a method to compute the two-point functions for an $O(N)$ scalar field model in de Sitter spacetime, avoiding the well known infrared problems for massless fields. The method is based on an exact treatment of the Euclidean zero modes and a perturbative one of the nonzero modes, and involves a partial resummation of the leading secular terms. This resummation, crucial to obtain a decay of the correlation functions, is implemented along with a double expansion in an effective coupling constant $\\sqrt\\lambda$ and in $1/N$. The results reduce to those known in the leading infrared approximation and coincide with the ones obtained directly in Lorentzian de Sitter spacetime in the large $N$ limit. The new method allows for a systematic calculation of higher order corrections both in $\\sqrt\\lambda$ and in $1/N$.
Holography and quantum states in elliptic de Sitter space
Energy Technology Data Exchange (ETDEWEB)
Halpern, Illan F. [Department of Physics, University of California,Berkeley, CA, 94720 (United States); Neiman, Yasha [Perimeter Institute for Theoretical Physics,31 Caroline Street N, Waterloo, ON, N2L 2Y5 (Canada)
2015-12-10
We outline a program for interpreting the higher-spin dS/CFT model in terms of physics in the causal patch of a dS observer. The proposal is formulated in “elliptic” de Sitter space dS{sub 4}/ℤ{sub 2}, obtained by identifying antipodal points in dS{sub 4}. We discuss recent evidence that the higher-spin model is especially well-suited for this, since the antipodal symmetry of bulk solutions has a simple encoding on the boundary. For context, we test some other (free and interacting) theories for the same property. Next, we analyze the notion of quantum field states in the non-time-orientable dS{sub 4}/ℤ{sub 2}. We compare the physics seen by different observers, with the outcome depending on whether they share an arrow of time. Finally, we implement the marriage between higher-spin holography and observers in dS{sub 4}/ℤ{sub 2}, in the limit of free bulk fields. We succeed in deriving an observer’s operator algebra and Hamiltonian from the CFT, but not her S-matrix. We speculate on the extension of this to interacting higher-spin theory.
Instanton tunneling for de Sitter space with real projective spatial sections
Energy Technology Data Exchange (ETDEWEB)
Ong, Yen Chin [Center for Astronomy and Astrophysics, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Yeom, Dong-han, E-mail: ongyenchin@sjtu.edu.cn, E-mail: innocent.yeom@gmail.com [Leung Center for Cosmology and Particle Astrophysics, National Taiwan University, Taipei 10617, Taiwan (China)
2017-04-01
The physics of tunneling from one spacetime to another is often understood in terms of instantons. For some instantons, it was recently shown in the literature that there are two complementary ''interpretations'' for their analytic continuations. Dubbed ''something-to-something'' and ''nothing-to-something'' interpretations, respectively, the former involves situation in which the initial and final hypersurfaces are connected by a Euclidean manifold, whereas the initial and final hypersurfaces in the latter case are not connected in such a way. We consider a de Sitter space with real projective space RP{sup 3} spatial sections, as was originally understood by de Sitter himself. This original version of de Sitter space has several advantages over the usual de Sitter space with S{sup 3} spatial sections. In particular, the interpretation of the de Sitter entropy as entanglement entropy is much more natural. We discuss the subtleties involved in the tunneling of such a de Sitter space.
International Nuclear Information System (INIS)
Anninos, Dionysios; Pastras, Georgios
2009-01-01
The local and global thermal phase structure for asymptotically anti-de Sitter black holes charged under an abelian gauge group, with both Gauss-Bonnet and quartic field strength corrections, is mapped out for all parameter space. We work in the grand canonical ensemble where the external electric potential is held fixed. The analysis is performed in an arbitrary number of dimensions, for all three possible horizon topologies - spherical, flat or hyperbolic. For spherical horizons, new metastable configurations are exhibited both for the pure Gauss-Bonnet theory as well as the pure higher derivative gauge theory and combinations thereof. In the pure Gauss-Bonnet theory with negative coefficient and five or more spatial dimensions, two locally thermally stable black hole solutions are found for a given temperature. Either one or both of them may be thermally favored over the anti-de Sitter vacuum - corresponding to a single or a double decay channel for the metastable black hole. Similar metastable configurations are uncovered for the theory with pure quartic field strength corrections, as well combinations of the two types of corrections, in three or more spatial dimensions. Finally, a secondary Hawking-Page transition between the smaller thermally favored black hole and thermal anti-de Sitter space is observed when both corrections are turned on and their couplings are both positive.
Temperature and entropy of Schwarzschild-de Sitter space-time
International Nuclear Information System (INIS)
Shankaranarayanan, S.
2003-01-01
In the light of recent interest in quantum gravity in de Sitter space, we investigate semiclassical aspects of four-dimensional Schwarzschild-de Sitter space-time using the method of complex paths. The standard semiclassical techniques (such as Bogoliubov coefficients and Euclidean field theory) have been useful to study quantum effects in space-times with single horizons; however, none of these approaches seem to work for Schwarzschild-de Sitter space-time or, in general, for space-times with multiple horizons. We extend the method of complex paths to space-times with multiple horizons and obtain the spectrum of particles produced in these space-times. We show that the temperature of radiation in these space-times is proportional to the effective surface gravity--the inverse harmonic sum of surface gravity of each horizon. For the Schwarzschild-de Sitter space-time, we apply the method of complex paths to three different coordinate systems--spherically symmetric, Painleve, and Lemaitre. We show that the equilibrium temperature in Schwarzschild-de Sitter space-time is the harmonic mean of cosmological and event horizon temperatures. We obtain Bogoliubov coefficients for space-times with multiple horizons by analyzing the mode functions of the quantum fields near the horizons. We propose a new definition of entropy for space-times with multiple horizons, analogous to the entropic definition for space-times with a single horizon. We define entropy for these space-times to be inversely proportional to the square of the effective surface gravity. We show that this definition of entropy for Schwarzschild-de Sitter space-time satisfies the D-bound conjecture
Eikonal instability of Gauss-Bonnet-(anti-)-de Sitter black holes
Konoplya, R. A.; Zhidenko, A.
2017-05-01
Here we have shown that asymptotically anti-de Sitter (AdS) black holes in the Einstein-Gauss-Bonnet (GB) theory are unstable under linear perturbations of space-time in some region of parameters. This (eikonal) instability develops at high multipole numbers. We found the exact parametric regions of the eikonal instability and extended this consideration to asymptotically flat and de Sitter cases. The approach to the threshold of instability is driven by purely imaginary quasinormal modes, which are similar to those found recently in Grozdanov, Kaplis, and Starinets, [J. High Energy Phys. 07 (2016) 151, 10.1007/JHEP07(2016)151] for the higher curvature corrected black hole with the planar horizon. The found instability may indicate limits of holographic applicability of the GB-AdS backgrounds. Recently, through the analysis of critical behavior in AdS space-time in the presence of the Gauss-Bonnet term, it was shown [Deppe et al, Phys. Rev. Lett. 114, 071102 (2015), 10.1103/PhysRevLett.114.071102], that, if the total energy content of the AdS space-time is small, then no black holes can be formed with mass less than some critical value. A similar mass gap was also found when considering collapse of mass shells in asymptotically flat Gauss-Bonnet theories [Frolov, Phys. Rev. Lett. 115, 051102 (2015), 10.1103/PhysRevLett.115.051102]. The found instability of all sufficiently small Einstein-Gauss-Bonnet-AdS, dS and asymptotically flat black holes may explain the existing mass gaps in their formation.
Representation of SO(4,1) group and Hawking effect in the de-Sitter space
International Nuclear Information System (INIS)
Bogush, A.A.; Otchik, V.S.
1983-01-01
Expression relating the solution of the equation for particles with spin 1/2 to matrix elements of group SO(4, 1), is obtained. When using the relation of the Dirac equation solutions in the de Sitter space with matrix elements of representations of group SO(4, 1) the presence of the Hawking effect in the space is established. The de Sitter space is considered as 4-dimensional hyperboloid, inserted into 5-dimensional pseudo-Euclidean space. It is established, that the average number of emitted spinor particles obeys the Fermi-Dirac distribution
Hawking radiation from the dilaton—(anti) de Sitter black hole via covariant anomaly
International Nuclear Information System (INIS)
Yi-Wen, Han; Yun, Hong; Zhi-Qing, Bao
2009-01-01
Adopting the anomaly cancellation method, initiated by Robinson and Wilczek recently, this paper discusses Hawking radiation from the dilaton—(anti) de Sitter black hole. To save the underlying gauge and general covariance, it introduces covariant fluxes of gauge and energy-momentum tensor to cancel the gauge and gravitational anomalies. The result shows that the introduced compensating fluxes are equivalent to those of a 2-dimensional blackbody radiation at Hawking temperature with appropriate chemical potential. (general)
Collision of domain walls in asymptotically anti-de Sitter spacetime
International Nuclear Information System (INIS)
Takamizu, Yu-ichi; Maeda, Kei-ichi
2006-01-01
We study collision of two domain walls in five-dimensional asymptotically anti-de Sitter spacetime. This may provide the reheating mechanism of an ekpyrotic (or cyclic) brane universe, in which two Bogomol'nyi-Prasad-Sommerfield branes collide and evolve into a hot big bang universe. We evaluate a change of scalar field making the domain wall and can investigate the effect of a negative cosmological term in the bulk to the collision process and the evolution of our universe
Perturbative S-matrix for massive scalar fields in global de Sitter space
International Nuclear Information System (INIS)
Marolf, Donald; Srednicki, Mark; Morrison, Ian A
2013-01-01
We construct a perturbative S-matrix for interacting massive scalar fields in global de Sitter space. Our S-matrix is formulated in terms of asymptotic particle states in the far past and future, taking appropriate care for light fields whose wavefunctions decay only very slowly near the de Sitter conformal boundaries. An alternative formulation expresses this S-matrix in terms of residues of poles in analytically-continued Euclidean correlators (computed in perturbation theory), making it clear that the standard Minkowski-space result is obtained in the flat-space limit. Our S-matrix transforms properly under CPT, is invariant under the de Sitter isometries and perturbative field redefinitions, and is unitary. This unitarity implies a de Sitter version of the optical theorem. We explicitly verify these properties to second order in the coupling for a general cubic interaction, including both tree- and loop-level contributions. Contrary to other statements in the literature, we find that a particle of any positive mass may decay at tree level to any number of particles, each of arbitrary positive masses. In particular, even very light fields (in the complementary series of de Sitter representations) are not protected from tree-level decays. (paper)
On the solution of the Dirac equation in de Sitter space
International Nuclear Information System (INIS)
Klishevich, V V; Tyumentsev, V A
2005-01-01
It is shown that the maximal number of first-order symmetry operators for the Dirac equation (including spin symmetries), both in arbitrary signature flat space and in de Sitter space, is equal. The isomorphic representation of 11-dimensional nonlinear symmetry algebra (W-algebra) of first-order operators for the Dirac operator in flat space and de Sitter space is considered. The algebra is an extension of the Lie algebra of the group of pseudo-orthogonal rotations and this extension is unique. We have found all linear Lie subalgebras in the nonlinear algebra that satisfy the conditions of the noncommutative integration theorem. Using one subalgebra we have integrated the Dirac equation in the generalized spherical system of coordinates and have constructed the complete class of exact solutions. The solution is found by a method that differs from the variable separation method and is new in the literature. The massive particle spectrum, models of particle into antiparticle transmutation, the disappearance of particles and the quantization conditions of the motion are discussed. One can use the results of the paper to pose the boundary problem for the Dirac equation in de Sitter space if the interval is used in the boundary condition. As an example, we consider a model of asymptotically flat space that is glued from the de Sitter space and flat space. We interpret the model as a gravitational well or barrier
Complexified de Sitter space: Analytic causal kernels and Kaellen-Lehmann-type representation
International Nuclear Information System (INIS)
Bros, J.
1991-01-01
Global analyticity properties of functions associated with causal kernels on de Sitter space are considered. These properties extend in a reasonable way those implied by the general framework of quantum field theory in complex Minkowski space. Mathematical results of J. Faraut, G.A. Viano and J. Bros (motivated in particular by complex angular momentum analysis in field theory) find here new applications. (orig.)
Hawking temperature and scalar field fluctuations in the de-Sitter space
International Nuclear Information System (INIS)
Rozhanskij, L.V.
1988-01-01
It is shown that diffusion equation for scalar field fluctuations in the de-Sitter space corresponds to Hawking temperature. The relationship between stationary solution of the equation and Hartle-Hawking instanton at random space dimensionality and any type of gravitational effect has been established
Pair creation of anti-de Sitter black holes on a cosmic string background
International Nuclear Information System (INIS)
Dias, Oscar J.C.
2004-01-01
We analyze the quantum process in which a cosmic string breaks in an anti-de Sitter (AdS) background, and a pair of charged or neutral black holes is produced at the ends of the strings. The energy to materialize and accelerate the pair comes from the string tension. In an AdS background this is the only study done on the process of production of a pair of correlated black holes with spherical topology. The acceleration A of the produced black holes is necessarily greater than √(|Λ|/3), where Λ A bh /4 , where A bh is the black hole horizon area. We also conclude that the general behavior of the pair creation rate with the mass and acceleration of the black holes is similar in the AdS, flat and de Sitter cases, and our AdS results reduce to the ones of the flat case when Λ→0
Tunneling across dilaton coupled black holes in anti de Sitter spacetime
International Nuclear Information System (INIS)
Ghosh, Tanwi; SenGupta, Soumitra
2011-01-01
Considering generalised action for dilaton coupled Maxwell-Einstein theory in four dimensions, Gao and Zhang obtained black holes solutions for asymptotically anti de Sitter (Ads) and de Sitter (ds) spacetimes. We study the Hawking radiation in Parikh-Wilczek's tunneling formalism as well as using Bogoliubov transformations. We compare the expression of the Hawking temperature obtained from these two different approaches. Stability and the extremality conditions for such black holes are discussed. The exact dependences of the Hawking temperature and flux on the dilaton coupling parameter are determined. It is shown that the Hawking flux increases with the dilaton coupling parameter. Finally we show that the expression for the Hawking flux obtained using Bogoliubov transformation matches exactly with flux calculated via chiral gauge and gravitational anomalies. This establishes a correspondence among all these different approaches of estimating Hawking radiation from these classes of black holes.
Thin-shell bubbles and information loss problem in anti de Sitter background
Energy Technology Data Exchange (ETDEWEB)
Sasaki, Misao [Yukawa Institute for Theoretical Physics,Kyoto University, Kyoto 606-8502 (Japan); Tomsk State Pedagogical University,634050 Tomsk (Russian Federation); Yeom, Dong-han [Yukawa Institute for Theoretical Physics,Kyoto University, Kyoto 606-8502 (Japan); Leung Center for Cosmology and Particle Astrophysics, National Taiwan University,Taipei 10617, Taiwan (China)
2014-12-24
We study the motion of thin-shell bubbles and their tunneling in anti de Sitter (AdS) background. We are interested in the case when the outside of a shell is a Schwarzschild-AdS space (false vacuum) and the inside of it is an AdS space with a lower vacuum energy (true vacuum). If a collapsing true vacuum bubble is created, classically it will form a Schwarzschild-AdS black hole. However, this collapsing bubble can tunnel to a bouncing bubble that moves out to spatial infinity. Then, although the classical causal structure of a collapsing true vacuum bubble has the singularity and the event horizon, quantum mechanically the wavefunction has support for a history without any singularity nor event horizon which is mediated by the non-perturbative, quantum tunneling effect. This may be regarded an explicit example that shows the unitarity of an asymptotic observer in AdS, while a classical observer who only follows the most probable history effectively lose information due to the formation of an event horizon.
Thin-shell bubbles and information loss problem in anti de Sitter background
International Nuclear Information System (INIS)
Sasaki, Misao; Yeom, Dong-han
2014-01-01
We study the motion of thin-shell bubbles and their tunneling in anti de Sitter (AdS) background. We are interested in the case when the outside of a shell is a Schwarzschild-AdS space (false vacuum) and the inside of it is an AdS space with a lower vacuum energy (true vacuum). If a collapsing true vacuum bubble is created, classically it will form a Schwarzschild-AdS black hole. However, this collapsing bubble can tunnel to a bouncing bubble that moves out to spatial infinity. Then, although the classical causal structure of a collapsing true vacuum bubble has the singularity and the event horizon, quantum mechanically the wavefunction has support for a history without any singularity nor event horizon which is mediated by the non-perturbative, quantum tunneling effect. This may be regarded an explicit example that shows the unitarity of an asymptotic observer in AdS, while a classical observer who only follows the most probable history effectively lose information due to the formation of an event horizon.
Semiclassical relations and IR effects in de Sitter and slow-roll space-times
DEFF Research Database (Denmark)
B. Giddings, Steven; Sloth, Martin Snoager
2010-01-01
We calculate IR divergent graviton one-loop corrections to scalar correlators in de Sitter space, and show that the leading IR contribution may be reproduced via simple semiclassical consistency relations. One can likewise use such semiclassical relations to calculate leading IR corrections to co...... with a sharp perturbative calculation of "missing information" in Hawking radiation....
Static, self-dual, finite action SU(3) gauge fields in the de Sitter space
International Nuclear Information System (INIS)
Chakrabarti, A.; Comtet, A.; Viswanathan, K.S.; Simon Fraser Univ., Burnaby, British Columbia
1980-01-01
Static, self-dual, finite action SU(3) gauge fields are constructed on the euclidean section of the positive curvature de Sitter metric with periodic time. Their relation to known time dependent flat space solutions is pointed out. Their significances and possible applications are indicated. (orig.)
One-loop effective action for non-local modified Gauss-Bonnet gravity in de Sitter space
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Cognola, Guido; Zerbini, Sergio [Universita di Trento (Italy); Istituto Nazionale di Fisica Nucleare Gruppo Collegato di Trento, Dipartimento di Fisica, Trento (Italy); Elizalde, Emilio [Consejo Superior de Investigaciones Cientificas (ICE/CSIC) and Institut d' Estudis Espacials de Catalunya (IEEC), Facultat Ciencies, Bellaterra (Barcelona) (Spain); Nojiri, Shin' ichi [Nagoya University, Department of Physics, Nagoya (Japan); Odintsov, Sergei D. [Consejo Superior de Investigaciones Cientificas (ICE/CSIC) and Institut d' Estudis Espacials de Catalunya (IEEC), Facultat Ciencies, Bellaterra (Barcelona) (Spain); ICREA, Barcelona (Spain); TSPU, Center of Theor. Phys., Tomsk (Russian Federation)
2009-12-15
We discuss the classical and quantum properties of non-local modified Gauss-Bonnet gravity in de Sitter space, using its equivalent representation via string-inspired local scalar-Gauss-Bonnet gravity with a scalar potential. A classical, multiple de Sitter universe solution is found where one of the de Sitter phases corresponds to the primordial inflationary epoch, while the other de Sitter space solution - the one with the smallest Hubble rate - describes the late-time acceleration of our universe. A Chameleon scenario for the theory under investigation is developed, and it is successfully used to show that the theory complies with gravitational tests. An explicit expression for the one-loop effective action for this non-local modified Gauss-Bonnet gravity in the de Sitter space is obtained. It is argued that this effective action might be an important step towards the solution of the cosmological constant problem. (orig.)
Gravitational and electromagnetic fields near an anti-de Sitter-like infinity
International Nuclear Information System (INIS)
Krtous, Pavel; Podolsky, Jiri
2004-01-01
We analyze the asymptotic structure of general gravitational and electromagnetic fields near an anti-de Sitter-like conformal infinity. The dependence of the radiative component of the fields on a null direction along which the infinity is approached is obtained. The directional pattern of outgoing and ingoing radiation, which supplements standard peeling property, is determined by the algebraic (Petrov) type of the fields and also by the orientation of the principal null directions with respect to timelike infinity. The dependence on the orientation is a new feature if compared to spacelike infinity
Configurational entropy of anti-de Sitter black holes
International Nuclear Information System (INIS)
Braga, Nelson R.F.; Rocha, Roldão da
2017-01-01
Recent studies indicate that the configurational entropy is an useful tool to investigate the stability and (or) the relative dominance of states for diverse physical systems. Recent examples comprise the connection between the variation of this quantity and the relative fraction of light mesons and glueballs observed in hadronic processes. Here we develop a technique for defining a configurational entropy for an AdS-Schwarzschild black hole. The achieved result corroborates consistency with the Hawking–Page phase transition. Namely, the dominance of the black hole configurational entropy will be shown to increase with the temperature. In order to verify the consistency of the new procedure developed here, we also consider the case of black holes in flat space-time. For such a black hole, it is known that evaporation leads to instability. The configurational entropy obtained for the flat space case is thoroughly consistent with the physical expectation. In fact, we show that the smaller the black holes, the more unstable they are. So, the configurational entropy furnishes a reliable measure for stability of black holes.
Configurational entropy of anti-de Sitter black holes
Energy Technology Data Exchange (ETDEWEB)
Braga, Nelson R.F., E-mail: braga@if.ufrj.br [Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, RJ 21941-972 (Brazil); Rocha, Roldão da, E-mail: roldao.rocha@ufabc.edu.br [Centro de Matemática, Computação e Cognição, Universidade Federal do ABC – UFABC, 09210-580, Santo André (Brazil)
2017-04-10
Recent studies indicate that the configurational entropy is an useful tool to investigate the stability and (or) the relative dominance of states for diverse physical systems. Recent examples comprise the connection between the variation of this quantity and the relative fraction of light mesons and glueballs observed in hadronic processes. Here we develop a technique for defining a configurational entropy for an AdS-Schwarzschild black hole. The achieved result corroborates consistency with the Hawking–Page phase transition. Namely, the dominance of the black hole configurational entropy will be shown to increase with the temperature. In order to verify the consistency of the new procedure developed here, we also consider the case of black holes in flat space-time. For such a black hole, it is known that evaporation leads to instability. The configurational entropy obtained for the flat space case is thoroughly consistent with the physical expectation. In fact, we show that the smaller the black holes, the more unstable they are. So, the configurational entropy furnishes a reliable measure for stability of black holes.
Reissner–Nordström Anti-de Sitter Black Holes in Mimetic F(R Gravity
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V. K. Oikonomou
2016-05-01
Full Text Available In this paper, we study under which conditions the Reissner–Nordström anti-de Sitter black hole can be a solution of the vacuum mimetic F ( R gravity with Lagrange multiplier and mimetic scalar potential. As the author demonstrates, the resulting picture in the mimetic F ( R gravity case is a trivial extension of the standard F ( R approach, and in effect, the metric perturbations in the mimetic F ( R gravity case, for the Reissner–Nordström anti-de Sitter black hole metric, at the first order of the perturbed variables are the same at the leading order.
Ghosh, Shubhrangshu; Banik, Prabir
2015-07-01
In this paper, we present a complete work on steady state spherically symmetric Bondi type accretion flow in the presence of cosmological constant (Λ) in both Schwarzschild-de Sitter (SDS) and Schwarzschild anti-de Sitter (SADS) backgrounds considering an isolated supermassive black hole (SMBH), with the inclusion of a simple radiative transfer scheme, in the pseudo-general relativistic paradigm. We do an extensive analysis on the transonic behavior of the Bondi type accretion flow onto the cosmological BHs including a complete analysis of the global parameter space and the stability of flow, and do a complete study of the global family of solutions for a generic polytropic flow. Bondi type accretion flow in SADS background renders multiplicity in its transonic behavior with inner "saddle" type and outer "center" type sonic points, with the transonic solutions forming closed loops or contours. There is always a limiting value for ∣Λ∣ up to which we obtain valid stationary transonic solutions, which correspond to both SDS and SADS geometries; this limiting value moderately increases with the increasing radiative efficiency of the flow, especially correspond to Bondi type accretion flow in SADS background. Repulsive Λ suppresses the Bondi accretion rate by an order of magnitude for relativistic Bondi type accretion flow for a certain range in temperature, and with a marginal increase in the Bondi accretion rate if the corresponding accretion flow occurs in SADS background. However, for a strongly radiative Bondi type accretion flow with high mass accretion rate, the presence of cosmological constant do not much influence the corresponding Bondi accretion rate of the flow. Our analysis show that the relic cosmological constant has a substantial effect on Bondi type accretion flow onto isolated SMBHs and their transonic solutions beyond length-scale of kiloparsecs, especially if the Bondi type accretion occurs onto the host supergiant ellipticals or central
International Nuclear Information System (INIS)
Daghigh, Ramin G; Green, Michael D
2009-01-01
We analyze analytically the asymptotic regions of the quasinormal mode frequency spectra with infinitely large overtone numbers for D-dimensional Schwarzschild black holes in anti de Sitter spacetimes. In this limit, we confirm the analytic results obtained previously in the literature using different methods. In addition, we show that in certain spacetime dimensions these techniques imply the existence of other regions of the asymptotic quasinormal mode frequency spectrum which have not previously appeared in the literature. For large black holes, some of these modes have a damping rate of 1.2T H , where T H is the Hawking temperature. This is less than the damping rate of the lowest overtone quasinormal mode calculated by other authors. It is not completely clear whether these modes actually exist or are an artifact of an unknown flaw in the analytic techniques being used. We discuss the possibility of the existence of these modes and explore some of the consequences. We also examine the possible connection between the asymptotic quasinormal modes of Schwarzschild-anti de Sitter black holes and the quantum level spacing of their horizon area spectrum.
de Sitter symmetry of Neveu-Schwarz spinors
International Nuclear Information System (INIS)
Epstein, Henri; Moschella, Ugo
2016-01-01
We study the relations between Dirac fields living on the 2-dimensional Lorentzian cylinder and the ones living on the double-covering of the 2-dimensional de Sitter manifold, here identified as a certain coset space of the group SL(2,R). We show that there is an extended notion of de Sitter covariance only for Dirac fields having the Neveu-Schwarz anti-periodicity and construct the relevant cocycle. Finally, we show that the de Sitter symmetry is naturally inherited by the Neveu-Schwarz massless Dirac field on the cylinder.
International Nuclear Information System (INIS)
Aldrovandi, R; Almeida, J P Beltran; Pereira, J G
2007-01-01
A special relativity based on the de Sitter group is introduced, which is a theory that might hold up in the presence of a non-vanishing cosmological constant. Like ordinary special relativity, it retains the quotient character of spacetime, and a notion of homogeneity. As a consequence, the underlying spacetime will be a de Sitter spacetime, whose associated kinematics will differ from that of ordinary special relativity. The corresponding modified notions of energy and momentum are obtained, and the exact relationship between them, which is invariant under a re-scaling of the involved quantities, explicitly exhibited. Since the de Sitter group can be considered a particular deformation of the Poincare group, this theory turns out to be a specific kind of deformed (or doubly) special relativity. Some experimental consequences, as well as the causal structure of spacetime-modified by the presence of the de Sitter horizon-are briefly discussed
PURE STATE ENTANGLEMENT ENTROPY IN NONCOMMUTATIVE 2D DE SITTER SPACE TIME
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M.F Ghiti
2014-12-01
Full Text Available Using the general modified field equation, a general noncommutative Klein-Gordon equation up to the second order of the noncommutativity parameter is derived in the context of noncommutative 2D De Sitter space-time. Using Bogoliubov coefficients and a special technics called conformal time; the boson-antiboson pair creation density is determined. The Von Neumann boson-antiboson pair creation quantum entanglement entropy is presented to compute the entanglement between the modes created presented.
Thermal properties of Green's functions in Rindler, de Sitter, and Schwarzschild spaces
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Dowker, J.S.
1978-01-01
The conventional massless scalar Green's functions in the Minkowski, de Sitter, and two-dimensional Schwarzschild spaces are reinterpreted as finite-temperature Green's functions and the corresponding averages of the stress-energy operator are calculated. The renormalization adopted consists of subtracting the zero-temperature quantities. In all cases the averages give the stress tensor of a purely Planck-type perfect gas
De Sitter projective relativity
Licata, Ignazio; Benedetto, Elmo
2017-01-01
This book presents the Projective approach to de Sitter Relativity. It traces the development of renewed interest in models of the universe at constant positive curvature such as "vacuum" geometry. The De Sitter Theory of Relativity, formulated in 1917 with Willem De Sitter's solution of the Einstein equations, was used in different fields during the 1950s and 1960s, in the work of H. Bacry, J.M. LevyLeblond and F.Gursey, to name some important contributors. From the 1960s to 1980s, L. Fantappié and G. Arcidiacono provided an elegant group approach to the De Sitter universe putting the basis for special and general projective relativity. Today such suggestions flow into a unitary scenario, and this way the De Sitter Relativity is no more a "missing opportunity" (F. Dyson, 1972), but has a central role in theoretical physics. In this volume a systematic presentation is given of the De Sitter Projective relativity, with the recent developments in projective general relativity and quantum cosmology.
Space Inside a Liquid Sphere Transforms into De Sitter Space by Hilbert Radius
Rabounski, Dmitri; Borissova, Larissa
2010-04-01
Consider space inside a sphere of incompressible liquid, and space surrounding a mass-point. Metrics of the spaces were deduced in 1916 by Karl Schwarzschild. 1) Our calculation shows that a liquid sphere can be in the state of gravitational collapse (g00 = 0) only if its mass and radius are close to those of the Universe (M = 8.7x10^55 g, a = 1.3x10^28 cm). However if the same mass is presented as a mass-point, the radius of collapse rg (Hilbert radius) is many orders lesser: g00 = 0 realizes in a mass-point's space by other conditions. 2) We considered a liquid sphere whose radius meets, formally, the Hilbert radius of a mass-point bearing the same mass: a = rg, however the liquid sphere is not a collapser (see above). We show that in this case the metric of the liquid sphere's internal space can be represented as de Sitter's space metric, wherein λ = 3/a^2 > 0: physical vacuum (due to the λ-term) is the same as the field of an ideal liquid where ρ0 0 (the mirror world liquid). The gravitational redshift inside the sphere is produced by the non-Newtonian force of repulsion (which is due to the λ-term, λ = 3/a^2 > 0); it is also calculated.
Cosmology at the boundary of de Sitter space using the dS/QFT correspondence
International Nuclear Information System (INIS)
Dias, Mafalda
2011-01-01
Using the de Sitter/quantum field theory correspondence in the context of inflation allows for the study of interesting, otherwise inaccessible physics. In particular, by studying inflation via its dual field theory at the boundary of the de Sitter space, it may be possible to study a regime of strongly coupled gravity at early times. The purpose of this work is to completely express cosmological observables in terms of the free parameters of a dual field theory and to compare them with cosmic microwave background data. In this way, constraints on the observational parameters constrains the validity of the strongly coupled inflation picture by imposing limits on the parameters of the field theory. The fit with data defines a limit for the consistency and validity of the approach taken and shows that, within this limit, the model is almost unconstrained, but quite predictive, producing power spectra of density perturbations extremely near scale invariance.
Nonlinear Evolution and Final Fate of Charged Anti-de Sitter Black Hole Superradiant Instability.
Bosch, Pablo; Green, Stephen R; Lehner, Luis
2016-04-08
We describe the full nonlinear development of the superradiant instability for a charged massless scalar field coupled to general relativity and electromagnetism, in the vicinity of a Reissner-Nordström-anti-de Sitter black hole. The presence of the negative cosmological constant provides a natural context for considering perfectly reflecting boundary conditions and studying the dynamics as the scalar field interacts repeatedly with the black hole. At early times, small superradiant perturbations grow as expected from linearized studies. Backreaction then causes the black hole to lose charge and mass until the perturbation becomes nonsuperradiant, with the final state described by a stable hairy black hole. For large gauge coupling, the instability extracts a large amount of charge per unit mass, resulting in greater entropy increase. We discuss the implications of the observed behavior for the general problem of superradiance in black hole spacetimes.
The first law of thermodynamics for Kerr-anti-de Sitter black holes
International Nuclear Information System (INIS)
Gibbons, G W; Perry, M J; Pope, C N
2005-01-01
We obtain expressions for the mass and angular momenta of rotating black holes in anti-de Sitter backgrounds in four, five and higher dimensions. We verify explicitly that our expressions satisfy the first law of thermodynamics, thus allowing an unambiguous identification of the entropy of these black holes with 1/4 of the area. We find that the associated thermodynamic potential equals the background-subtracted Euclidean action multiplied by the temperature. Our expressions differ from many given in the literature. We find that in more than four dimensions, only our expressions satisfy the first law of thermodynamics. Moreover, in all dimensions we show that our expression for the mass coincides with that given by the conformal conserved charge introduced by Ashtekar, Magnon and Das. We indicate the relevance of these results to the AdS/CFT correspondence
Breit-Wigner resonances and the quasinormal modes of anti-de Sitter black holes
International Nuclear Information System (INIS)
Berti, Emanuele; Cardoso, Vitor; Pani, Paolo
2009-01-01
We show that the theory of Breit-Wigner resonances can be used as an efficient numerical tool to compute black hole quasinormal modes. For illustration, we focus on the Schwarzschild anti-de Sitter (SAdS) spacetime. The resonance method is better suited to small SAdS black holes than the traditional series expansion method, allowing us to confirm that the damping time scale of small SAdS black holes for scalar and gravitational fields is proportional to r + -2l-2 , where r + is the horizon radius. The proportionality coefficients are in good agreement with analytic calculations. We also examine the eikonal limit of SAdS quasinormal modes, confirming quantitatively Festuccia and Liu's [arXiv:0811.1033] prediction of the existence of very long-lived modes. Our results are particularly relevant for the AdS/CFT correspondence, since long-lived modes presumably dominate the decay time scale of the perturbations.
Spin Interaction under the Collision of Two Kerr-(Anti-de Sitter Black Holes
Directory of Open Access Journals (Sweden)
Bogeun Gwak
2017-12-01
Full Text Available We investigate herein the spin interaction during collisions between Kerr-(anti-de Sitter black holes. The spin interaction potential depends on the relative rotation directions of the black holes, and this potential can be released as gravitational radiation upon collision. The energy of the radiation depends on the cosmological constant and corresponds to the spin interaction potential in the limit that one of the black holes has negligibly small mass and angular momentum. We then determine the approximate overall behaviors of the upper bounds on the radiation using thermodynamics. The results indicate that the spin interaction can consistently contribute to the radiation. In addition, the radiation depends on the stability of the black hole produced by the collision.
Thermodynamics and stability of flat anti-de Sitter black strings
International Nuclear Information System (INIS)
Chen Si; Schleich, Kristin; Witt, Donald M.
2008-01-01
We examine the thermodynamics and stability of 5-dimensional flat anti-de Sitter (AdS) black strings, locally asymptotically anti-de Sitter spacetimes whose spatial sections are AdS black holes with Ricci flat horizons. We find that there is a phase transition for the flat AdS black string when the AdS soliton string is chosen as the thermal background. We find that this bulk phase transition corresponds to a 4-dimensional flat AdS black hole to AdS soliton phase transition on the boundary Karch-Randall branes. We compute the possibility of a phase transition from a flat AdS black string to a 5-dimensional AdS soliton and show that, though possible for certain thin black strings, the transition to the AdS soliton string is preferred. In contrast to the case of the Schwarzschild-AdS black string, we find that the specific heat of the flat AdS black string is always positive; hence it is thermodynamically stable. We show numerically that both the flat AdS black string and AdS soliton string are free of a Gregory-Laflamme instability for all values of the mass parameter. Therefore thermodynamic stability implies perturbative stability for this spacetime. This may indicate that a generalization of the Gubser-Mitra conjecture, in which the assumption of a translational killing vector is weakened to that of a conformal killing vector of translational form, holds under certain conditions.
Gravitational quasinormal modes of static Einstein-Gauss-Bonnet anti-de Sitter black holes
Ma, Hong; Li, Jin
2018-04-01
In this paper, we describe quasinormal modes (QNMs) for gravitational perturbations of Einstein-Gauss-Bonnet black holes (BHs) in higher dimensional spacetimes, and derive the corresponding parameters of such black holes in three types of spacetime (flat, de Sitter (dS) and anti-de Sitter (AdS)). Our attention is concentrated on discussing the (in)stability of Einstein-Gauss-Bonnet AdS BHs through the temporal evolution of all types of gravitational perturbation fields (tensor, vector and scalar). It is concluded that the potential functions in vector and scalar gravitational perturbations have negative regions, which suppress quasinormal ringing. Furthermore, the influences of the Gauss-Bonnet coupling parameter α, the number of dimensions n and the angular momentum quantum number l on the Einstein-Gauss-Bonnet AdS BHs quasinormal spectrum are analyzed. The QNM frequencies have greater oscillation and lower damping rate with the growth of α. This indicates that QNM frequencies become increasingly unstable with large α. Meanwhile, the dynamic evolutions of the perturbation field are compliant with the results of computation from the Horowitz and Hubeny method. Because the number of extra dimensions is connected with the string scale, the relationship between α and properties of Einstein-Gauss-Bonnet AdS BHs might be beneficial for the exploitation of string theory and extra-dimensional brane worlds. Supported by FAPESP (2012/08934-0), National Natural Science Foundation of China (11205254, 11178018, 11375279, 11605015), the Natural Science Foundation Project of CQ CSTC (2011BB0052), and the Fundamental Research Funds for the Central Universities (106112016CDJXY300002, 106112017CDJXFLX0014, CDJRC10300003)
Energy Technology Data Exchange (ETDEWEB)
Vasiliev, M A
1987-11-01
Linearized curvatures are constructed for massless higher spin fields on the (anti-) de Sitter background. The quite uniform description for free massless fields of all integer and half-integer spins s greater than or equal to 3/2 is presented, based on these curvatures. In particular, the actions and the equations of motion are given in a simple form. The proposed linearized curvatures provide 'initial data' for determination of a non-Abelian higher spin symmetry that may correspond to a hypothetical non-trivial theory of higher spins interacting with gravity and themselves. It is noted that the conjugation law for fermion fields should be modified drastically after transition from the anti-de-Sitter geometry to the de Sitter one.
Auto-localization in de-Sitter space
International Nuclear Information System (INIS)
Karch, Andreas
2003-01-01
We point out that gravity on dS n gives rise to a localized graviton on dS n-1 . This way one can derive a recursion relation for the entropy of dS spaces, which might have interesting implications for dS holography. In the same spirit we study domain walls interpolating between dS spaces with different cosmological constant. Our observation gives an easy way to calculate what fraction of the total entropy can be accessed by an observer stuck on the bubble wall. (author)
Vacuum state of the Dirac field in de Sitter space and entanglement entropy
Energy Technology Data Exchange (ETDEWEB)
Kanno, Sugumi [Department of Theoretical Physics and History of Science,University of the Basque Country,48080 Bilbao (Spain); IKERBASQUE, Basque Foundation for Science,Maria Diaz de Haro 3, 48013, Bilbao (Spain); Sasaki, Misao [Center for Gravitational Physics,Yukawa Institute for Theoretical Physics, Kyoto University,Kyoto 606-8502 (Japan); Tanaka, Takahiro [Department of Physics, Kyoto University,Kyoto 606-8502 (Japan); Center for Gravitational Physics,Yukawa Institute for Theoretical Physics, Kyoto University,Kyoto 606-8502 (Japan)
2017-03-13
We compute the entanglement entropy of a free massive Dirac field between two causally disconnected open charts in de Sitter space. We first derive the Bunch-Davies vacuum mode functions of the Dirac field. We find there exists no supercurvature mode for the Dirac field. We then give the Bogoliubov transformation between the Bunch-Davies vacuum and the open chart vacua that makes the reduced density matrix diagonal. We find that the Dirac field becomes more entangled than a scalar field as m{sup 2}/H{sup 2} becomes small, and the difference is maximal in the massless limit.
The Cardy-Verlinde formula and entropy of topological Kerr-Newman black holes in de Sitter spaces
International Nuclear Information System (INIS)
Setare, M.R.; Altaie, M.B.
2003-01-01
In this paper we show that the entropy of a cosmological horizon in 4-dimensional topological Kerr-Newman-de Sitter spaces can be described by the Cardy-Verlinde formula, which is supposed to be an entropy formula of conformal field theory in any number of dimensions. Furthermore, we find that the entropy of a black hole horizon can also be rewritten in terms of the Cardy-Verlinde formula for these black holes in de Sitter spaces, if we use the definition due to Abbott and Deser for conserved charges in asymptotically de Sitter spaces. Such results presume a well-defined dS/CFT correspondence, which has not yet attained the credibility of its AdS analogue. (orig.)
Massive gravity in de Sitter space via the gravitational Higgs mechanism
International Nuclear Information System (INIS)
Iglesias, Alberto; Kakushadze, Zurab
2010-01-01
In this paper we discuss massive gravity in de Sitter space via the gravitational Higgs mechanism, which provides a nonlinear definition thereof. The Higgs scalars are described by a nonlinear sigma model, which includes higher derivative terms required to obtain the Fierz-Pauli mass term. Using the aforesaid nonperturbative definition, we address the appearance of an enhanced local symmetry and a null norm state in the linearized massive gravity in de Sitter space at the special value of the graviton mass to the Hubble parameter ratio. By studying full nonperturbative equations of motion, we argue that there is no enhanced symmetry in the full nonlinear theory. We then argue that in the full nonlinear theory no null norm state is expected to arise at the aforesaid special value. This suggests that no ghost might be present for lower graviton mass values and the full nonlinear theory might be unitary for all values of the graviton mass and the Hubble parameter with no van Dam-Veltman-Zakharov discontinuity. We argue that this is indeed the case by studying the full nonlinear Hamiltonian for the relevant conformal and helicity-0 longitudinal modes. In particular, we argue that no negative norm state is present in the full nonlinear theory.
New Einstein-Sasaki and Einstein spaces from Kerr-de Sitter
International Nuclear Information System (INIS)
Cvetic, M.; Lue, H.; Pope, C.N.; Page, Don N.
2009-01-01
In this paper, which is an elaboration of our results in Phys. Rev. Lett. 95:071101, 2005 (hep-th/0504225), we construct new Einstein-Sasaki spaces L p,q,r 1 ,...,r n-1 in all odd dimensions D = 2n+1 ≥ 5. They arise by taking certain BPS limits of the Euclideanised Kerr-de Sitter metrics. This yields local Einstein-Sasaki metrics of cohomogeneity n, with toric U(1) n+1 principal orbits, and n real non-trivial parameters. By studying the structure of the degenerate orbits we show that for appropriate choices of the parameters, characterised by the (n+1) coprime integers (p,q,r 1 ,...,r n-1 ), the local metrics extend smoothly onto complete and non-singular compact Einstein-Sasaki manifolds L p,q,r 1 ,...,r n-1 . We also construct new complete and non-singular compact Einstein spaces Λ p,q,r 1 ,...,r n in D = 2n+1 that are not Sasakian, by choosing parameters appropriately in the Euclideanised Kerr-de Sitter metrics when no BPS limit is taken.
Quintessence Reissner Nordström Anti de Sitter Black Holes and Joule Thomson Effect
Ghaffarnejad, H.; Yaraie, E.; Farsam, M.
2018-06-01
In this work we investigate corrections of the quintessence regime of the dark energy on the Joule-Thomson (JT) effect of the Reissner Nordström anti de Sitter (RNAdS) black hole. The quintessence dark energy has equation of state as p q = ω ρ q in which -1black hole mass, we calculate inversion temperature T i of the quintessence RNAdS black hole where its cooling phase is changed to heating phase at a particular (inverse) pressure P i . Position of the inverse point { T i , P i } is determined by crossing the inverse curves with the corresponding Gibbons-Hawking temperature on the T-P plan. We determine position of the inverse point versus different numerical values of the mass M and the charge Q of the quintessence AdS RN black hole. The cooling-heating phase transition (JT effect) is happened for M > Q in which the causal singularity is still covered by the horizon. Our calculations show sensitivity of the inverse point { T i , P i } position on the T-P plan to existence of the quintessence dark energy just for large numerical values of the AdS RN black holes charge Q. In other words the quintessence dark energy dose not affect on position of the inverse point when the AdS RN black hole takes on small charges.
International Nuclear Information System (INIS)
Peng Junjin; Wu Shuangqing
2008-01-01
Motivated by the success of the recently proposed method of anomaly cancellation to derive Hawking fluxes from black hole horizons of spacetimes in various dimensions, we have further extended the covariant anomaly cancellation method shortly simplified by Banerjee and Kulkarni to explore the Hawking radiation of the (3+1)-dimensional charged rotating black strings and their higher dimensional extensions in anti-de Sitter spacetimes, whose horizons are not spherical but can be toroidal, cylindrical or planar, according to their global identifications. It should be emphasized that our analysis presented here is very general in the sense that the determinant of the reduced (1+1)-dimensional effective metric from these black strings need not be equal to one (√(-g)≠1). Our results indicate that the gauge and energy-momentum fluxes needed to cancel the (1+1)-dimensional covariant gauge and gravitational anomalies are compatible with the Hawking fluxes. Besides, thermodynamics of these black strings are studied in the case of a variable cosmological constant
Spherical and planar three-dimensional anti-de Sitter black holes
International Nuclear Information System (INIS)
Zanchin, Vilson T; Miranda, Alex S
2004-01-01
The technique of dimensional reduction was used in a recent paper (Zanchin V T, Kleber A and Lemos J P S 2002 Phys. Rev. D 66 064022) where a three-dimensional (3D) Einstein-Maxwell-dilaton theory was built from the usual four-dimensional (4D) Einstein-Maxwell-Hilbert action for general relativity. Starting from a class of 4D toroidal black holes in asymptotically anti-de Sitter (AdS) spacetimes several 3D black holes were obtained and studied in such a context. In the present work we choose a particular case of the 3D action which presents Maxwell field, dilaton field and an extra scalar field, besides gravity field and a negative cosmological constant, and obtain new 3D static black hole solutions whose horizons may have spherical or planar topology. We show that there is a 3D static spherically symmetric solution analogous to the 4D Reissner-Nordstroem-AdS black hole, and obtain other new 3D black holes with planar topology. From the static spherical solutions, new rotating 3D black holes are also obtained and analysed in some detail
Dynamics in non-globally-hyperbolic static spacetimes: III. Anti-de Sitter spacetime
International Nuclear Information System (INIS)
Ishibashi, Akihiro; Wald, Robert M
2004-01-01
In recent years, there has been considerable interest in theories formulated in anti-de Sitter (AdS) spacetime. However, AdS spacetime fails to be globally hyperbolic, so a classical field satisfying a hyperbolic wave equation on AdS spacetime need not have a well-defined dynamics. Nevertheless, AdS spacetime is static, so the possible rules of dynamics for a field satisfying a linear wave equation are constrained by our previous general analysis-given in paper II-where it was shown that the possible choices of dynamics correspond to choices of positive, self-adjoint extensions of a certain differential operator, A. In the present paper, we reduce the analysis of electromagnetic and gravitational perturbations in AdS spacetime to scalar wave equations. We then apply our general results to analyse the possible dynamics of scalar, electromagnetic and gravitational perturbations in AdS spacetime. In AdS spacetime, the freedom (if any) in choosing self-adjoint extensions of A corresponds to the freedom (if any) in choosing suitable boundary conditions at infinity, so our analysis determines all the possible boundary conditions that can be imposed at infinity. In particular, we show that other boundary conditions besides the Dirichlet and Neumann conditions may be possible, depending on the value of the effective mass for scalar field perturbations, and depending on the number of spacetime dimensions and type of mode for electromagnetic and gravitational perturbations
Wang, Mengjie; Herdeiro, Carlos; Jing, Jiliang
2017-11-01
We study Dirac quasinormal modes of Schwarzschild-anti-de Sitter (Schwarzschild-AdS) black holes, following the generic principle for allowed boundary conditions proposed in [M. Wang, C. Herdeiro, and M. O. P. Sampaio, Phys. Rev. D 92, 124006 (2015)., 10.1103/PhysRevD.92.124006]. After deriving the equations of motion for Dirac fields on the aforementioned background, we impose vanishing energy flux boundary conditions to solve these equations. We find a set of two Robin boundary conditions are allowed. These two boundary conditions are used to calculate Dirac normal modes on empty AdS and quasinormal modes on Schwarzschild-AdS black holes. In the former case, we recover the known normal modes of empty AdS; in the latter case, the two sets of Robin boundary conditions lead to two different branches of quasinormal modes. The impact on these modes of the black hole size, the angular momentum quantum number and the overtone number are discussed. Our results show that vanishing energy flux boundary conditions are a robust principle, applicable not only to bosonic fields but also to fermionic fields.
Negative norm states in de Sitter space and QFT without renormalization procedure
International Nuclear Information System (INIS)
Takook, M.V.
2002-01-01
In recent papers, 1,2 it has been shown that the presence of negative norm states or negative frequency solutions are indispensable for a fully covariant quantization of the minimally coupled scalar field in de Sitter space. Their presence, while leaving unchanged the physical content of the theory, offers the advantage of eliminating any ultraviolet divergence in the vacuum energy 2 and infrared divergence in the two point function. 3 We attempt here to extend this method to the interacting quantum field in Minkowski space-time. As an illustration of the procedure, we consider the λϕ 4 theory in Minkowski space-time. The mathematical consequences of this method is the disappearance of the ultraviolet divergence to the one-loop approximation. This means, the effect of these auxiliary negative norm states is to allow an automatic renormalization of the theory in this approximation. (author)
Pair of accelerated black holes in an anti-de Sitter background: The AdS C metric
International Nuclear Information System (INIS)
Dias, Oscar J.C.; Lemos, Jose P.S.
2003-01-01
The anti-de Sitter C metric (AdS C metric) is characterized by a quite interesting new feature when compared with the C metric in flat or de Sitter backgrounds. Indeed, contrary to what happens in these two last exact solutions, the AdS C metric only describes a pair of accelerated black holes if the acceleration parameter satisfies A>1/l, where l is the cosmological length. The two black holes cannot interact gravitationally and their acceleration is totally provided by the pressure exerted by a strut that pushes the black holes apart. Our analysis is based on the study of the causal structure, on the description of the solution in the AdS 4-hyperboloid in a 5D Minkowski spacetime, and on the physics of the strut. We also analyze the cases A=1/l and A<1/l that represent a single accelerated black hole in the AdS background
$O(N)$ model in Euclidean de Sitter space: beyond the leading infrared approximation
Nacir, Diana López; Trombetta, Leonardo G
2016-01-01
We consider an $O(N)$ scalar field model with quartic interaction in $d$-dimensional Euclidean de Sitter space. In order to avoid the problems of the standard perturbative calculations for light and massless fields, we generalize to the $O(N)$ theory a systematic method introduced previously for a single field, which treats the zero modes exactly and the nonzero modes perturbatively. We compute the two-point functions taking into account not only the leading infrared contribution, coming from the self-interaction of the zero modes, but also corrections due to the interaction of the ultraviolet modes. For the model defined in the corresponding Lorentzian de Sitter spacetime, we obtain the two-point functions by analytical continuation. We point out that a partial resummation of the leading secular terms (which necessarily involves nonzero modes) is required to obtain a decay at large distances for massless fields. We implement this resummation along with a systematic double expansion in an effective coupling c...
International Nuclear Information System (INIS)
Cardoso, Vitor; Konoplya, Roman; Lemos, Jose P. S.
2003-01-01
We present a thorough analysis of the quasinormal (QN) behavior associated with the decay of scalar, electromagnetic, and gravitational perturbations of Schwarzschild black holes in anti-de Sitter (AdS) spacetimes. As is known, the AdS QN spectrum crucially depends on the relative size of the black hole to the AdS radius. There are three different types of behavior depending on whether the black hole is large, intermediate, or small. The results of previous works, concerning lower overtones for large black holes, are completed here by obtaining higher overtones for all three black hole regimes. There are two major conclusions that one can draw from this work: First, asymptotically for high overtones, all the modes are evenly spaced, and this holds for all three types of regime, large, intermediate, and small black holes, independently of l, where l is the quantum number characterizing the angular distribution; second, the spacing between modes is apparently universal in that it does not depend on the field; i.e., scalar, electromagnetic, and gravitational QN modes all have the same spacing for high overtones. We are also able to prove why scalar and gravitational perturbations are isospectral, asymptotically for high overtones, by introducing appropriate superpartner potentials
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Silverstein, Eva
2008-01-01
We present a framework for de Sitter model building in type IIA string theory, illustrated with specific examples. We find metastable de Sitter (dS) minima of the potential for moduli obtained from a compactification on a product of two nil three-manifolds (which have negative scalar curvature) combined with orientifolds, branes, fractional Chern-Simons forms, and fluxes. As a discrete quantum number is taken large, the curvature, field strengths, inverse volume, and four-dimensional string coupling become parametrically small, and the de Sitter Hubble scale can be tuned parametrically smaller than the scales of the moduli, Kaluza Klein (KK), and winding mode masses. A subtle point in the construction is that although the curvature remains consistently weak, the circle fibers of the nilmanifolds become very small in this limit (though this is avoided in illustrative solutions at modest values of the parameters). In the simplest version of the construction, the heaviest moduli masses are parametrically of the same order as the lightest KK and winding masses. However, we provide a method for separating these marginally overlapping scales, and more generally the underlying supersymmetry of the model protects against large corrections to the low-energy moduli potential
Semiclassical relations and IR effects in de Sitter and slow-roll space-times
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Giddings, Steven B. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Sloth, Martin S., E-mail: giddings@physics.ucsb.edu, E-mail: sloth@cern.ch [CERN, Physics Department, Theory Unit, CH-1211 Geneva 23 (Switzerland)
2011-01-01
We calculate IR divergent graviton one-loop corrections to scalar correlators in de Sitter space, and show that the leading IR contribution may be reproduced via simple semiclassical consistency relations. One can likewise use such semiclassical relations to calculate leading IR corrections to correlators in slow-roll inflation. The regulated corrections shift the tensor/scalar ratio and consistency relation of single field inflation, and non-gaussianity parameters averaged over very large distances. For inflation of sufficient duration, for example arising from a chaotic inflationary scenario, these corrections become of order unity. First-order corrections of this size indicate a breakdown of the perturbative expansion, and suggest the need for a non-perturbative description of the corresponding regime. This is analogous to a situation argued to arise in black hole evolution, and to interfere with a sharp perturbative calculation of ''missing information'' in Hawking radiation.
Semiclassical relations and IR effects in de Sitter and slow-roll space-times
International Nuclear Information System (INIS)
Giddings, Steven B.; Sloth, Martin S.
2011-01-01
We calculate IR divergent graviton one-loop corrections to scalar correlators in de Sitter space, and show that the leading IR contribution may be reproduced via simple semiclassical consistency relations. One can likewise use such semiclassical relations to calculate leading IR corrections to correlators in slow-roll inflation. The regulated corrections shift the tensor/scalar ratio and consistency relation of single field inflation, and non-gaussianity parameters averaged over very large distances. For inflation of sufficient duration, for example arising from a chaotic inflationary scenario, these corrections become of order unity. First-order corrections of this size indicate a breakdown of the perturbative expansion, and suggest the need for a non-perturbative description of the corresponding regime. This is analogous to a situation argued to arise in black hole evolution, and to interfere with a sharp perturbative calculation of ''missing information'' in Hawking radiation
International Nuclear Information System (INIS)
Zanchin, Vilson T.; Kleber, Antares; Lemos, Jose P.S.
2002-01-01
The dimensional reduction of black hole solutions in four-dimensional (4D) general relativity is performed and new 3D black hole solutions are obtained. Considering a 4D spacetime with one spacelike Killing vector, it is possible to split the Einstein-Hilbert-Maxwell action with a cosmological term in terms of 3D quantities. Definitions of quasilocal mass and charges in 3D spacetimes are reviewed. The analysis is then particularized to the toroidal charged rotating anti-de Sitter black hole. The reinterpretation of the fields and charges in terms of a three-dimensional point of view is given in each case, and the causal structure analyzed
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Peter, I. J.
1995-06-01
The work deals with space-times with fixed background metric. The topics were arranged in a straight course, the first chapter collects basic facts on Lorentzian manifolds as time-orientability, causal structure, ... Further free neutral scalar fields and spinor fields described by the Klein-Gordon equation resp. the Dirac equation are dealt with. Having in mind the construction of the Weyl algebra and the Fermi algebra in the second chapter, it was put emphasis on the structure of the spaces of solutions of these equations: In the first case the space of solutions is a symplectic vector space in a canonical manner, in the second case a Hilbert space. It was made some effort to stay as general as possible. Most of the material in the second chapter already exists for several years, but it is largely scattered over various journal articles. In the third chapter the construction of a vacuum on the special example of deSitter universe is described. A close investigation of a recent work by J. Bros and U. Moschella made it possible to refine a result concerning temperature felt by an accelerated observer in deSitter space. The last part of this thesis is concerned with vacua for spinor fields on the two-dimensional deSitter universe. A procedure introduced by R. Haag, H. Narnhofer and U. Stein for four dimensional space-times does not seem to work in two dimensions. (author)
Quantum break-time of de Sitter
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Dvali, Gia; Gómez, César; Zell, Sebastian, E-mail: georgi.dvali@physik.uni-muenchen.de, E-mail: cesar.gomez@uam.es, E-mail: sebastian.zell@campus.lmu.de [Arnold Sommerfeld Center, Ludwig-Maximilians-Universität, Theresienstraße 37, 80333 München (Germany)
2017-06-01
The quantum break-time of a system is the time-scale after which its true quantum evolution departs from the classical mean field evolution. For capturing it, a quantum resolution of the classical background—e.g., in terms of a coherent state—is required. In this paper, we first consider a simple scalar model with anharmonic oscillations and derive its quantum break-time. Next, following [1], we apply these ideas to de Sitter space. We formulate a simple model of a spin-2 field, which for some time reproduces the de Sitter metric and simultaneously allows for its well-defined representation as quantum coherent state of gravitons. The mean occupation number N of background gravitons turns out to be equal to the de Sitter horizon area in Planck units, while their frequency is given by the de Sitter Hubble parameter. In the semi-classical limit, we show that the model reproduces all the known properties of de Sitter, such as the redshift of probe particles and thermal Gibbons-Hawking radiation, all in the language of quantum S -matrix scatterings and decays of coherent state gravitons. Most importantly, this framework allows to capture the 1/ N -effects to which the usual semi-classical treatment is blind. They violate the de Sitter symmetry and lead to a finite quantum break-time of the de Sitter state equal to the de Sitter radius times N . We also point out that the quantum-break time is inversely proportional to the number of particle species in the theory. Thus, the quantum break-time imposes the following consistency condition: older and species-richer universes must have smaller cosmological constants. For the maximal, phenomenologically acceptable number of species, the observed cosmological constant would saturate this bound if our Universe were 10{sup 100} years old in its entire classical history.
Quantum break-time of de Sitter
Dvali, Gia; Gómez, César; Zell, Sebastian
2017-06-01
The quantum break-time of a system is the time-scale after which its true quantum evolution departs from the classical mean field evolution. For capturing it, a quantum resolution of the classical background—e.g., in terms of a coherent state—is required. In this paper, we first consider a simple scalar model with anharmonic oscillations and derive its quantum break-time. Next, following [1], we apply these ideas to de Sitter space. We formulate a simple model of a spin-2 field, which for some time reproduces the de Sitter metric and simultaneously allows for its well-defined representation as quantum coherent state of gravitons. The mean occupation number N of background gravitons turns out to be equal to the de Sitter horizon area in Planck units, while their frequency is given by the de Sitter Hubble parameter. In the semi-classical limit, we show that the model reproduces all the known properties of de Sitter, such as the redshift of probe particles and thermal Gibbons-Hawking radiation, all in the language of quantum S-matrix scatterings and decays of coherent state gravitons. Most importantly, this framework allows to capture the 1/N-effects to which the usual semi-classical treatment is blind. They violate the de Sitter symmetry and lead to a finite quantum break-time of the de Sitter state equal to the de Sitter radius times N. We also point out that the quantum-break time is inversely proportional to the number of particle species in the theory. Thus, the quantum break-time imposes the following consistency condition: older and species-richer universes must have smaller cosmological constants. For the maximal, phenomenologically acceptable number of species, the observed cosmological constant would saturate this bound if our Universe were 10100 years old in its entire classical history.
Density fluctuations in the de Sitter universe
International Nuclear Information System (INIS)
Banerjee, N.; Mallik, S.
1991-01-01
The de Sitter space-time appears to be the most widely chosen manifold to study quantum field theories on curved space-time. The reason is, of course, its high symmetry and the related fact that the mode functions can be obtained exactly in terms of known functions. Thus the different problems of quantization on curved space-time, like the non-uniqueness of the vacuum, regularization and renormalization of the stress tensor, have all been studied extensively in this model. The other reason of interest in the de Sitter geometry is related to the inflationary scenario of the early universe. For a brief period, the energy density of the false (symmetric) vacuum may dominate the total energy density, giving rise to de Sitter space-time. The resulting inflation may solve a number of outstanding problems of cosmology and particle physics. The properties of a Higgs-type scalar field theory is of central importance in the investigation of such a scenario. In this paper, a scalar Higgs field theory in de Sitter space-time has been investigated using the real time formulation of Semenoff and Weiss. The authors calculate the two-point function at late times and use it to obtain a general expression for the amplitude of fluctuation in energy density on scales which come out of the de Sitter horizon
International Nuclear Information System (INIS)
Myung, Y.S.
2003-01-01
We calculate corrections to the Bekenstein-Hawking entropy formula for the five-dimensional topological AdS (TAdS)-black holes and topological de Sitter (TdS) spaces due to thermal fluctuations. We can derive all thermal properties of the TdS spaces from those of the TAdS black holes by replacing k by -k. Also we obtain the same correction to the Cardy-Verlinde formula for TAdS and TdS cases including the cosmological horizon of the Schwarzschild-de Sitter (SdS) black hole. Finally we discuss the AdS/CFT and dS/CFT correspondences and their dynamic correspondences
Graviatoms with de Sitter Interior
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Irina Dymnikova
2013-01-01
Full Text Available We present a graviatom with de Sitter interior as a new candidate to atomic dark matter generically related to a vacuum dark energy through its de Sitter vacuum interior. It is a gravitationally bound quantum system consisting of a nucleus represented by a regular primordial black hole (RPBH, its remnant or gravitational vacuum soliton G-lump, and a charged particle. We estimate probability of formation of RPBHs and G-lumps in the early Universe and evaluate energy spectrum and electromagnetic radiation of graviatom which can in principle bear information about a fundamental symmetry scale responsible for de Sitter interior and serve as its observational signatures.
Thermodynamics of de Sitter universes
International Nuclear Information System (INIS)
Huang Chaoguang; Liu Liao; Wang Bobo
2002-01-01
It is shown that the first law of thermodynamics can be applied to the de Sitter universe to relate its vacuum energy, pressure, entropy of horizon, chemical potential, etc., when the cosmological constant changes due to the fluctuation of the vacuum or other reasons. The second law should be reformulated in the form that the spontaneous decay of the vacuum never makes the entropy of the de Sitter universe decrease. The third law of thermodynamics, applying to the de Sitter universe, implies that the cosmological constant cannot reach zero by finite physical processes. The relation to the holographic principle is also briefly discussed
Evidence for a bound on the lifetime of de Sitter space
International Nuclear Information System (INIS)
Freivogel, Ben; Lippert, Matthew
2008-01-01
Recent work has suggested a surprising new upper bound on the lifetime of de Sitter vacua in string theory. The bound is parametrically longer than the Hubble time but parametrically shorter than the recurrence time. We investigate whether the bound is satisfied in a particular class of de Sitter solutions, the KKLT vacua. Despite the freedom to make the supersymmetry breaking scale exponentially small, which naively would lead to extremely stable vacua, we find that the lifetime is always less than about exp(10 22 ) Hubble times, in agreement with the proposed bound. This result, however, is contingent on several estimates and assumptions; in particular, we rely on a conjectural upper bound on the Euler number of the Calabi-Yau fourfolds used in KKLT compactifications.
Ringing in de Sitter spacetime
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Alex Buchel
2018-03-01
Full Text Available Hydrodynamics is a universal effective theory describing relaxation of quantum field theories towards equilibrium. Massive QFTs in de Sitter spacetime are never at equilibrium. We use holographic gauge theory/gravity correspondence to describe relaxation of a QFT to its Bunch–Davies vacuum — an attractor of its late-time dynamics. Specifically, we compute the analogue of the quasinormal modes describing the relaxation of a holographic toy model QFT in de Sitter.
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Chen Qiang; Ren Ji-Rong
2013-01-01
In this paper, we use the modified Hod's treatment and the Kunstatter's method to study the horizon area spectrum and entropy spectrum in Gauss—Bonnet de-Sitter space-time, which is regarded as the natural generalization of Einstein gravity by including higher derivative correction terms to the original Einstein—Hilbert action. The horizon areas have some properties that are very different from the vacuum solutions obtained from the frame of Einstein gravity. With the new physical interpretation of quasinormal modes, the area/entropy spectrum for the event horizon for near-extremal Gauss—Bonnet de Sitter black holes are obtained. Meanwhile, we also extend the discussion of area/entropy quantization to the non-extremal black holes solutions. (general)
The de Sitter relativistic top theory
International Nuclear Information System (INIS)
Armenta, J.; Nieto, J.A.
2005-01-01
We discuss the relativistic top theory from the point of view of the de Sitter (or anti-de Sitter) group. Our treatment rests on the Hanson-Regge spherical relativistic top Lagrangian formulation. We propose an alternative method for studying spinning objects via Kaluza-Klein theory. In particular, we derive the relativistic top equations of motion starting with the geodesic equation for a point particle in 4+N dimensions. We compare our approach with Fukuyama's formulation of spinning objects, which is also based on Kaluza-Klein theory. We also report a generalization of our approach to a 4+N+D dimensional theory
New instabilities of de Sitter spacetimes
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Copsey, Keith; Mann, Robert
2010-01-01
We construct an instanton describing the pair production of non-Kaluza-Klein bubbles of nothing in higher odd-dimensional de Sitter spaces. In addition to showing that higher-dimensional de Sitter spaces have a nonzero probability to become topologically nontrivial, this process provides direct evidence for the association of entropy with cosmological horizons as well as evidence that non-Kaluza-Klein bubbles of nothing are a necessary ingredient in string theory or any other consistent quantum theory of gravity in higher dimensions.
Energy Technology Data Exchange (ETDEWEB)
Lin Kai, E-mail: lk314159@126.co [Institute of Theoretical Physics, China West Normal University, NanChong, SiChuan 637002 (China); Yang Shuzheng, E-mail: szyangcwnu@126.co [Institute of Theoretical Physics, China West Normal University, NanChong, SiChuan 637002 (China)
2009-10-12
Applying the method beyond semiclassical approximation, fermion tunneling from higher-dimensional anti-de Sitter Schwarzschild black hole is researched. In our work, the 'tortoise' coordinate transformation is introduced to simplify Dirac equation, so that the equation proves that only the (r-t) sector is important to our research. Because we only need to study the (r-t) sector, the Dirac equation is decomposed into several pairs of equations spontaneously, and we then prove the components of wave functions are proportional to each other in every pair of equations. Therefore, the suitable action forms of the wave functions are obtained, and finally the correctional Hawking temperature and entropy can be determined via the method beyond semiclassical approximation.
Page, Don N.
2018-01-01
In an asymptotically flat spacetime of dimension d >3 and with the Newtonian gravitational constant G , a spherical black hole of initial horizon radius rh and mass M ˜rhd -3/G has a total decay time to Hawking emission of td˜rhd -1/G ˜G2 /(d -3 )M(d -1 )/(d -3 ) which grows without bound as the radius rh and mass M are taken to infinity. However, in asymptotically anti-de Sitter spacetime with a length scale ℓ and with absorbing boundary conditions at infinity, the total Hawking decay time does not diverge as the mass and radius go to infinity but instead remains bounded by a time of the order of ℓd-1/G .
International Nuclear Information System (INIS)
Akcay, Sarp; Matzner, Richard A
2011-01-01
It is now widely accepted that the universe as we understand it is accelerating in expansion and fits the de Sitter model rather well. As such, a realistic assumption of black holes must place them on a de Sitter background and not Minkowski as is typically done in general relativity. The most astrophysically relevant black hole is the uncharged, rotating Kerr solution, a member of the more general Kerr-Newman metrics. A generalization of the rotating Kerr black hole to a solution of the Einstein's equation with a cosmological constant Λ was discovered by Carter (1973 Les Astres Occlus ed B DeWitt and C M DeWitt (New York: Gordon and Breach)). It is typically referred to as the Kerr-de Sitter spacetime. Here, we discuss the horizon structure of this spacetime and its dependence on Λ. We recall that in a Λ > 0 universe, the term 'extremal black hole' refers to a black hole with angular momentum J > M 2 . We obtain explicit numerical results for the black hole's maximal spin value and get a distribution of admissible Kerr holes in the (Λ, spin) parameter space. We look at the conformal structure of the extended spacetime and the embedding of the 3-geometry of the spatial hypersurfaces. In analogy with Reissner-Nordstroem-de Sitter spacetime, in particular by considering the Kerr-de Sitter causal structure as a distortion of the Reissner-Nordstroem-de Sitter one, we show that spatial sections of the extended spacetime are 3-spheres containing two-dimensional topologically spherical sections of the horizons of Kerr holes at the poles. Depending on how a t = constant 3-space is defined, these holes may be seen as black or white holes (four possible combinations).
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Nariai, Hidekazu; Ishihara, Hideki.
1983-01-01
Various geometrical properties of Nariai's less-familiar solution of the vacuum Einstein equations R sub( mu nu ) = lambda g sub( mu nu ) is f irst summarized in comparison with de Sitter's well-known solution. Next an extension of both solutions is performed in a six-dimensional space on the supposition that such an extension will in future become useful to elucidate more closely the creation of particles in an inflationary stage of the big-bang universe. For preparation, the behavior of a massive scalar field in the extended space-time is studied in a classical level. (author)
Applications of gauge/gravity dualities with charged Anti-de Sitter black holes
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Grass, Viviane Theresa
2010-01-01
In this thesis, we deal with different applications of the Anti-de Sitter/Conformal Field Theory (AdS/CFT) correspondence. The AdS/CFT correspondence, which is also more generally referred to as gauge/gravity duality, is a conjectured duality in superstring theory between strongly-coupled four-dimensional N=4 superconformal Yang-Mills theory and weakly-coupled type IIB string theory in five-dimensional AdS spacetime. This duality provides a powerful method to investigate strongly-coupled low-energy systems in four dimensions by substitutionally carrying out calculations in five-dimensional weakly-coupled supergravity. In this work, we use the AdS/CFT correspondence to explore three different strongly-coupled systems, namely a brane world accommodating a strongly-coupled field theory, a strongly-coupled fluid on a three-sphere and a strongly-coupled p-wave superfluid. In all these cases, the dual supergravity descriptions involve charged AdS black holes. The first system studied here is a Randall-Sundrum brane world moving in the background of a five-dimensional non-extremal black hole of N=2 gauged supergravity. The equations of motion of the brane are found to be equal to the Friedmann-Robertson-Walker (FRW) equations for a closed universe. The closed brane universe has special thermodynamic properties. The energy of the brane field theory exhibits a subextensive Casimir contribution, and the entropy can be expressed as a Cardy-Verlinde-type formula. We show that the equations for both quantities can take forms that strongly resemble the two FRW equations. At the horizon of the black hole, these two sets of equations are shown to even merge with each other which might suggest the existence of a common underlying theory. In addition, as a by-product result, the non-extremal black hole solutions considered here are found to admit an alternative description in terms of first-order flow equations similar to those which are well-known from the attractor mechanism of
Applications of gauge/gravity dualities with charged Anti-de Sitter black holes
Energy Technology Data Exchange (ETDEWEB)
Grass, Viviane Theresa
2010-05-17
In this thesis, we deal with different applications of the Anti-de Sitter/Conformal Field Theory (AdS/CFT) correspondence. The AdS/CFT correspondence, which is also more generally referred to as gauge/gravity duality, is a conjectured duality in superstring theory between strongly-coupled four-dimensional N=4 superconformal Yang-Mills theory and weakly-coupled type IIB string theory in five-dimensional AdS spacetime. This duality provides a powerful method to investigate strongly-coupled low-energy systems in four dimensions by substitutionally carrying out calculations in five-dimensional weakly-coupled supergravity. In this work, we use the AdS/CFT correspondence to explore three different strongly-coupled systems, namely a brane world accommodating a strongly-coupled field theory, a strongly-coupled fluid on a three-sphere and a strongly-coupled p-wave superfluid. In all these cases, the dual supergravity descriptions involve charged AdS black holes. The first system studied here is a Randall-Sundrum brane world moving in the background of a five-dimensional non-extremal black hole of N=2 gauged supergravity. The equations of motion of the brane are found to be equal to the Friedmann-Robertson-Walker (FRW) equations for a closed universe. The closed brane universe has special thermodynamic properties. The energy of the brane field theory exhibits a subextensive Casimir contribution, and the entropy can be expressed as a Cardy-Verlinde-type formula. We show that the equations for both quantities can take forms that strongly resemble the two FRW equations. At the horizon of the black hole, these two sets of equations are shown to even merge with each other which might suggest the existence of a common underlying theory. In addition, as a by-product result, the non-extremal black hole solutions considered here are found to admit an alternative description in terms of first-order flow equations similar to those which are well-known from the attractor mechanism of
M-theory and stringy corrections to anti-de Sitter black holes and conformal field theories
International Nuclear Information System (INIS)
Caldarelli, Marco M.; Klemm, Dietmar
1999-01-01
We consider black holes in anti-de Sitter space AdS p+2 (p = 2, 3, 5), which have hyperbolic, flat or spherical event horizons. The O(α' 3 ) corrections (or the leading corrections in powers of the eleven-dimensional Planck length, in the case of M-theory compactifications) to the black hole metrics are computed for the various topologies and dimensions. We investigate the consequences of the stringy or M-theory corrections for the black hole thermodynamics. In particular, we show the emergence of a stable branch of small spherical black holes. Surprisingly, for any of the considered dimension and topologies, the corrected thermodynamical quantities turn out to coincide with those calculated within a simplified approach, which uses only the unperturbed metric. We obtain the corrected Hawking-Page transition temperature for black holes with spherical horizons, and show that for p = 3 this phase transition disappears at a value of α' considerably smaller than that estimated previously by Gao and Li. Using the AdS/CFT correspondence, we determine the S 1 x S 3 N = 4 SYM phase diagram for sufficiently large 't Hooft coupling, and show that the critical point at which the Hawking-Page transition disappears (the correspondence point of Horowitz-Polchinski), occurs at g 2 YM N ∼ 20.5. The d = 4 and d = 7 black hole phase diagrams are also determined, and connection is made with the corresponding boundary CFTs. Finally, for flat and hyperbolic horizons, we show that the leading stringy or M-theory corrections do not give rise to any phase transition. However, if the horizon is compactified to a torus T p or to a quotient of hyperbolic space, H p /Γ, the appearance of light winding modes around non-contractible cycles signal new phase transitions, which in the toroidal case have previously been discussed by Barbon et al. We comment on these phase transitions for SYM on H p /Γ and on T p , when the moduli of the torus are taken into account
Quantum Cramer–Rao Bound for a Massless Scalar Field in de Sitter Space
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Marcello Rotondo
2017-10-01
Full Text Available How precisely can we estimate cosmological parameters by performing a quantum measurement on a cosmological quantum state? In quantum estimation theory, the variance of an unbiased parameter estimator is bounded from below by the inverse of measurement-dependent Fisher information and ultimately by quantum Fisher information, which is the maximization of the former over all positive operator-valued measurements. Such bound is known as the quantum Cramer –Rao bound. We consider the evolution of a massless scalar field with Bunch–Davies vacuum in a spatially flat FLRW spacetime, which results in a two-mode squeezed vacuum out-state for each field wave number mode. We obtain the expressions of the quantum Fisher information as well as the Fisher informations associated to occupation number measurement and power spectrum measurement, and show the specific results of their evolution for pure de Sitter expansion and de Sitter expansion followed by a radiation-dominated phase as examples. We will discuss these results from the point of view of the quantum-to-classical transition of cosmological perturbations and show quantitatively how this transition and the residual quantum correlations affect the bound on the precision.
Anderson, Paul R.; Mottola, Emil; Sanders, Dillon H.
2018-03-01
The decay rate of the Bunch-Davies state of a massive scalar field in the expanding flat spatial sections of de Sitter space is determined by an analysis of the particle pair creation process in real time. The Feynman definition of particle and antiparticle Fourier mode solutions of the scalar wave equation and their adiabatic phase analytically continued to the complexified time domain show conclusively that the Bunch-Davies state is not the vacuum state at late times. The closely analogous creation of charged particle pairs in a uniform electric field is reviewed and Schwinger's result for the vacuum decay rate is recovered by this same real time analysis. The vacuum decay rate in each case is also calculated by switching the background field on adiabatically, allowing it to act for a very long time, and then adiabatically switching it off again. In both the uniform electric field and de Sitter cases, the particles created while the field is switched on are verified to be real, in the sense that they persist in the final asymptotic flat zero-field region. In the de Sitter case, there is an interesting residual dependence of the rate on how the de Sitter phase is ended, indicating a greater sensitivity to spatial boundary conditions. The electric current of the created particles in the E -field case and their energy density and pressure in the de Sitter case are also computed, and the magnitude of their backreaction effects on the background field estimated. Possible consequences of the Hubble scale instability of the de Sitter vacuum for cosmology, vacuum dark energy, and the cosmological "constant" problem are discussed.
Wave equations on a de Sitter fiber bundle. [Semiclassical wave function, bundle space, L-S coupling
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Drechsler, W [Max-Planck-Institut fuer Physik und Astrophysik, Muenchen (F.R. Germany)
1975-01-01
A gauge theory of strong interaction is developed based on fields defined on a fiber bundle. The structural group of the bundle is taken to be the Lsub(4,1) de Sitter group. An internal variable xi, varying in the fiber over a space-time point x, is introduced as a means to describe - with the help of a semiclassical wave function psi(x,xi) defined on the bundle space - the internal structure of extended hadrons in a framework using differential geometric techniques. Three basic nonlinear wave equations for psi(x,xi) are established which are of integro-differential type. The nonlinear coupling terms in these de Sitter gauge invariant equations represent physically a generalized spin orbit coupling or a generalized spin coupling for the motion taking place in the fiber. The motivation for using a bigger space for the definition of hadronic matter wave functions as well as the implications of this geometric approach to strong interaction physics is discussed in detail, in particular with respect to the problem of hadronic constituents. The proposed fiber bundle formalism allows a dynamical description of extended structures for hadrons without implying the necessity of introducing any constituents.
International Nuclear Information System (INIS)
Akbar, M.M.; D'Eath, P.D.
2003-01-01
The classical boundary-value problem of the Einstein field equations is studied with an arbitrary cosmological constant, in the case of a compact (S 3 ) boundary given a biaxial Bianchi-IX positive-definite three-metric, specified by two radii (a,b). For the simplest, four-ball, topology of the manifold with this boundary, the regular classical solutions are found within the family of Taub-NUT-(anti)de Sitter metrics with self-dual Weyl curvature. For arbitrary choice of positive radii (a,b), we find that there are three solutions for the infilling geometry of this type. We obtain exact solutions for them and for their Euclidean actions. The case of negative cosmological constant is investigated further. For reasonable squashing of the three-sphere, all three infilling solutions have real-valued actions which possess a 'cusp catastrophe' structure with a non-self-intersecting 'catastrophe manifold' implying that the dominant contribution comes from the unique real positive-definite solution on the ball. The positive-definite solution exists even for larger deformations of the three-sphere, as long as a certain inequality between a and b holds. The action of this solution is proportional to -a 3 for large a (∼b) and hence larger radii are favoured. The same boundary-value problem with more complicated interior topology containing a 'bolt' is investigated in a forthcoming paper
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Uchikata, Nami; Yoshida, Shijun
2011-01-01
We investigate quasinormal modes of a massless charged scalar field on a small Reissner-Nordstroem-anti-de Sitter (RN-AdS) black hole both with analytical and numerical approaches. In the analytical approach, by using the small black hole approximation (r + + /L→0, where r + and L stand for the black hole event horizon radius and the AdS scale, respectively. We then show that the small RN-AdS black hole is unstable if its quasinormal modes satisfy the superradiance condition and that the instability condition of the RN-AdS black hole in the limit of r + /L→0 is given by Q>(3/eL)Q c , where Q, Q c , and e are the charge of the black hole, the critical (maximum) charge of the black hole, and the charge of the scalar field, respectively. In the numerical approach, we calculate the quasinormal modes for the small RN-AdS black holes with r + + =0.2L, 0.1L, and 0.01L become unstable against scalar perturbations with eL=4 when the charge of the black hole satisfies Q > or approx. 0.8Q c , 0.78Q c , and 0.76Q c , respectively.
Phase structure of the Born-Infeld-anti-de Sitter black holes probed by non-local observables
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Zeng, Xiao-Xiong [Chongqing Jiaotong University, School of Material Science and Engineering, Chongqing (China); Chinese Academy of Sciences, Institute of Theoretical Physics, Beijing (China); Liu, Xian-Ming [Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, MA (United States); Hubei University for Nationalities, Center for Theoretical Physics, School of Sciences, Enshi, Hubei (China); Li, Li-Fang [Chinese Academy of Sciences, State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Beijing (China)
2016-11-15
With the non-local observables such as two point correlation function and holographic entanglement entropy, we probe the phase structure of the Born-Infeld-anti-de Sitter black holes. For the case bQ > 0.5, where b is the Born-Infeld parameter and Q is the charge of the black hole, the phase structure is found to be similar to that of the Van der Waals phase transition, namely the black hole undergoes a first order phase transition and a second order phase transition before it reaches a stable phase. While for the case bQ < 0.5, a new phase branch emerges besides the Van der Waals phase transition. For the first order phase transition, the equal area law is checked, and for the second order phase transition, the critical exponent of the heat capacity is obtained. All these results are found to be the same as that observed in the entropy-temperature plane. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Ciufolini, Ignazio [Universita del Salento, Dipt. Ingegneria dell' Innovazione, Lecce (Italy); Centro Fermi, Rome (Italy); Matzner, Richard [University of Texas, Theory Group, Austin (United States); Gurzadyan, Vahe [Alikhanian National Laboratory and Yerevan State University, Center for Cosmology and Astrophysics, Yerevan (Armenia); Penrose, Roger [University of Oxford, Mathematical Institute, Oxford (United Kingdom)
2017-12-15
In two previous papers we presented the LARES 2 space experiment aimed at a very accurate test of frame-dragging and at other tests of fundamental physics and measurements of space geodesy and geodynamics. We presented the error sources of the LARES 2 experiment, its error budget and Monte Carlo simulations and covariance analyses confirming an accuracy of a few parts in one thousand in the test of frame-dragging. Here we discuss the impact of the orbital perturbation known as the de Sitter effect, or geodetic precession, in the error budget of the LARES 2 frame-dragging experiment. We show that the uncertainty in the de Sitter effect has a negligible impact in the final error budget because of the very accurate results now available for the test of the de Sitter precession and because of its very nature. The total error budget in the LARES 2 test of frame-dragging remains at a level of the order of 0.2%, as determined in the first two papers of this series. (orig.)
International Nuclear Information System (INIS)
Ciufolini, Ignazio; Matzner, Richard; Gurzadyan, Vahe; Penrose, Roger
2017-01-01
In two previous papers we presented the LARES 2 space experiment aimed at a very accurate test of frame-dragging and at other tests of fundamental physics and measurements of space geodesy and geodynamics. We presented the error sources of the LARES 2 experiment, its error budget and Monte Carlo simulations and covariance analyses confirming an accuracy of a few parts in one thousand in the test of frame-dragging. Here we discuss the impact of the orbital perturbation known as the de Sitter effect, or geodetic precession, in the error budget of the LARES 2 frame-dragging experiment. We show that the uncertainty in the de Sitter effect has a negligible impact in the final error budget because of the very accurate results now available for the test of the de Sitter precession and because of its very nature. The total error budget in the LARES 2 test of frame-dragging remains at a level of the order of 0.2%, as determined in the first two papers of this series. (orig.)
De Sitter stability and coarse graining
International Nuclear Information System (INIS)
Markkanen, T.
2018-01-01
We present a 4-dimensional back reaction analysis of de Sitter space for a conformally coupled scalar field in the presence of vacuum energy initialized in the Bunch-Davies vacuum. In contrast to the usual semi-classical prescription, as the source term in the Friedmann equations we use expectation values where the unobservable information hidden by the cosmological event horizon has been neglected i.e. coarse grained over. It is shown that in this approach the energy-momentum is precisely thermal with constant temperature despite the dilution from the expansion of space due to a flux of energy radiated from the horizon. This leads to a self-consistent solution for the Hubble rate, which is gradually evolving and at late times deviates significantly from de Sitter. Our results hence imply de Sitter space to be unstable in this prescription. The solution also suggests dynamical vacuum energy: the continuous flux of energy is balanced by the generation of negative vacuum energy, which accumulatively decreases the overall contribution. Finally, we show that our results admit a thermodynamic interpretation which provides a simple alternate derivation of the mechanism. For very long times the solutions coincide with flat space. (orig.)
De Sitter stability and coarse graining
Energy Technology Data Exchange (ETDEWEB)
Markkanen, T. [Imperial College London, Department of Physics, London (United Kingdom); King' s College London, Department of Physics, London (United Kingdom)
2018-02-15
We present a 4-dimensional back reaction analysis of de Sitter space for a conformally coupled scalar field in the presence of vacuum energy initialized in the Bunch-Davies vacuum. In contrast to the usual semi-classical prescription, as the source term in the Friedmann equations we use expectation values where the unobservable information hidden by the cosmological event horizon has been neglected i.e. coarse grained over. It is shown that in this approach the energy-momentum is precisely thermal with constant temperature despite the dilution from the expansion of space due to a flux of energy radiated from the horizon. This leads to a self-consistent solution for the Hubble rate, which is gradually evolving and at late times deviates significantly from de Sitter. Our results hence imply de Sitter space to be unstable in this prescription. The solution also suggests dynamical vacuum energy: the continuous flux of energy is balanced by the generation of negative vacuum energy, which accumulatively decreases the overall contribution. Finally, we show that our results admit a thermodynamic interpretation which provides a simple alternate derivation of the mechanism. For very long times the solutions coincide with flat space. (orig.)
International Nuclear Information System (INIS)
Joung, Euihun; Mourad, Jihad; Parentani, Renaud
2007-01-01
We use an algebraic approach based on representations of de Sitter group to construct covariant quantum fields in arbitrary dimensions. We study the complementary and the discrete series which correspond to light and massless fields and which lead new feature with respect to the massive principal series we previously studied (hep-th/0606119). When considering the complementary series, we make use of a non-trivial scalar product in order to get local expressions in the position representation. Based on these, we construct a family of covariant canonical fields parametrized by SU(1, 1)/U(1). Each of these correspond to the dS invariant alpha-vacua. The behavior of the modes at asymptotic times brings another difficulty as it is incompatible with the usual definition of the in and out vacua. We propose a generalized notion of these vacua which reduces to the usual conformal vacuum in the conformally massless limit. When considering the massless discrete series we find that no covariant field obeys the canonical commutation relations. To further analyze this singular case, we consider the massless limit of the complementary scalar fields we previously found. We obtain canonical fields with a deformed representation by zero modes. The zero modes have a dS invariant vacuum with singular norm. We propose a regularization by a compactification of the scalar field and a dS invariant definition of the vertex operators. The resulting two-point functions are dS invariant and have a universal logarithmic infrared divergence
De Sitter structured connection and gauge translations
International Nuclear Information System (INIS)
Aldinger, R.R.
1986-01-01
A local gauge field description of space-time is discussed using fiber bundle techniques as a theoretical framework. The basic idea is to endow ordinary Minkowski space, M 4 , with a somewhat richer structure than that implied by relativity by attaching to each position x epsilon M 4 a copy of a four-dimensional micro-space of constant curvature characterized by an elementary subatomic length parameter R of the order of a Fermi, thus allowing for additional internal degrees-of-freedom. Therefore, two sets of variables are introduced: (i) the usual space-time variables x which determine an element of M 4 and (ii) a second set zeta which are elements of an internal space F (which is identified with the fiber of a bundle constructed over M 4 ). Consequently, they consider a fiber bundle E(B,F,G,P) constructed over a four-dimensional base manifold B (which is taken to be the usual Minkowski space, M 4 ), possessing a four-dimensional fiber F, and associated with the principal bundle P=P(B,G) (on which the connection is defined). The structural (gauge) group G of the bundle plays the role of an internal symmetry group and therefore determines the possible motions of the internal degrees-of-freedom belonging to the fibers. As fiber they choose a four-dimensional pseudo-Riemannian space of constant (negative) curvature R:F = SO(4,1)/SO(3,1) (i.e., a de Sitter space) which contains, at each point of contact with base manifold M 4 , a tangent space which is isomorphic to Minkowski space. The structural group of the bundle is a de Sitter SO(4,1) which contains a Lorentz subgroup and a four parameter family of transformations (the de Sitter boosts), which in the limit R → ∞ corresponding to translations. 10 references
Massive scalar field evolution in de Sitter
Energy Technology Data Exchange (ETDEWEB)
Markkanen, Tommi [Department of Physics, King’s College London,Strand, London WC2R 2LS (United Kingdom); Rajantie, Arttu [Department of Physics, Imperial College London,London SW7 2AZ (United Kingdom)
2017-01-30
The behaviour of a massive, non-interacting and non-minimally coupled quantised scalar field in an expanding de Sitter background is investigated by solving the field evolution for an arbitrary initial state. In this approach there is no need to choose a vacuum in order to provide a definition for particle states, nor to introduce an explicit ultraviolet regularization. We conclude that the expanding de Sitter space is a stable equilibrium configuration under small perturbations of the initial conditions. Depending on the initial state, the energy density can approach its asymptotic value from above or below, the latter of which implies a violation of the weak energy condition. The backreaction of the quantum corrections can therefore lead to a phase of super-acceleration also in the non-interacting massive case.
Kerr metric in the deSitter background
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Vaidya, P.C.
1984-01-01
In addition to the Kerr metric with cosmological constant Λ several other metrics are presented giving a Kerr-like solution of Einstein's equations in the background of deSitter universe. A new metric of what may be termed as rotating deSitter space-time devoid of matter but containing null fluid with twisting null rays, has been presented. This metric reduces to the standard deSitter metric when the twist in the rays vanishes. Kerr metric in this background is the immediate generalization of Schwarzschild's exterior metric with cosmological constant. (author)
On a canonical quantization of 3D Anti de Sitter pure gravity
Kim, Jihun; Porrati, Massimo
2015-10-01
We perform a canonical quantization of pure gravity on AdS 3 using as a technical tool its equivalence at the classical level with a Chern-Simons theory with gauge group SL(2,{R})× SL(2,{R}) . We first quantize the theory canonically on an asymptotically AdS space -which is topologically the real line times a Riemann surface with one connected boundary. Using the "constrain first" approach we reduce canonical quantization to quantization of orbits of the Virasoro group and Kähler quantization of Teichmüller space. After explicitly computing the Kähler form for the torus with one boundary component and after extending that result to higher genus, we recover known results, such as that wave functions of SL(2,{R}) Chern-Simons theory are conformal blocks. We find new restrictions on the Hilbert space of pure gravity by imposing invariance under large diffeomorphisms and normalizability of the wave function. The Hilbert space of pure gravity is shown to be the target space of Conformal Field Theories with continuous spectrum and a lower bound on operator dimensions. A projection defined by topology changing amplitudes in Euclidean gravity is proposed. It defines an invariant subspace that allows for a dual interpretation in terms of a Liouville CFT. Problems and features of the CFT dual are assessed and a new definition of the Hilbert space, exempt from those problems, is proposed in the case of highly-curved AdS 3.
``Massless'' vector field in de Sitter universe
Garidi, T.; Gazeau, J.-P.; Rouhani, S.; Takook, M. V.
2008-03-01
We proceed to the quantization of the massless vector field in the de Sitter (dS) space. This work is the natural continuation of a previous article devoted to the quantization of the dS massive vector field [J. P. Gazeau and M. V. Takook, J. Math. Phys. 41, 5920 (2000); T. Garidi et al., ibid. 43, 6379 (2002).] The term ``massless'' is used by reference to conformal invariance and propagation on the dS lightcone whereas ``massive'' refers to those dS fields which unambiguously contract to Minkowskian massive fields at zero curvature. Due to the combined occurrences of gauge invariance and indefinite metric, the covariant quantization of the massless vector field requires an indecomposable representation of the de Sitter group. We work with the gauge fixing corresponding to the simplest Gupta-Bleuler structure. The field operator is defined with the help of coordinate-independent de Sitter waves (the modes). The latter are simple to manipulate and most adapted to group theoretical approaches. The physical states characterized by the divergencelessness condition are, for instance, easy to identify. The whole construction is based on analyticity requirements in the complexified pseudo-Riemannian manifold for the modes and the two-point function.
''Massless'' vector field in de Sitter universe
International Nuclear Information System (INIS)
Garidi, T.; Gazeau, J.-P.; Rouhani, S.; Takook, M. V.
2008-01-01
We proceed to the quantization of the massless vector field in the de Sitter (dS) space. This work is the natural continuation of a previous article devoted to the quantization of the dS massive vector field [J. P. Gazeau and M. V. Takook, J. Math. Phys. 41, 5920 (2000); T. Garidi et al., ibid. 43, 6379 (2002).] The term ''massless'' is used by reference to conformal invariance and propagation on the dS lightcone whereas ''massive'' refers to those dS fields which unambiguously contract to Minkowskian massive fields at zero curvature. Due to the combined occurrences of gauge invariance and indefinite metric, the covariant quantization of the massless vector field requires an indecomposable representation of the de Sitter group. We work with the gauge fixing corresponding to the simplest Gupta-Bleuler structure. The field operator is defined with the help of coordinate-independent de Sitter waves (the modes). The latter are simple to manipulate and most adapted to group theoretical approaches. The physical states characterized by the divergencelessness condition are, for instance, easy to identify. The whole construction is based on analyticity requirements in the complexified pseudo-Riemannian manifold for the modes and the two-point function
De Sitter hunting in a classical landscape
International Nuclear Information System (INIS)
Danielsson, U.H.; Van Riet, T.; Haque, S.S.; Koerber, P.; Shiu, G.; Wrase, T.
2011-01-01
We elaborate on the construction of de Sitter solutions from IIA orientifolds of SU(3)-structure manifolds that solve the 10-dimensional equations of motion at tree-level in the approximation of smeared sources. First we classify geometries that are orbifolds of a group manifold covering space which, upon the proper inclusion of O6 planes, can be described within the framework of N = 1 supergravity in 4D. Then we scan systematically for de Sitter solutions, obtained as critical points of an effective 4D potential. Apart from finding many new solutions we emphasize the challenges in constructing explicit classical de Sitter vacua, which have sofar not been met. These challenges are interesting avenues for further research and include finding solutions that are perturbatively stable, satisfy charge and flux quantization, and have genuine localized (versus smeared) orientifold sources. This paper intends to be self-contained and pedagogical, and thus can serve as a guide to the necessary technical tools required for this line of research. In an appendix we explain how to study flux and charge quantization in the presence of a non-trivial H-field using twisted homology. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
On a Canonical Quantization of 3D Anti de Sitter Pure Gravity
Kim, Jihun
2015-10-14
We perform a canonical quantization of pure gravity on AdS3 using as a technical tool its equivalence at the classical level with a Chern-Simons theory with gauge group SL(2,R)xSL(2,R). We first quantize the theory canonically on an asymptotically AdS space --which is topologically the real line times a Riemann surface with one connected boundary. Using the "constrain first" approach we reduce canonical quantization to quantization of orbits of the Virasoro group and Kaehler quantization of Teichmuller space. After explicitly computing the Kaehler form for the torus with one boundary component and after extending that result to higher genus, we recover known results, such as that wave functions of SL(2,R) Chern-Simons theory are conformal blocks. We find new restrictions on the Hilbert space of pure gravity by imposing invariance under large diffeomorphisms and normalizability of the wave function. The Hilbert space of pure gravity is shown to be the target space of Conformal Field Theories with continuous sp...
Relativistic rotators: a quantum mechanical de Sitter bundle
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Boehm, A.
1976-02-01
If de Sitter fiber bundle over space time is the classical picture of hadrons then for a quantum mechanical description one has to generalize the concept of a principal fiber bundle to a bundle that contains the representation of the group of motion. This idea is related to the relativistic rotator model, and the radius of the de Sitter fiber is determined from the experimental hadron spectrum
On a canonical quantization of 3D Anti de Sitter pure gravity
Energy Technology Data Exchange (ETDEWEB)
Kim, Jihun [Center for Cosmology and Particle Physics, Department of Physics,New York University, 4 Washington Place, New York, NY 10003 (United States); Porrati, Massimo [Center for Cosmology and Particle Physics, Department of Physics,New York University, 4 Washington Place, New York, NY 10003 (United States); CERN PH-TH, CH 1211,Geneva 23 (Switzerland)
2015-10-14
We perform a canonical quantization of pure gravity on AdS{sub 3} using as a technical tool its equivalence at the classical level with a Chern-Simons theory with gauge group SL(2,ℝ)×SL(2,ℝ). We first quantize the theory canonically on an asymptotically AdS space –which is topologically the real line times a Riemann surface with one connected boundary. Using the “constrain first” approach we reduce canonical quantization to quantization of orbits of the Virasoro group and Kähler quantization of Teichmüller space. After explicitly computing the Kähler form for the torus with one boundary component and after extending that result to higher genus, we recover known results, such as that wave functions of SL(2,ℝ) Chern-Simons theory are conformal blocks. We find new restrictions on the Hilbert space of pure gravity by imposing invariance under large diffeomorphisms and normalizability of the wave function. The Hilbert space of pure gravity is shown to be the target space of Conformal Field Theories with continuous spectrum and a lower bound on operator dimensions. A projection defined by topology changing amplitudes in Euclidean gravity is proposed. It defines an invariant subspace that allows for a dual interpretation in terms of a Liouville CFT. Problems and features of the CFT dual are assessed and a new definition of the Hilbert space, exempt from those problems, is proposed in the case of highly-curved AdS{sub 3}.
Thermodynamics of Born-Infeld-anti-de Sitter black holes in the grand canonical ensemble
International Nuclear Information System (INIS)
Fernando, Sharmanthie
2006-01-01
The main objective of this paper is to study thermodynamics and stability of static electrically charged Born-Infeld black holes in AdS space in D=4. The Euclidean action for the grand canonical ensemble is computed with the appropriate boundary terms. The thermodynamical quantities such as the Gibbs free energy, entropy and specific heat of the black holes are derived from it. The global stability of black holes are studied in detail by studying the free energy for various potentials. For small values of the potential, we find that there is a Hawking-Page phase transition between a BIAdS black hole and the thermal-AdS space. For large potentials, the black hole phase is dominant and is preferred over the thermal-AdS space. Local stability is studied by computing the specific heat for constant potentials. The nonextreme black holes have two branches: small black holes are unstable and the large black holes are stable. The extreme black holes are shown to be stable both globally as well as locally. In addition to the thermodynamics, we also show that the phase structure relating the mass M and the charge Q of the black holes is similar to the liquid-gas-solid phase diagram
Building an explicit de Sitter
International Nuclear Information System (INIS)
Louis, Jan; Hamburg Univ.; Rummel, Markus; Valandro, Roberto; Westphal, Alexander
2012-11-01
We construct an explicit example of a de Sitter vacuum in type IIB string theory that realizes the proposal of Kaehler uplifting. As the large volume limit in this method depends on the rank of the largest condensing gauge group we carry out a scan of gauge group ranks over the Kreuzer-Skarke set of toric Calabi-Yau threefolds. We find large numbers of models with the largest gauge group factor easily exceeding a rank of one hundred. We construct a global model with Kaehler uplifting on a two-parameter model on CP 4 11169 , by an explicit analysis from both the type IIB and F-theory point of view. The explicitness of the construction lies in the realization of a D7 brane configuration, gauge flux and RR and NS flux choices, such that all known consistency conditions are met and the geometric moduli are stabilized in a metastable de Sitter vacuum with spontaneous GUT scale supersymmetry breaking driven by an F-term of the Kaehler moduli.
Building an explicit de Sitter
Energy Technology Data Exchange (ETDEWEB)
Louis, Jan [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Hamburg Univ. (Germany). Zentrum fuer Mathematische Physik; Rummel, Markus; Valandro, Roberto [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Westphal, Alexander [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Gruppe Theorie
2012-11-15
We construct an explicit example of a de Sitter vacuum in type IIB string theory that realizes the proposal of Kaehler uplifting. As the large volume limit in this method depends on the rank of the largest condensing gauge group we carry out a scan of gauge group ranks over the Kreuzer-Skarke set of toric Calabi-Yau threefolds. We find large numbers of models with the largest gauge group factor easily exceeding a rank of one hundred. We construct a global model with Kaehler uplifting on a two-parameter model on CP{sup 4}{sub 11169}, by an explicit analysis from both the type IIB and F-theory point of view. The explicitness of the construction lies in the realization of a D7 brane configuration, gauge flux and RR and NS flux choices, such that all known consistency conditions are met and the geometric moduli are stabilized in a metastable de Sitter vacuum with spontaneous GUT scale supersymmetry breaking driven by an F-term of the Kaehler moduli.
Holography in three-dimensional Kerr-de Sitter space with a gravitational Chern-Simons term
International Nuclear Information System (INIS)
Park, Mu-In
2008-01-01
The holographic description of the three-dimensional Kerr-de Sitter space with a gravitational Chern-Simons term is studied, in the context of dS/CFT correspondence. The space has only one (cosmological) event horizon and its mass and angular momentum are identified from the holographic energy-momentum tensor at the asymptotic infinity. The thermodynamic entropy of the cosmological horizon is computed directly from the first law of thermodynamics, with the conventional Hawking temperature, and it is found that the usual Gibbons-Hawking entropy is modified. It is remarked that, due to the gravitational Chern-Simons term, (a) the results go beyond the analytic continuation from AdS, (b) the maximum-mass/N-bound conjecture may be violated and (c) the three-dimensional cosmology is chiral. A statistical mechanical computation of the entropy, from a Cardy-like formula for a dual CFT at the asymptotic boundary, is discussed. Some remarks on the technical differences in the Chern-Simons energy-momentum tensor, from the literature, are also made
Kerr-Newman metric in deSitter background
International Nuclear Information System (INIS)
Patel, L.K.; Koppar, S.S.; Bhatt, P.V.
1987-01-01
In addition to the Kerr-Newman metric with cosmological constant several other metrics are presented giving Kerr-Newman type solutions of Einstein-Maxwell field equations in the background of deSitter universe. The electromagnetic field in all the solutions is assumed to be source-free. A new metric of what may be termed as an electrovac rotating deSitter space-time- a space-time devoid of matter but containing source-free electromagnetic field and a null fluid with twisting rays-has been presented. In the absence of the electromagnetic field, these solutions reduce to those discussed by Vaidya (1984). 8 refs. (author)
Inflation as de Sitter instability
Energy Technology Data Exchange (ETDEWEB)
Cadoni, Mariano; Franzin, Edgardo [Universita di Cagliari, Cittadella Universitaria, Dipartimento di Fisica, Monserrato (Italy); INFN, Sezione di Cagliari, Monserrato (Italy); Mignemi, Salvatore [INFN, Sezione di Cagliari, Monserrato (Italy); Universita di Cagliari, Dipartimento di Matematica e Informatica, Cagliari (Italy)
2016-09-15
We consider cosmological inflation generated by a scalar field slowly rolling off from a de Sitter maximum of its potential. The models belong to the class of hilltop models and represent the most general model of this kind in which the scalar potential can be written as the sum of two exponentials. The minimally coupled Einstein-scalar gravity theory obtained in this way is the cosmological version of a two-scale generalization of known holographic models, allowing for solitonic solutions interpolating between an AdS spacetime in the infrared and scaling solutions in the ultraviolet. We then investigate cosmological inflation in the slow-roll approximation. Our model reproduces correctly, for a wide range of its parameters, the most recent experimental data for the power spectrum of primordial perturbations. Moreover, it predicts inflation at energy scales of four to five orders of magnitude below the Planck scale. At the onset of inflation, the mass of the tachyonic excitation, i.e. of the inflaton, turns out to be seven to eight orders of magnitude smaller than the Planck mass. (orig.)
Holographic space-time from the Big Bang to the de Sitter era
Banks, Tom
2009-07-01
I review the holographic theory of space-time and its applications to cosmology. Much of this has appeared before, but this discussion is more unified and concise. I also include some material on work in progress, whose aim is to understand compactification in terms of finite-dimensional super-algebras. This is an expanded version of a lecture I gave at the conference on Liouville Quantum Gravity and Statistical Systems, in memory of Alexei Zamolodchikov, at the Poncelet Institute in Moscow, 21-24 June 2008.
Holographic space-time from the Big Bang to the de Sitter era
Energy Technology Data Exchange (ETDEWEB)
Banks, Tom [Deptartment of Physics/SCIPP, University of California, Santa Cruz, CA 95064 (United States); Deptartment of Physics and Astronomy/NHETC, Rutgers University, Piscataway, NJ 08854 (United States)
2009-07-31
I review the holographic theory of space-time and its applications to cosmology. Much of this has appeared before, but this discussion is more unified and concise. I also include some material on work in progress, whose aim is to understand compactification in terms of finite-dimensional super-algebras. This is an expanded version of a lecture I gave at the conference on Liouville Quantum Gravity and Statistical Systems, in memory of Alexei Zamolodchikov, at the Poncelet Institute in Moscow, 21-24 June 2008.
Energy Technology Data Exchange (ETDEWEB)
Moritz, Jakob; Retaloza, Ander; Westphal, Alexander
2017-07-15
Using a 10D lift of non-perturbative volume stabilization in type IIB string theory we study the limitations for obtaining de Sitter vacua. Based on this we find that the simplest KKLT vacua with a single Kahler modulus stabilized by a gaugino condensate cannot be uplifted to de Sitter. Rather, the uplift flattens out due to stronger backreaction on the volume modulus than has previously been anticipated, resulting in vacua which are meta-stable and SUSY breaking, but that are always AdS. However, we also show that setups such as racetrack stabilization can avoid this issue. In these models it is possible to obtain supersymmetric AdS vacua with a cosmological constant that can be tuned to zero while retaining finite moduli stabilization. In this regime, it seems that de Sitter uplifts are possible with negligible backreaction on the internal volume. We exhibit this behavior also from the 10D perspective.
International Nuclear Information System (INIS)
Moritz, Jakob; Retaloza, Ander; Westphal, Alexander
2017-07-01
Using a 10D lift of non-perturbative volume stabilization in type IIB string theory we study the limitations for obtaining de Sitter vacua. Based on this we find that the simplest KKLT vacua with a single Kahler modulus stabilized by a gaugino condensate cannot be uplifted to de Sitter. Rather, the uplift flattens out due to stronger backreaction on the volume modulus than has previously been anticipated, resulting in vacua which are meta-stable and SUSY breaking, but that are always AdS. However, we also show that setups such as racetrack stabilization can avoid this issue. In these models it is possible to obtain supersymmetric AdS vacua with a cosmological constant that can be tuned to zero while retaining finite moduli stabilization. In this regime, it seems that de Sitter uplifts are possible with negligible backreaction on the internal volume. We exhibit this behavior also from the 10D perspective.
Transforming to Lorentz gauge on de Sitter
Miao, S. P.; Tsamis, N.C.; Woodard, R.P.
2009-01-01
We demonstrate that certain gauge fixing functionals cannot be added to the action on backgrounds such as de Sitter, in which a linearization instability is present. We also construct the field-dependent gauge transformation that carries the electromagnetic vector potential from a convenient, non-de
Quasinormal modes in pure de Sitter spacetimes
International Nuclear Information System (INIS)
Du Daping; Wang Bin; Su Ruheng
2004-01-01
We have studied scalar perturbations as well as fermion perturbations in pure de Sitter spacetimes. For scalar perturbations we have shown that well-defined quasinormal modes in d-dimensions can exist provided that the mass of scalar field m>(d-1/2l). The quasinormal modes of fermion perturbations in three and four dimensional cases have also been investigated. We found that different from other dimensional cases, in the three dimensional pure de Sitter spacetime there is no quasinormal mode for the s-wave. This interesting difference caused by the spacial dimensions is true for both scalar and fermion perturbations
de Sitter relativity in static charts
Energy Technology Data Exchange (ETDEWEB)
Cotaescu, Ion I. [West University of Timisoara, Timisoara (Romania)
2018-02-15
The relative geodesic motion in static (and spherically symmetric) local charts on the (1 + 3)-dimensional de Sitter spacetimes is studied in terms of conserved quantities. The Lorentzian isometries are derived, relating the coordinates of the local chart of a fixed observer with the coordinates of a mobile chart considered as the rest frame of a massive particle freely moving on a timelike geodesic. The time dilation and Lorentz contraction are discussed pointing out some notable features of the de Sitter relativity in static charts. (orig.)
All possible de-Sitter superalgebras and the presence of ghosts
International Nuclear Information System (INIS)
Lukierski, J.; Nowicki, A.
1984-09-01
De-Sitter superalgebras which supersymmetrize SO(d;1) by introducing the spinorial supercharges, exist for d=2,3,4 and 5. It is shown however that it is possible only for d=2 to write a nontrivial representation of de-Sitter superalgebra in the Hilbert space, with positive-definite metric. (orig.)
Directory of Open Access Journals (Sweden)
Waldyr A. Rodrigues
2016-01-01
Full Text Available We discuss the physics of interacting fields and particles living in a de Sitter Lorentzian manifold (dSLM, a submanifold of a 5-dimensional pseudo-Euclidean (5dPE equipped with a metric tensor inherited from the metric of the 5dPE space. The dSLM is naturally oriented and time oriented and is the arena used to study the energy-momentum conservation law and equations of motion for physical systems living there. Two distinct de Sitter space-time structures MdSL and MdSTP are introduced given dSLM, the first equipped with the Levi-Civita connection of its metric field and the second with a metric compatible parallel connection. Both connections are used only as mathematical devices. Thus, for example, MdSL is not supposed to be the model of any gravitational field in the General Relativity Theory (GRT. Misconceptions appearing in the literature concerning the motion of free particles in dSLM are clarified. Komar currents are introduced within Clifford bundle formalism permitting the presentation of Einstein equation as a Maxwell like equation and proving that in GRT there are infinitely many conserved currents. We prove that in GRT even when the appropriate Killing vector fields exist it is not possible to define a conserved energy-momentum covector as in special relativistic theories.
Dappiaggi, Claudio; Ferreira, Hugo R. C.; Juárez-Aubry, Benito A.
2018-04-01
We study a real, massive Klein-Gordon field in the Poincaré fundamental domain of the (d +1 )-dimensional anti-de Sitter (AdS) spacetime, subject to a particular choice of dynamical boundary conditions of generalized Wentzell type, whereby the boundary data solves a nonhomogeneous, boundary Klein-Gordon equation, with the source term fixed by the normal derivative of the scalar field at the boundary. This naturally defines a field in the conformal boundary of the Poincaré fundamental domain of AdS. We completely solve the equations for the bulk and boundary fields and investigate the existence of bound state solutions, motivated by the analogous problem with Robin boundary conditions, which are recovered as a limiting case. Finally, we argue that both Robin and generalized Wentzell boundary conditions are distinguished in the sense that they are invariant under the action of the isometry group of the AdS conformal boundary, a condition which ensures in addition that the total flux of energy across the boundary vanishes.
Directory of Open Access Journals (Sweden)
Ran Li
2016-07-01
Full Text Available Reissner–Nordström Anti-de Sitter (RNAdS black holes are unstable against the charged scalar field perturbations due to the well-known superradiance phenomenon. We present the time domain analysis of charged scalar field perturbations in the RNAdS black hole background in general dimensions. We show that the instabilities of charged scalar field can be explicitly illustrated from the time profiles of evolving scalar field. By using the Prony method to fit the time evolution data, we confirm the mode that dominates the long time behavior of scalar field is in accordance with the quasinormal mode from the frequency domain analysis. The superradiance origin of the instability can also be demonstrated by comparing the real part of the dominant mode with the superradiant condition of charged scalar field. It is shown that all the unstable modes are superradiant, which is consistent with the analytical result in the frequency domain analysis. Furthermore, we also confirm there exists the rapid exponential growing modes in the RNAdS case, which makes the RNAdS black hole a good test ground to investigate the nonlinear evolution of superradiant instability.
HKT geometry and de Sitter supergravity
International Nuclear Information System (INIS)
Grover, Jai; Gutowski, Jan B.; Herdeiro, Carlos A.R.; Sabra, Wafic
2009-01-01
Solutions of five-dimensional minimal de Sitter supergravity admitting Killing spinors are considered. It is shown that the 'timelike' solutions are determined in terms of a four-dimensional hyper-Kaehler torsion (HKT) manifold. If the HKT manifold is conformally hyper-Kaehler the most general solution can be obtained from a sub-class of supersymmetric solutions of minimal N=2 ungauged supergravity, by means of a simple transformation. Examples include a multi-BMPV de Sitter solution, describing multiple rotating black holes co-moving with the expansion of the universe. If the HKT manifold is not conformally hyper-Kaehler, examples admitting a tri-holomorphic Killing vector field are constructed in terms of certain solutions of three-dimensional Einstein-Weyl geometry
Cosmic curvature from de Sitter equilibrium cosmology.
Albrecht, Andreas
2011-10-07
I show that the de Sitter equilibrium cosmology generically predicts observable levels of curvature in the Universe today. The predicted value of the curvature, Ω(k), depends only on the ratio of the density of nonrelativistic matter to cosmological constant density ρ(m)(0)/ρ(Λ) and the value of the curvature from the initial bubble that starts the inflation, Ω(k)(B). The result is independent of the scale of inflation, the shape of the potential during inflation, and many other details of the cosmology. Future cosmological measurements of ρ(m)(0)/ρ(Λ) and Ω(k) will open up a window on the very beginning of our Universe and offer an opportunity to support or falsify the de Sitter equilibrium cosmology.
Stress tensor fluctuations in de Sitter spacetime
Energy Technology Data Exchange (ETDEWEB)
Pérez-Nadal, Guillem; Verdaguer, Enric [Departament de Física Fonamental and Institut de Ciències del Cosmos, Universitat de Barcelona, Av. Diagonal 647, 08028 Barcelona (Spain); Roura, Albert, E-mail: guillem@ffn.ub.es, E-mail: albert.roura@aei.mpg.de, E-mail: enric.verdaguer@ub.edu [Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut, Am Mühlenberg 1, 14476 Golm (Germany)
2010-05-01
The two-point function of the stress tensor operator of a quantum field in de Sitter spacetime is calculated for an arbitrary number of dimensions. We assume the field to be in the Bunch-Davies vacuum, and formulate our calculation in terms of de Sitter-invariant bitensors. Explicit results for free minimally coupled scalar fields with arbitrary mass are provided. We find long-range stress tensor correlations for sufficiently light fields (with mass m much smaller than the Hubble scale H), namely, the two-point function decays at large separations like an inverse power of the physical distance with an exponent proportional to m{sup 2}/H{sup 2}. In contrast, we show that for the massless case it decays at large separations like the fourth power of the physical distance. There is thus a discontinuity in the massless limit. As a byproduct of our work, we present a novel and simple geometric interpretation of de Sitter-invariant bitensors for pairs of points which cannot be connected by geodesics.
International Nuclear Information System (INIS)
Dias, Goncalo A. S.; Lemos, Jose P. S.
2009-01-01
The Hamiltonian thermodynamics formalism is applied to the general d-dimensional Reissner-Nordstroem-anti-de Sitter black hole with spherical, planar, and hyperbolic horizon topology. After writing its action and performing a Legendre transformation, surface terms are added in order to guarantee a well-defined variational principle with which to obtain sensible equations of motion, and also to allow later on the thermodynamical analysis. Then a Kuchar canonical transformation is done, which changes from the metric canonical coordinates to the physical parameters coordinates. Again, a well-defined variational principle is guaranteed through boundary terms. These terms influence the falloff conditions of the variables and at the same time the form of the new Lagrange multipliers. Reduction to the true degrees of freedom is performed, which are the conserved mass and charge of the black hole. Upon quantization a Lorentzian partition function Z is written for the grand canonical ensemble, where the temperature T and the electric potential φ are fixed at infinity. After imposing Euclidean boundary conditions on the partition function, the respective effective action I * , and thus the thermodynamical partition function, is determined for any dimension d and topology k. This is a quite general action. Several previous results can be then condensed in our single general formula for the effective action I * . Phase transitions are studied for the spherical case, and it is shown that all the other topologies have no phase transitions. A parallel with the Bose-Einstein condensation can be established. Finally, the expected values of energy, charge, and entropy are determined for the black hole solution.
On classical de Sitter and Minkowski solutions with intersecting branes
Andriot, David
2018-03-01
Motivated by the connection of string theory to cosmology or particle physics, we study solutions of type II supergravities having a four-dimensional de Sitter or Minkowski space-time, with intersecting D p -branes and orientifold O p -planes. Only few such solutions are known, and we aim at a better characterisation. Modulo a few restrictions, we prove that there exists no classical de Sitter solution for any combination of D 3/ O 3 and D 7/ O 7, while we derive interesting constraints for intersecting D 5/ O 5 or D 6/ O 6, or combinations of D 4/ O 4 and D 8/ O 8. Concerning classical Minkowski solutions, we understand some typical features, and propose a solution ansatz. Overall, a central information appears to be the way intersecting D p / O p overlap each other, a point we focus on.
Refining the boundaries of the classical de Sitter landscape
Energy Technology Data Exchange (ETDEWEB)
Andriot, David [Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut,Am Mühlenberg 1, 14467 Potsdam-Golm (Germany); Institut für Mathematik, Humboldt-Universität zu Berlin, IRIS-Adlershof,Zum Großen Windkanal 6, 12489 Berlin (Germany); Blåbäck, Johan [Institut de Physique Théorique, Université Paris Saclay, CEA, CNRS,F-91191 Gif sur Yvette (France)
2017-03-20
We derive highly constraining no-go theorems for classical de Sitter backgrounds of string theory, with parallel sources; this should impact the embedding of cosmological models. We study ten-dimensional vacua of type II supergravities with parallel and backreacted orientifold O{sub p}-planes and D{sub p}-branes, on four-dimensional de Sitter space-time times a compact manifold. Vacua for p=3, 7 or 8 are completely excluded, and we obtain tight constraints for p=4, 5, 6. This is achieved through the derivation of an enlightening expression for the four-dimensional Ricci scalar. Further interesting expressions and no-go theorems are obtained. The paper is self-contained so technical aspects, including conventions, might be of more general interest.
Quantum corrections for spinning particles in de Sitter
Energy Technology Data Exchange (ETDEWEB)
Fröb, Markus B. [Department of Mathematics, University of York, Heslington, York, YO10 5DD (United Kingdom); Verdaguer, Enric, E-mail: mbf503@york.ac.uk, E-mail: enric.verdaguer@ub.edu [Departament de Física Quàntica i Astrofísica, Institut de Ciències del Cosmos (ICC), Universitat de Barcelona (UB), C/ Martí i Franquès 1, 08028 Barcelona (Spain)
2017-04-01
We compute the one-loop quantum corrections to the gravitational potentials of a spinning point particle in a de Sitter background, due to the vacuum polarisation induced by conformal fields in an effective field theory approach. We consider arbitrary conformal field theories, assuming only that the theory contains a large number N of fields in order to separate their contribution from the one induced by virtual gravitons. The corrections are described in a gauge-invariant way, classifying the induced metric perturbations around the de Sitter background according to their behaviour under transformations on equal-time hypersurfaces. There are six gauge-invariant modes: two scalar Bardeen potentials, one transverse vector and one transverse traceless tensor, of which one scalar and the vector couple to the spinning particle. The quantum corrections consist of three different parts: a generalisation of the flat-space correction, which is only significant at distances of the order of the Planck length; a constant correction depending on the undetermined parameters of the renormalised effective action; and a term which grows logarithmically with the distance from the particle. This last term is the most interesting, and when resummed gives a modified power law, enhancing the gravitational force at large distances. As a check on the accuracy of our calculation, we recover the linearised Kerr-de Sitter metric in the classical limit and the flat-space quantum correction in the limit of vanishing Hubble constant.
Analytic extension of the Schwarzschild-de Sitter metric
International Nuclear Information System (INIS)
Bazanski, S.L.; Ferrari, V.
1986-01-01
In this paper, co-ordinates are derived that are regular, respectively, in the neighbourhood of the two horizons which exist in the so-called Schwarzschild-de Sitter solution known in general relativity, and it is constructed a manifold that is the analytic extension of the manifold being the domain of classical Schwarzschild-de Sitter co-ordinates
Discrete symmetries and de Sitter spacetime
Energy Technology Data Exchange (ETDEWEB)
Cotăescu, Ion I., E-mail: gpascu@physics.uvt.ro; Pascu, Gabriel, E-mail: gpascu@physics.uvt.ro [West University of Timişoara, V. Pârvan Ave. 4, RO-300223 Timişoara (Romania)
2014-11-24
Aspects of the ambiguity in defining quantum modes on de Sitter spacetime using a commuting system composed only of differential operators are discussed. Discrete symmetries and their actions on the wavefunction in commonly used coordinate charts are reviewed. It is argued that the system of commuting operators can be supplemented by requiring the invariance of the wavefunction to combined discrete symmetries- a criterion which selects a single state out of the α-vacuum family. Two such members of this family are singled out by particular combined discrete symmetries- states between which exists a well-known thermality relation.
Physical renormalization condition for de Sitter QED
Hayashinaka, Takahiro; Xue, She-Sheng
2018-05-01
We considered a new renormalization condition for the vacuum expectation values of the scalar and spinor currents induced by a homogeneous and constant electric field background in de Sitter spacetime. Following a semiclassical argument, the condition named maximal subtraction imposes the exponential suppression on the massive charged particle limit of the renormalized currents. The maximal subtraction changes the behaviors of the induced currents previously obtained by the conventional minimal subtraction scheme. The maximal subtraction is favored for a couple of physically decent predictions including the identical asymptotic behavior of the scalar and spinor currents, the removal of the IR hyperconductivity from the scalar current, and the finite current for the massless fermion.
Zero modes in de Sitter background
Energy Technology Data Exchange (ETDEWEB)
Einhorn, Martin B. [Kavli Institute for Theoretical Physics, University of California,Santa Barbara, CA 93106-4030 (United States); Jones, D.R. Timothy [Kavli Institute for Theoretical Physics, University of California,Santa Barbara, CA 93106-4030 (United States); Dept. of Mathematical Sciences, University of Liverpool,Liverpool L69 3BX (United Kingdom)
2017-03-28
There are five well-known zero modes among the fluctuations of the metric of de Sitter (dS) spacetime. For Euclidean signature, they can be associated with certain spherical harmonics on the S{sup 4} sphere, viz., the vector representation 5 of the global SO(5) isometry. They appear, for example, in the perturbative calculation of the on-shell effective action of dS space, as well as in models containing matter fields. These modes are shown to be associated with collective modes of S{sup 4} corresponding to certain coherent fluctuations. When dS space is embedded in flat five dimensions E{sup 5}, they may be seen as a legacy of translation of the center of the S{sup 4} sphere. Rigid translations of the S{sup 4}-sphere on E{sup 5} leave the classical action invariant but are unobservable displacements from the point of view of gravitational dynamics on S{sup 4}. Thus, unlike similar moduli, the center of the sphere is not promoted to a dynamical degree of freedom. As a result, these zero modes do not signify the possibility of physically realizable fluctuations or flat directions for the metric of dS space. They are not associated with Killing vectors on S{sup 4} but can be identified with certain non-isometric, conformal Killing forms that locally correspond to a rescaling of the volume element dV{sub 4}. We frame much of our discussion in the context of renormalizable gravity, but, to the extent that they only depend upon the global symmetry of the background, the conclusions should apply equally to the corresponding zero modes found in Einstein gravity. Although their existence has only been demonstrated at one-loop, we expect that these zero modes will be present to all orders in perturbation theory. They will occur for Lorentzian signature as well, so long as the hyperboloid H{sup 4} is locally stable, but there remain certain infrared issues that need to be clarified. We conjecture that they will appear in any gravitational theory having dS background as a
Entropy of Vaidya-deSitter Spacetime
Institute of Scientific and Technical Information of China (English)
LI Xiang; ZHAO Zheng
2001-01-01
As a statistical model of black hole entropy, the brick-wall method based on the thermal equilibrium in a large scale cannot be applied to the cases out of equilibrium, such as the non-static hole or the case with two horizons.However, the leading term of hole entropy called the Bekenstein-Hawking entropy comes from the contribution of the field near the horizon. According to this idea, the entropy of Vaidya-deSitter spacetime is calculated. A difference from the static case is that the result proportional to the area of horizon relies on a time-dependent cut-off. The condition of local equilibrium near the horizon is used as a working postulate.
Twin paradox in de Sitter spacetime
International Nuclear Information System (INIS)
Boblest, Sebastian; Wunner, Guenter; Mueller, Thomas
2011-01-01
The 'twin paradox' of special relativity offers the possibility of making interstellar flights within a lifetime. For very long journeys with velocities close to the speed of light, however, we have to take into account the expansion of the universe. Inspired by the work of Rindler on hyperbolic motion in curved spacetime, we study the worldline of a uniformly accelerated observer in de Sitter spacetime and the communication between the travelling observer and an observer at rest. This paper is intended to give graduate students who are familiar with special relativity and have some basic experience of general relativity a deeper insight into accelerated motion in general relativity, into the relationship between the proper times of different observers and the propagation of light signals between them, and into the use of compactification to describe the global structure of a relativistic model.
A de Sitter tachyon thick braneworld
Energy Technology Data Exchange (ETDEWEB)
Germán, Gabriel; Herrera-Aguilar, Alfredo; Malagón-Morejón, Dagoberto [Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Apdo. Postal 48-3, 62251, Cuernavaca, Morelos (Mexico); Mora-Luna, Refugio Rigel [Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio C-3, Ciudad Universitaria, C.P. 58040, Morelia, Michoacán (Mexico); Rocha, Roldão da, E-mail: gabriel@fis.unam.mx, E-mail: aha@fis.unam.mx, E-mail: malagon@ifm.umich.mx, E-mail: rigel@ifm.umich.mx, E-mail: roldao.rocha@ufabc.edu.br [Centro de Matemática, Computação e Cognição, Universidade Federal do ABC, Rua Santa Adélia, 166 09210-170, Santo André, SP (Brazil)
2013-02-01
Among the multiple 5D thick braneworld models that have been proposed in the last years, in order to address several open problems in modern physics, there is a specific one involving a tachyonic bulk scalar field. Delving into this framework, a thick braneworld with a cosmological background induced on the brane is here investigated. The respective field equations — derived from the model with a warped 5D geometry — are highly non-linear equations, admitting a non-trivial solution for the warp factor and the tachyon scalar field as well, in a de Sitter 4D cosmological background. Moreover, the non-linear tachyonic scalar field, that generates the brane in complicity with warped gravity, has the form of a kink-like configuration. Notwithstanding, the non-linear field equations restricting character does not allow one to easily find thick brane solutions with a decaying warp factor which leads to the localization of 4D gravity and other matter fields. We derive such a thick brane configuration altogether in this tachyon-gravity setup. When analyzing the spectrum of gravity fluctuations in the transverse traceless sector, the 4D gravity is shown to be localized due to the presence of a single zero mode bound state, separated by a continuum of massive Kaluza-Klein (KK) modes by a mass gap. It contrasts with previous results, where there is a KK massive bound excitation providing no clear physical interpretation. The mass gap is determined by the scale of the metric parameter H. Finally, the corrections to Newton's law in this model are computed and shown to decay exponentially. It is in full compliance to corrections reported in previous results (up to a constant factor) within similar braneworlds with induced 4D de Sitter metric, despite the fact that the warp factor and the massive modes have a different form.
Higher order corrections to asymptotic-de Sitter inflation
Mohsenzadeh, M.; Yusofi, E.
2017-08-01
Since trans-Planckian considerations can be associated with the re-definition of the initial vacuum, we investigate further the influence of trans-Planckian physics on the spectra produced by the initial quasi-de Sitter (dS) state during inflation. We use the asymptotic-dS mode to study the trans-Planckian correction of the power spectrum to the quasi-dS inflation. The obtained spectra consist of higher order corrections associated with the type of geometry and harmonic terms sensitive to the fluctuations of space-time (or gravitational waves) during inflation. As an important result, the amplitude of the power spectrum is dependent on the choice of c, i.e. the type of space-time in the period of inflation. Also, the results are always valid for any asymptotic dS space-time and particularly coincide with the conventional results for dS and flat space-time.
Energy Technology Data Exchange (ETDEWEB)
Kirchbach, M. [Instituto de Fisica, UASLP, San Luis Potosi (Mexico); Compean, C.B. [Instituto Tecnologico de San Luis Potosi, Soledad de Graciano Sanchez (Mexico)
2017-04-15
In the article under discussion the analysis of the spectra of the unflavored mesons lead us to some intriguing insights into the possible geometry of space-time outside the causal Minkowski light cone and into the nature of strong interactions. In applying the potential theory concept of geometrization of interactions, we showed that the meson masses are best described by a confining potential composed by the centrifugal barrier on the three-dimensional spherical space, S{sup 3}, and of a charge-dipole potential constructed from the Green function to the S{sup 3} Laplacian. The dipole potential emerged in view of the fact that S{sup 3} does not support single-charges without violation of the Gauss theorem and the superposition principle, thus providing a natural stage for the description of the general phenomenon of confined charge-neutral systems. However, in the original article we did not relate the charge-dipoles on S{sup 3} to the color neutral mesons, and did not express the magnitude of the confining dipole potential in terms of the strong coupling α{sub S} and the number of colors, N{sub c}, the subject of the addendum. To the amount S{sup 3} can be thought of as the unique closed space-like geodesic of a four-dimensional de Sitter space-time, dS{sub 4}, we hypothesized the space-like region outside the causal Einsteinian light cone (it describes virtual processes, among them interactions) as the (1+4)-dimensional subspace of the conformal (2+4) space-time, foliated with dS{sub 4} special relativity for strong interaction processes. The potential designed in this way predicted meson spectra of conformal degeneracy patterns, and in accord with the experimental observations. We now extract the α{sub s} values in the infrared from data on meson masses. The results obtained are compatible with the α{sub s} estimates provided by other approaches. (orig.)
Area spectrum of the D-dimensional de Sitter spacetime
International Nuclear Information System (INIS)
Lopez-Ortega, A.
2009-01-01
The determination of the quantum area spectrum of a black hole horizon by means of its asymptotic quasinormal frequencies has been explored recently. We believe that for D-dimensional de Sitter horizon we must study if the idea works. Thus taking into account the local description of the thermodynamics of horizons proposed by Padmanabhan and the results of Hod, Kunstatter, and Maggiore we study the area spectrum of the D-dimensional de Sitter horizon.
Area spectrum of the D-dimensional de Sitter spacetime
Energy Technology Data Exchange (ETDEWEB)
Lopez-Ortega, A., E-mail: alopezo@ipn.m [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Legaria, Instituto Politecnico Nacional, Calzada Legaria 694 Colonia Irrigacion, Delegacion Miguel Hidalgo, Mexico, D.F., C.P. 11500 (Mexico)
2009-11-23
The determination of the quantum area spectrum of a black hole horizon by means of its asymptotic quasinormal frequencies has been explored recently. We believe that for D-dimensional de Sitter horizon we must study if the idea works. Thus taking into account the local description of the thermodynamics of horizons proposed by Padmanabhan and the results of Hod, Kunstatter, and Maggiore we study the area spectrum of the D-dimensional de Sitter horizon.
CFT description of three-dimensional Kerr-de Sitter spacetime
International Nuclear Information System (INIS)
Fjelstad, Jens; Hwang, Stephen; Maansson, Teresia
2002-01-01
We describe three-dimensional Kerr-de Sitter space using similar methods as recently applied to the BTZ black hole. A rigorous form of the classical connection between gravity in three dimensions and two-dimensional conformal field theory is employed, where the fundamental degrees of freedom are described in terms of two dependent SL(2,C) currents. In contrast to the BTZ case, however, quantization does not give the Bekenstein-Hawking entropy connected to the cosmological horizon of Kerr-de Sitter space
CFT description of three-dimensional Kerr-de Sitter spacetime
Energy Technology Data Exchange (ETDEWEB)
Fjelstad, Jens E-mail: jens.fjelstad@kau.se; Hwang, Stephen E-mail: stephen.hwang@kau.se; Maansson, Teresia E-mail: teresia@physto.se
2002-10-07
We describe three-dimensional Kerr-de Sitter space using similar methods as recently applied to the BTZ black hole. A rigorous form of the classical connection between gravity in three dimensions and two-dimensional conformal field theory is employed, where the fundamental degrees of freedom are described in terms of two dependent SL(2,C) currents. In contrast to the BTZ case, however, quantization does not give the Bekenstein-Hawking entropy connected to the cosmological horizon of Kerr-de Sitter space.
Gravitationally induced adiabatic particle production: from big bang to de Sitter
de Haro, Jaume; Pan, Supriya
2016-08-01
In the background of a flat homogeneous and isotropic space-time, we consider a scenario of the Universe driven by the gravitationally induced ‘adiabatic’ particle production with constant creation rate. We have shown that this Universe attains a big bang singularity in the past and at late-time it asymptotically becomes de Sitter. To clarify this model Universe, we performed a dynamical analysis and found that the Universe attains a thermodynamic equilibrium in this late de Sitter phase. Finally, for the first time, we have discussed the possible effects of ‘adiabatic’ particle creations in the context of loop quantum cosmology.
Thermal interpretation of infrared dynamics in de Sitter
Energy Technology Data Exchange (ETDEWEB)
Rigopoulos, Gerasimos, E-mail: gerasimos.rigopoulos@ncl.ac.uk [School of Mathematics and Statistics, Newcastle University, Herschel Building, Newcastle upon Tyne, NE1 7RU U.K. (United Kingdom)
2016-07-01
The infrared dynamics of a light, minimally coupled scalar field in de Sitter spacetime with Ricci curvature R = 12 H {sup 2}, averaged over horizon sized regions of physical volume V {sub H} = (4π/3)(1/ H ){sup 3}, can be interpreted as Brownian motion in a medium with de Sitter temperature T {sub DS} = h-bar H /2π. We demonstrate this by directly deriving the effective action of scalar field fluctuations with wavelengths larger than the de Sitter curvature radius and generalizing Starobinsky's seminal results on stochastic inflation. The effective action describes stochastic dynamics and the fluctuating force drives the field to an equilibrium characterized by a thermal Gibbs distribution at temperature T {sub DS} which corresponds to a de Sitter invariant state. Hence, approach towards this state can be interpreted as thermalization. We show that the stochastic kinetic energy of the coarse-grained description corresponds to the norm of ∂{sub μ}φ and takes a well defined value per horizon volume ½((∇φ){sup 2}) = − ½ T {sub DS}/ V {sub H} . This approach allows for the non-perturbative computation of the de Sitter invariant stress energy tensor ( T {sub μν}) for an arbitrary scalar potential.
A de Sitter tachyonic braneworld revisited
Barbosa-Cendejas, Nandinii; Cartas-Fuentevilla, Roberto; Herrera-Aguilar, Alfredo; Rigel Mora-Luna, Refugio; da Rocha, Roldão
2018-01-01
Within the framework of braneworlds, several interesting physical effects can be described in a wide range of energy scales, starting from high-energy physics to cosmology and low-energy physics. An usual way to generate a thick braneworld model relies in coupling a bulk scalar field to higher dimensional warped gravity. Quite recently, a novel braneworld was generated with the aid of a tachyonic bulk scalar field, having several remarkable properties. It comprises a regular and stable solution that contains a relevant 3-brane with de Sitter induced metric, arising as an exact solution to the 5D field equations, describing the inflationary eras of our Universe. Besides, it is asymptotically flat, despite of the presence of a negative 5D cosmological constant, which is an interesting feature that contrasts with most of the known, asymptotically either dS or AdS models. Moreover, it encompasses a graviton spectrum with a single massless bound state, accounting for 4D gravity localized on the brane, separated from the continuum of Kaluza-Klein massive graviton modes by a mass gap that makes the 5D corrections to Newton's law to decay exponentially. Finally, gauge, scalar and fermion fields are also shown to be localized on this braneworld. In this work, we show that this tachyonic braneworld allows for a nontrivial solution with a vanishing 5D cosmological constant that preserves all the above mentioned remarkable properties with a less amount of parameters, constituting an important contribution to the construction of a realistic cosmological braneworld model.
On the ghost-induced instability on de Sitter background
Peter, Patrick; Salles, Filipe de O.; Shapiro, Ilya L.
2018-03-01
It is known that the perturbative instability of tensor excitations in higher derivative gravity may not take place if the initial frequency of the gravitational waves is below the Planck threshold. One can assume that this is a natural requirement if the cosmological background is sufficiently mild, since in this case the situation is qualitatively close to the free gravitational wave in flat space. Here, we explore the opposite situation and consider the effect of a very far from Minkowski radiation-dominated or de Sitter cosmological background with a large Hubble rate, e.g., typical of an inflationary period. It turns out that, then, for initial Planckian or even trans-Planckian frequencies, the instability is rapidly suppressed by the very fast expansion of the Universe.
Brane induced supersymmetry breaking and de Sitter supergravity
Energy Technology Data Exchange (ETDEWEB)
Bandos, Igor [Department of Theoretical Physics, University of the Basque Country UPV/EHU, P.O. Box 644, 48080 Bilbao (Spain); IKERBASQUE, Basque Foundation for Science, 48011 Bilbao (Spain); Martucci, Luca [Dipartimento di Fisica e Astronomia “Galileo Galilei”, Università di Padova, Via Marzolo 8, 35131 Padova (Italy); I.N.F.N. Sezione di Padova, Via Marzolo 8, 35131 Padova (Italy); Sorokin, Dmitri [I.N.F.N. Sezione di Padova, Via Marzolo 8, 35131 Padova (Italy); Dipartimento di Fisica e Astronomia “Galileo Galilei”, Università di Padova, Via Marzolo 8, 35131 Padova (Italy); Tonin, Mario [Dipartimento di Fisica e Astronomia “Galileo Galilei”, Università di Padova, Via Marzolo 8, 35131 Padova (Italy); I.N.F.N. Sezione di Padova, Via Marzolo 8, 35131 Padova (Italy)
2016-02-12
We obtain a four-dimensional supergravity with spontaneously broken supersymmetry allowing for de Sitter vacua by coupling a superspace action of minimal N=1, D=4 supergravity to a locally supersymmetric generalization of the Volkov-Akulov goldstino action describing the dynamics of a space-filling non-BPS 3-brane in N=1, D=4 superspace. To the quadratic order in the goldstino field the obtained action coincides with earlier constructions of supergravities with nilpotent superfields, while matching the higher-order contributions will require a non-linear redefinition of fields. In the unitary gauge, in which the goldstino field is set to zero, the action coincides with that of Volkov and Soroka. We also show how a nilpotency constraint on a chiral curvature superfield emerges in this formulation.
de Sitter group as a symmetry for optical decoherence
International Nuclear Information System (INIS)
Baskal, S; Kim, Y S
2006-01-01
Stokes parameters form a Minkowskian 4-vector under various optical transformations. As a consequence, the resulting two-by-two density matrix constitutes a representation of the Lorentz group. The associated Poincare sphere is a geometric representation of the Lorentz group. Since the Lorentz group preserves the determinant of the density matrix, it cannot accommodate the decoherence process through the decaying off-diagonal elements of the density matrix, which yields to an increase in the value of the determinant. It is noted that the O(3, 2) de Sitter group contains two Lorentz subgroups. The change in the determinant in one Lorentz group can be compensated by the other. It is thus possible to describe the decoherence process as a symmetry transformation in the O(3, 2) space. It is shown also that these two coupled Lorentz groups can serve as a concrete example of Feynman's rest of the universe
Scheme dependence of quantum gravity on de Sitter background
Energy Technology Data Exchange (ETDEWEB)
Kitamoto, Hiroyuki, E-mail: kitamoto@post.kek.jp [KEK Theory Center, Tsukuba, Ibaraki 305-0801 (Japan); Kitazawa, Yoshihisa, E-mail: kitazawa@post.kek.jp [KEK Theory Center, Tsukuba, Ibaraki 305-0801 (Japan); The Graduate University for Advanced Studies (Sokendai), Department of Particle and Nuclear Physics, Tsukuba, Ibaraki 305-0801 (Japan)
2013-08-11
We extend our investigation of the IR effects on the local dynamics of matter fields in quantum gravity. Specifically we clarify how the IR effects depend on the change of the quantization scheme: different parametrization of the metric and the matter field redefinition. Conformal invariance implies effective Lorentz invariance of the matter system in de Sitter space. An arbitrary choice of the parametrization of the metric and the matter field redefinition does not preserve the effective Lorentz invariance of the local dynamics. As for the effect of different parametrization of the metric alone, the effective Lorentz symmetry breaking term can be eliminated by shifting the background metric. In contrast, we cannot compensate the matter field redefinition dependence by such a way. The effective Lorentz invariance can be retained only when we adopt the specific matter field redefinitions where all dimensionless couplings become scale invariant at the classical level. This scheme is also singled out by unitarity as the kinetic terms are canonically normalized.
Quantum loop corrections of a charged de Sitter black hole
Naji, J.
2018-03-01
A charged black hole in de Sitter (dS) space is considered and logarithmic corrected entropy used to study its thermodynamics. Logarithmic corrections of entropy come from thermal fluctuations, which play a role of quantum loop correction. In that case we are able to study the effect of quantum loop on black hole thermodynamics and statistics. As a black hole is a gravitational object, it helps to obtain some information about the quantum gravity. The first and second laws of thermodynamics are investigated for the logarithmic corrected case and we find that it is only valid for the charged dS black hole. We show that the black hole phase transition disappears in the presence of logarithmic correction.
A Spacetime Foam Approach to the Schwarzschild-de Sitter Entropy
Directory of Open Access Journals (Sweden)
Remo Garattini
2000-03-01
Full Text Available The entropy for a black hole in a de Sitter space is approached within the framework of spacetime foam. A simple model made by N wormholes in a semiclassical approximation, is taken under examination to compute the entropy for such a case. An extension to the extreme case when the black hole and cosmological horizons are equal is discussed.
Spectator electric fields, de Sitter spacetime, and the Schwinger effect
Giovannini, Massimo
2018-03-01
During a de Sitter stage of expansion, the spectator fields of different spin are constrained by the critical density bound and by further requirements determined by their specific physical nature. The evolution of spectator electric fields in conformally flat background geometries is occasionally concocted by postulating the existence of ad hoc currents, but this apparently innocuous trick violates the second law of thermodynamics. Such a problem occurs, in particular, for those configurations (customarily employed for the analysis of the Schwinger effect in four-dimensional de Sitter backgrounds) leading to an electric energy density which is practically unaffected by the expansion of the underlying geometry. The obtained results are compared with more mundane situations where Joule heating develops in the early stages of a quasi-de Sitter phase.
Rest frames and relativistic effects on de Sitter spacetimes
Energy Technology Data Exchange (ETDEWEB)
Cotaescu, Ion I. [West University of Timisoara, Timisoara (Romania)
2017-07-15
It is shown that the Nachtmann boosting method of introducing coordinates on de Sitter manifolds can be completed with suitable gauge transformations able to keep under control the transformation under isometries of the conserved quantities. With this method, the rest local charts (or natural frames) are defined pointing out the role of the conserved quantities in investigating the relative geodesic motion. The advantages of this approach can be seen from the applications presented here. For the first time, the simple kinematic effects, the electromagnetic field of a free falling charge and the binary fission are solved in terms of conserved quantities on the expanding portion of the de Sitter spacetime. (orig.)
Super-Hubble de Sitter fluctuations and the dynamical RG
Energy Technology Data Exchange (ETDEWEB)
Burgess, C.P. [Department of Physics and Astronomy, McMaster University, Hamilton, Ontario (Canada); Leblond, L.; Shandera, S. [Perimeter Institute for Theoretical Physics, Waterloo, Ontario (Canada); Holman, R., E-mail: cburgess@perimeterinstitute.ca, E-mail: lleblond@perimeterinstitute.ca, E-mail: rha@andrew.cmu.edu, E-mail: sshandera@perimeterinstitute.ca [Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States)
2010-03-01
Perturbative corrections to correlation functions for interacting theories in de Sitter spacetime often grow secularly with time, due to the properties of fluctuations on super-Hubble scales. This growth can lead to a breakdown of perturbation theory at late times. We argue that Dynamical Renormalization Group (DRG) techniques provide a convenient framework for interpreting and resumming these secularly growing terms. In the case of a massless scalar field in de Sitter with quartic self-interaction, the resummed result is also less singular in the infrared, in precisely the manner expected if a dynamical mass is generated. We compare this improved infrared behavior with large-N expansions when applicable.
Entropy of Kerr-de Sitter black hole
Li, Huai-Fan; Ma, Meng-Sen; Zhang, Li-Chun; Zhao, Ren
2017-07-01
Based on the consideration that the black hole horizon and the cosmological horizon of Kerr-de Sitter black hole are not independent of each other, we conjecture the total entropy of the system should have an extra term contributed from the correlations between the two horizons, except for the sum of the two horizon entropies. By employing globally effective first law and effective thermodynamic quantities, we obtain the corrected total entropy and find that the region of stable state for Kerr-de Sitter is related to the angular velocity parameter a, i.e., the region of stable state becomes bigger as the rotating parameters a is increases.
Cosmological term in general relativity theory and localization of de Sitter and Einstein groups
International Nuclear Information System (INIS)
Tunyak, V.N.
1984-01-01
The theory of gauge gravitational field with the de Sitter group localization is formulated. proceeding from the de Sitter Universe tetrad components the relationship between Riemann metrics and de Sitter gauge field is established. It is shown that General relativity theory (GRT) with a cosmological term is the simplest variant of the de Sitter gauge gravitation theory passing in the limit of infinite curvature radius of the de Sitter Universe into the Poincare - invariant GRT without cosmological term. Similarly the theory of gauge gravitational field at localization of the dynamical group of the Einstein homogeneous static Universe (Einstein group RxSO(4)) is formulated
Snyder-de Sitter model from two-time physics
International Nuclear Information System (INIS)
Carrisi, M. C.; Mignemi, S.
2010-01-01
We show that the symplectic structure of the Snyder model on a de Sitter background can be derived from two-time physics in seven dimensions and propose a Hamiltonian for a free particle consistent with the symmetries of the model.
A photon propagator on de Sitter in covariant gauges
Domazet, S.; Prokopec, T.
2014-01-01
We construct a de Sitter invariant photon propagator in general covariant gauges. Our result is a natural generalization of the Allen-Jacobson photon propagator in Feynman gauge. Our propagator reproduces the correct response to a point static charge and the one-loop electromagnetic stress-energy
De Sitter universes and the emerging landscape in string theory
Indian Academy of Sciences (India)
We discuss a recent proposal to construct de Sitter vacua in string theory. It is based on flux compactifications in string theory where all the moduli are stabilised and supersymmetry is broken with control. The resulting picture is that of a complicated landscape with many vacua of widely varying values for the cosmological ...
Equatorial circular orbits in the Kerr-de Sitter spacetimes
International Nuclear Information System (INIS)
Stuchlik, Zdenek; Slany, Petr
2004-01-01
Equatorial motion of test particles in Kerr-de Sitter spacetimes is considered. Circular orbits are determined, their properties are discussed for both black-hole and naked-singularity spacetimes, and their relevance for thin accretion disks is established. The circular orbits constitute two families that coalesce at the so-called static radius. The orientation of the motion along the circular orbits is, in accordance with case of asymptotically flat Kerr spacetimes, defined by relating the motion to the locally nonrotating frames. The minus-family orbits are all counterrotating, while the plus-family orbits are usually corotating relative to these frames. However, the plus-family orbits become counterrotating in the vicinity of the static radius in all Kerr-de Sitter spacetimes, and they become counterrotating in the vicinity of the ring singularity in Kerr-de Sitter naked-singularity spacetimes with a low enough rotational parameter. In such spacetimes, the efficiency of the conversion of the rest energy into heat energy in the geometrically thin plus-family accretion disks can reach extremely high values exceeding the efficiency of the annihilation process. The transformation of a Kerr-de Sitter naked singularity into an extreme black hole due to accretion in the thin disks is briefly discussed for both the plus-family and minus-family disks. It is shown that such a conversion leads to an abrupt instability of the innermost parts of the plus-family accretion disks that can have strong observational consequences
de Sitter limit of inflation and nonlinear perturbation theory
DEFF Research Database (Denmark)
R. Jarnhus, Philip; Sloth, Martin Snoager
2007-01-01
We study the fourth order action of the comoving curvature perturbation in an inflationary universe in order to understand more systematically the de Sitter limit in nonlinear cosmological perturbation theory. We derive the action of the curvature perturbation to fourth order in the comoving gaug...
How to use retarded Green's functions in de Sitter spacetime
International Nuclear Information System (INIS)
Higuchi, Atsushi; Cheong, Lee Yen
2008-01-01
We demonstrate in examples that the covariant retarded Green's functions in electromagnetism and linearized gravity work as expected in de Sitter spacetime. We first clarify how retarded Green's functions should be used in spacetimes with spacelike past infinity such as de Sitter spacetime. In particular, we remind the reader of a general formula which gives the field for given initial data on a Cauchy surface and a given source (a charge or stress-energy tensor distribution) in its future. We then apply this formula to three examples: (i) electromagnetism in the future of a Cauchy surface in Minkowski spacetime, (ii) electromagnetism in de Sitter spacetime, and (iii) linearized gravity in de Sitter spacetime. In each example the field is reproduced correctly as predicted by the general argument. In the third example we construct a linearized gravitational field from two equal point masses located at the 'North and South Poles' which is nonsingular on the cosmological horizon and satisfies a covariant gauge condition and show that this field is reproduced by the retarded Green's function with corresponding gauge parameters.
Perturbative quantization of superstring theory in Anti de-Sitter spaces
Energy Technology Data Exchange (ETDEWEB)
Sundin, Per
2010-07-12
In this thesis we study superstring theory on AdS{sub 5} x S{sup 5}, AdS{sub 3} x S{sup 3} and AdS{sub 4} x CP{sub 3}. A shared feature of each theory is that their corresponding symmetry algebras allows for a decomposition under a Z{sub 4} grading. The grading can be realized through an automorphism which allows for a convenient construction of the string Lagrangians directly in terms of graded components. We adopt a uniform light-cone gauge and expand in a near plane wave limit, or equivalently, an expansion in transverse string coordinates. With a main focus on the two critical string theories, we perform a perturbative quantization up to quartic order in the number of fields. Each string theory is, through holographic descriptions, conjectured to be dual to lower dimensional gauge theories. The conjectures imply that the conformal dimensions of single trace operators in gauge theory should be equal to the energy of string states. What is more, through the use of integrable methods, one can write down a set of Bethe equations whose solutions encode the full spectral problem. One main theme of this thesis is to match the predictions of these equations, written in a language suitable for the light-cone gauge we employ, against explicit string theory calculations. We do this for a large class of string states and the perfect agreement we find lends strong support for the validity of the conjectures. (orig.)
The gravitational exclusion principle and null states in anti-de Sitter space
International Nuclear Information System (INIS)
Castro, Alejandra; Maloney, Alexander; Hartman, Thomas
2011-01-01
The holographic principle implies a vast reduction in the number of degrees of freedom of quantum gravity. This idea can be made precise in AdS 3 , where the the stringy or gravitational exclusion principle asserts that certain perturbative excitations are not present in the exact quantum spectrum. We show that this effect is visible directly in the bulk gravity theory: the norm of the offending linearized state is zero or negative. When the norm is negative, the theory is signalling its own breakdown as an effective field theory; this provides a perturbative bulk explanation for the stringy exclusion principle. When the norm vanishes the bulk state is null rather than physical. This implies that certain non-trivial diffeomorphisms must be regarded as gauge symmetries rather than spectrum-generating elements of the asymptotic symmetry group. This leads to subtle effects in the computation of one-loop determinants for Einstein gravity, higher spin theories and topologically massive gravity in AdS 3 . In particular, heat kernel methods do not capture the correct spectrum of a theory with null states. Communicated by S Ross
Nonlinear dynamics and the instability of Anti-de Sitter space
Dimitrakopoulos, F.
2017-01-01
The study of stability of gravitational systems under small perturbations dates back to the days of celestial mechanics and the problem of stability of our solar system over long periods of time when the gravitational effects of the planets are taken into account and therefore deviations from the
One-Loop Test of Quantum Black Holes in anti-de Sitter Space
Liu, James T.; Pando Zayas, Leopoldo A.; Rathee, Vimal; Zhao, Wenli
2018-06-01
Within 11-dimensional supergravity we compute the logarithmic correction to the entropy of magnetically charged asymptotically AdS4 black holes with arbitrary horizon topology. We find perfect agreement with the expected microscopic result arising from the dual field theory computation of the topologically twisted index. Our result relies crucially on a particular limit to the extremal black hole case and clarifies some aspects of quantum corrections in asymptotically AdS spacetimes.
Perturbative quantization of superstring theory in Anti de-Sitter spaces
International Nuclear Information System (INIS)
Sundin, Per
2010-01-01
In this thesis we study superstring theory on AdS 5 x S 5 , AdS 3 x S 3 and AdS 4 x CP 3 . A shared feature of each theory is that their corresponding symmetry algebras allows for a decomposition under a Z 4 grading. The grading can be realized through an automorphism which allows for a convenient construction of the string Lagrangians directly in terms of graded components. We adopt a uniform light-cone gauge and expand in a near plane wave limit, or equivalently, an expansion in transverse string coordinates. With a main focus on the two critical string theories, we perform a perturbative quantization up to quartic order in the number of fields. Each string theory is, through holographic descriptions, conjectured to be dual to lower dimensional gauge theories. The conjectures imply that the conformal dimensions of single trace operators in gauge theory should be equal to the energy of string states. What is more, through the use of integrable methods, one can write down a set of Bethe equations whose solutions encode the full spectral problem. One main theme of this thesis is to match the predictions of these equations, written in a language suitable for the light-cone gauge we employ, against explicit string theory calculations. We do this for a large class of string states and the perfect agreement we find lends strong support for the validity of the conjectures. (orig.)
Instanton transition in thermal and moduli deformed de Sitter cosmology
International Nuclear Information System (INIS)
Kounnas, Costas; Partouche, Herve
2008-01-01
We consider the de Sitter cosmology deformed by the presence of a thermal bath of radiation and/or time-dependent moduli fields. Depending on the parameters, either a first or second-order phase transition can occur. In the first case, an instanton allows a double analytic continuation. It induces a probability to enter the inflationary evolution by tunnel effect from another cosmological solution. The latter starts with a big bang and, in the case the transition does not occur, ends with a big crunch. A temperature duality exchanges the two cosmological branches. In the limit where the pure de Sitter universe is recovered, the tunnel effect reduces to a 'creation from nothing', due to the vanishing of the big bang branch. However, the latter may be viable in some range of the deformation parameter. In the second case, there is a smooth evolution from a big bang to the inflationary phase
High overtones of Schwarzschild-de-Sitter quasinormal spectrum
International Nuclear Information System (INIS)
Konoplya, R.A.; Zhidenko, A.
2004-01-01
We find the high overtones of gravitational and electromagnetic quasinormal spectrum of the Schwarzschild-de Sitter black hole. The calculations show that the real parts of the electromagnetic modes asymptotically approach zero. The gravitational modes show more peculiar behavior at large n: the real part oscillates as a function of imaginary even for very high overtones and these oscillations settles to some 'profile' which just repeats itself with further increasing of the overtone number n. This lets us judge that Reω is not a constant as n →∞ but rather some oscillating function. The spacing for imaginary part Imω n+1 -Imω n for electromagnetic perturbations at high n slowly approach k e as n→∞, where k e is the surface gravity. In addition we find the lower QN modes for which the values obtained with numerical methods are in a very good agreement with those obtained through the 6th order WKB technique. (author)
Asymptotic symmetries in de Sitter and inflationary spacetimes
Energy Technology Data Exchange (ETDEWEB)
Ferreira, Ricardo Z.; Sandora, McCullen; Sloth, Martin S., E-mail: ferreira@cp3.sdu.dk, E-mail: sandora@cp3.sdu.dk, E-mail: sloth@cp3.sdu.dk [CP3-Origins, Center for Cosmology and Particle Physics Phenomenology, University of Southern Denmark, Campusvej 55, 5230 Odense M (Denmark)
2017-04-01
Soft gravitons produced by the expansion of de Sitter can be viewed as the Nambu-Goldstone bosons of spontaneously broken asymptotic symmetries of the de Sitter spacetime. We explicitly construct the associated charges, and show that acting with the charges on the vacuum creates a new state equivalent to a change in the local coordinates induced by the soft graviton. While the effect remains unobservable within the domain of a single observer where the symmetry is unbroken, this change is physical when comparing different asymptotic observers, or between a transformed and un-transformed initial state, consistent with the scale-dependent statistical anisotropies previously derived using semiclassical relations. We then compute the overlap, (0| 0'), between the unperturbed de Sitter vacuum |0), and the state | 0') obtained by acting N times with the charge. We show that when N→ M {sub p} {sup 2}/ H {sup 2} this overlap receives order one corrections and 0(0| 0')→ , which corresponds to an infrared perturbative breakdown after a time t {sub dS} ∼ M {sub p} {sup 2}/ H {sup 3} has elapsed, consistent with earlier arguments in the literature arguing for a perturbative breakdown on this timescale. We also discuss the generalization to inflation, and rederive the 3-point and one-loop consistency relations.
Spontaneously broken continuous symmetries in hyperbolic (or open) de Sitter spacetime
International Nuclear Information System (INIS)
Ratra, B.
1994-01-01
The functional Schroedinger approach is used to study scalar field theory in hyperbolic (or open) de Sitter spacetime. While on intermediate length scales (small compared to the spatial curvature length scale) the massless minimally coupled scalar field two-point correlation function does have a term that varies logarithmically with scale, as in flat and closed de Sitter spacetime, the spatial curvature tames the infrared behavior of this correlation function at larger scales in the open model. As a result, and contrary to what happens in flat and closed de Sitter spacetime, spontaneously broken continuous symmetries are not restored in open de Sitter spacetime (with more than one spatial dimension)
arXiv On classical de Sitter and Minkowski solutions with intersecting branes
Andriot, David
2018-03-09
Motivated by the connection of string theory to cosmology or particle physics, we study solutions of type II supergravities having a four-dimensional de Sitter or Minkowski space-time, with intersecting D$_{p}$ -branes and orientifold O$_{p}$ -planes. Only few such solutions are known, and we aim at a better characterisation. Modulo a few restrictions, we prove that there exists no classical de Sitter solution for any combination of D$_{3}$/O$_{3}$ and D$_{7}$/O$_{7}$, while we derive interesting constraints for intersecting D$_{5}$/O$_{5}$ or D$_{6}$/O$_{6}$, or combinations of D$_{4}$/O$_{4}$ and D$_{8}$/O$_{8}$. Concerning classical Minkowski solutions, we understand some typical features, and propose a solution ansatz. Overall, a central information appears to be the way intersecting D$_{p}$ /O$_{p}$ overlap each other, a point we focus on.
Inflation including collapse of the wave function: the quasi-de Sitter case
Energy Technology Data Exchange (ETDEWEB)
Leon, Gabriel [Universidad de Buenos Aires, Ciudad Universitaria-PabI, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina); Landau, Susana J. [Universidad de Buenos Aires y IFIBA, CONICET, Ciudad Universitaria-PabI, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina); Piccirilli, Maria Pia [Universidad Nacional de La Plata, Grupo de Astrofisica, Relatividad y Cosmologia, Facultad de Ciencias Astronomicas y Geofisicas, Pcia de Buenos Aires (Argentina)
2015-08-15
The precise physical mechanism describing the emergence of the seeds of cosmic structure from a perfect isotropic and homogeneous universe has not been fully explained by the standard version of inflationary models. To handle this shortcoming, D. Sudarsky and collaborators have developed a proposal: the self-induced collapse hypothesis. In this scheme, the objective collapse of the inflaton wave function is responsible for the emergence of inhomogeneity and anisotropy at all scales. In previous papers, the proposal was developed with an almost exact de Sitter space-time approximation for the background that led to a perfect scale-invariant power spectrum. In the present article, we consider a full quasi-de Sitter expansion and calculate the primordial power spectrum for three different choices of the self-induced collapse. The consideration of a quasi-de Sitter background allows us to distinguish departures from an exact scale-invariant power spectrum that are due to the inclusion of the collapse hypothesis. These deviations are also different from the prediction of standard inflationary models with a running spectral index. A comparison with the primordial power spectrum and the CMB temperature fluctuation spectrum preferred by the latest observational data is also discussed. From the analysis performed in this work, it follows that most of the collapse schemes analyzed in this paper are viable candidates to explain the present observations of the CMB fluctuation spectrum. (orig.)
Inflation including collapse of the wave function: the quasi-de Sitter case
International Nuclear Information System (INIS)
Leon, Gabriel; Landau, Susana J.; Piccirilli, Maria Pia
2015-01-01
The precise physical mechanism describing the emergence of the seeds of cosmic structure from a perfect isotropic and homogeneous universe has not been fully explained by the standard version of inflationary models. To handle this shortcoming, D. Sudarsky and collaborators have developed a proposal: the self-induced collapse hypothesis. In this scheme, the objective collapse of the inflaton wave function is responsible for the emergence of inhomogeneity and anisotropy at all scales. In previous papers, the proposal was developed with an almost exact de Sitter space-time approximation for the background that led to a perfect scale-invariant power spectrum. In the present article, we consider a full quasi-de Sitter expansion and calculate the primordial power spectrum for three different choices of the self-induced collapse. The consideration of a quasi-de Sitter background allows us to distinguish departures from an exact scale-invariant power spectrum that are due to the inclusion of the collapse hypothesis. These deviations are also different from the prediction of standard inflationary models with a running spectral index. A comparison with the primordial power spectrum and the CMB temperature fluctuation spectrum preferred by the latest observational data is also discussed. From the analysis performed in this work, it follows that most of the collapse schemes analyzed in this paper are viable candidates to explain the present observations of the CMB fluctuation spectrum. (orig.)
High energy physics signatures from inflation and conformal symmetry of de Sitter
International Nuclear Information System (INIS)
Kehagias, A.; Riotto, A.
2015-01-01
During inflation, the geometry of spacetime is described by a (quasi-)de Sitter phase. Inflationary observables are determined by the underlying (softly broken) de Sitter isometry group SO(1, 4) which acts like a conformal group on R 3 : when the fluctuations are on super-Hubble scales, the correlators of the scalar fields are constrained by conformal invariance. Heavy fields with mass m larger than the Hubble rate H correspond to operators with imaginary dimensions in the dual Euclidean three-dimensional conformal field theory. By making use of the dS/CFT correspondence we show that, besides the Boltzmann suppression expected from the thermal properties of de Sitter space, the generic effect of heavy fields in the inflationary correlators of the light fields is to introduce power-law suppressed corrections of the form O(H 2 / m 2 ). This can be seen, for instance, at the level of the four-point correlator for which we provide the correction due to a massive scalar field exchange. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Achterbergh, J.M.I.M.; Vriens, D.J.
2011-01-01
- Purpose – The purpose of this paper is to show how the viable system model (VSM) and de Sitter's design theory can complement each other in the context of the diagnosis and design of viable organizations. - Design/methodology/approach – Key concepts from Beer's model and de Sitter's design theory
Gravitational radiation reaction in the NUT-de Sitter spacetime
International Nuclear Information System (INIS)
Ahmed, M.
1988-07-01
The equations for gravitational perturbation in the NUT-de Sitter spacetime are obtained. Using these equations, some preliminary calculations have been made with a view to constructing the retarded Green functions. Then with the help of the retarded Green functions, the radiative Green functions have been constructed. With the aid of these radiative Green functions, the reaction force on a particle is computed and this reaction force is then shown to account correctly for the energy and the angular momentum carried away by gravitational radiation to infinity and to the horizon. (author). 9 refs
The deflationary universe: An instability of the de Sitter universe
International Nuclear Information System (INIS)
Barrow, J.D.
1986-01-01
The relevance is discussed of the initial value structure of the cosmological problem for inflationary explanations of its present structure. Existing proofs of the cosmic ''no hair'' conjecture are found to make use of an unrealistic strong energy condition on the stress tensor of the matter fields not driving the inflation. It is shown by explicit example that the no hair conjecture fails even in isotropic cosmological models if the strong energy condition is relaxed. A class of exact cosmological models are given which begin in a de Sitter state but subsequently deflate towards the flat Friedman model. Various implications of these examples are discussed. (orig.)
On de Sitter-like and Minkowski-like spacetimes
International Nuclear Information System (INIS)
Luebbe, Christian; Kroon, Juan Antonio Valiente
2009-01-01
Friedrich's proofs for the global existence results of de Sitter-like spacetimes and of semi-global existence of Minkowski-like spacetimes (Friedrich 1986 Commun. Math. Phys. 107 587) are re-examined and discussed, making use of the extended conformal field equations and a gauge based on conformal geodesics. In this gauge, the location of the conformal boundary of the spacetimes is known a priori once the initial data have been prescribed. Thus, it provides an analysis which is conceptually and calculationally simpler.
Schwinger mechanism in electromagnetic field in de Sitter spacetime
Directory of Open Access Journals (Sweden)
Bavarsad Ehsan
2018-01-01
Full Text Available We investigate Schwinger scalar pair production in a constant electromagnetic field in de Sitter (dS spacetime. We obtain the pair production rate, which agrees with the Hawking radiation in the limit of zero electric field in dS. The result describes how a cosmic magnetic field affects the pair production rate. In addition, using a numerical method we study the effect of the magnetic field on the induced current. We find that in the strong electromagnetic field the current has a linear response to the electric and magnetic fields, while in the infrared regime, is inversely proportional to the electric field and leads to infrared hyperconductivity.
Is the Einstein de Sitter model actually ruled out?
International Nuclear Information System (INIS)
Blanchard, A.
2003-01-01
The standard model for cosmology which is now strongly favored is a flat model, dominated by a vacuum density term. However, the actual direct evidences for such term are limited, essentially based on the supernova probe, i.e. based on a standard candle hypothesis. Here I would like to point out that contrary to the general belief there is room for an Einstein de Sitter universe. Actually several independent measurements, not based on stellar reference, pointed towards a high matter density Universe, weakening the need for a cosmological constant
Exact Solution of Klein-Gordon and Dirac Equations with Snyder-de Sitter Algebra
Merad, M.; Hadj Moussa, M.
2018-01-01
In this paper, we present the exact solution of the (1+1)-dimensional relativistic Klein-Gordon and Dirac equations with linear vector and scalar potentials in the framework of deformed Snyder-de Sitter model. We introduce some changes of variables, we show that a one-dimensional linear potential for the relativistic system in a space deformed can be equivalent to the trigonometric Rosen-Morse potential in a regular space. In both cases, we determine explicitly the energy eigenvalues and their corresponding eigenfunctions expressed in terms of Romonovski polynomials. The limiting cases are analyzed for α 1 and α 2 → 0 and are compared with those of literature.
Quasinormal modes of Kerr-de Sitter black holes
International Nuclear Information System (INIS)
Yoshida, Shijun; Uchikata, Nami; Futamase, Toshifumi
2010-01-01
We calculate the fundamental quasinormal modes of the Kerr-de Sitter black hole for the first time. In order to calculate the quasinormal modes, we employ the master equations derived by Suzuki, Takasugi, and Umetsu, who transform the Teukolsky equations for the Kerr-de Sitter black hole into the standard form of the Heun's equation. The transformed functions are expanded around the outer horizon of the black hole or the symmetric axis in the Froebenius series whose coefficients satisfy a three-term recurrence relation. These three-term recurrence relations allow us to use Leaver's continued fraction method to calculate the angular separation constant and the quasinormal mode frequency. Any unstable fundamental quasinormal mode is not found in this paper. It is also observed that for some black holes characterized by a large mass parameter, some retrograde modes in the slow rotation limit become prograde as the black hole spin increases. This phenomenon does not occur for the fundamental modes of the Kerr black hole.
De Sitter vacua from heterotic M-theory
International Nuclear Information System (INIS)
Becker, Melanie; Curio, Gottfried; Krause, Axel
2004-01-01
It is shown how metastable de Sitter vacua might arise from heterotic M-theory. The balancing of its two non-perturbative effects, open membrane instantons against gaugino condensation on the hidden boundary, which act with opposing forces on the interval length, is used to stabilize the orbifold modulus (dilaton) and other moduli. The non-perturbative effects break supersymmetry spontaneously through F-terms which leads to a positive vacuum energy density. In contrast to the situation for the weakly coupled heterotic string, the charged scalar matter fields receive non-vanishing vacuum expectation values and therefore masses in a phenomenologically relevant regime. It is important that in order to obtain these de Sitter vacua we are not relying on exotic effects or fine-tuning of parameters. Vacua with more realistic supersymmetry breaking scales and gravitino masses are obtained by breaking the hidden E 8 gauge group down to groups of smaller rank. Also small values for the open membrane instanton Pfaffian are favored in this respect. Finally we outline how the incorporation of additional flux superpotentials can be used to stabilize the remaining moduli
A note on entropy of de Sitter black holes
Energy Technology Data Exchange (ETDEWEB)
Bhattacharya, Sourav [University of Crete, ITCP and Department of Physics, Heraklion (Greece); Inter-University Centre for Astronomy and Astrophysics (IUCAA), Pune (India)
2016-03-15
A de Sitter black hole or a black hole spacetime endowed with a positive cosmological constant has two Killing horizons - a black hole and a cosmological event horizon surrounding it. It is natural to expect that the total Bekenstein-Hawking entropy of such spacetimes should be the sum of the two horizons' areas. In this work we apply the recently developed formalism using the Gibbons-Hawking-York boundary term and the near horizon symmetries to derive the total entropy of such two horizon spacetimes. We construct a suitable general geometric set up for general stationary axisymmetric spacetimes with two or more than two commuting Killing vector fields in an arbitrary spacetime dimensions. This framework helps us to deal with both horizons on an equal footing. We show that in order to obtain the total entropy of such spacetimes, the near horizon mode functions for the diffeomorphism generating vector fields have to be restricted in a certain manner, compared to the single horizon spacetimes. We next discuss specific known exact solutions belonging to the Kerr-Newman or the Plebanski-Demianski-de Sitter families to show that they fall into the category of our general framework. We end with a sketch of further possible extensions of this work. (orig.)
De Sitter en Einstein. ‘Het lijkt mij dat Einstein hier een vergissing begaan heeft’
Directory of Open Access Journals (Sweden)
Jan Guichelaar
2016-10-01
Full Text Available De Sitter and EinsteinWillem de Sitter’s interest in gravity was based on his work on celestial mechanics, in particular on the four big moons of Jupiter. His work on cosmology was based on the general theory of relativity of Albert Einstein. De Sitter published in 1917, on request of Arthur Eddington to inform the English astronomers, a series of four articles in The Observatory and the Monthly Notices of the Royal Astronomical Society. Einstein developed his own cosmological models, containing mass. De Sitter found a different solution and described a universe without mass. Einstein could not accept De Sitter’s model and they ‘fought out’ two controversies in their correspondence. In theend Einstein had to confess De Sitter was mainly right in his criticisms. In 1932 Einstein and De Sitter published an article on a new model, the so-called Einstein-De Sitter Model of the universe. So, De Sitter was able to do fundamental work in classical celestial mechanics as well as in the new cosmological theories.
Relativistic thick discs in the Kerr-de Sitter backgrounds
International Nuclear Information System (INIS)
Slany, Petr; StuchlIk, Zdenek
2005-01-01
Perfect fluid tori with a uniform distribution of the specific angular momentum, l(r, θ) = const, orbiting the Kerr-de Sitter black holes or naked singularities are studied. It is well known that the structure of equipotential surfaces of such marginally stable tori reflects the basic properties of any tori with a general distribution of the specific angular momentum. Closed equipotential surfaces corresponding to stationary thick discs are allowed only in the spacetimes admitting stable circular geodesics. The last closed surface crosses itself in the cusp(s) enabling the outflow of matter from the torus due to the violation of hydrostatic equilibrium. The inner cusp enables an accretion onto the central object. The influence of the repulsive cosmological constant, Λ > 0, on the equipotential surfaces lies in the existence of the outer cusp (with a stabilizing effect on the thick discs) and in the strong collimation of open equipotential surfaces along the rotational axis. Both the effects take place near a so-called static radius where the gravitational attraction is just balanced by the cosmic repulsion. The outer cusp enables excretion, i.e., the outflow of matter from the torus into the outer space. The plus-family discs (which are always co-rotating in the black-hole backgrounds but can be counter-rotating, even with negative energy of the fluid elements, in some naked-singularity backgrounds) are thicker and more extended than the minus-family ones (which are always counter-rotating in all backgrounds). For co-rotating discs in the naked-singularity spacetimes, the potential well between the centre of the disc and its edges at the cusps is usually much higher than in the black-hole spacetimes. If the parameters of naked-singularity spacetimes are very close to the parameters of extreme black-hole spacetimes, the family of possible disc-like configurations includes members with two isolated discs where the inner one is always a counter-rotating accretion
Entropy of Reissner–Nordström–de Sitter black hole
Energy Technology Data Exchange (ETDEWEB)
Zhang, Li-Chun [Department of Physics, Shanxi Datong University, Datong 037009 (China); Institute of Theoretical Physics, Shanxi Datong University, Datong 037009 (China); Zhao, Ren [Institute of Theoretical Physics, Shanxi Datong University, Datong 037009 (China); Ma, Meng-Sen, E-mail: mengsenma@gmail.com [Department of Physics, Shanxi Datong University, Datong 037009 (China); Institute of Theoretical Physics, Shanxi Datong University, Datong 037009 (China)
2016-10-10
Based on the consideration that the black hole horizon and the cosmological horizon of Reissner–Nordström black hole in de Sitter space are not independent each other, we conjecture the total entropy of the system should have an extra term contributed from the entanglement between the two horizons, except for the sum of the two horizon entropies. Making use of the globally effective first law and the effective thermodynamic quantities, we derive the total entropy and find that it will diverge as the two horizons tend to coincide.
Energy, momentum and angular momentum conservations in de Sitter gravity
International Nuclear Information System (INIS)
Lu, Jia-An
2016-01-01
In de Sitter (dS) gravity, where gravity is a gauge field introduced to realize the local dS invariance of the matter field, two kinds of conservation laws are derived. The first kind is a differential equation for a dS-covariant current, which unites the canonical energy-momentum (EM) and angular momentum (AM) tensors. The second kind presents a dS-invariant current which is conserved in the sense that its torsion-free divergence vanishes. The dS-invariant current unites the total (matter plus gravity) EM and AM currents. It is well known that the AM current contains an inherent part, called the spin current. Here it is shown that the EM tensor also contains an inherent part, which might be observed by its contribution to the deviation of the dust particle’s world line from a geodesic. All the results are compared to the ordinary Lorentz gravity. (paper)
Quantum statistical entropy for Kerr-de Sitter black hole
Institute of Scientific and Technical Information of China (English)
Zhang Li-Chun; Wu Yue-Qin; Zhao Ren
2004-01-01
Improving the membrane model by which the entropy of the black hole is studied, we study the entropy of the black hole in the non-thermal equilibrium state. To give the problem stated here widespread meaning, we discuss the (n+2)-dimensional de Sitter spacetime. Through discussion, we obtain that the black hole's entropy which contains two horizons (a black hole's horizon and a cosmological horizon) in the non-thermal equilibrium state comprises the entropy corresponding to the black hole's horizon and the entropy corresponding to the cosmological horizon. Furthermore, the entropy of the black hole is a natural property of the black hole. The entropy is irrelevant to the radiation field out of the horizon. This deepens the understanding of the relationship between black hole's entropy and horizon's area. A way to study the bosonic and fermionic entropy of the black hole in high non-thermal equilibrium spacetime is given.
Thermodynamics of de Sitter black holes: Thermal cosmological constant
International Nuclear Information System (INIS)
Sekiwa, Y.
2006-01-01
We study the thermodynamic properties associated with the black hole event horizon and the cosmological horizon for black hole solutions in asymptotically de Sitter spacetimes. We examine thermodynamics of these horizons on the basis of the conserved charges according to Teitelboim's method. In particular, we have succeeded in deriving the generalized Smarr formula among thermodynamical quantities in a simple and natural way. We then show that cosmological constant must decrease when one takes into account the quantum effect. These observations have been obtained if and only if the cosmological constant plays the role of a thermodynamical state variable. We also touch upon the relation between inflation of our universe and a phase transition of black holes
International Nuclear Information System (INIS)
Stuchlik, Zdenek; Hledik, Stanislav; Soltes, Jiri; Ostgaard, Erlend
2001-01-01
Null geodesics and embedding diagrams of central planes in the ordinary space geometry and the optical reference geometry of the interior Schwarzschild--de Sitter spacetimes with uniform density are studied. For completeness, both positive and negative values of the cosmological constant are considered. The null geodesics are restricted to the central planes of these spacetimes, and their properties can be reflected by an 'effective potential.' If the interior spacetime is extremely compact, the effective potential has a local maximum corresponding to a stable circular null geodesic around which bound null geodesics are concentrated. The upper limit on the size of the interior spacetimes containing bound null geodesics is R=3M, independently of the value of the cosmological constant. The embedding diagrams of the central planes of the ordinary geometry into three-dimensional Euclidean space are well defined for the complete interior of all spacetimes with a repulsive cosmological constant, but the planes cannot be embedded into the Euclidean space in the case of spacetimes with subcritical values of an attractive cosmological constant. On the other hand, the embedding diagrams of the optical geometry are well defined for all of the spacetimes, and the turning points of these diagrams correspond to the radii of the circular null geodesics. All the embedding diagrams, for both the ordinary and optical geometry, are smoothly matched to the corresponding embedding diagrams of the external vacuum Schwarzschild--de Sitter spacetimes
Holographic dual of de Sitter universe with AdS bubbles
International Nuclear Information System (INIS)
Kanno, Sugumi; Sasaki, Misao; Soda, Jiro
2012-01-01
We study the proposal that a de Sitter (dS) universe with an Anti-de Sitter (AdS) bubble can be replaced by a dS universe with a boundary CFT. To explore this duality, we consider incident gravitons coming from the dS universe through the bubble wall into the AdS bubble in the original picture. In the dual picture, this process has to be identified with the absorption of gravitons by CFT matter. We have obtained a general formula for the absorption probability in general d+1 spacetime dimensions. The result shows the different behavior depending on whether spacetime dimensions are even or odd. We find that the absorption process of gravitons from the dS universe by CFT matter is controlled by localized gravitons (massive bound state modes in the Kaluza-Klein decomposition) in the dS universe. The absorption probability is determined by the effective degrees of freedom of the CFT matter and the effective gravitational coupling constant which encodes information of localized gravitons. We speculate that the dual of (d+1)-dimensional dS universe with an AdS bubble is also dual to a d-dimensional dS universe with CFT matter.
Dynamics of quantum entanglement in de Sitter spacetime and thermal Minkowski spacetime
Directory of Open Access Journals (Sweden)
Zhiming Huang
2017-10-01
Full Text Available We investigate the dynamics of entanglement between two atoms in de Sitter spacetime and in thermal Minkowski spacetime. We treat the two-atom system as an open quantum system which is coupled to a conformally coupled massless scalar field in the de Sitter invariant vacuum or to a thermal bath in the Minkowski spacetime, and derive the master equation that governs its evolution. We compare the phenomena of entanglement creation, degradation, revival and enhancement for the de Sitter spacetime case with that for the thermal Minkowski spacetime case. We find that the entanglement dynamics of two atoms for these two spacetime cases behave quite differently. In particular, the two atoms interacting with the field in the thermal Minkowski spacetime (with the field in the de Sitter-invariant vacuum, under certain conditions, could be entangled, while they would not become entangled in the corresponding de Sitter case (in the corresponding thermal Minkowski case. Thus, although a single static atom in the de Sitter-invariant vacuum responds as if it were bathed in thermal radiation in a Minkowski universe, with the help of the different dynamic evolution behaviors of entanglement for two atoms one can in principle distinguish these two universes.
Entangled de Sitter from stringy axionic Bell pair I. An analysis using Bunch-Davies vacuum
International Nuclear Information System (INIS)
Choudhury, Sayantan; Panda, Sudhakar
2018-01-01
In this work, we study the quantum entanglement and compute entanglement entropy in de Sitter space for a bipartite quantum field theory driven by an axion originating from Type IIB string compactification on a Calabi-Yau three fold (CY 3 ) and in the presence of an NS5 brane. For this computation, we consider a spherical surface S 2 , which divides the spatial slice of de Sitter (dS 4 ) into exterior and interior sub-regions. We also consider the initial choice of vacuum to be Bunch-Davies state. First we derive the solution of the wave function of the axion in a hyperbolic open chart by constructing a suitable basis for Bunch-Davies vacuum state using Bogoliubov transformation. We then derive the expression for density matrix by tracing over the exterior region. This allows us to compute the entanglement entropy and Renyi entropy in 3 + 1 dimension. Furthermore, we quantify the UV-finite contribution of the entanglement entropy which contain the physics of long range quantum correlations of our expanding universe. Finally, our analysis complements the necessary condition for generating non-vanishing entanglement entropy in primordial cosmology due to the axion. (orig.)
Entangled de Sitter from stringy axionic Bell pair I. An analysis using Bunch-Davies vacuum
Energy Technology Data Exchange (ETDEWEB)
Choudhury, Sayantan [Inter-University Centre for Astronomy and Astrophysics, Pune (India); Tata Institute of Fundamental Research, Department of Theoretical Physics, Mumbai (India); Panda, Sudhakar [Institute of Physics, Bhubaneswar, Odisha (India); National Institute of Science Education and Research, Bhubaneswar, Odisha (India); Homi Bhabha National Institute, Mumbai (India)
2018-01-15
In this work, we study the quantum entanglement and compute entanglement entropy in de Sitter space for a bipartite quantum field theory driven by an axion originating from Type IIB string compactification on a Calabi-Yau three fold (CY{sup 3}) and in the presence of an NS5 brane. For this computation, we consider a spherical surface S{sup 2}, which divides the spatial slice of de Sitter (dS{sub 4}) into exterior and interior sub-regions. We also consider the initial choice of vacuum to be Bunch-Davies state. First we derive the solution of the wave function of the axion in a hyperbolic open chart by constructing a suitable basis for Bunch-Davies vacuum state using Bogoliubov transformation. We then derive the expression for density matrix by tracing over the exterior region. This allows us to compute the entanglement entropy and Renyi entropy in 3 + 1 dimension. Furthermore, we quantify the UV-finite contribution of the entanglement entropy which contain the physics of long range quantum correlations of our expanding universe. Finally, our analysis complements the necessary condition for generating non-vanishing entanglement entropy in primordial cosmology due to the axion. (orig.)
Euclidean action for vacuum decay in a de Sitter universe
International Nuclear Information System (INIS)
Balek, V.; Demetrian, M.
2005-01-01
The behavior of the action of the instantons describing vacuum decay in a de Sitter is investigated. For a near-to-limit instanton (a Coleman-de Luccia instanton close to some Hawking-Moss instanton) we find approximate formulas for the Euclidean action by expanding the scalar field and the metric of the instanton in the powers of the scalar field amplitude. The order of the magnitude of the correction to the Hawking-Moss action depends on the order of the instanton (the number of crossings of the barrier by the scalar field): for instantons of odd and even orders the correction is of the fourth and third order in the scalar field amplitude, respectively. If a near-to-limit instanton of the first order exists in a potential with the curvature at the top of the barrier greater than 4x(Hubble constant) 2 , which is the case if the fourth derivative of the potential at the top of the barrier is greater than some negative limit value, the action of the instanton is less than the Hawking-Moss action and, consequently, the instanton determines the outcome of the vacuum decay if no other Coleman-de Luccia instanton is admitted by the potential. A numerical study shows that for the quartic potential the physical mode of the vacuum decay is given by the Coleman-de Luccia instanton of the first order also in the region of parameters in which the potential admits two instantons of the second order
Photon motion in Kerr-de Sitter spacetimes
Energy Technology Data Exchange (ETDEWEB)
Charbulak, Daniel; Stuchlik, Zdenek [Silesian University in Opava, Institute of Physics and Research Centre of Theoretical Physics and Astrophysics, Faculty of Philosophy and Science, Opava (Czech Republic)
2017-12-15
We study the general motion of photons in the Kerr-de Sitter black-hole and naked singularity spacetimes. The motion is governed by the impact parameters X, related to the axial symmetry of the spacetime, and q, related to its hidden symmetry. Appropriate 'effective potentials' governing the latitudinal and radial motion are introduced and their behavior is examined by the 'Chinese boxes' technique giving regions allowed for the motion in terms of the impact parameters. Restrictions on the impact parameters X and q are established in dependence on the spacetime parameters M, Λ, a. The motion can be of orbital type (crossing the equatorial plane, q > 0) and vortical type (tied above or below the equatorial plane, q < 0). It is shown that for negative values of q, the reality conditions imposed on the latitudinal motion yield stronger constraints on the parameter X than that following from the reality condition of the radial motion, excluding the existence of vortical motion of constant radius. The properties of the spherical photon orbits of the orbital type are determined and used along with the properties of the effective potentials as criteria of classification of the KdS spacetimes according to the properties of the motion of the photon. (orig.)
Effective long wavelength scalar dynamics in de Sitter
Energy Technology Data Exchange (ETDEWEB)
Moss, Ian; Rigopoulos, Gerasimos, E-mail: ian.moss@newcastle.ac.uk, E-mail: gerasimos.rigopoulos@ncl.ac.uk [School of Mathematics and Statistics, Newcastle University, Herschel Building, Newcastle upon Tyne, NE1 7RU U.K. (United Kingdom)
2017-05-01
We discuss the effective infrared theory governing a light scalar's long wavelength dynamics in de Sitter spacetime. We show how the separation of scales around the physical curvature radius k / a ∼ H can be performed consistently with a window function and how short wavelengths can be integrated out in the Schwinger-Keldysh path integral formalism. At leading order, and for time scales Δ t >> H {sup −1}, this results in the well-known Starobinsky stochastic evolution. However, our approach allows for the computation of quantum UV corrections, generating an effective potential on which the stochastic dynamics takes place. The long wavelength stochastic dynamical equations are now second order in time, incorporating temporal scales Δ t ∼ H {sup −1} and resulting in a Kramers equation for the probability distribution—more precisely the Wigner function—in contrast to the more usual Fokker-Planck equation. This feature allows us to non-perturbatively evaluate, within the stochastic formalism, not only expectation values of field correlators, but also the stress-energy tensor of φ.
International Nuclear Information System (INIS)
Chu, Yi-Zen
2014-01-01
Motivated by the desire to understand the causal structure of physical signals produced in curved spacetimes – particularly around black holes – we show how, for certain classes of geometries, one might obtain its retarded or advanced minimally coupled massless scalar Green's function by using the corresponding Green's functions in the higher dimensional Minkowski spacetime where it is embedded. Analogous statements hold for certain classes of curved Riemannian spaces, with positive definite metrics, which may be embedded in higher dimensional Euclidean spaces. The general formula is applied to (d ≥ 2)-dimensional de Sitter spacetime, and the scalar Green's function is demonstrated to be sourced by a line emanating infinitesimally close to the origin of the ambient (d + 1)-dimensional Minkowski spacetime and piercing orthogonally through the de Sitter hyperboloids of all finite sizes. This method does not require solving the de Sitter wave equation directly. Only the zero mode solution to an ordinary differential equation, the “wave equation” perpendicular to the hyperboloid – followed by a one-dimensional integral – needs to be evaluated. A topological obstruction to the general construction is also discussed by utilizing it to derive a generalized Green's function of the Laplacian on the (d ≥ 2)-dimensional sphere
Gauge formulation of gravitation theories. I. The Poincare, de Sitter, and conformal cases
International Nuclear Information System (INIS)
Ivanov, E.A.; Niederle, J.
1982-01-01
The gauge formulations of various gravitation theories are discussed. They are based on the approach in which we have the group Diff R 4 acting on x/sup μ/ and in which we attach to every x/sup μ/ a tangent space with the group of action H. Group H does not act on x/sup μ/ and plays the role of an internal (global) symmetry group in the standard Yang-Mills theory. The matter fields in the theory transform according to representations of H and are assumed to be scalars of Diff R 4 . The full invariance group of the Lagrangian is then of the form H/sup loc/xDiff R 4 . Here H/sup loc/ is a local gauge group obtained from H exactly as in the Yang-Mills theory. The approach has two characteristic features: (i) The group H/sup loc/ must be spontaneously broken in order to exclude redundant gauge fields (the Lorentz connections) from the theory in a way covariant with respect to the gauge transformations. (ii) To different H there correspond different gravitational theories, all invariant under Diff R 4 but differing in backgrounds. Thus if H is isomorphic to the Poincare group the corresponding gauge theory turns out to be equivalent to the usual Einstein or Einstein-Cartan theory of gravity in the Minkowski space as a background. The other choices for H considered in the paper are the de Sitter groups and the conformal group. They yield the Einstein theory with a negative (or positive) cosmological term in the corresponding de Sitter space and the Weyl or Cartan-Weyl theory (depending on realization of the conformal group), respectively
Pair of accelerated black holes in a de Sitter background: The dS C metric
International Nuclear Information System (INIS)
Dias, Oscar J.C.; Lemos, Jose P.S.
2003-01-01
Following the work of Kinnersley and Walker for flat spacetimes, we analyzed the anti-de Sitter C metric in a previous paper. In this paper we study the de Sitter C metric (dS C metric). The C metric with a generic cosmological constant and other extra parameters was introduced by Plebanski and Demianski. When one then sets to zero some of the extra parameters, and works with a positive cosmological constant, one has the dS C metric which has been analyzed and physically interpreted by Podolsky and Griffiths. It describes a pair of accelerated black holes in the dS background with the acceleration being provided (in addition to the cosmological constant) by a strut that pushes away the two black holes or, alternatively, by a string that pulls them. We extend their analysis mainly in four directions. First, we draw the Carter-Penrose diagrams of the massless uncharged dS C metric, of the massive uncharged dS C metric and of the massive charged dS C metric. These diagrams allow us to clearly identify the presence of two dS black holes and to conclude that they cannot interact gravitationally. Second, we reexamine the embedding of the dS C metric in the 5D Minkowski spacetime and we represent the motion of the dS C metric origin in the dS 4-hyperboloid as well as the localization of the strut. Third, we comment on the physical properties of the strut that connects the two black holes. Finally, we find the range of parameters that correspond to nonextreme black holes, extreme black holes, and naked particles
Pair creation of higher dimensional black holes on a de Sitter background
International Nuclear Information System (INIS)
Dias, Oscar J.C.; Lemos, Jose P.S.
2004-01-01
We study in detail the quantum process in which a pair of black holes is created in a higher D-dimensional de Sitter (dS) background. The energy to materialize and accelerate the pair comes from the positive cosmological constant. The instantons that describe the process are obtained from the Tangherlini black hole solutions. Our pair creation rates reduce to the pair creation rate for Reissner-Nordstroem-dS solutions when D=4. Pair creation of black holes in the dS background becomes less suppressed when the dimension of the spacetime increases. The dS space is the only background in which we can discuss analytically the pair creation process of higher dimensional black holes, since the C-metric and the Ernst solutions, which describe, respectively, a pair accelerated by a string and by an electromagnetic field, are not known yet in a higher dimensional spacetime
Non-minimal Particle Creation from Asymptotic-de Sitter Inflation
Yusofi, E.; Mohsenzadeh, M.
2018-06-01
A general form of quasi-de Sitter(dS) modes is used to study the creation of particle during the inflation. Actually, by considering the general form of inflaton field equation as a function of the Hankel function index and by using the Planck 2015 constraint on spectral index, we obtain the possible new constraints for the values of coupling constant in the era with asymptotic-dS space-time. Then, we explicitly calculate the general form of expectation value of the created particles in terms of the Hankel function index and the conformal time. The correction terms in the number of created particles are very tiny in the early time but can have the significant effects in the later universe. Our result is general and at the early time limit confirm the conventional special results for the Minkowski and dS background.
The structure of perturbative quantum gravity on a de Sitter background
International Nuclear Information System (INIS)
Tsamis, N.C.; Woodward, R.P.
1992-05-01
Classical gravitation on de Sitter space suffers from a linearization instability. One consequence is that the response to a spatially localized distribution of positive energy cannot be globally regular. We use this fact to show that no causal Green's function can give the correct linearized response to certain bilocalized distributions, even though these distributions obey the constraints of linearization stability. We avoid the problem by working on the open submanifold spanned by conformal coordinates. The retarded Green's function is first computed in a simple gauge, then the rest of the propagator is inferred by analyticity -- up to the usual ambiguity about real, analytic and homogeneous terms. We show that the latter can be chosen so as to give a propagator which does not grow in any direction. The ghost propagator is also given and the interaction vertices are worked out
Kaluza–Klein-type models of de Sitter and Poincaré gauge theories of gravity
International Nuclear Information System (INIS)
Lu Jiaan; Huang Chaoguang
2013-01-01
We construct Kaluza–Klein-type models with a de Sitter or Minkowski bundle in the de Sitter or Poincaré gauge theory of gravity, respectively. A manifestly gauge-invariant formalism has been given. The gravitational dynamics is constructed by the geometry of the de Sitter or Minkowski bundle and a global section which plays an important role in the gauge-invariant formalism. Unlike the old Kaluza–Klein-type models of gauge theory of gravity, a suitable cosmological term can be obtained in the Lagrangian of our models and the models in the spin-current-free and torsion-free limit will come back to general relativity with a corresponding cosmological term. We also generalize the results to the case with a variable cosmological term. (paper)
Large-Scale Corrections to the CMB Anisotropy from Asymptotic de Sitter Mode
Sojasi, A.
2018-01-01
In this study, large-scale effects from asymptotic de Sitter mode on the CMB anisotropy are investigated. Besides the slow variation of the Hubble parameter onset of the last stage of inflation, the recent observational constraints from Planck and WMAP on spectral index confirm that the geometry of the universe can not be pure de Sitter in this era. Motivated by these evidences, we use this mode to calculate the power spectrum of the CMB anisotropy on the large scale. It is found that the CMB spectrum is dependent on the index of Hankel function ν which in the de Sitter limit ν → 3/2, the power spectrum reduces to the scale invariant result. Also, the result shows that the spectrum of anisotropy is dependent on angular scale and slow-roll parameter and these additional corrections are swept away by a cutoff scale parameter H ≪ M ∗ < M P .
On the de Sitter and Nariai spacetimes in a generalized theory of gravitation
International Nuclear Information System (INIS)
Nariai, Hidekazu.
1985-07-01
A possibility of obtaining the de Sitter and Nariai spacetimes in a generalized theory of gravitation (which was in succession proposed by Utiyama-DeWitt, Parker-Fulling-Hu and Gurovich-Starobinski) is examined. It is shown that the generalized theory with a suitable fixation of three parameters admit both spacetimes, just like the general theory of relativity. (author)
On inflation and de Sitter in non-geometric string backgrounds
Energy Technology Data Exchange (ETDEWEB)
Hassler, Falk; Massai, Stefano [Arnold-Sommerfeld-Center for Theoretical Physics, Fakultaet fuer Physik, Ludwig-Maximilians-Universitaet Muenchen (Germany); Luest, Dieter [Arnold-Sommerfeld-Center for Theoretical Physics, Fakultaet fuer Physik, Ludwig-Maximilians-Universitaet Muenchen (Germany); Max-Planck-Institut fuer Physik, Muenchen (Germany)
2017-10-15
We study the problem of obtaining de Sitter and inflationary vacua from dimensional reduction of double field theory (DFT) on nongeometric string backgrounds. In this context, we consider a new class of effective potentials that admit Minkowski and de Sitter minima. We then construct a simple model of chaotic inflation arising from T-fold backgrounds and we discuss the possibility of trans-Planckian field range from nongeometric monodromies as well as the conditions required to get slow roll. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Dirac equation in a de Sitter expansion for massive neutrinos from modern Kaluza-Klein theory
International Nuclear Information System (INIS)
Sánchez, Pablo Alejandro; Anabitarte, Mariano; Bellini, Mauricio
2012-01-01
Using the modern Kaluza-Klein theory of gravity (or the Induced Matter theory), we study the Dirac equation for massive neutrinos on a de Sitter background metric from a 5D Riemann-flat (and hence Ricci-flat) extended de Sitter metric, on which is defined the vacuum for test massless 1/2-spin neutral fields minimally coupled to gravity and free of any other interactions. We obtain that the effective 4D masses of the neutrinos can only take three possible values, which are related to the (static) foliation of the fifth and noncompact extra dimension.
Gravitationally induced adiabatic particle production: from big bang to de Sitter
International Nuclear Information System (INIS)
Haro, Jaume de; Pan, Supriya
2016-01-01
In the background of a flat homogeneous and isotropic space–time, we consider a scenario of the Universe driven by the gravitationally induced ‘adiabatic’ particle production with constant creation rate. We have shown that this Universe attains a big bang singularity in the past and at late-time it asymptotically becomes de Sitter. To clarify this model Universe, we performed a dynamical analysis and found that the Universe attains a thermodynamic equilibrium in this late de Sitter phase. Finally, for the first time, we have discussed the possible effects of ‘adiabatic’ particle creations in the context of loop quantum cosmology. (paper)
Mass Formulae for Broken Supersymmetry in Curved Space-Time
Ferrara, Sergio
2016-01-01
We derive the mass formulae for ${\\cal N}=1$, $D=4$ matter-coupled Supergravity for broken (and unbroken) Supersymmetry in curved space-time. These formulae are applicable to de Sitter configurations as is the case for inflation. For unbroken Supersymmetry in anti-de Sitter (AdS) one gets the mass relations modified by the AdS curvature. We compute the mass relations both for the potential and its derivative non-vanishing.
Quantum Scalar Corrections to the Gravitational Potentials on de Sitter Background
Park, Sohyun; Prokopec, Tomislav; Woodard, R. P.
We employ the graviton self-energy induced by a massless, minimally coupled (MMC) scalar on de Sitter background to compute the quantum corrections to the gravitational potentials of a static point particle with a mass $M$. The Schwinger-Keldysh formalism is used to derive real and causal effective
Gauge-invariant metric fluctuations from NKK theory of gravity: de Sitter expansion
International Nuclear Information System (INIS)
Aguilar, Jose Edgar Madriz; Anabitarte, Mariano; Bellini, Mauricio
2006-01-01
In this Letter we study gauge-invariant metric fluctuations from a noncompact Kaluza-Klein (NKK) theory of gravity in de Sitter expansion. We recover the well-known result δρ/ρ∼2Φ, obtained from the standard 4D semiclassical approach to inflation. The spectrum for these fluctuations should be dependent of the fifth (spatial-like) coordinate
A sufficient condition for de Sitter vacua in type IIB string theory
Energy Technology Data Exchange (ETDEWEB)
Rummel, Markus [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Westphal, Alexander [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2011-07-15
We derive a sufficient condition for realizing meta-stable de Sitter vacua with small positive cosmological constant within type IIB string theory flux compactifications with spontaneously broken supersymmetry. There are a number of 'lamp post' constructions of de Sitter vacua in type IIB string theory and supergravity. We show that one of them - the method of 'Kaehler uplifting' by F-terms from an interplay between non-perturbative effects and the leading {alpha}'-correction - allows for a more general parametric understanding of the existence of de Sitter vacua. The result is a condition on the values of the flux induced superpotential and the topological data of the Calabi-Yau compactification, which guarantees the existence of a meta-stable de Sitter vacuum if met. Our analysis explicitly includes the stabilization of all moduli, i.e. the Kaehler, dilaton and complex structure moduli, by the interplay of the leading perturbative and non-perturbative effects at parametrically large volume. (orig.)
Santa Vélez, Camilo; Enea Romano, Antonio
2018-05-01
Static coordinates can be convenient to solve the vacuum Einstein's equations in presence of spherical symmetry, but for cosmological applications comoving coordinates are more suitable to describe an expanding Universe, especially in the framework of cosmological perturbation theory (CPT). Using CPT we develop a method to transform static spherically symmetric (SSS) modifications of the de Sitter solution from static coordinates to the Newton gauge. We test the method with the Schwarzschild de Sitter (SDS) metric and then derive general expressions for the Bardeen's potentials for a class of SSS metrics obtained by adding to the de Sitter metric a term linear in the mass and proportional to a general function of the radius. Using the gauge invariance of the Bardeen's potentials we then obtain a gauge invariant definition of the turn around radius. We apply the method to an SSS solution of the Brans-Dicke theory, confirming the results obtained independently by solving the perturbation equations in the Newton gauge. The Bardeen's potentials are then derived for new SSS metrics involving logarithmic, power law and exponential modifications of the de Sitter metric. We also apply the method to SSS metrics which give flat rotation curves, computing the radial energy density profile in comoving coordinates in presence of a cosmological constant.
Dirac equation for massive neutrinos in a Schwarzschild-de Sitter spacetime from a 5D vacuum
International Nuclear Information System (INIS)
Sánchez, Pablo Alejandro; Anabitarte, Mariano; Bellini, Mauricio
2011-01-01
Starting from a Dirac equation for massless neutrino in a 5D Ricci-flat background metric, we obtain the effective 4D equation for massive neutrino in a Schwarzschild-de Sitter (SdS) background metric from an extended SdS 5D Ricci-flat metric. We use the fact that the spin connection is defined to an accuracy of a vector, so that the covariant derivative of the spinor field is strongly dependent of the background geometry. We show that the mass of the neutrino can be induced from the extra space-like dimension.
Stable de Sitter vacua in four-dimensional supergravity originating from five dimensions
International Nuclear Information System (INIS)
Oegetbil, O.
2008-01-01
The five-dimensional stable de Sitter ground states in N=2 supergravity obtained by gauging SO(1,1) symmetry of the real symmetric scalar manifold (in particular, a generic Jordan family manifold of the vector multiplets) simultaneously with a subgroup R s of the R-symmetry group descend to four-dimensional de Sitter ground states under certain conditions. First, the holomorphic section in four dimensions has to be chosen carefully by using the symplectic freedom in four dimensions; second, a group contraction is necessary to bring the potential into a desired form. Under these conditions, stable de Sitter vacua can be obtained in dimensionally reduced theories (from 5D to 4D) if the semidirect product of SO(1,1) with R (1,1) together with a simultaneous R s is gauged. We review the stable de Sitter vacua in four dimensions found in earlier literature for N=2 Yang-Mills Einstein supergravity with the SO(2,1)xR s gauge group in a symplectic basis that comes naturally after dimensional reduction. Although this particular gauge group does not descend directly from five dimensions, we show that its contraction does. Hence, two different theories overlap in certain limits. Examples of stable de Sitter vacua are given for the cases: (i) R s =U(1) R , (ii) R s =SU(2) R , and (iii) N=2 Yang-Mills/Einstein supergravity theory coupled to a universal hypermultiplet. We conclude with a discussion regarding the extension of our results to supergravity theories with more general homogeneous scalar manifolds.
Poincare and de Sitter gauge theories of gravity with propagating torsion
International Nuclear Information System (INIS)
Tseytlin, A.A.
1982-01-01
We consider a gauge approach to the gravitational theory based on the local Poincare P 10 de Sitter S 10 groups. The P 10 gauge rotations and translations take place in the tangent spaces to the space-time manifold. We interpret the independence of matter fields from the tangent vectors as the necessity to use a nonlinear realization of the P 10 or S 10 groups thus effectively breaking the full symmetry to the Lorentz group. The Lagrangian we choose is the S 10 Yang-Mills invariant with the space-time metric expressed in terms of the translational part of the S 10 nonlinear gauge field. Various consequences of the theory are discussed, including the correspondence with general relativity, the propagating spin-connection interactions, the analogy with the chiral Higgs mechanism, instantonlike solutions, a possibility of gravitational repulsion due to the noncompactness of the Lorentz group, etc. We also analyze the quantization of the theories with torsion with special emphasis on the presence of the nonlinear realization. We stress the possibility of obtaining a renormalizable theory if the metric is not quantized but is expressed in terms of a mean value of the quantized S 10 nonlinear gauge field
Can De Sitter spacetime be a final state of the contracting universe
International Nuclear Information System (INIS)
Berezin, V.A.
1984-01-01
This chapter attempts to phenomenologically describe the final stage of the Universe contraction. A model equation of state is used to demonstrate that during a cosmological contraction a de Sitter spacetime may be produced. It is shown that a equilibrium thermodynamic description of the matter in cosmological models leads to the absence of particle creation. It is proposed that these nonequilibrium processes be taken into account by introducing a new additional thermodynamic variable showing the explicit time dependence of all thermodynamic potentials into the thermodynamic relations. The spacetime is assumed to be homogeneous and isotropic, and the energy momentum tensor includes not only the energy density and pressure for the matter and radiation, but it also includes contributions due to vacuum polarization by correspondent fields. It is demonstrated that it is possible to reach in principle the de Sitter spacetime as the limit of the contraction
Restoration of the covariant gauge α in the initial field of gravity in de Sitter spacetime
Energy Technology Data Exchange (ETDEWEB)
Cheong, Lee Yen; Yan, Chew Xiao [Department of Fundamental and Applied Sciences, Universiti Teknologi Petronas, Bandar Seri Iskandar, Tronoh 31750, Perak (Malaysia)
2014-03-05
The gravitational field generated by a mass term and the initial surface through covariant retarded Green's function for linearized gravity in de Sitter spacetime was studied recently [4, 5] with the covariant gauges set to β = 2/3 and α = 5/3. In this paper we extend the work to restore the gauge parameter α in the field coming from the initial data using the method of shifting the parameter. The α terms in the initial field cancels exactly with the one coming from the source term. Consequently, the correct field configuration, with two equal mass points moving in its geodesic, one located at the North pole and another one located at the South pole, is reproduced in the whole manifold of de Sitter spacetime.
Late-time structure of the Bunch-Davies de Sitter wavefunction
Energy Technology Data Exchange (ETDEWEB)
Anninos, Dionysios [Stanford Institute of Theoretical Physics, Stanford University, Stanford (United States); Anous, Tarek [Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge (United States); Freedman, Daniel Z. [Stanford Institute of Theoretical Physics, Stanford University, Stanford (United States); Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge (United States); Department of Mathematics, Massachusetts Institute of Technology, Cambridge (United States); Konstantinidis, George [Stanford Institute of Theoretical Physics, Stanford University, Stanford (United States)
2015-11-30
We examine the late time behavior of the Bunch-Davies wavefunction for interacting light fields in a de Sitter background. We use perturbative techniques developed in the framework of AdS/CFT, and analytically continue to compute tree and loop level contributions to the Bunch-Davies wavefunction. We consider self-interacting scalars of general mass, but focus especially on the massless and conformally coupled cases. We show that certain contributions grow logarithmically in conformal time both at tree and loop level. We also consider gauge fields and gravitons. The four-dimensional Fefferman-Graham expansion of classical asymptotically de Sitter solutions is used to show that the wavefunction contains no logarithmic growth in the pure graviton sector at tree level. Finally, assuming a holographic relation between the wavefunction and the partition function of a conformal field theory, we interpret the logarithmic growths in the language of conformal field theory.
Thermodynamics of de Sitter black holes with a conformally coupled scalar field
International Nuclear Information System (INIS)
Barlow, Anne-Marie; Doherty, Daniel; Winstanley, Elizabeth
2005-01-01
We study the thermodynamics of de Sitter black holes with a conformally coupled scalar field. The geometry is that of the lukewarm Reissner-Nordstroem-de Sitter black holes, with the event and cosmological horizons at the same temperature. This means that the region between the event and cosmological horizons can form a regular Euclidean instanton. The entropy is modified by the nonminimal coupling of the scalar field to the geometry, but can still be derived from the Euclidean action, provided suitable modifications are made to deal with the electrically charged case. We use the first law as derived from the isolated horizons formalism to compute the local horizon energies for the event and cosmological horizons
The de Sitter spacetime as an attractor solution in fourth-order gravity
International Nuclear Information System (INIS)
Schmidt, H.-J.
1988-01-01
We investigate the general vacuum solution of fourth-order gravity, and include the Bach tensor. For L 2 = 1.3μR 2 + 1/2αC 2 the expanding de Sitter spacetime is an attractor in the set of axially symmetric Bianchi type-I models if and only if αμ ≤ 0 or α > 4μ holds. It will be argued that this result holds true for a large class of inhomogeneous models. As a byproduct, a new closed-form cosmological solution, is obtained. It is also shown that the de Sitter spacetime is an attractor for the Bach-Einstein gravity with a minimally coupled scalar field φ. Specialised to Einstein gravity (i.e. α = 0 above) this conformal equivalence remains a non-trivial one. (author)
Backreaction from non-conformal quantum fields in de Sitter spacetime
Energy Technology Data Exchange (ETDEWEB)
Perez-Nadal, Guillem; Verdaguer, Enric [Departament de Fisica Fonamental and Institut de Ciencies del Cosmos, Universitat de Barcelona, Av Diagonal 647, 08028 Barcelona (Spain); Roura, Albert [Theoretical Division, T-8, Los Alamos National Laboratory, M.S. B285, Los Alamos, NM 87545 (United States)
2008-08-07
We study the backreaction on the mean field geometry due to a non-conformal quantum field in a Robertson-Walker background. In the regime of small mass and small deviation from conformal coupling, we compute perturbatively the expectation value of the stress tensor of the field for a variety of vacuum states, and use it to obtain explicitly the semiclassical gravity solutions for isotropic perturbations around de Sitter spacetime, which is found to be stable. Our results clearly show the crucial role of the non-local terms that appear in the effective action: they cancel the contribution from local terms proportional to the logarithm of the scale factor which would otherwise become dominant at late times and prevent the existence of a stable self-consistent de Sitter solution. Finally, the opposite regime of a strongly non-conformal field with a large mass is also considered.
Metastable SUSY breaking, de Sitter moduli stabilisation and Kaehler moduli inflation
International Nuclear Information System (INIS)
Krippendorf, Sven; Quevedo, Fernando
2009-01-01
We study the influence of anomalous U(1) symmetries and their associated D-terms on the vacuum structure of global field theories once they are coupled to N = 1 supergravity and in the context of string compactifications with moduli stabilisation. In particular, we focus on a IIB string motivated construction of the ISS scenario and examine the influence of one additional U(1) symmetry on the vacuum structure. We point out that in the simplest one-Kaehler modulus compactification, the original ISS vacuum gets generically destabilised by a runaway behaviour of the potential in the modulus direction. In more general compactifications with several Kaehler moduli, we find a novel realisation of the LARGE volume scenario with D-term uplifting to de Sitter space and both D-term and F-term supersymmetry breaking. The structure of soft supersymmetry breaking terms is determined in the preferred scenario where the standard model cycle is not stabilised non-perturbatively and found to be flavour universal. Our scenario also provides a purely supersymmetric realisation of Kaehler moduli (blow-up and fibre) inflation, with similar observational properties as the original proposals but without the need to include an extra (non-SUSY) uplifting term.
Metastable SUSY Breaking, de Sitter Moduli Stabilisation and Kähler Moduli Inflation
Krippendorf, Sven
2009-01-01
We study the influence of anomalous U(1) symmetries and their associated D-terms on the vacuum structure of global field theories once they are coupled to N=1 supergravity and in the context of string compactifications with moduli stabilisation. In particular, we focus on a IIB string motivated construction of the ISS scenario and examine the influence of one additional U(1) symmetry on the vacuum structure. We point out that in the simplest one-Kahler modulus compactification, the original ISS vacuum gets generically destabilised by a runaway behaviour of the potential in the modulus direction. In more general compactifications with several Kahler moduli, we find a novel realisation of the LARGE volume scenario with D-term uplifting to de Sitter space and both D-term and F-term supersymmetry breaking. The structure of soft supersymmetry breaking terms is determined in the preferred scenario where the standard model cycle is not stabilised non-perturbatively and found to be flavour universal. Our scenario als...
On the covariant gauge {alpha} of the linearized gravity in de Sitter spacetime
Energy Technology Data Exchange (ETDEWEB)
Cheong, Lee Yen [Department of Fundamental and Applied Science Universiti Teknologi Petronas, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia)
2012-09-26
In previous work, we studied the linearized gravity with covariant gauge {beta}= 2/3 and {alpha}= 5/3. It was found that the sum of the source and initial contributions reproduces the correct field configuration over the whole de Sitter spacetime. In this paper, we extend this work to generalizing the linearized gravitational field in an arbitrary value of the gauge parameter {alpha} but the gauge parameter {beta} remains the same.
Quasinormal modes of the near extremal Schwarzschild-de Sitter black hole
International Nuclear Information System (INIS)
Cardoso, Vitor; Lemos, Jose P.S.
2003-01-01
We present an exact expression for the quasinormal modes of scalar, electromagnetic, and gravitational perturbations of a near extremal Schwarzschild-de Sitter black hole and we show that is why a previous approximation holds exactly in this near extremal regime. In particular, our results give the asymptotic behavior of the quasinormal frequencies for highly damped modes, which has recently attracted much attention due to the proposed identification of its real part with the Barbero-Immirzi parameter
Linear waves on higher dimensional Schwarzschild black holes and Schwarzschild de Sitter spacetimes
Schlue, Volker
2012-01-01
I study linear waves on higher dimensional Schwarzschild black holes and Schwarzschild de Sitter spacetimes. In the first part of this thesis two decay results are proven for general finite energy solutions to the linear wave equation on higher dimensional Schwarzschild black holes. I establish uniform energy decay and improved interior first order energy decay in all dimensions with rates in accordance with the 3 + 1-dimensional case. The method of proof departs from earlier work on th...
All gaugings and stable de Sitter in D=7 half-maximal supergravity
Energy Technology Data Exchange (ETDEWEB)
Dibitetto, Giuseppe [Institutionen för fysik och astronomi, University of Uppsala, Box 803, SE-751 08 Uppsala (Sweden); Fernández-Melgarejo, Jose J. [Jefferson Physical Laboratory, Harvard University, Cambridge, MA 02138 (United States); Marqués, Diego [Instituto de Astronomía y Física del Espacio (CONICET-UBA) C.C. 67 - Suc. 28, 1428 Buenos Aires (Argentina)
2015-11-05
We study the general formulation of gauged supergravity in seven dimensions with sixteen supercharges keeping duality covariance by means of the embedding tensor formalism. We first classify all inequivalent duality orbits of consistent deformations. Secondly, we analyse the complete set of critical points in a systematic way. Interestingly, we find the first examples of stable de Sitter solutions within a theory with such a large amount of supersymmetry.
On a quantized scalar field in the de Sitter and Nariai universes
International Nuclear Information System (INIS)
Nariai, Hidekazu.
1984-08-01
After canonical quantization of a massive or massless scalar field in the de Sitter and Nariai universes (both of which satisfy the same Einstein equations with a non-vanishing cosmological constant, Rsub(μν)=Agsub(μν), but their topological structures differ from each other), the uniquely obtained 4-dimensional commutation functions in both universes are comparatively studied with due emphasis on their topological structures, as well as the difference of couplings to the background universe. (author)
Thermodynamics of the Schwarzschild-de Sitter black hole: Thermal stability of the Nariai black hole
International Nuclear Information System (INIS)
Myung, Yun Soo
2008-01-01
We study the thermodynamics of the Schwarzschild-de Sitter black hole in five dimensions by introducing two temperatures based on the standard and Bousso-Hawking normalizations. We use the first-law of thermodynamics to derive thermodynamic quantities. The two temperatures indicate that the Nariai black hole is thermodynamically unstable. However, it seems that black hole thermodynamics favors the standard normalization and does not favor the Bousso-Hawking normalization
De Sitter self-consistent cosmology for Weinberg-type fields
International Nuclear Information System (INIS)
Castagnino, M.A.
1986-01-01
Weinberg-type fields, which transform under the (s,0)+(0,s) representation of the Lorentz group, in the de Sitter spacetime are studied. The vacuum expectation value of the energy-momentum tensor trace is renormalized using the adiabatic regularisation scheme. The relation imposed by the semiclassical Einstein equations among the scalar curvature R and the mass of the fields is studied. Results are explicitly drawn for s = 0, 1/2 and 1. (author)
Massless scalar field in de Sitter spacetime: unitary quantum time evolution
International Nuclear Information System (INIS)
Cortez, Jerónimo; Blas, Daniel Martín-de; Marugán, Guillermo A Mena; Velhinho, José M
2013-01-01
We prove that, under the standard conformal scaling, a free scalar field in de Sitter spacetime admits an O(4)-invariant Fock quantization such that time evolution is unitarily implemented. Since this applies in particular to the massless case, this result disproves previous claims in the literature. We discuss the relationship between this quantization with unitary dynamics and the family of O(4)-invariant Hadamard states given by Allen and Folacci, as well as with the Bunch–Davies vacuum. (paper)
Kerr-de Sitter spacetime, Penrose process, and the generalized area theorem
Bhattacharya, Sourav
2018-04-01
We investigate various aspects of energy extraction via the Penrose process in the Kerr-de Sitter spacetime. We show that the increase in the value of a positive cosmological constant, Λ , always reduces the efficiency of this process. The Kerr-de Sitter spacetime has two ergospheres associated with the black hole and the cosmological event horizons. We prove by analyzing turning points of the trajectory that the Penrose process in the cosmological ergoregion is never possible. We next show that in this process both the black hole and cosmological event horizons' areas increase, and the latter becomes possible when the particle coming from the black hole ergoregion escapes through the cosmological event horizon. We identify a new, local mass function instead of the mass parameter, to prove this generalized area theorem. This mass function takes care of the local spacetime energy due to the cosmological constant as well, including that which arises due to the frame-dragging effect due to spacetime rotation. While the current observed value of Λ is quite small, its effect in this process could be considerable in the early Universe scenario where its value is much larger, where the two horizons could have comparable sizes. In particular, the various results we obtain here are also evaluated in a triply degenerate limit of the Kerr-de Sitter spacetime we find, in which radial values of the inner, the black hole and the cosmological event horizons are nearly coincident.
Hydrogen-like spectrum of spontaneously created brane universes with de-Sitter ground state
Davidson, Aharon
2018-05-01
Unification of Randall-Sundrum and Regge-Teitelboim brane cosmologies gives birth to a serendipitous Higgs-deSitter interplay. A localized Dvali-Gabadadze-Porrati scalar field, governed by a particular (analytically derived) double-well quartic potential, becomes a mandatory ingredient for supporting a deSitter brane universe. When upgraded to a general Higgs potential, the brane surface tension gets quantized, resembling a Hydrogen atom spectrum, with deSitter universe serving as the ground state. This reflects the local/global structure of the Euclidean manifold: From finite energy density no-boundary initial conditions, via a novel acceleration divide filter, to exact matching conditions at the exclusive nucleation point. Imaginary time periodicity comes as a bonus, with the associated Hawking temperature vanishing at the continuum limit. Upon spontaneous creation, while a finite number of levels describe universes dominated by a residual dark energy combined with damped matter oscillations, an infinite tower of excited levels undergo a Big Crunch.
Kam, Chon-Fai; Liu, Ren-Bao
2017-08-29
Berry phases and gauge structures are fundamental quantum phenomena. In linear quantum mechanics the gauge field in parameter space presents monopole singularities where the energy levels become degenerate. In nonlinear quantum mechanics, which is an effective theory of interacting quantum systems, there can be phase transitions and hence critical surfaces in the parameter space. We find that these critical surfaces result in a new type of gauge field singularity, namely, a conic singularity that resembles the big bang of a 2 + 1 dimensional de Sitter universe, with the fundamental frequency of Bogoliubov excitations acting as the cosmic scale, and mode softening at the critical surface, where the fundamental frequency vanishes, causing a causal singularity. Such conic singularity may be observed in various systems such as Bose-Einstein condensates and molecular magnets. This finding offers a new approach to quantum simulation of fundamental physics.
Remarks on quantum field theory on de Sitter and anti-de Sitter ...
Indian Academy of Sciences (India)
2012-06-14
Jun 14, 2012 ... Abstract. This is a short review of work done in common with Jacques Bros, Michel Gaudin,. Ugo Moschella, and Vincent Pasquier. ... This short review is limited to work done in recent years with the authors quoted in the abstract. ..... We shall not deal in detail with ˜Xd. Axioms can be formulated for quantum ...
The flux-scaling scenario. De Sitter uplift and axion inflation
Energy Technology Data Exchange (ETDEWEB)
Blumenhagen, Ralph; Damian, Cesar; Herschmann, Daniela; Sun, Rui [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Muenchen (Germany); Font, Anamaria [Departamento de Fisica, Centro de Fisica Teorica y Computacional, Facultad de Ciencias, Universidad Central de Venezuela, Caracas (Venezuela, Bolivarian Republic of)
2016-06-15
Non-geometric flux-scaling vacua provide promising starting points to realize axion monodromy inflation via the F-term scalar potential. We show that these vacua can be uplifted to Minkowski and de Sitter by adding an D3-brane or a D-term containing geometric and non-geometric fluxes. These uplifted non-supersymmetric models are analyzed with respect to their potential to realize axion monodromy inflation self-consistently. Admitting rational values of the fluxes, we construct examples with the required hierarchy of mass scales. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
The flux-scaling scenario. De Sitter uplift and axion inflation
International Nuclear Information System (INIS)
Blumenhagen, Ralph; Damian, Cesar; Herschmann, Daniela; Sun, Rui; Font, Anamaria
2016-01-01
Non-geometric flux-scaling vacua provide promising starting points to realize axion monodromy inflation via the F-term scalar potential. We show that these vacua can be uplifted to Minkowski and de Sitter by adding an D3-brane or a D-term containing geometric and non-geometric fluxes. These uplifted non-supersymmetric models are analyzed with respect to their potential to realize axion monodromy inflation self-consistently. Admitting rational values of the fluxes, we construct examples with the required hierarchy of mass scales. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
A Review on the Cosmology of the de Sitter Horndeski Models
Directory of Open Access Journals (Sweden)
Nelson J. Nunes
2017-03-01
Full Text Available We review the most general scalar-tensor cosmological models with up to second-order derivatives in the field equations that have a fixed spatially flat de Sitter critical point independent of the material content or vacuum energy. This subclass of the Horndeski Lagrangian is capable of dynamically adjusting any value of the vacuum energy of the matter fields at the critical point. We present the cosmological evolution of the linear models and the non-linear models with shift symmetry. We come to the conclusion that the shift symmetric non-linear models can deliver a viable background compatible with current observations.
Indications of de Sitter spacetime from classical sequential growth dynamics of causal sets
International Nuclear Information System (INIS)
Ahmed, Maqbool; Rideout, David
2010-01-01
A large class of the dynamical laws for causal sets described by a classical process of sequential growth yields a cyclic universe, whose cycles of expansion and contraction are punctuated by single 'origin elements' of the causal set. We present evidence that the effective dynamics of the immediate future of one of these origin elements, within the context of the sequential growth dynamics, yields an initial period of de Sitter-like exponential expansion, and argue that the resulting picture has many attractive features as a model of the early universe, with the potential to solve some of the standard model puzzles without any fine-tuning.
Kanti, P.; Pappas, T.
2017-07-01
The absence of a true thermodynamical equilibrium for an observer located in the causal area of a Schwarzschild-de Sitter spacetime has repeatedly raised the question of the correct definition of its temperature. In this work, we consider five different temperatures for a higher-dimensional Schwarzschild-de Sitter black hole: the bare T0, the normalized TBH, and three effective ones given in terms of both the black-hole and cosmological horizon temperatures. We find that these five temperatures exhibit similarities but also significant differences in their behavior as the number of extra dimensions and the value of the cosmological constant are varied. We then investigate their effect on the energy emission spectra of Hawking radiation. We demonstrate that the radiation spectra for the normalized temperature TBH—proposed by Bousso and Hawking over twenty years ago—leads to the dominant emission curve, while the other temperatures either support a significant emission rate only in a specific Λ regime or have their emission rates globally suppressed. Finally, we compute the bulk-over-brane emissivity ratio and show that the use of different temperatures may lead to different conclusions regarding the brane or bulk dominance.
Open string fluctuations in AdS space with and without torsion
DEFF Research Database (Denmark)
Larsen, A.L.; Lomholt, Michael Andersen
2003-01-01
The equations of motion and boundary conditions for the fluctuations around a classical open string, in a curved space-time with torsion, are considered in compact and world-sheet covariant form. The rigidly rotating open strings in anti-de Sitter space with and without torsion are investigated...
Hawking radiation as tunneling from the event horizon of NUT-Kerr-Newman de Sitter black hole
International Nuclear Information System (INIS)
Hui-Ling, Li; Shu-Shenh, Yang; Qing-Quan, Jiang; De-Jiang, Qi
2005-01-01
Adopting the method of quantum radiation as tunneling, Hawking radiation as tunneling from the event horizon of NUT-Kerr-Newman de Sitter black hole is studied. The result indicates that the tunneling rate of the particle on the event horizon is related to the change of Bekenstein-Hawking entropy and the real spectrum is not strictly thermal at all
Expanding plasmas from anti de Sitter black holes
Energy Technology Data Exchange (ETDEWEB)
Camilo, Giancarlo [Instituto de Fisica, Universidade de Sao Paulo, Departamento de Fisica Matematica, Sao Paulo (Brazil)
2016-12-15
We introduce a new foliation of AdS{sub 5} black holes such that the conformal boundary takes the form of a 4-dimensional FLRW spacetime with scale factor a(t). The foliation employs Eddington-Finkelstein-like coordinates and is applicable to a large class of AdS black holes, supported by matter fields or not, considerably extending previous efforts in the literature. We argue that the holographic dual picture of a CFT plasma on a FLRW background provides an interesting prototype to study the nonequilibrium dynamics of expanding plasmas and use holographic renormalization to extract the renormalized energy-momentum tensor of the dual plasma. We illustrate the procedure for three black holes of interest, namely AdS-Schwarzschild, AdS-Gauss-Bonnet, and AdS-Reissner-Nordstroem. For the latter, as a by-product, we show that the nonequilibrium dynamics of a CFT plasma subject to a quench in the chemical potential (i.e., a time-dependent chemical potential) resembles a cosmological evolution with the scale factor a(t) being inversely related to the quench profile μ(t). (orig.)
Expanding plasmas from anti de Sitter black holes
International Nuclear Information System (INIS)
Camilo, Giancarlo
2016-01-01
We introduce a new foliation of AdS_5 black holes such that the conformal boundary takes the form of a 4-dimensional FLRW spacetime with scale factor a(t). The foliation employs Eddington-Finkelstein-like coordinates and is applicable to a large class of AdS black holes, supported by matter fields or not, considerably extending previous efforts in the literature. We argue that the holographic dual picture of a CFT plasma on a FLRW background provides an interesting prototype to study the nonequilibrium dynamics of expanding plasmas and use holographic renormalization to extract the renormalized energy-momentum tensor of the dual plasma. We illustrate the procedure for three black holes of interest, namely AdS-Schwarzschild, AdS-Gauss-Bonnet, and AdS-Reissner-Nordstroem. For the latter, as a by-product, we show that the nonequilibrium dynamics of a CFT plasma subject to a quench in the chemical potential (i.e., a time-dependent chemical potential) resembles a cosmological evolution with the scale factor a(t) being inversely related to the quench profile μ(t). (orig.)
The collapse of an anti-de Sitter bubble
International Nuclear Information System (INIS)
Abbott, L.F.; Coleman, S.
1985-01-01
We prove that the ultimate fate of a bubble of negative energy density which forms in a metastable universe of zero energy density is gravitational collapse. We improve on previous treatments in that we allow departures from O(3,1) symmetry in the initial state, so long as they are not too great. (orig.)
Huang, Chao-Guang; Guo, Han-Ying; Tian, Yu; Xu, Zhan; Zhou, Bin
2004-01-01
Based on the Beltrami-de Sitter spacetime, we present the Newton-Hooke model under the Newton-Hooke contraction of the $BdS$ spacetime with respect to the transformation group, algebra and geometry. It is shown that in Newton-Hooke space-time, there are inertial-type coordinate systems and inertial-type observers, which move along straight lines with uniform velocity. And they are invariant under the Newton-Hooke group. In order to determine uniquely the Newton-Hooke limit, we propose the Gal...
International Nuclear Information System (INIS)
Paudel, Eak Raj
2007-01-01
Gravitational field of Schwarzschild and Schwarzschild de-sitter Black hole with a straight string passing through it. In such space analytical and numerical solutions of null and time like geodesics are investigated. The string parameter a + is found to affect both the angle of deflection in null geodesics and the precession of perihelion on time like geodesics .It is seen that the deflection of null and time like geodesics near the gravitating mass of de-sitter space time increases with t he gravitational field of a straight string in flat space time has the property that the Newtonian potential vanishes yet there are non trivial gravitational effects. A test particle is neither attracted nor repelled by a string, yet the conical nature of space outside of string produces observable effects such as light deflection . Schwarzschild Black hole is a mathematical solution to the Einstein's field equations and corresponds to the gravitational field of massive compact spherically symmetric ob normal. References 1. Aryal, M.M, A. Vilenkin and L.H Ford, 1986, Phys.Rev. D32 ,2262 2. Moriyasu ,K ., 1980 , An introduction to gauge Invariance 3. Vilenkin A., 1985 , Physical reports , cosmic strings and Domain walls 4. Berry, M. , 1976 , Principle of cosmology and Gravitation 5. Mishner , C.W ., K.S .Throne , J.A wheeler , 1973. (Author)
Charged de Sitter-like black holes: quintessence-dependent enthalpy and new extreme solutions
Energy Technology Data Exchange (ETDEWEB)
Azreg-Ainou, Mustapha [Baskent University, Faculty of Engineering, Ankara (Turkey)
2015-01-01
We consider Reissner-Nordstroem black holes surrounded by quintessence where both a non-extremal event horizon and a cosmological horizon exist besides an inner horizon (-1 ≤ ω < -1/3). We determine new extreme black hole solutions that generalize the Nariai horizon to asymptotically de Sitter-like solutions for any order relation between the squares of the charge q{sup 2} and the mass parameter M{sup 2} provided q{sup 2} remains smaller than some limit, which is larger than M{sup 2}. In the limit case q{sup 2} = 9ω{sup 2}M{sup 2}/(9ω{sup 2}-1), we derive the general expression of the extreme cosmo-blackhole, where the three horizons merge, and we discuss some of its properties.We also show that the endpoint of the evaporation process is independent of any order relation between q{sup 2} and M{sup 2}. The Teitelboim energy and the Padmanabhan energy are related by a nonlinear expression and are shown to correspond to different ensembles. We also determine the enthalpy H of the event horizon, as well as the effective thermodynamic volume which is the conjugate variable of the negative quintessential pressure, and show that in general the mass parameter and the Teitelboim energy are different from the enthalpy and internal energy; only in the cosmological case, that is, for Reissner-Nordstroem-de Sitter black hole we have H = M. Generalized Smarr formulas are also derived. It is concluded that the internal energy has a universal expression for all static charged black holes, with possibly a variable mass parameter, but it is not a suitable thermodynamic potential for static-black-hole thermodynamics if M is constant. It is also shown that the reverse isoperimetric inequality holds. We generalize the results to the case of the Reissner-Nordstroem-de Sitter black hole surrounded by quintessence with two physical constants yielding two thermodynamic volumes. (orig.)
De Sitter and scaling solutions in a higher-order modified teleparallel theory
Energy Technology Data Exchange (ETDEWEB)
Paliathanasis, Andronikos, E-mail: anpaliat@phys.uoa.gr [Instituto de Ciencias Físicas y Matemáticas, Universidad Austral de Chile, Valdivia (Chile)
2017-08-01
The existence and the stability conditions for some exact relativistic solutions of special interest are studied in a higher-order modified teleparallel gravitational theory. The theory with the use of a Lagrange multiplier is equivalent with that of General Relativity with a minimally coupled noncanonical field. The conditions for the existence of de Sitter solutions and ideal gas solutions in the case of vacuum are studied as also the stability criteria. Furthermore, in the presence of matter the behaviour of scaling solutions is given. Finally, we discuss the degrees of freedom of the field equations and we reduce the field equations in an algebraic equation, where in order to demonstrate our result we show how this noncanonical scalar field can reproduce the Hubble function of Λ-cosmology.
Schwarzschild-de Sitter spacetime: The role of temperature in the emission of Hawking radiation
Pappas, Thomas; Kanti, Panagiota
2017-12-01
We consider a Schwarzschild-de Sitter (SdS) black hole, and focus on the emission of massless scalar fields either minimally or non-minimally coupled to gravity. We use six different temperatures, two black-hole and four effective ones for the SdS spacetime, as the question of the proper temperature for such a background is still debated in the literature. We study their profiles under the variation of the cosmological constant, and derive the corresponding Hawking radiation spectra. We demonstrate that only few of these temperatures may support significant emission of radiation. We finally compute the total emissivities for each temperature, and show that the non-minimal coupling constant of the scalar field to gravity also affects the relative magnitudes of the energy emission rates.
On moduli stabilisation and de Sitter vacua in MSSM heterotic orbifolds
Energy Technology Data Exchange (ETDEWEB)
Parameswaran, Susha L. [Uppsala Univ. (Sweden). Dept. of Physics and Astronomy; Ramos-Sanchez, Saul [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Zavala, Ivonne [Bonn Univ. (Germany). Bethe Center for Theoretical Physics and Physikalisches Inst.
2010-09-15
We study the problem of moduli stabilisation in explicit heterotic orbifold compactifications, whose spectra contain the MSSM plus some vector-like exotics that can be decoupled. Considering all the bulk moduli, we obtain the 4D low energy effective action for the compactification, which has contributions from various, computable, perturbative and non-perturbative effects. Hidden sector gaugino condensation and string worldsheet instantons result in a combination of racetrack, KKLT and cusp-form contributions to the superpotential, which lift all the bulk moduli directions. We point out the properties observed in our concrete models, which tend to be missed when only ''generic'' features of a model are assumed. We search for interesting vacua and find several de Sitter solutions, but so far, they all turn out to be unstable. (orig.)
Gravitational Collapse of Charged Matter in Einstein-DeSitter Universe
Avinash, K.; Krishnan, V.
1997-11-01
Gravitational collapse of charged matter in expanding universe is studied. We consider a quasi neutral electron-ion-massive grain plasma in which all the three species are expanding at the same rate i.e., ni ∝ 1/R^3 [ ni is the number density of the i^ th species and R is the scale factor ]. In Einstein-DeSitter universe the scale factor R goes as ~ t^2/3. The electrons and ions follow Boltzmann's relation. The stability of this equilibrium is studied on Jeans times scale. Depending on the ratio a = fracq d^2Gmd^2 the growth of gravitational collapse is further moderated from t^2/3 growth. For a=1, the instability is completely quenched. In curvature and radiation dominated universe, there is no additional effect due to finite charge of the matter.
Reissner--Nordstroem--de Sitter metric, the third law, and cosmic censorship
International Nuclear Information System (INIS)
Lake, K.
1979-01-01
The essential features of the Reissner--Nordstroem--de Sitter metric are examined in relation to the third law of black-hole mechanics and the cosmic censorship hypothesis for a nonasymptotically flat situation. The evolution of thin charged dust shells in this metric shows that the thermodynamic character of cosmological event horizons differs from that of black-hole horizons in that a degenerate horizon can be produced in a finite time. Nonetheless the spirit of the third law is preserved since the resultant degenerate configurations do not represent physically attainable limits in our Universe. It is shown that the nakedly singular character of the analytic extensions to these solutions represents an unplysical idealization due to the inherent instability of Killing horizons to the past of their bifurcation. This adds support to the spirit of strong cosmic censorship
Scalar potential from de Sitter brane in 5D and effective cosmological constant
International Nuclear Information System (INIS)
Ito, Masato
2004-01-01
We derive the scalar potential in zero mode effective action arising from a de Sitter brane embedded in five dimensions with bulk cosmological constant Λ. The scalar potential for a scalar field canonically normalized is given by the sum of exponential potentials. In the case of Λ = 0 and Λ > 0, we point out that the scalar potential has an unstable maximum at the origin and exponentially vanishes for large positive scalar field. In the case of Λ < 0, the scalar potential has an unstable maximum at the origin and a local minimum. It is shown that the positive cosmological constant in dS brane is reduced by negative potential energy of scalar at minimum and that effective cosmological constant depends on a dimensionless quantity. Furthermore, we discuss the fate of our universe including the potential energy of the scalar. (author)
De Sitter vacua and inflation in no-scale string models
Energy Technology Data Exchange (ETDEWEB)
Gross, Christian
2009-09-15
This thesis studies the question of how de Sitter vacua and slow-roll inflation may be realized in string-motivated models. More specifically, we consider 4d N = 1 supergravity theories (without vector multiplets) with Kaehler potentials which are 'no-scale' at leading order. Such theories frequently arise in the moduli sector of string compactifications. We discuss a condition on the scalar geometry (defined by the Kaehler potential) and on the direction of supersymmetry breaking in the scalar manifold, which has to be met in order for the average of the masses of the sGoldstinos to be positive, and hence for metastable vacua to be possible. This condition also turns out to be necessary for the existence of trajectories admitting slow-roll inflation. Its implications for certain scalar manifolds which arise from Calabi-Yau string compactifications are discussed. In particular, for two-moduli models arising from compactifications of heterotic- and type IIB string theory, a simple criterion on the intersection numbers needs to be satisfied for possible de Sitter phases to exist. In addition, we show that subleading corrections breaking the no-scale property may allow the condition on the scalar geometry to be fulfilled, even when it is violated at leading order. Finally, we develop a procedure to construct superpotentials for a given viable Kaehler potential, such that the scalar potential has a realistic local minimum. We propose two-moduli models, with superpotentials which could arise from flux backgrounds and non-perturbative effects, which have a viable vacuum without employing subleading corrections or an uplifting sector. (orig.)
International Nuclear Information System (INIS)
Higuchi, A.
1987-01-01
The symmetric tensor spherical harmonics (STSH's) on the N-sphere (S/sup N/), which are defined as the totally symmetric, traceless, and divergence-free tensor eigenfunctions of the Laplace--Beltrami (LB) operator on S/sup N/, are studied. Specifically, their construction is shown recursively starting from the lower-dimensional ones. The symmetric traceless tensors induced by STSH's are introduced. These play a crucial role in the recursive construction of STSH's. The normalization factors for STSH's are determined by using their transformation properties under SO(N+1). Then the symmetric, traceless, and divergence-free tensor eigenfunctions of the LB operator in the N-dimensional de Sitter space-time which are obtained by the analytic continuation of the STSH's on S/sup N/ are studied. Specifically, the allowed eigenvalues of the LB operator under the restriction of unitarity are determined. Our analysis gives a group-theoretical explanation of the forbidden mass range observed earlier for the spin-2 field theory in de Sitter space-time
Nonextreme and ultraextreme domain walls and their global space-times
International Nuclear Information System (INIS)
Cvetic, M.; Griffies, S.; Soleng, H.H.
1993-01-01
Nonextreme walls (bubbles with two insides) and ultraextreme walls (bubbles of false vacuum decay) are discussed. Their respective energy densities are higher and lower than that of the corresponding extreme (supersymmetric), planar domain wall. These singularity free space-times exhibit nontrivial causal structure analogous to certain nonextreme black holes. We focus on anti--de Sitter--Minkowski walls and comment on Minkowski-Minkowski walls with trivial extreme limit, as well as walls adjacent to de Sitter space-times with no extreme limit
Mass formulae for broken supersymmetry in curved space-time
Energy Technology Data Exchange (ETDEWEB)
Ferrara, Sergio [Theoretical Physics Department, CERN, Geneva (Switzerland); INFN - Laboratori Nazionali di Frascati, Frascati (Italy); Department of Physics and Astronomy, U.C.L.A, Los Angeles, CA (United States); Proeyen, Antoine van [KU Leuven, Institute for Theoretical Physics, Leuven (Belgium)
2016-11-15
We derive the mass formulae for N = 1, D = 4 matter-coupled Supergravity for broken (and unbroken) Supersymmetry in curved space-time. These formulae are applicable to De Sitter configurations as is the case for inflation. For unbroken Supersymmetry in anti-de Sitter (AdS) one gets the mass relations modified by the AdS curvature. We compute the mass relations both for the potential and its derivative non-vanishing. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
International Nuclear Information System (INIS)
Hasan, M. Khayrul; Ali, M. Hossain
2009-01-01
We formulate the general relativistic magnetohydrodynamic equations for isothermal plasma in spatially flat Reissner–Nordström–de Sitter metric by using 3+1 split of spacetime. Respective perturbed equations are linearized for rotating magnetized surroundings. These are then Fourier analyzed and the corresponding dispersion relations are obtained. These relations are discussed both analytically and numerically in order to investigate the nature of waves with positive angular frequency around the horizon
Entropy of Reissner-Nordstrom-De Sitter Black Hole in Nonthermal Equilibrium
Institute of Scientific and Technical Information of China (English)
ZHAO Ren; ZHANG Jun-Fang; ZHANG Li-Chun
2002-01-01
By making use of the method of quantum statistics, we directly derive the partition function of bosonic and fermionic fields in Reissner-Nordstrom-De Sitter black hole and obtain the integral expression of black hole's entropy and the entropy to which the cosmic horizon surface corresponds. It avoids the difficulty in solving the wave equation of various particles. Then via the improved brick-wall method, i.e. the membrane model, we calculate black hole's entropy and cosmic entropy and find out that if we let the integral upper limit and lower limit both tend to the horizon, the entropy of black hole is proportional to the area of horizon and the entropy to which cosmic horizon surface corresponds is proportional to the area of cosmic horizon. In our result, the stripped term and the divergent logarithmic term in the original brick-wall method no longer exist. In the whole process, the physical idea is clear and the calculation is simple.We offer a new simple and direct way for calculating the entropy of different complicated black holes.
Regular black holes: electrically charged solutions, Reissner-Nordstroem outside a De Sitter core
Energy Technology Data Exchange (ETDEWEB)
Lemos, Jose P.S. [Universidade Tecnica de Lisboa (CENTRA/IST/UTL) (Portugal). Instituto Superior Tecnico. Centro Multidisciplinar de Astrofisica; Zanchin, Vilson T. [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil). Centro de Ciencias Naturais e Humanas
2011-07-01
Full text: The understanding of the inside of a black hole is of crucial importance in order to have the correct picture of a black hole as a whole. The singularities that lurk inside of the usual black hole solutions are things to avoid. Their substitution by a regular part is of great interest, the process generating regular black holes. In the present work regular black hole solutions are found within general relativity coupled to Maxwell's electromagnetism and charged matter. We show that there are objects which correspond to regular charged black holes, whose interior region is de Sitter, whose exterior region is Reissner-Nordstroem, and the boundary between both regions is made of an electrically charged spherically symmetric coat. There are several solutions: the regular nonextremal black holes with a null matter boundary, the regular nonextremal black holes with a timelike matter boundary, the regular extremal black holes with a timelike matter boundary, and the regular overcharged stars with a timelike matter boundary. The main physical and geometrical properties of such charged regular solutions are analyzed. (author)
International Nuclear Information System (INIS)
Bellucci, S.; Saharian, A. A.
2008-01-01
We investigate the Wightman function, the vacuum expectation values of the field squared, and the energy-momentum tensor for a scalar field with a general curvature coupling parameter in (D+1)-dimensional de Sitter (dS) spacetime with an arbitrary number of compactified spatial dimensions. Both cases of periodicity and antiperiodicity conditions along the compactified dimensions are considered. Recurrence formulas are derived which express the vacuum expectation values for the dS spacetime of topology R p x(S 1 ) q in the form of the sum of the vacuum expectation values in the topology R p+1 x(S 1 ) q-1 and the part induced by the compactness of the (p+1)th spatial dimension. The behavior of the topological parts is investigated in various asymptotic regions of the parameters. In the early stages of the cosmological evolution, the topological parts dominate the contribution in the expectation values due to the uncompactified dS part. In this limit the behavior of the topological parts does not depend on the curvature coupling parameter and coincides with that for a conformally coupled massless field. At late stages of the cosmological expansion, the expectation values are dominated by the part corresponding to uncompactified dS spacetime. The vanishing of the topological parts is monotonic or oscillatory in dependence of the mass and the curvature coupling parameter of the field
Directory of Open Access Journals (Sweden)
R. da Rocha
2017-12-01
Full Text Available Sound waves on a fluid stream, in a de Laval nozzle, are shown to correspond to quasinormal modes emitted by black holes that are physical solutions in a quadratic curvature gravity with cosmological constant. Sound waves patterns in transsonic regimes at a laboratory are employed here to provide experimental data regarding generalized theories of gravity, comprised by the exact de Sitter-like solution and a perturbative solution around the Schwarzschildâde Sitter standard solution as well. Using the classical tests of General Relativity to bound free parameters in these solutions, acoustic perturbations on fluid flows in nozzles are then regarded, to study quasinormal modes of these black holes solutions, providing deviations of the de Laval nozzle cross-sectional area, when compared to the Schwarzschild solution. The fluid sonic point in the nozzle, for sound waves in the fluid, is shown to implement the acoustic event horizon corresponding to quasinormal modes. Keywords: Black holes, Fluid branes, Fluid dynamics, Quadratic curvature gravity, de Laval nozzle
International Nuclear Information System (INIS)
Loran, Farhang
2004-01-01
We solve Klein-Gordon equation for massless scalars on (d+1)-dimensional Minkowski (Euclidean) space in terms of the Cauchy data on the hypersurface t=0. By inserting the solution into the action of massless scalars in Minkowski (Euclidean) space we obtain the action of dual theory on the boundary t=0 which is exactly the holographic dual of conformally coupled scalars on (d+1)-dimensional (Euclidean anti) de Sitter space obtained in (A)dS/CFT correspondence. The observed equivalence of dual theories is explained using the one-to-one map between conformally coupled scalar fields on Minkowski (Euclidean) space and (Euclidean anti) de Sitter space which is an isomorphism between the hypersurface t=0 of Minkowski (Euclidean) space and the boundary of (A)dS space
Pappas, T.; Kanti, P.; Pappas, N.
2016-01-01
In this work, we study the propagation of scalar fields in the gravitational background of a higher-dimensional Schwarzschild-de-Sitter black hole as well as on the projected-on-the-brane 4-dimensional background. The scalar fields have also a non-minimal coupling to the corresponding, bulk or brane, scalar curvature. We perform a comprehensive study by deriving exact numerical results for the greybody factors, and study their profile in terms of particle and spacetime properties. We then pro...
International Nuclear Information System (INIS)
Chen Shiwu; Liu Xiongwei; Lin Kai; Zeng Xiaoxiong; Yang Shuzheng
2008-01-01
Hawking radiation from cosmological horizon and event horizon of the Reissner-Nordstroem de Sitter black hole with a global monopole is studied via a new method that was propounded by Robinson and Wilzek and elaborated by Banerjee and Kulkarni. The results show that the gauge current and energy-momentum tensor fluxes, which required keeping gauge covariance and general coordinate invariance at the quantum level in the effective field theory, are exactly equivalent to those of Hawking radiation from the event horizon and the cosmological horizon, respectively
Bulk and brane decay of a (4+n)-dimensional Schwarzschild-de Sitter black hole: Scalar radiation
International Nuclear Information System (INIS)
Kanti, P.; Grain, J.; Barrau, A.
2005-01-01
In this paper, we extend the idea that the spectrum of Hawking radiation can reveal valuable information on a number of parameters that characterize a particular black hole background--such as the dimensionality of spacetime and the value of coupling constants--to gain information on another important aspect: the curvature of spacetime. We investigate the emission of Hawking radiation from a D-dimensional Schwarzschild-de Sitter black hole emitted in the form of scalar fields, and employ both analytical and numerical techniques to calculate greybody factors and differential energy emission rates on the brane and in the bulk. The energy emission rate of the black hole is significantly enhanced in the high-energy regime with the number of spacelike dimensions. On the other hand, in the low-energy part of the spectrum, it is the cosmological constant that leaves a clear footprint, through a characteristic, constant emission rate of ultrasoft quanta determined by the values of black hole and cosmological horizons. Our results are applicable to 'small' black holes arising in theories with an arbitrary number and size of extra dimensions, as well as to pure 4-dimensional primordial black holes, embedded in a de Sitter spacetime
Pappas, T.; Kanti, P.; Pappas, N.
2016-07-01
In this work, we study the propagation of scalar fields in the gravitational background of a higher-dimensional Schwarzschild-de Sitter black hole as well as on the projected-on-the-brane four-dimensional background. The scalar fields have also a nonminimal coupling to the corresponding, bulk or brane, scalar curvature. We perform a comprehensive study by deriving exact numerical results for the greybody factors, and study their profile in terms of particle and spacetime properties. We then proceed to derive the Hawking radiation spectra for a higher-dimensional Schwarzschild-de Sitter black hole, and we study both bulk and brane channels. We demonstrate that the nonminimal field coupling, which creates an effective mass term for the fields, suppresses the energy emission rates while the cosmological constant assumes a dual role. By computing the relative energy rates and the total emissivity ratio for bulk and brane emission, we demonstrate that the combined effect of a large number of extra dimensions and value of the field coupling gives to the bulk channel the clear domination in the bulk-brane energy balance.
Coulomb’s law corrections and fermion field localization in a tachyonic de Sitter thick braneworld
International Nuclear Information System (INIS)
Cartas-Fuentevilla, Roberto; Escalante, Alberto; Germán, Gabriel; Herrera-Aguilar, Alfredo; Mora-Luna, Refugio Rigel
2016-01-01
Following recent studies which show that it is possible to localize gravity as well as scalar and gauge vector fields in a tachyonic de Sitter thick braneworld, we investigate the solution of the gauge hierarchy problem, the localization of fermion fields in this model, the recovering of the Coulomb law on the non-relativistic limit of the Yukawa interaction between bulk fermions and gauge bosons localized in the brane, and confront the predicted 5D corrections to the photon mass with its upper experimental/observational bounds, finding the model physically viable since it passes these tests. In order to achieve the latter aims we first consider the Yukawa interaction term between the fermionic and the tachyonic scalar fields MF(T)ΨΨ-bar in the action and analyze four distinct tachyonic functions F(T) that lead to four different structures of the respective fermionic mass spectra with different physics. In particular, localization of the massless left-chiral fermion zero mode is possible for three of these cases. We further analyze the phenomenology of these Yukawa interactions among fermion fields and gauge bosons localized on the brane and obtain the crucial and necessary information to compute the corrections to Coulomb’s law coming from massive KK vector modes in the non-relativistic limit. These corrections are exponentially suppressed due to the presence of the mass gap in the mass spectrum of the bulk gauge vector field. From our results we conclude that corrections to Coulomb’s law in the thin brane limit have the same form (up to a numerical factor) as far as the left-chiral massless fermion field is localized on the brane. Finally we compute the corrections to the Coulomb’s law for an arbitrarily thick brane scenario which can be interpreted as 5D corrections to the photon mass. By performing consistent estimations with brane phenomenology, we found that the predicted corrections to the photon mass, which are well bounded by the experimentally
Coulomb’s law corrections and fermion field localization in a tachyonic de Sitter thick braneworld
Energy Technology Data Exchange (ETDEWEB)
Cartas-Fuentevilla, Roberto; Escalante, Alberto [Instituto de Física, Benemérita Universidad Autónoma de Puebla,Apdo. postal J-48, 72570 Puebla, Pue. (Mexico); Germán, Gabriel [Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México,Apdo. Postal 48-3, 62251 Cuernavaca, Morelos (Mexico); Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road,Oxford, OX1 3NP (United Kingdom); Herrera-Aguilar, Alfredo [Instituto de Física, Benemérita Universidad Autónoma de Puebla,Apdo. postal J-48, 72570 Puebla, Pue. (Mexico); Institutode Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo,Edificio C-3, Ciudad Universitaria, CP 58040, Morelia, Michoacán (Mexico); Mora-Luna, Refugio Rigel [Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México,Apdo. Postal 48-3, 62251 Cuernavaca, Morelos (Mexico)
2016-05-11
Following recent studies which show that it is possible to localize gravity as well as scalar and gauge vector fields in a tachyonic de Sitter thick braneworld, we investigate the solution of the gauge hierarchy problem, the localization of fermion fields in this model, the recovering of the Coulomb law on the non-relativistic limit of the Yukawa interaction between bulk fermions and gauge bosons localized in the brane, and confront the predicted 5D corrections to the photon mass with its upper experimental/observational bounds, finding the model physically viable since it passes these tests. In order to achieve the latter aims we first consider the Yukawa interaction term between the fermionic and the tachyonic scalar fields MF(T)ΨΨ-bar in the action and analyze four distinct tachyonic functions F(T) that lead to four different structures of the respective fermionic mass spectra with different physics. In particular, localization of the massless left-chiral fermion zero mode is possible for three of these cases. We further analyze the phenomenology of these Yukawa interactions among fermion fields and gauge bosons localized on the brane and obtain the crucial and necessary information to compute the corrections to Coulomb’s law coming from massive KK vector modes in the non-relativistic limit. These corrections are exponentially suppressed due to the presence of the mass gap in the mass spectrum of the bulk gauge vector field. From our results we conclude that corrections to Coulomb’s law in the thin brane limit have the same form (up to a numerical factor) as far as the left-chiral massless fermion field is localized on the brane. Finally we compute the corrections to the Coulomb’s law for an arbitrarily thick brane scenario which can be interpreted as 5D corrections to the photon mass. By performing consistent estimations with brane phenomenology, we found that the predicted corrections to the photon mass, which are well bounded by the experimentally
Stuchlík, Zdeněk; Charbulák, Daniel; Schee, Jan
2018-03-01
We construct the light escape cones of isotropic spot sources of radiation residing in special classes of reference frames in the Kerr-de Sitter (KdS) black hole spacetimes, namely in the fundamental class of `non-geodesic' locally non-rotating reference frames (LNRFs), and two classes of `geodesic' frames, the radial geodesic frames (RGFs), both falling and escaping, and the frames related to the circular geodesic orbits (CGFs). We compare the cones constructed in a given position for the LNRFs, RGFs, and CGFs. We have shown that the photons locally counter-rotating relative to LNRFs with positive impact parameter and negative covariant energy are confined to the ergosphere region. Finally, we demonstrate that the light escaping cones govern the shadows of black holes located in front of a radiating screen, as seen by the observers in the considered frames. For shadows related to distant static observers the LNRFs are relevant.
Schwarzschildâde Sitter spacetime: The role of temperature in the emission of Hawking radiation
Directory of Open Access Journals (Sweden)
Thomas Pappas
2017-12-01
Full Text Available We consider a Schwarzschildâde Sitter (SdS black hole, and focus on the emission of massless scalar fields either minimally or non-minimally coupled to gravity. We use six different temperatures, two black-hole and four effective ones for the SdS spacetime, as the question of the proper temperature for such a background is still debated in the literature. We study their profiles under the variation of the cosmological constant, and derive the corresponding Hawking radiation spectra. We demonstrate that only few of these temperatures may support significant emission of radiation. We finally compute the total emissivities for each temperature, and show that the non-minimal coupling constant of the scalar field to gravity also affects the relative magnitudes of the energy emission rates.
Einstein's cosmology review of 1933: a new perspective on the Einstein-de Sitter model of the cosmos
O'Raifeartaigh, Cormac; O'Keeffe, Michael; Nahm, Werner; Mitton, Simon
2015-09-01
We present a first English translation and analysis of a little-known review of relativistic cosmology written by Albert Einstein in late 1932. The article, which was published in 1933 in a book of Einstein papers translated into French, contains a substantial review of static and dynamic relativistic models of the cosmos, culminating in a discussion of the Einstein-de Sitter model. The article offers a valuable contemporaneous insight into Einstein's cosmology in the early 1930s and confirms that his interest lay in the development of the simplest model of the cosmos that could account for observation. The article also confirms that Einstein did not believe that simplified relativistic models could give an accurate description of the early universe.
Hod, Shahar
2018-05-01
The quasinormal resonant modes of massless neutral fields in near-extremal Kerr-Newman-de Sitter black-hole spacetimes are calculated in the eikonal regime. It is explicitly proved that, in the angular momentum regime a bar >√{1 - 2 Λ bar/4 + Λ bar / 3 }, the black-hole spacetimes are characterized by slowly decaying resonant modes which are described by the compact formula ℑ ω (n) =κ+ ṡ (n + 1/2 ) [here the physical parameters { a bar ,κ+ , Λ bar , n } are respectively the dimensionless angular momentum of the black hole, its characteristic surface gravity, the dimensionless cosmological constant of the spacetime, and the integer resonance parameter]. Our results support the validity of the Penrose strong cosmic censorship conjecture in these black-hole spacetimes.
Lie-Hamilton systems on curved spaces: a geometrical approach
Herranz, Francisco J.; de Lucas, Javier; Tobolski, Mariusz
2017-12-01
A Lie-Hamilton system is a nonautonomous system of first-order ordinary differential equations describing the integral curves of a t-dependent vector field taking values in a finite-dimensional Lie algebra, a Vessiot-Guldberg Lie algebra, of Hamiltonian vector fields relative to a Poisson structure. Its general solution can be written as an autonomous function, the superposition rule, of a generic finite family of particular solutions and a set of constants. We pioneer the study of Lie-Hamilton systems on Riemannian spaces (sphere, Euclidean and hyperbolic plane), pseudo-Riemannian spaces (anti-de Sitter, de Sitter, and Minkowski spacetimes) as well as on semi-Riemannian spaces (Newtonian spacetimes). Their corresponding constants of motion and superposition rules are obtained explicitly in a geometric way. This work extends the (graded) contraction of Lie algebras to a contraction procedure for Lie algebras of vector fields, Hamiltonian functions, and related symplectic structures, invariants, and superposition rules.
The Effect of de-Sitter Like Background on Increasing the Zero Point Budget of Dark Energy
Directory of Open Access Journals (Sweden)
Haidar Sheikhahmadi
2016-01-01
Full Text Available During this work, using subtraction renormalization mechanism, zero point quantum fluctuations for bosonic scalar fields in a de-Sitter like background are investigated. By virtue of the observed value for spectral index, ns(k, for massive scalar field the best value for the first slow roll parameter, ϵ, is achieved. In addition, the energy density of vacuum quantum fluctuations for massless scalar field is obtained. The effects of these fluctuations on other components of the universe are studied. By solving the conservation equation, for some different examples, the energy density for different components of the universe is obtained. In the case which all components of the universe are in an interaction, the different dissipation functions, Q~i, are considered. The time evolution of ρDE(z/ρcri(z shows that Q~=3γH(tρm has the best agreement in comparison to observational data including CMB, BAO, and SNeIa data set.
N=4 superconformal mechanics and the potential structure of AdS spaces
International Nuclear Information System (INIS)
Donets, E.E.; Pashnev, A.I.; Tsulaya, M.M.; Rivelles, V.O.; Sorokin, D.P.
2000-01-01
The dynamics of an N=4 spinning particle in a curved background is described using the N=4 superfield formalism. The SU(2) local xSU(2) global N=4 superconformal symmetry of the particle action requires the background to be a real 'Kaehler-like' manifold whose metric is generated by a sigma-model superpotential. The anti-de-Sitter spaces are shown to belong to this class of manifolds
Some Peculiarities of Newton-Hooke Space-Times
Tian, Yu
2011-01-01
Newton-Hooke space-times are the non-relativistic limit of (anti-)de Sitter space-times. We investigate some peculiar facts about the Newton-Hooke space-times, among which the "extraordinary Newton-Hooke quantum mechanics" and the "anomalous Newton-Hooke space-times" are discussed in detail. Analysis on the Lagrangian/action formalism is performed in the discussion of the Newton-Hooke quantum mechanics, where the path integral point of view plays an important role, and the physically measurab...
Daudé, Thierry
2017-01-01
In this paper, the authors study the direct and inverse scattering theory at fixed energy for massless charged Dirac fields evolving in the exterior region of a Kerr-Newman-de Sitter black hole. In the first part, they establish the existence and asymptotic completeness of time-dependent wave operators associated to our Dirac fields. This leads to the definition of the time-dependent scattering operator that encodes the far-field behavior (with respect to a stationary observer) in the asymptotic regions of the black hole: the event and cosmological horizons. The authors also use the miraculous property (quoting Chandrasekhar)-that the Dirac equation can be separated into radial and angular ordinary differential equations-to make the link between the time-dependent scattering operator and its stationary counterpart. This leads to a nice expression of the scattering matrix at fixed energy in terms of stationary solutions of the system of separated equations. In a second part, the authors use this expression of ...
Extremal limits of the C metric: Nariai, Bertotti-Robinson, and anti-Nariai C metrics
International Nuclear Information System (INIS)
Dias, Oscar J.C.; Lemos, Jose P.S.
2003-01-01
In two previous papers we have analyzed the C metric in a background with a cosmological constant Λ, namely, the de-Sitter (dS) C metric (Λ>0), and the anti-de Sitter (AdS) C metric (Λ 0, Λ=0, and Λ 2 xS-tilde 2 ) to each point in the deformed two-sphere S-tilde 2 corresponds a dS 2 spacetime, except for one point which corresponds to a dS 2 spacetime with an infinite straight strut or string. There are other important new features that appear. One expects that the solutions found in this paper are unstable and decay into a slightly nonextreme black hole pair accelerated by a strut or by strings. Moreover, the Euclidean version of these solutions mediate the quantum process of black hole pair creation that accompanies the decay of the dS and AdS spaces
International Nuclear Information System (INIS)
Starobinskij, A.A.
1983-01-01
Spectrum of primary adiabatic perturbations and gravitational waves formed in the proposed earlier by the author nonsingular cosmological model with the initial quantum de Sitter stage generated by gravitational vacuum polarization is calculated. The spectrum of gravitational waves appears to be flat, the spectrum of adiabatic perturbations is close to the flat one. The large-scale anisotropy of the temperature T of the relic electromagnetic radiation due to these fluctuations is found. It is shown that the most promising way to detect the anisotropy in the case of a flat perturbation spectrum is the investigation of correlations of ΔT/T at the angles of 5 deg - 10 deg
De Sitter vacua in no-scale supergravities and Calabi-Yau string models
Covi, Laura; Gross, Christian; Louis, Jan; Palma, Gonzalo A; Scrucca, Claudio A
2008-01-01
We perform a general analysis on the possibility of obtaining metastable vacua with spontaneously broken N=1 supersymmetry and non-negative cosmological constant in the moduli sector of string models. More specifically, we study the condition under which the scalar partners of the Goldstino are non-tachyonic, which depends only on the Kahler potential. This condition is not only necessary but also sufficient, in the sense that all of the other scalar fields can be given arbitrarily large positive square masses if the superpotential is suitably tuned. We consider both heterotic and orientifold string compactifications in the large-volume limit and show that the no-scale property shared by these models severely restricts the allowed values for the `sGoldstino' masses in the superpotential parameter space. We find that a positive mass term may be achieved only for certain types of compactifications and specific Goldstino directions. Additionally, we show how subleading corrections to the Kahler potential which b...
de Sitter vacua in no-scale supergravities and Calabi-Yau string models
International Nuclear Information System (INIS)
Covi, L.; Gross, C.; Scrucca, C.A.
2008-04-01
We perform a general analysis on the possibility of obtaining metastable vacua with spontaneously broken N = 1 supersymmetry and non-negative cosmological constant in the moduli sector of string models. More specifically, we study the condition under which the scalar partners of the Goldstino are non-tachyonic, which depends only on the Kaehler potential. This condition is not only necessary but also sufficient, in the sense that all of the other scalar fields can be given arbitrarily large positive square masses if the superpotential is suitably tuned. We consider both heterotic and orientifold string compactifications in the large-volume limit and show that the no-scale property shared by these models severely restricts the allowed values for the 'sGoldstino' masses in the superpotential parameter space. We find that a positive mass term may be achieved only for certain types of compactifications and specific Goldstino directions. Additionally, we show how subleading corrections to the Kaehler potential which break the no-scale property may allow to lift these masses. (orig.)
Directory of Open Access Journals (Sweden)
José M. Hernández Hernández
2004-12-01
Full Text Available Se realizó estudio descriptivo prospectivo en mujeres cuidadoras de niños en el área de salud de Cabezas, provincia Matanzas, en el período octubre 2002 - marzo 2003, con el objetivo de valorar aspectos vinculados a la cultura sanitaria en relación con la salud infantil. Se aplicó una encuesta para evaluar el cuidado de la enfermedad diarreica aguda, la enfermedad respiratoria aguda, la conducta ante cuadros febriles, uso de antibióticos y otros temas. Se apreció que sólo el 30,86 % de las cuidadoras obtuvo una valoración adecuada respecto al tratamiento de estas afecciones y problemas. En la atención a la enfermedad diarreica aguda y la enfermedad respiratoria aguda se encontró un mayor nivel de conocimientos con respecto a los otros temas. La identificación de síntomas y signos de alarma ante la fiebre, la aplicación de medidas higiénicas para la prevención de la sepsis urinaria en las hembras, la ingestión de agua hervida y la atención adecuada de la fiebre, fueron las temáticas con menor dominio.A descriptive and prospective study was conducted among baby sitters in the health area of Cabezas, province of Matanzas, from October 2002 to March 2003, to assess aspects connected with the health culture in the field of children's health. A survey was done to evaluate the care of acute diarrheal disease, acute respiratory disease, the conduct followed in febrile pictures, use of antibiotics and other topics. It was found that only 30.86 % of these women had an adequate assessment concernign these affections and problems. It was observed a higher level of knowledge in the acute diarrheal disease and in the acute respiratory disease compared with other topics. The identification of symptoms and signs of alarm in the case of fever, the application of health measures for preventing urinary sepsis in the females, the ingestion of boiled water and the appropiate attention to fever were the topics with less control.
Asymptotically anti-de Sitter spacetimes and scalar fields with a logarithmic branch
International Nuclear Information System (INIS)
Henneaux, Marc; Martinez, Cristian; Troncoso, Ricardo; Zanelli, Jorge
2004-01-01
We consider a self-interacting scalar field whose mass saturates the Breitenlohner-Freedman bound, minimally coupled to Einstein gravity with a negative cosmological constant in D≥3 dimensions. It is shown that the asymptotic behavior of the metric has a slower fall-off than that of pure gravity with a localized distribution of matter, due to the back-reaction of the scalar field, which has a logarithmic branch decreasing as r -(D-1)/2 ln r for large radius r. We find the asymptotic conditions on the fields which are invariant under the same symmetry group as pure gravity with negative cosmological constant (conformal group in D-1 dimensions). The generators of the asymptotic symmetries are finite even when the logarithmic branch is considered but acquire, however, a contribution from the scalar field
Asymptotically warped anti-de Sitter spacetimes in topologically massive gravity
International Nuclear Information System (INIS)
Henneaux, Marc; Martinez, Cristian; Troncoso, Ricardo
2011-01-01
Asymptotically warped AdS spacetimes in topologically massive gravity with negative cosmological constant are considered in the case of spacelike stretched warping, where black holes have been shown to exist. We provide a set of asymptotic conditions that accommodate solutions in which the local degree of freedom (the ''massive graviton'') is switched on. An exact solution with this property is explicitly exhibited and possesses a slower falloff than the warped AdS black hole. The boundary conditions are invariant under the semidirect product of the Virasoro algebra with a u(1) current algebra. We show that the canonical generators are integrable and finite. When the graviton is not excited, our analysis is compared and contrasted with earlier results obtained through the covariant approach to conserved charges. In particular, we find agreement with the conserved charges of the warped AdS black holes as well as with the central charges in the algebra.
Thermodynamics of DBI Black Holes in Anti-de Sitter Spacetime
International Nuclear Information System (INIS)
Jia Dongyan; Yue Ruihong; Huang Shiming
2011-01-01
Through the gauge field theory, we obtain the solution of the DBI-AdS black hole. In the meantime, according to the relations between the action and the grand partition function, we obtain the grand partition function in the DBI-AdS black hole. The temperature and the potential of the DBI-AdS black hole are gained from differential of the grand partition function. With the thermodynamic relations, other thermodynamics are also obtained. The solution and the thermodynamics of the DBI-AdS black hole are turned out that they can reduce to the case of a charged black hole in four-dimensional spacetimes. (general)
Gyromagnetic ratio of charged Kerr-anti-de Sitter black holes
International Nuclear Information System (INIS)
Aliev, Alikram N
2007-01-01
We examine the gyromagnetic ratios of rotating and charged AdS black holes in four and higher spacetime dimensions. We compute the gyromagnetic ratio for Kerr-AdS black holes with an arbitrary electric charge in four dimensions and show that it corresponds to g = 2 irrespective of the AdS nature of the spacetime. We also compute the gyromagnetic ratio for Kerr-AdS black holes with a single angular momentum and with a test electric charge in all higher dimensions. The gyromagnetic ratio crucially depends on the dimensionless ratio of the rotation parameter to the curvature radius of the AdS background. At the critical limit, when the boundary Einstein universe is rotating at the speed of light, it exhibits a striking feature leading to g 2 regardless of the spacetime dimension. Next, we extend our consideration to include the exact metric for five-dimensional rotating charged black holes in minimal gauged supergravity. We show that the value of the gyromagnetic ratio found in the 'test-charge' approach remains unchanged for these black holes
Charged anti-de Sitter BTZ black holes in Maxwell-f(T) gravity
Nashed, G. G. L.; Capozziello, S.
2018-05-01
Inspired by the Bañados, Teitelboim and Zanelli (BTZ) formalism, we discuss the Maxwell-f(T) gravity in (2 + 1) dimensions. The main task is to derive exact solutions for a special form of f(T) = T + 𝜖T2, with T being the torsion scalar of Weitzenböck geometry. To this end, a triad field is applied to the equations of motion of charged f(T) and sets of circularly symmetric noncharged and charged solutions have been derived. We show that, in the charged case, the monopole-like and the ln terms are linked by a correlative constant despite the known results in teleparallel geometry and its extensions.39 Furthermore, it is possible to show that the event horizon is not identical with the Cauchy horizon due to such a constant. The singularities and the horizons of these black holes are examined: they are new and have no analogue in the literature due to the fact that their curvature singularities are soft. We calculate the energy content of these solutions by using the general vector form of the energy-momentum within the framework of f(T) gravity. Finally, some thermodynamical quantities, like entropy and Hawking temperature, are derived.
Unstable Mode Solutions to the Klein-Gordon Equation in Kerr-anti-de Sitter Spacetimes
Dold, Dominic
2017-03-01
For any cosmological constant {Λ = -3/ℓ2 r+2 > |a|ℓ}. We obtain an analogous result for Neumann boundary conditions if {5/4 < α < 9/4}. Moreover, in the Dirichlet case, one can prove that, for any Kerr-AdS spacetime violating the Hawking-Reall bound, there exists an open family of masses {α} such that the corresponding Klein-Gordon equation permits exponentially growing mode solutions. Our result adopts methods of Shlapentokh-Rothman developed in (Commun. Math. Phys. 329:859-891, 2014) and provides the first rigorous construction of a superradiant instability for negative cosmological constant.
Asymptotically spacelike warped anti-de Sitter spacetimes in generalized minimal massive gravity
International Nuclear Information System (INIS)
Setare, M R; Adami, H
2017-01-01
In this paper we show that warped AdS 3 black hole spacetime is a solution of the generalized minimal massive gravity (GMMG) and introduce suitable boundary conditions for asymptotically warped AdS 3 spacetimes. Then we find the Killing vector fields such that transformations generated by them preserve the considered boundary conditions. We calculate the conserved charges which correspond to the obtained Killing vector fields and show that the algebra of the asymptotic conserved charges is given as the semi direct product of the Virasoro algebra with U (1) current algebra. We use a particular Sugawara construction to reconstruct the conformal algebra. Thus, we are allowed to use the Cardy formula to calculate the entropy of the warped black hole. We demonstrate that the gravitational entropy of the warped black hole exactly coincides with what we obtain via Cardy’s formula. As we expect, the warped Cardy formula also gives us exactly the same result as we obtain from the usual Cardy’s formula. We calculate mass and angular momentum of the warped black hole and then check that obtained mass, angular momentum and entropy to satisfy the first law of the black hole mechanics. According to the results of this paper we believe that the dual theory of the warped AdS 3 black hole solution of GMMG is a warped CFT. (paper)
The geometry of plane waves in spaces of constant curvature
International Nuclear Information System (INIS)
Tran, H.V.
1988-01-01
We examined the geometry of possible plane wave fronts in spaces of constant curvature for three cases in which the cosmological constant is positive, zero, or negative. The cosmological constant and a second-order invariant determined by a congruence of null rays were used in the investigation. We embedded the spaces under investigation in a flat five-dimensional space, and studied the null hyperplanes passing through the origin of the flat five-dimensional space. The embedded spaces are represented by quadrics in the five-dimensional space. The plane wave fronts are represented by the intersection of the quadric with null hyperplanes passing through the origin of the five-dimensional space. We concluded that in Minkowski spaces (zero cosmological constant), the plane-fronted waves will intersect if and only if the second-order invariant mentioned above is non-zero. For deSitter spaces (positive cosmological constant), plane-fronted waves will always intersect. For anti-deSitter spaces (negative cosmological constant), plane-fronted waves may but need not intersect
Booted domain wall and charged Kaigorodov space
International Nuclear Information System (INIS)
Cai Ronggen
2003-01-01
The Kaigorodov space is a homogeneous Einstein space and it describes a pp-wave propagating in anti-de Sitter space. It is conjectured in the literature that M-theory or string theory on the Kaigorodov space times a compact manifold is dual to a conformal field theory in an infinitely-boosted frame with constant momentum density. In this Letter we present a charged generalization of the Kaigorodov space by boosting a non-extremal charged domain wall to the ultrarelativity limit where the boost velocity approaches the speed of light. The finite boost of the domain wall solution gives the charged generalization of the Carter-Novotny-Horsky metric. We study the thermodynamics associated with the charged Carter-Novotny-Horsky space and discuss its relation to that of the static black domain walls and its implications in the domain wall/QFT (quantum field theory) correspondence
Evolution from pure states into mixed states in de Sitter space
International Nuclear Information System (INIS)
Sakagami, Masa-aki.
1987-03-01
An attempt is made to clarify realization of a classical distribution from quantum fluctuations of the order parameter in the inflationary universe. We discuss destruction of quantum coherence associated with a state of the order parameter in models where it interacts with the environment. For that purpose, the time evolution of the reduced density matrix ρ tilde, which is obtained by coarse-graining of the environment, is investigated. It is shown that off-diagonal elements of ρ tilde decrease as the phase transition proceeds. (author)
Time-dependent gravitating solitons in five dimensional warped space-times
Giovannini, Massimo
2007-01-01
Time-dependent soliton solutions are explicitly derived in a five-dimensional theory endowed with one (warped) extra-dimension. Some of the obtained geometries, everywhere well defined and technically regular, smoothly interpolate between two five-dimensional anti-de Sitter space-times for fixed value of the conformal time coordinate. Time dependent solutions containing both topological and non-topological sectors are also obtained. Supplementary degrees of freedom can be also included and, in this case, the resulting multi-soliton solutions may describe time-dependent kink-antikink systems.
Nariai, Bertotti-Robinson, and anti-Nariai solutions in higher dimensions
International Nuclear Information System (INIS)
Cardoso, Vitor; Dias, Oscar J.C.; Lemos, Jose P.S.
2004-01-01
We find all higher dimensional solutions of Einstein-Maxwell theory that are the topological product of two manifolds of constant curvature. These solutions include the higher dimensional Nariai, Bertotti-Robinson and anti-Nariai solutions and the anti-de Sitter Bertotti-Robinson solutions with toroidal and hyperbolic topology (Plebanski-Hacyan solutions). We give explicit results for any dimension D≥4. These solutions are generated from the appropriate extremal limits of the higher dimensional near-extreme black holes in de Sitter and anti-de Sitter backgrounds. Thus, we also find the mass and charge parameters of higher dimensional extreme black holes as a function of the radius of the degenerate horizon
Mechanics and Newton-Cartan-like gravity on the Newton-Hooke space-time
International Nuclear Information System (INIS)
Tian Yu; Guo Hanying; Huang Chaoguang; Xu Zhan; Zhou Bin
2005-01-01
We focus on the dynamical aspects on Newton-Hooke space-time NH + mainly from the viewpoint of geometric contraction of the de Sitter spacetime with Beltrami metric. (The term spacetime is used to denote a space with non-degenerate metric, while the term space-time is used to denote a space with degenerate metric.) We first discuss the Newton-Hooke classical mechanics, especially the continuous medium mechanics, in this framework. Then, we establish a consistent theory of gravity on the Newton-Hooke space-time as a kind of Newton-Cartan-like theory, parallel to the Newton's gravity in the Galilei space-time. Finally, we give the Newton-Hooke invariant Schroedinger equation from the geometric contraction, where we can relate the conservative probability in some sense to the mass density in the Newton-Hooke continuous medium mechanics. Similar consideration may apply to the Newton-Hooke space-time NH - contracted from anti-de Sitter spacetime
Rubin, Vera C.
2010-07-01
Charlotte Moore Sitterly was a scientist in an era when it was rare for a woman to have the opportunity to devote her life to forefront science. Following her graduation from Swarthmore College in 1920, she accepted a position at Princeton University as an assistant to Henry Norris Russell. In 1925 she started a study of the solar spectrum. She could then not know that she would devote much of her scientific career to gathering basic atomic data that are invaluable to the scientific community, even today. In 1931 she obtained a Ph.D. degree at the University of California, Berkeley, and returned to Princeton as a staff member of the Princeton University Observatory. In 1945 Moore moved to the National Bureau of Standards (NBS), to supervise preparation of the widely-used tables of atomic energy levels. Following the successful launching (1946) of a V2 rocket to obtain the ultraviolet spectrum of the Sun, she started working also with Richard Tousey and his group at the Naval Research Laboratory (NRL). Ultimately, they extended the solar spectrum down to 2200 angstroms. She continued her affiliations with both the NBS and the NRL until her death in 1990. Charlotte Moore was a rare scientist who devoted her career to obtaining accurate numbers, thus enabling the scientific community to open her tables and know that the data are reliable.
Superintegrability on Three-Dimensional Riemannian and Relativistic Spaces of Constant Curvature
Directory of Open Access Journals (Sweden)
Francisco José Herranz
2006-01-01
Full Text Available A family of classical superintegrable Hamiltonians, depending on an arbitrary radial function, which are defined on the 3D spherical, Euclidean and hyperbolic spaces as well as on the (2+1D anti-de Sitter, Minkowskian and de Sitter spacetimes is constructed. Such systems admit three integrals of the motion (besides the Hamiltonian which are explicitly given in terms of ambient and geodesic polar coordinates. The resulting expressions cover the six spaces in a unified way as these are parametrized by two contraction parameters that govern the curvature and the signature of the metric on each space. Next two maximally superintegrable Hamiltonians are identified within the initial superintegrable family by finding the remaining constant of the motion. The former potential is the superposition of a (curved central harmonic oscillator with other three oscillators or centrifugal barriers (depending on each specific space, so that this generalizes the Smorodinsky-Winternitz system. The latter one is a superposition of the Kepler-Coulomb potential with another two oscillators or centrifugal barriers. As a byproduct, the Laplace-Runge-Lenz vector for these spaces is deduced. Furthermore both potentials are analysed in detail for each particular space. Some comments on their generalization to arbitrary dimension are also presented.
International Nuclear Information System (INIS)
Urano, Miho; Tomimatsu, Akira; Saida, Hiromi
2009-01-01
The mechanical first law (MFL) of black hole spacetimes is a geometrical relation which relates variations of the mass parameter and horizon area. While it is well known that the MFL of an asymptotic flat black hole is equivalent to its thermodynamical first law, however we do not know the detail of the MFL of black hole spacetimes with a cosmological constant which possess a black hole and cosmological event horizons. This paper aims to formulate an MFL of the two-horizon spacetimes. For this purpose, we try to include the effects of two horizons in the MFL. To do so, we make use of the Iyer-Wald formalism and extend it to regard the mass parameter and the cosmological constant as two independent variables which make it possible to treat the two horizons on the same footing. Our extended Iyer-Wald formalism preserves the existence of the conserved Noether current and its associated Noether charge, and gives an abstract form of the MFL of black hole spacetimes with a cosmological constant. Then, as a representative application of this formalism, we derive the MFL of the Schwarzschild-de Sitter (SdS) spacetime. Our MFL of the SdS spacetime relates the variations of three quantities: the mass parameter, the total area of the two horizons and the volume enclosed by the two horizons. If our MFL is regarded as a thermodynamical first law of the SdS spacetime, it offers a thermodynamically consistent description of the SdS black hole evaporation process: the mass decreases while the volume and the entropy increase. In our suggestion, a generalized second law is not needed to ensure the second law of SdS thermodynamics for its evaporation process.
International Nuclear Information System (INIS)
Fronsdal, C.
1987-01-01
Singletons exist, as particles and as local fields, only in 3+2 de Sitter space. Their kinematical properties make them natural candidates for constituents of massless fields, and perhaps for quarks. It is interesting to find out how to describe this type of compositeness in flat space. A theory of interacting singleton fields in de Sitter space is now available, and in this paper we study the flat-space limit of the Green's functions of that theory. The flat-space limit is an autonomous theory of Green's functions, but is not an operator field theory. The three-point function is calculated and its flat-space limit is found to reveal glimpses of a physical interpretation. Causal and spectral properties are in accord with the tenets of axiomatic field theory. The theory is a generalization of local field theory, in which photons appear as composite objects although the physical S matrix is the same as in conventional QED
U(N) instantons on N=(1/2) superspace: Exact solution and geometry of moduli space
International Nuclear Information System (INIS)
Britto, Ruth; Feng Bo; Lunin, Oleg; Rey, Soo-Jong
2004-01-01
We construct the exact solution of one (anti-)instanton in N=(1/2) super Yang-Mills theory defined on non(anti-)commutative superspace. We first identify N=(1/2) superconformal invariance as maximal spacetime symmetry. For the gauge group U(2), the SU(2) part of the solution is given by the standard (anti-)instanton, but the U(1) field strength also turns out to be nonzero. The solution is SO(4) rotationally symmetric. For the gauge group U(N), in contrast with the U(2) case, we show that the entire U(N) part of the solution is deformed by non(anti-)commutativity and fermion zero modes. The solution is no longer rotationally symmetric; it is polarized into an axially symmetric configuration because of the underlying non(anti-)commutativity. We compute the 'information metric' of one (anti-)instanton. We find that the moduli space geometry is deformed from the hyperbolic space H 5 (Euclidean anti-de Sitter space) in a way anticipated from reduced spacetime symmetry. Remarkably, the volume measure of the moduli space turns out to be independent of the non(anti-)commutativity. Implications for D branes in the Ramond-Ramond flux background and the gauge-gravity correspondence are discussed
International Nuclear Information System (INIS)
Rey, Soo-Jong; Suyama, Takao; Yamaguchi, Satoshi
2009-01-01
We study Wilson loop operators in three-dimensional, N = 6 superconformal Chern-Simons theory dual to IIA superstring theory on AdS 4 x CP 3 . Novelty of Wilson loop operators in this theory is that, for a given contour, there are two linear combinations of Wilson loop transforming oppositely under time-reversal transformation. We show that one combination is holographically dual to IIA fundamental string, while orthogonal combination is set to zero. We gather supporting evidences from detailed comparative study of generalized time-reversal transformations in both D2-brane worldvolume and ABJM theories. We then classify supersymmetric Wilson loops and find at most 1/6 supersymmetry. We next study Wilson loop expectation value in planar perturbation theory. For circular Wilson loop, we find features remarkably parallel to circular Wilson loop in N = 4 super Yang-Mills theory in four dimensions. First, all odd loop diagrams vanish identically and even loops contribute nontrivial contributions. Second, quantum corrected gauge and scalar propagators take the same form as those of N = 4 super Yang-Mills theory. Combining these results, we propose that expectation value of circular Wilson loop is given by Wilson loop expectation value in pure Chern-Simons theory times zero-dimensional Gaussian matrix model whose variance is specified by an interpolating function of 't Hooft coupling. We suggest the function interpolates smoothly between weak and strong coupling regime, offering new test ground of the AdS/CFT correspondence.
Energy Technology Data Exchange (ETDEWEB)
Anabalón, Andrés, E-mail: andres.anabalon-at@uai.cl [Departamento de Ciencias, Facultad de Artes Liberales y Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez, Viña del Mar (Chile); Astefanesei, Dumitru [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Casilla 4059, Valparaíso (Chile)
2015-03-26
We review the existence of exact hairy black holes in asymptotically flat, anti-de Sitter and de Sitter space-times. We briefly discuss the issue of stability and the charging of the black holes with a Maxwell field.
The de Finetti theorem for test spaces
International Nuclear Information System (INIS)
Barrett, Jonathan; Leifer, Matthew
2009-01-01
We prove a de Finetti theorem for exchangeable sequences of states on test spaces, where a test space is a generalization of the sample space of classical probability theory and the Hilbert space of quantum theory. The standard classical and quantum de Finetti theorems are obtained as special cases. By working in a test space framework, the common features that are responsible for the existence of these theorems are elucidated. In addition, the test space framework is general enough to imply a de Finetti theorem for classical processes. We conclude by discussing the ways in which our assumptions may fail, leading to probabilistic models that do not have a de Finetti theorem.
Gauss-Bonnet black holes in dS spaces
International Nuclear Information System (INIS)
Cai Ronggen; Guo Qi
2004-01-01
We study the thermodynamic properties associated with the black hole horizon and cosmological horizon for the Gauss-Bonnet solution in de Sitter space. When the Gauss-Bonnet coefficient is positive, a locally stable small black hole appears in the case of spacetime dimension d=5, the stable small black hole disappears, and the Gauss-Bonnet black hole is always unstable quantum mechanically when d≥6. On the other hand, the cosmological horizon is found to be always locally stable independent of the spacetime dimension. But the solution is not globally preferred; instead, the pure de Sitter space is globally preferred. When the Gauss-Bonnet coefficient is negative, there is a constraint on the value of the coefficient, beyond which the gravity theory is not well defined. As a result, there is not only an upper bound on the size of black hole horizon radius at which the black hole horizon and cosmological horizon coincide with each other, but also a lower bound depending on the Gauss-Bonnet coefficient and spacetime dimension. Within the physical phase space, the black hole horizon is always thermodynamically unstable and the cosmological horizon is always stable; furthermore, as in the case of the positive coefficient, the pure de Sitter space is still globally preferred. This result is consistent with the argument that the pure de Sitter space corresponds to an UV fixed point of dual field theory
Emergent gravity in spaces of constant curvature
Energy Technology Data Exchange (ETDEWEB)
Alvarez, Orlando; Haddad, Matthew [Department of Physics, University of Miami,1320 Campo Sano Ave, Coral Gables, FL 33146 (United States)
2017-03-07
In physical theories where the energy (action) is localized near a submanifold of a constant curvature space, there is a universal expression for the energy (or the action). We derive a multipole expansion for the energy that has a finite number of terms, and depends on intrinsic geometric invariants of the submanifold and extrinsic invariants of the embedding of the submanifold. This is the second of a pair of articles in which we try to develop a theory of emergent gravity arising from the embedding of a submanifold into an ambient space equipped with a quantum field theory. Our theoretical method requires a generalization of a formula due to by Hermann Weyl. While the first paper discussed the framework in Euclidean (Minkowski) space, here we discuss how this framework generalizes to spaces of constant sectional curvature. We focus primarily on anti de Sitter space. We then discuss how such a theory can give rise to a cosmological constant and Planck mass that are within reasonable bounds of the experimental values.
Anti-D3 branes and moduli in non-linear supergravity
Garcia del Moral, Maria P.; Parameswaran, Susha; Quiroz, Norma; Zavala, Ivonne
2017-10-01
Anti-D3 branes and non-perturbative effects in flux compactifications spontaneously break supersymmetry and stabilise moduli in a metastable de Sitter vacua. The low energy 4D effective field theory description for such models would be a supergravity theory with non-linearly realised supersymmetry. Guided by string theory modular symmetry, we compute this non-linear supergravity theory, including dependence on all bulk moduli. Using either a constrained chiral superfield or a constrained vector field, the uplifting contribution to the scalar potential from the anti-D3 brane can be parameterised either as an F-term or Fayet-Iliopoulos D-term. Using again the modular symmetry, we show that 4D non-linear supergravities that descend from string theory have an enhanced protection from quantum corrections by non-renormalisation theorems. The superpotential giving rise to metastable de Sitter vacua is robust against perturbative string-loop and α' corrections.
Quantum theory of spinor field in four-dimensional Riemannian space-time
International Nuclear Information System (INIS)
Shavokhina, N.S.
1996-01-01
The review deals with the spinor field in the four-dimensional Riemannian space-time. The field beys the Dirac-Fock-Ivanenko equation. Principles of quantization of the spinor field in the Riemannian space-time are formulated which in a particular case of the plane space-time are equivalent to the canonical rules of quantization. The formulated principles are exemplified by the De Sitter space-time. The study of quantum field theory in the De Sitter space-time is interesting because it itself leads to a method of an invariant well for plane space-time. However, the study of the quantum spinor field theory in an arbitrary Riemannian space-time allows one to take into account the influence of the external gravitational field on the quantized spinor field. 60 refs
Special Sitters: Youth as Respite Care Providers.
Edgar, Eugene B.; And Others
1988-01-01
A training program taught 120 teenage sitters child care skills identified as important by parents (N=250) of children with disabilities. Training included first aid and 15 hours of instruction emphasizing communication, responsive play, simple behavior management, handling of emergencies, and interviews with parents. The program also linked…
Vacuum polarization on black hole space times
International Nuclear Information System (INIS)
Jensen, B.P.
1985-01-01
The effects of vacuum polarization in black hole space times are examined. Particular attention is given to the vacuum physics inside the event horizon. The analytic properties of the solutions to the radial wave equation in Schwarzs child space time as functions of argument, frequency, and angular momentum are given. These functions are employed to define the Feynmann Green function (G/sub F/(x,x') for a scalar field subject to the Hartle-Hawking boundary conditions. An examination of the Schwarzschild mode functions near r = 0 is provided. This work is necessary background for a future calculation of 2 > and the quantum stress-energy tensor for small r. Some opinions are given on how this calculation might be performed. A solution of the one-loop Einstein equations for Schwarzs child Anti-deSitter (SAdS) space time is presented, using Page's approximation to the quantum stress tensor. The resulting perturbed metric is shown to be unphysical, as it leads to a system of fields with infinite total energy. This problem is believed to be due to a failure of Page's method in SAdS. Suggestions are given on how one might correct the method
Uso de los antisépticos en atención primaria
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M. Isabel Gutiérrez Pérez
2014-05-01
Otro uso de los antisépticos es el cuidado de heridas producidas por la implantación de objetos dentro de la estética corporal (piercing y similares, siendo recomendable el empleo de antisépticos transparentes que permitan observar la evolución de la técnica.
Aportaciones al estudio de la actividad antimicrobiana de los antisépticos y desinfectantes
Hernández Rodríguez, Águeda
2006-01-01
Consultable des del TDX Títol obtingut de la portada digitalitzada Las infecciones nosocomiales (IN) provocan una elevada morbilidad y mortalidad, una gran carga de trabajo para el personal y un elevado coste económico. El uso eficaz de los biocidas, antisépticos y desinfectantes, junto con la desinfección de los dispositivos médicos y de superficies, el lavado de manos y las técnicas de barrera, constituyen las medidas de prevención de dichas IN. El desarrollo de estudios sobre la acti...
Activité anti-inflammatoire de l'extrait aqueux des feuilles de Elaeis ...
African Journals Online (AJOL)
Elaeis guineensis est souvent utilisée en médecine traditionnelle africaine dans la prise en charge de nombreuses pathologies. Ces travaux avaient pour objectif de faire une étude phytochimique et de déterminer l'activité anti-inflammatoire de l'extrait aqueux des feuilles de Elaeis guineensis. Le modèle de l'œdème.
Deformed conformal and super-Poincare symmetries in the non- (anti-) commutative spaces
International Nuclear Information System (INIS)
Banerjee, R.; Lee, C.; Siwach, S.
2006-01-01
Generators of the super-Poincare algebra in the non- (anti-) commutative superspace are represented using appropriate higher derivative operators defined in this quantum superspace. Also discussed are the analogous representations of the conformal and superconformal symmetry generators in the deformed spaces. This construction is obtained by generalizing the recent work of Wess et al. on the Poincare generators in the θ-deformed Minkowski space, or by using the substitution rules we derived on the basis of the phase-space structures of non- (anti-) commutative-space variables. Even with the non-zero deformation parameters the algebras remain unchanged although the comultiplication rules are deformed. The transformation of the fields under deformed symmetry is also discussed. Our construction can be used for systematic development of field theories in the deformed spaces. (orig.)
Directory of Open Access Journals (Sweden)
Cristina Marta Del-Ben
2005-01-01
Full Text Available Nos últimos anos, tem havido um interesse crescente a respeito de uma melhor compreensão sobre o comportamento anti-social. O aumento da criminalidade e violência urbanas pode ter contribuído para esse maior interesse. Além de fatores psicossociais, outros biológicos têm sido implicados na fisiopatogenia do transtorno de personalidade anti-social (TPAS. Estudos de neuroimagem apontam o envolvimento de estruturas cerebrais frontais, especialmente o córtex orbitofrontal, e a amígdala. Também tem sido sugerido que prejuízos na função serotonérgica estariam associados à ocorrência de comportamento anti-social, já que pacientes com diagnóstico de TPAS apresentam respostas hormonais atenuadas a desafios farmacológicos com drogas que aumentam a função serotonérgica cerebral e redução da concentração de receptores serotonérgicos. Uma abordagem ampla dos diferentes fatores possivelmente envolvidos na fisiopatogenia do TPAS poderia contribuir para o desenvolvimento de novas técnicas de prevenção e intervenção.Violence and crime have been increasing considerably in urban societies. As a consequence, some efforts have been made aiming at a better understanding of antisocial bevaviour. Apart from psychosocial factors, some evidences suggest the occurrence of biological factors in the pathogenesis of antisocial personality disorders (ASPD. Neuroimaging studies have shown the involvement of prefrontal areas, especially orbitofrontal cortex, and amygdala. Also, impaired serotonin (5-HT neurotransmission has been implicated, since patients with ASPD present alterations in measures of 5-Ht system, such as blunted hormonal response to 5-HT pharmacological challenges and reduced 5-HT receptors numbers. A comprehensive approach of antisocial behavior, including biological and psychosocial aspects could lead to the development of new techniques for prevention and intervention in ASPD.
Thermodynamic instability of charged dilaton black holes in AdS spaces
International Nuclear Information System (INIS)
Sheykhi, A.; Dehghani, M. H.; Hendi, S. H.
2010-01-01
We study thermodynamic instability of a class of (n+1)-dimensional charged dilatonic spherically symmetric black holes in the background of the anti-de Sitter universe. We calculate the quasilocal mass of the anti-de Sitter dilaton black hole through the use of the subtraction method of Brown and York. We find a Smarr-type formula and perform a stability analysis in the canonical ensemble and disclose the effect of the dilaton field on the thermal stability of the solutions. Our study shows that the solutions are thermally stable for small α, while for large α the system has an unstable phase, where α is a coupling constant between the dilaton and matter field.
Enjuagues de Calendula officinalis como alternativa de los antisépticos orales
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Luis Fang Mercado
Full Text Available En la progresión de la enfermedad periodontal intervienen múltiples factores, incluyendo los diversos microorganismos orales que conforman la placa bacteriana o patógenos libres en cavidad oral que logran desencadenar una respuesta inmunológica e inflamatoria en el huésped. Existen herramientas químicas que combaten cualquier posibilidad de colonización e infección por parte de algún microorganismo. Los antisépticos orales son de gran utilidad especialmente luego de cirugías periodontales. Es allí donde su importancia se hace casi imprescindible, para controlar la noxa, pero a su vez deben facilitar el proceso de cicatrización de los tejidos involucrados. El objetivo del presente manuscrito consistió en reportar y describir un caso clínico donde el empleo de clorhexidina al 0,12 % como antiséptico oral postoperatorio no favoreció la cicatrización adecuada de los tejidos mucosos luego de realizarse un injerto gingival libre. Como alternativa antiséptica se prescribieron enjuagues a base de Caléndula, observándose cicatrización de los tejidos afectados a los pocos días de uso. Se discute que posterior a todo proceso operatorio de carácter quirúrgico se debe colocar en una balanza riesgo-beneficio, donde se escoge la posibilidad de evitar la infección posoperatoria o la cicatrización oportuna de esta. Los enjuagues orales de caléndula permitieron la cicatrización oportuna; los colutorios de caléndula contemplan una pequeña proporción de capacidad antimicrobiana y una alta habilidad inductora de la cicatrización tisular.
Deng, Gao-Ming; Huang, Yong-Chang
2018-03-01
The geodesics of tunneling particles were derived unnaturally and awkwardly in previous works. For one thing, the previous derivation was inconsistent with the variational principle of action. Moreover, the definition of geodesic equations for massive particles was quite different from that of massless case. Even worse, the relativistic and nonrelativistic foundations were mixed with each other during the past derivation of geodesics. As a highlight, remedying the urgent shortcomings, we improve treatment to derive the geodesic equations of massive and massless particles in a unified and self-consistent way. Besides, we extend to investigate the Hawking radiation via tunneling from Reissner-Nordström black holes in the context of AdS spacetime. Of special interest, the trick of utilizing the first law of black hole thermodynamics manifestly simplifies the calculation of tunneling integration.
Newton's law in de Sitter brane
International Nuclear Information System (INIS)
Ghoroku, Kazuo; Nakamura, Akihiro; Yahiro, Masanobu
2003-01-01
Newton potential has been evaluated for the case of dS brane embedded in Minkowski, dS 5 and AdS 5 bulks. We point out that only the AdS 5 bulk might be consistent with the Newton's law from the brane-world viewpoint when we respect a small cosmological constant observed at present universe
De Sitter vacua of strongly interacting QFT
Energy Technology Data Exchange (ETDEWEB)
Buchel, Alex [Department of Applied Mathematics, University of Western Ontario,London, Ontario N6A 5B7 (Canada); Department of Physics and Astronomy, University of Western Ontario,London, Ontario N6A 5B7 (Canada); Perimeter Institute for Theoretical Physics,Waterloo, Ontario N2J 2W9 (Canada); Karapetyan, Aleksandr [Department of Applied Mathematics, University of Western Ontario,London, Ontario N6A 5B7 (Canada)
2017-03-22
We use holographic correspondence to argue that Euclidean (Bunch-Davies) vacuum is a late-time attractor of the dynamical evolution of quantum gauge theories at strong coupling. The Bunch-Davies vacuum is not an adiabatic state, if the gauge theory is non-conformal — the comoving entropy production rate is nonzero. Using the N=2{sup ∗} gauge theory holography, we explore prospects of explaining current accelerated expansion of the Universe as due to the vacuum energy of a strongly coupled QFT.
Higgs instability and de Sitter radiation
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Gaurav Goswami
2015-12-01
Full Text Available If the Standard Model (SM of elementary particle physics is assumed to hold good to arbitrarily high energies, then, for the best fit values of the parameters, the scalar potential of the Standard Model Higgs field turns negative at a high scale μinst. If the physics beyond the SM is such that it does not modify this feature of the Higgs potential and if the Hubble parameter during inflation (Hinf is such that Hinf≫μinst, then, quantum fluctuations of the SM Higgs during inflation make it extremely unlikely that after inflation it will be found in the metastable vacuum at the weak scale. In this work, we assume that (i during inflation, the SM Higgs is in Bunch–Davies vacuum state, and, (ii the question about the stability of the effective potential must be answered in the frame of the freely falling observer (just like in Minkowski spacetime, and then use the well-known fact that the freely falling observer finds Bunch–Davies vacuum to be in thermal state to show that the probability to end up in the electroweak vacuum after inflation is reasonably high.
International Nuclear Information System (INIS)
Villasenor, R.F.; Bonilla, J.L.L.; Zuniga, G.O.; Matos, T.
1989-01-01
The authors study space-times embedded in E 5 (that means, pseudo-euclidean five-dimensional spaces) in the intrinsic rigidity case, i.e., when the second fundamental form b if can be determined by the internal geometry of the four-dimensional Riemannian space R 4 . They write down the Gauss and Codazzi equations determining the local isometric embedding of R 4 in E 5 and give some consequences of it. They prove that when there exists intrinsic rigidity, then b if is a linear combination of the metric and Ricci tensor; it is given some applications for the de Sitter and Einstein models
Fan, Xiaoqiang; Wang, Liping
2015-07-01
Multialkylated cyclopentanes (MACs), a class of synthetic hydrocarbon fluid have attracted intensive interest as possible space lubricants due to a series of unique physical and chemical properties. Here, we used graphene with high mechanical strength and chemical inertness as lubricant additive to explore its potential for space application. The effects of space irradiation on graphene and the tribological properties of graphene as lubricant additive were firstly investigated in detail under simulated space environment composed of high vacuum, high/low temperature and irradiation. Results demonstrate that graphene not only possesses outstanding anti-irradiation capacity but also significantly improves the space performance and tribological properties of MACs, which depends on the excellent physicochemical properties and high load-carrying ability of graphene as well as more effective separation of the sliding surfaces.
An alternative path to the boundary: The CFT as the Fourier space of AdS
Tolfree, Ian M.
2009-12-01
In this thesis we shed new light on the conjectured duality between an n + 1 dimensional theory of gravity in anti de Sitter space (AdS) and an n dimensional conformal field theory (CFT) by showing that the CFT can be interpreted as the Fourier space of AdS. We then make use of this to gain insight into the nature of black hole entropy. In the first part of this thesis, we give an introduction to the ideas of and review the basics of the AdS/CFT. In the next section we make use of well known integral geometry techniques to derive the Fourier transformation of a function on AdS and see it is a function with compact support on the boundary. Comparing this to the literature, we find that the Green's functions from the literature are actually the Fourier weights of the transformation and that the boundary values of fields appearing in the correspondence are the Fourier coefficients of the transformation. One is thus left to interpret the CFT as the quantized version of a classical theory in AdS and the dual operator as the Fourier coefficients. Group theoretic considerations are discussed in relation to the transformation and its potential use in constructing QCD like theories. In the last section, we then build upon this to study the BTZ black hole. Named after its authors, Banados, Teitelboim and Zanelli, the BTZ black hole is a three dimensional (two space plus one time dimension) black hole in anti de Sitter space. Following standard procedures for modifying Fourier Transformations to accommodate quotient spaces we arrive at a mapping in a black hole background consistent with known results that yields the exact micro-states of a scalar field in a black hole background. We find that the micro-states are the Fourier coefficients on the boundary, which transform under the principal series representation of SL(2, R). Using the knowledge of how to represent a bulk scalar field in the CFT, and knowing how a black hole interacts with a scalar field, we deduce the
Asymptotic symmetries of Rindler space at the horizon and null infinity
International Nuclear Information System (INIS)
Chung, Hyeyoun
2010-01-01
We investigate the asymptotic symmetries of Rindler space at null infinity and at the event horizon using both systematic and ad hoc methods. We find that the approaches that yield infinite-dimensional asymptotic symmetry algebras in the case of anti-de Sitter and flat spaces only give a finite-dimensional algebra for Rindler space at null infinity. We calculate the charges corresponding to these symmetries and confirm that they are finite, conserved, and integrable, and that the algebra of charges gives a representation of the asymptotic symmetry algebra. We also use relaxed boundary conditions to find infinite-dimensional asymptotic symmetry algebras for Rindler space at null infinity and at the event horizon. We compute the charges corresponding to these symmetries and confirm that they are finite and integrable. We also determine sufficient conditions for the charges to be conserved on-shell, and for the charge algebra to give a representation of the asymptotic symmetry algebra. In all cases, we find that the central extension of the charge algebra is trivial.
Calvo Aurrekoetxea, Josu
2017-01-01
En este Trabajo Fin de Grado se hace un estudio de la Teoría de la Inflación Cósmica como solución de los problemas de la teoría del Big Bang a partir del acoplo gravitatorio de un campo escalar. Además, se analizan potenciales con mínimos con constante cosmológica positiva de Sitter (dS), negativa Anti-de Sitter (AdS) y las transiciones cosmológicas entre ellos. Por último, se presenta un modelo dS-dS para el cual el escenario final es una región con multiples universos inflacionarios; pudie...
D-particle Recoil Space Times and "Glueball" Masses
Mavromatos, Nikolaos E; Mavromatos, Nick E.; Winstanley, Elizabeth
2001-01-01
We discuss the properties of matter in a D-dimensional anti-de-Sitter-type space time induced dynamically by the recoil of a very heavy D(irichlet)-particle defect embedded in it. The particular form of the recoil geometry, which from a world-sheet view point follows from logarithmic conformal field theory deformations of the pertinent sigma-models, results in the presence of both infrared and ultraviolet (spatial) cut-offs. These are crucial in ensuring the presence of mass gaps in scalar matter propagating in the D-particle recoil space time. The analogy of this problem with the Liouville-string approach to QCD, suggested earlier by John Ellis and one of the present authors, prompts us to identify the resulting scalar masses with those obtained in the supergravity approach based on the Maldacena's conjecture, but without the imposition of any supersymmetry in our case. Within reasonable numerical uncertainties, we observe that agreement is obtained between the two approaches for a particular value of the ra...
Determinación de anticuerpos anti Neospora caninum en vacas de la provincia de Sugamuxi, Colombia
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Martín Orlando Pulido Medellín
2013-01-01
Full Text Available El objetivo fue determinar la presencia de anticuerpos anti Neospora caninum en vacas mediante la técnica de ELISA indirecta en el valle de Sugamuxi, Colombia, identificando las variables que influyen en la susceptibilidad de los bovinos al protozoo. Se tomaron muestras de sangre a 400 hembras bovinas y fueron evaluadas por medio de ELISA indirecta. Se determinó una seroprevalencia de Neospora caninum del 57.5 %; no se halló relación entre las hembras en gestación y la presencia del parásito; para la presencia de celo se encontró que el 27.7 % de vacas infectadas por el parásito presentaron repetición de éste. La presencia del parásito fue del 100 % en hembras con historial de cinco partos. Los resultados de este estudio muestran la presencia de anticuerpos anti Neospora caninum en los animales pertenecientes a fincas lecheras de la provincia de Sugamuxi, y la alta prevalencia muestra el riesgo potencial para este tipo de explotaciones.
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Guillermo Mora
2007-12-01
Conclusiones. La prevalencia de anticuerpos anti-T. cruzi en pacientes portadores de marcapaso es alta. La implantación de marcapasos se presentó más tempranamente en el grupo seropositivo. No hay adecuada sospecha clínica ni información al paciente sobre el diagnóstico de la enfermedad de Chagas.
Chen, Long; Zhang, Yidu; Wu, Qiong; Jie, Zhang
2018-02-01
A graphene coating anti-/de-icing experiment was proposed by employing water-borne and oily graphene coatings on the composite material anti-/de-icing component. Considering the characteristics of helicopter rotor sensitivity to icing, a new graphene coating enhancing thermal conductivity of anti-/de-icing component was proposed. The anti-/de-icing experiment was conducted to validate the effectiveness of graphene coating. The results of the experiment show that the graphene coatings play a prominent role in controlling the heat transfer of anti-/de-icing component. The anti-/de-icing effect of oily graphene coating is superior to water-borne graphene.
CONHECIMENTO DE GESTANTES SOBRE O EXAME ANTI-HIV NO PRÉ-NATAL
KARLA DE ABREU PEIXOTO MOREIRA; LÍGIA DE OLIVEIRA BRAGA; ÂNGELA MARIA LEAL DE MORAES VIEIRA; MARIA VERACI OLIVEIRA QUEIROZ
2006-01-01
La epidemia de SIDA afecta cada vez más a las mujeres en edad fértil. La realización del examen anti-VIH durante el prenatal es una importante estrategia para reducir la morbio mortalidad por esta causa. El objetivo planteado fue el de investigar el nivel de conocimiento de las embarazadas cuanto a la importancia de la realización del examen anti-VIH en el prenatal. Estudio descriptivo con 50 embarazadas mayores de 18 años, que realizaban prenatal de bajo riesgo en consulta subsiguiente sin d...
ELISA indireto para detecção de Ig G anti-vírus da doença de newcastle em soro de codorna
Daniela Duarte de Oliveira
2004-01-01
Foram desenvolvidos e comparados dois ELISAs para detecção de IgG de codorna (Coturnix coturnix japônica) contra o vírus da doença de Newcastle (VDN). Um deles utilizando anticorpo secundário de camundongo anti-IgG de codorna e o outro, conjugado anti-IgG de galinha. Para a produção de anticorpo secundário (IgG de camundongo anti-IgG de codorna), métodos de purificação de IgG de codorna foram avaliados utilizando 30 amostras de soros e gemas de ovos de codornas, confirmados posteriormente por...
On the Gauss Map of Surfaces of Revolution with Lightlike Axis in Minkowski 3-Space
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Minghao Jin
2013-01-01
Full Text Available By studying the Gauss map G and Laplace operator Δh of the second fundamental form h, we will classify surfaces of revolution with a lightlike axis in 3-dimensional Minkowski space and also obtain the surface of Enneper of the 2nd kind, the surface of Enneper of the 3rd kind, the de Sitter pseudosphere, and the hyperbolic pseudosphere that satisfy condition ΔhG=ΛG, Λ being a 3×3 real matrix.
Charlotte Moore Sitterly: A Life of Spectroscopy
Rubin, Vera C.
2010-01-01
Dr. Charlotte Moore Sitterly was a scientist in an era when it was rare for a woman to have the opportunity to devote her life to forefront science. Following her graduation from Swarthmore College in 1920, she accepted a position at Princeton University as an assistant to Henry Norris Russell. In 1925 she started a study of the solar spectrum. She could then not know that she would devote much of her scientific career to gathering basic atomic data that are invaluable to the scientific community, even today. In 1931 she obtained a PhD degree at U. California, Berkeley, and returned to Princeton as a staff member of the Princeton University Observatory. In 1945 she moved to the National Bureau of Science (NBS), to supervise preparation of the widely used tables of atomic energy levels. Following the successful lunching (1946) of a V2 rocket to obtain the ultra violet spectrum of the sun, Moore started working with Richard Tousey and his group at the Naval Research Laboratory (NRL). Ultimately, they extended the solar spectrum down to 2200 angstroms. She continued her affiliations with NBS and NRL until her death in 1990. Charlotte Moore was rare scientist who devoted her career to obtaining accurate numbers, thus enabling the scientific community to open her tables and know that the data are accurate.
México, ejemplo de las politicas anti-desarrollo del Consenso de Washington
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Arturo Guillén
2012-08-01
Full Text Available A partir de los avances logrados por el "nuevo-desarrollismo", examina las políticas macroeconómicas implementadas en México en el contexto del Consenso de Washington, la cuales en el caso mexicano fueron institucionalizadas con la firma del Tratado de Libre Comercio de América del Norte (TLCAN. Este tratado consolidó el modelo neoliberal y aherrojó la suerte de la economía mexicana al desempeño de la economía de Estados Unidos. Se analiza la economía mexicana como un caso paradigmático de los efectos anti-crecimiento, de desarticulación de los sistemas productivos y desestabilizadores de las políticas procíclicas inspiradas en el Consenso de Washington. Se concluye que los principales obstáculos para implementar una estrategia alternativa de desarrollo en México, orientada al crecimiento sustentable con equidad, son políticos y residen en la dominación del poder político por una oligarquía financiera rentista que carece de todo idea de proyecto nacional,A partir dos avanços conseguidos pelo "novo-desenvolvimentismo", o artigo examina as políticas macroeconômicas implementadas no México no contexto do Consenso de Washington, as quais, no caso mexicano, foram institucionalizadas com a assinatura do Tratado de Livre Comércio de América do Norte (TLCAN. Este tratado consolidou o modelo neoliberal e agrilhoou a sorte da economia mexicana ao desempenho da economia dos Estados Unidos. No artigo, a economia mexicana analisa-se como um caso paradigmático dos efeitos anticrescimento, de desarticulação dos sistemas produtivos e desestabilizadores das políticas pró-cíclicas inspiradas no Consenso de Washington. Conclui-se que os principais obstáculos para levar à prática uma estratégia alternativa de desenvolvimento no México, orientada ao crescimento sustentável com equidade, são políticos e residem na dominação do poder político por uma oligarquia financeira rentista que carece de qualquer ideia de projeto
Santos, Paola; López-Vallejo, Fabian; Soto, Carlos-Y
2017-08-01
Tuberculosis (TB) is one of the most important public health problems around the world. The emergence of multi-drug-resistant (MDR) and extensively drug-resistant (XDR) Mycobacterium tuberculosis strains has driven the finding of alternative anti-TB targets. In this context, P-type ATPases are interesting therapeutic targets due to their key role in ion homeostasis across the plasma membrane and the mycobacterial survival inside macrophages. In this review, in silico and experimental strategies used for the rational design of new anti-TB drugs are presented; in addition, the chemical space distribution based on the structure and molecular properties of compounds with anti-TB and anti-P-type ATPase activity is discussed. The chemical space distribution compared to public compound libraries demonstrates that natural product libraries are a source of novel chemical scaffolds with potential anti-P-type ATPase activity. Furthermore, compounds that experimentally display anti-P-type ATPase activity belong to a chemical space of molecular properties comparable to that occupied by those approved for oral use, suggesting that these kinds of molecules have a good pharmacokinetic profile (drug-like) for evaluation as potential anti-TB drugs. © 2017 John Wiley & Sons A/S.
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Lucienir Pains DUARTE
2002-04-01
Full Text Available Four pentacyclic triterpenes isolated from Austroplenckia populnea and four compounds of known anti T. cruzi or anti-malarial activity were tested. Of those triterpenes tested 20alpha-hydroxy-tingenone showed high activity, epikatonic acid was less active, while populnilic and populninic acids were inactive against the trypanosome of the subgenus Schizotrypanum tested. Benzonidazole, nifurtimox, ketoconazole and primaquine presented a remarkable dose-dependent inhibitory effect reaching practically to a total growth inhibition of the parasite at the end of incubation time. The trypanosome tested appear to be a suitable model for preliminary screen for anti T. (S. cruzi compounds.Foram testados quatro triterpenos pentacíclicos isolados de Austroplenckia populnea e quatro compostos de conhecida atividade anti-T. cruzi ou anti-malárica. Dos triterpenos testados 20alfa-hidroxi-tingenona mostrou atividade elevada, ácido epicatônico foi menos ativo, enquanto ácido populnílico e populnínico foram inativos contra o tripanossoma do subgênero Schizotrypanum testado. Benzonidazole, nifurtimox, cetoconazole e primaquina apresentaram efeito inibitório dose-dependente atingindo praticamente a inibição total do crescimento do parasita no final do tempo de incubação. O tripanossoma testado mostrou ser um modelo adequado para uma seleção preliminar de compostos anti. T. (S. cruzi.
Perfil lipídico e uso de anti-TNF-α
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Antonio Carlos Ferraz Filho
2013-10-01
Full Text Available O uso do anti-TNF alfa tem sido associado a várias alterações no perfil lipídico, embora o estudo dessas alterações tenha gerado resultados que ainda são conflitantes. O conhecimento desse fato é de grande importância quando se observa a associação entre doenças reumáticas e aterogenêse acelerada. Esta pesquisa foi feita com o intuito de verificar alterações no perfil lipídico de usuários de anti-TNF-α na população do sul do Brasil e sua associação com tempo de uso, indicações, gênero do paciente e tipo de anti-TNF. Para tanto, analisaram-se os perfis de colesterol total (TC, HDL colesterol (HDLc, LDL colesterol (LDLc, índice aterogênico (IAT e triglicerídeos (TGs de 58 pacientes (42 com artrite reumatoide e 16 com espondiloartrites antes e depois do uso desse medicamento por um tempo mediano de 16,0 meses. Não se observaram alterações nos níveis de CT, HDLc, LDLc e IAT (P = NS. Todavia, houve um aumento significativo nos níveis de TGs (P = 0,03. A diferença mediana dos valores de TGs entre primeira e segunda medidas foi de 16 mg/dL, e esse aumento não estava associado ao gênero do paciente, tempo de uso, indicação de uso ou tipo de anti-TNF-α (P = NS. Concluiu-se que o uso de anti TNF-α está associado com aumento nos valores de TGs.
International Nuclear Information System (INIS)
Burdík, C; Reshetnyak, A
2012-01-01
We derive non-linear commutator HS symmetry algebra, which encode unitary irreducible representations of AdS group subject to Young tableaux Y(s 1 ,..., s k ) with κ ≥ 2 rows on d-dimensional anti-de-Sitter space. Auxiliary representations for specially deformed non-linear HS symmetry algebra in terms of generalized Verma module in order to additively convert a subsystem of second-class constraints in the HS symmetry algebra into one with first-class constraints are found explicitly for the case of HS fields for κ = 2 Young tableaux. The oscillator realization over Heisenberg algebra for obtained Verma module is constructed. The results generalize the method of auxiliary representations construction for symplectic sp(2κ) algebra used for mixed-symmetry HS fields on a flat spaces and can be extended on a case of arbitrary HS fields in AdS-space. Gauge-invariant unconstrained reducible Lagrangian formulation for free bosonic HS fields with generalized spin (s 1 , s 2 ) is derived.
Anti-hierarchical evolution of the active galactic nucleus space density in a hierarchical universe
International Nuclear Information System (INIS)
Enoki, Motohiro; Ishiyama, Tomoaki; Kobayashi, Masakazu A. R.; Nagashima, Masahiro
2014-01-01
Recent observations show that the space density of luminous active galactic nuclei (AGNs) peaks at higher redshifts than that of faint AGNs. This downsizing trend in the AGN evolution seems to be contradictory to the hierarchical structure formation scenario. In this study, we present the AGN space density evolution predicted by a semi-analytic model of galaxy and AGN formation based on the hierarchical structure formation scenario. We demonstrate that our model can reproduce the downsizing trend of the AGN space density evolution. The reason for the downsizing trend in our model is a combination of the cold gas depletion as a consequence of star formation, the gas cooling suppression in massive halos, and the AGN lifetime scaling with the dynamical timescale. We assume that a major merger of galaxies causes a starburst, spheroid formation, and cold gas accretion onto a supermassive black hole (SMBH). We also assume that this cold gas accretion triggers AGN activity. Since the cold gas is mainly depleted by star formation and gas cooling is suppressed in massive dark halos, the amount of cold gas accreted onto SMBHs decreases with cosmic time. Moreover, AGN lifetime increases with cosmic time. Thus, at low redshifts, major mergers do not always lead to luminous AGNs. Because the luminosity of AGNs is correlated with the mass of accreted gas onto SMBHs, the space density of luminous AGNs decreases more quickly than that of faint AGNs. We conclude that the anti-hierarchical evolution of the AGN space density is not contradictory to the hierarchical structure formation scenario.
Anti-hierarchical evolution of the active galactic nucleus space density in a hierarchical universe
Energy Technology Data Exchange (ETDEWEB)
Enoki, Motohiro [Faculty of Business Administration, Tokyo Keizai University, Kokubunji, Tokyo 185-8502 (Japan); Ishiyama, Tomoaki [Center for Computational Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan); Kobayashi, Masakazu A. R. [Research Center for Space and Cosmic Evolution, Ehime University, Matsuyama, Ehime 790-8577 (Japan); Nagashima, Masahiro, E-mail: enokimt@tku.ac.jp [Faculty of Education, Nagasaki University, Nagasaki, Nagasaki 852-8521 (Japan)
2014-10-10
Recent observations show that the space density of luminous active galactic nuclei (AGNs) peaks at higher redshifts than that of faint AGNs. This downsizing trend in the AGN evolution seems to be contradictory to the hierarchical structure formation scenario. In this study, we present the AGN space density evolution predicted by a semi-analytic model of galaxy and AGN formation based on the hierarchical structure formation scenario. We demonstrate that our model can reproduce the downsizing trend of the AGN space density evolution. The reason for the downsizing trend in our model is a combination of the cold gas depletion as a consequence of star formation, the gas cooling suppression in massive halos, and the AGN lifetime scaling with the dynamical timescale. We assume that a major merger of galaxies causes a starburst, spheroid formation, and cold gas accretion onto a supermassive black hole (SMBH). We also assume that this cold gas accretion triggers AGN activity. Since the cold gas is mainly depleted by star formation and gas cooling is suppressed in massive dark halos, the amount of cold gas accreted onto SMBHs decreases with cosmic time. Moreover, AGN lifetime increases with cosmic time. Thus, at low redshifts, major mergers do not always lead to luminous AGNs. Because the luminosity of AGNs is correlated with the mass of accreted gas onto SMBHs, the space density of luminous AGNs decreases more quickly than that of faint AGNs. We conclude that the anti-hierarchical evolution of the AGN space density is not contradictory to the hierarchical structure formation scenario.
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Juan Rojas
2010-07-01
Full Text Available Objetivos: Determinar la actividad anti Trypanosoma cruzi in vitro de los aceites esenciales de 10 plantas medicinales. Además, determinar la actividad citotóxica de los aceites contra células de mamíferos y la actividad modulatoria de los aceites sobre el óxido nítrico. Diseño: Estudio experimental in vitro. Institución: Instituto de Investigaciones Clínicas e Instituto de Medicina Tropical, Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Perú. Material biológico: Epimastigotes de Trypanosoma cruzi, células Raw 264.7, aceites esenciales de Mentha X piperita L (menta, Rosmarinus officinalis L (romero, Chenopodium ambrosioides L (paico, Eucaliptus globulus Labill (eucalipto, Artemisia absinthium L (ajenjo, Melissa officinalis L (toronjil, Minthostachys setosa Brig (muña, Cimbopogon citratus (hierba luisa, Aloysia triphylla (cedrón y Mentha spicata L (hierba buena. Método: La actividad tripanocida se evaluó contra epimastigotes cultivados en medio LIT, incubados por 48 horas a 37ºC en incubador humidificado con CO2 al 5%. El cristal violeta se utilizó como control positivo. La actividad citotóxica de los productos contra células mamíferas se evaluó en células RAW 264.7 y la actividad modulatoria de los compuestos sobre óxido nítrico también se determinó en los cultivos de células RAW 264.7. Principales medidas de resultados: Porcentaje de inhibición de viabilidad y CI50. Resultados: Los aceites esenciales de Cymbopogon citratus (hierba luisa y Aloysia triphylla (cedrón inhibieron significativamente el crecimiento de la forma epimastigote de T. cruzi, con una CI50 de 63,09 y 96,49 μg/mL, respectivamente. No hubo variaciσn significativa de la concentraciσn de óxido nítrico y tampoco se evidenció citotoxicidad. Conclusiones: Los aceites esenciales de Cymbopogon citratus y Aloysia triphylla mostraron actividad anti-Trypanosoma cruzi in vitro y no fueron citotóxicas para las células mamíferas.
Seroprevalence des anticorps anti-HBc chez les donneurs de sang ...
African Journals Online (AJOL)
'hépatite virale demeure une priorité pour les centres de qualification des produits sanguins labiles au Togo. Objectif: Déterminer la séroprévalence des anticorps anti-HBc au sein des donneurs de sang en vue d'estimer le niveau de risque ...
Anuncian primera produccion controlada de anti-atomos frios
2002-01-01
"Un equipo internacional que trabaja con el desacelerador de antiprotones del CERN, en Ginebra, ha conseguido la primera produccion controlada de miles de atomos de hidrogeno de baja energia, lo que facilitara en el futuro los analisis de precision en varias disciplinas cientificas" (1 page).
Consistent Lorentz violation in flat and curved space
International Nuclear Information System (INIS)
Dvali, Gia; Pujolas, Oriol; Redi, Michele
2007-01-01
Motivated by the severity of the bounds on Lorentz violation in the presence of ordinary gravity, we study frameworks in which Lorentz violation does not affect the spacetime geometry. We show that there are at least two inequivalent classes of spontaneous Lorentz breaking that even in the presence of gravity result in Minkowski space. The first one generically corresponds to the condensation of tensor fields with tachyonic mass, which in turn is related to ghost condensation. In the second class, realized by the Dvali-Gabadadze-Porrati model or theories of massive gravitons, spontaneous Lorentz breaking is induced by the expectation value of sources. The generalization to de Sitter space is also discussed
Mannheim Curves in Nonflat 3-Dimensional Space Forms
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Wenjing Zhao
2015-01-01
Full Text Available We consider the Mannheim curves in nonflat 3-dimensional space forms (Riemannian or Lorentzian and we give the concept of Mannheim curves. In addition, we investigate the properties of nonnull Mannheim curves and their partner curves. We come to the conclusion that a necessary and sufficient condition is that a linear relationship with constant coefficients will exist between the curvature and the torsion of the given original curves. In the case of null curve, we reveal that there are no null Mannheim curves in the 3-dimensional de Sitter space.
Aglutinina anti-T (Thomsen-Friedenreich na doença de Chagas
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Marcos Palatnik
1986-10-01
Full Text Available Uma amostra de soros de pacientes e controles de uma área endêmica da Doença de Chagas do País foi titulada contra hemácias de grupo O tratadas pela neuraminidase (células OT ativadas e hemacias normais de grupo A e B (sistema ABO. Também foram feitos alguns testes de aglutinação de hemácias de pacientes com cardiomiopatia com as lectinas de amendoim (anti-T + anti-Tk e com anticorpo humano anti-T. O escore médio da aglutinina anti-T dos pacientes foi similar ao do grupo controle. En- tretanto, o escore médio dos indivíduos com a forma cardíaca íoi significantemente maior que o dos pacientes assintomáticos e também maior que o do grupo controle. A comparação entre indivíduos com sorologia diagnóstica positiva versus negativa foi não significante. Nem a sorologia para Chagas nem as variáveis raça, sexo, idade, idade ao quadrado, in-fecção intestinal parasitária, teor de proteínas do soro, volume globular eritrocitário (hema-tócrito, grau de palidez da mucosa bucal, cardíomiopatia e os termos de interação sexo x idade, sexo x idade ao quadrado, estão associados significativamente com o logaritmo do título ou com o logaritmo do escore de aglutinação. Os escores de aglutinação das aglutininas anti-A e anti-B do sistema de grupo sangüíneo ABO estão dentro da faixa de variação normal. As hemácias de pacientes com a forma cardíaca não são aglutinadas nem pelas lectinas de amendoim (antiT + anti-Tk e da soja (anti-T nem pela aglutinina anti-T de origem humana. A prova de Coombs direta foi negativa em todos os pacientes, demonstrando a aparente ausência de imunoglobulinas IgG e IgM na superfície eritrocitária. O fato de que o aumento dos níveis de anti-T só foi detectado em uma das formas clínicas da doença em pacientes da mesma área endêmica constitui um argumento contra a possibilidade de que a variação observada seja produzida por uma infecção concomitante.
CONHECIMENTO DE GESTANTES SOBRE O EXAME ANTI-HIV NO PRÉ-NATAL
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KARLA DE ABREU PEIXOTO MOREIRA
2006-01-01
Full Text Available La epidemia de SIDA afecta cada vez más a las mujeres en edad fértil. La realización del examen anti-VIH durante el prenatal es una importante estrategia para reducir la morbio mortalidad por esta causa. El objetivo planteado fue el de investigar el nivel de conocimiento de las embarazadas cuanto a la importancia de la realización del examen anti-VIH en el prenatal. Estudio descriptivo con 50 embarazadas mayores de 18 años, que realizaban prenatal de bajo riesgo en consulta subsiguiente sin diagnóstico firmado para SIDA. La edad de las embarazadas predominó entre 20 a 25 años; la mayoría había sido abordada en consultas anteriores sobre la importancia del examen anti-VIH y un 92% confirmó que había realizado ese examen después de la primera consulta de prenatal. Se reafirman los beneficios de este examen en el prenatal y la importancia de la educación en la salud durante la prevención y el control de la enfermedad.
Ação anti-úlcera e cicatrizante de algumas plantas brasileiras
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Elfriede Marianne Bacchi
Full Text Available Apresentamos uma revisão de algumas plantas brasileiras, existentes na região de São Paulo, conhecida por sua ação anti-úlcera e cicatrizante. As espécies citadas neste trabalho são: sucupira, jucá,erva de bugre, taiuiá, cipó-chumbo,coipó-caboclo, carobinha, saião, cordão de frade, aroeira e estoraque do campo.
Magnetic De-spinning of Space Objects
National Aeronautics and Space Administration — Objects in orbit about the earth rotate such that a service spacecraft cannot grapple to them. There are few techniques available to despin a space object without...
Elementary particles in curved spaces
International Nuclear Information System (INIS)
Lazanu, I.
2004-01-01
The theories in particle physics are developed currently, in Minkowski space-time starting from the Poincare group. A physical theory in flat space can be seen as the limit of a more general physical theory in a curved space. At the present time, a theory of particles in curved space does not exist, and thus the only possibility is to extend the existent theories in these spaces. A formidable obstacle to the extension of physical models is the absence of groups of motion in more general Riemann spaces. A space of constant curvature has a group of motion that, although differs from that of a flat space, has the same number of parameters and could permit some generalisations. In this contribution we try to investigate some physical implications of the presumable existence of elementary particles in curved space. In de Sitter space (dS) the invariant rest mass is a combination of the Poincare rest mass and the generalised angular momentum of a particle and it permits to establish a correlation with the vacuum energy and with the cosmological constant. The consequences are significant because in an experiment the local structure of space-time departs from the Minkowski space and becomes a dS or AdS space-time. Discrete symmetry characteristics of the dS/AdS group suggest some arguments for the possible existence of the 'mirror matter'. (author)
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Gustavo Scola
2011-07-01
Full Text Available There are many studies about the biological activities of Vitis vinifera grape seeds, which are rich in phenolic compounds, known by their several health beneficial effects. However, until now there is no data about biological activities of the seeds of V. labrusca, specie found in South and North America. Every year, the global wine production (around 260 million hL generates about 19.5 million ton of wastes, which are usually discarded in the environment. The aim of this research was to evaluate the antioxidant and anti-inflammatory activities of aqueous extracts of seeds from wine wastes of Vitis labrusca (cv. 'Bordo' and 'Isabella'. Both extracts showed significant antioxidant and anti-inflammatory activities, which are positively correlated with total phenolic content, suggesting that these compounds might be the major contributors to the biological activity of these extracts. These results indicate that water extraction from winery wastes is an option to obtain phenolic compounds with antioxidant and anti-inflammatory activities helping to maintain environmental balance.Apesar de existirem vários estudos sobre a atividade biológica de sementes de uva de Vitis vinifera, ricas em compostos fenólicos com reconhecidos efeitos benéficos à saúde, não existem, até o momento, dados a respeito da atividade biológica de sementes de V. labrusca, espécie amplamente encontrada na América do Sul e do Norte. A cada ano, a produção mundial de vinho (cerca de 260 milhões de hL gera, aproximadamente, 19,5 milhões de toneladas de resíduos, usualmente descartados no meio ambiente. Em vista disso, o objetivo deste estudo foi avaliar as atividades antioxidante e anti-inflamatória de extratos aquosos de sementes de resíduos de vinificação de V. labrusca (cv. 'Bordo' e 'Isabel'. Os resultados mostraram que ambos os extratos apresentam significante atividade antioxidante e anti-inflamatória, as quais apresentam correlação positiva com o
manifestação de síndrome anti-sintetase
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Mário Pires
2014-03-01
Apresentamos o caso de um homem com diagnóstico efectuado há 13 anos, no contexto de internamento por uma “pneumonia”, com queixas de dispneia para esforços e cansaço fácil com 3 meses de evolução. Durante o internamento é identificada uma doença pulmonar intersticial e, posteriormente surge um quadro de mialgias com elevação marcada das enzimas musculares. A electromiografia mostrou um padrão sugestivo de miopatia e identificou-se anticorpos anti-Jo-1, estabelecendo-se o diagnóstico de síndrome anti-sintetase. Sob terapêutica imunossupressora desde então, mantém seguimento em consulta externa, encontrando-se clinicamente bem.
Quantum field theory with a momentum space of constant curvature (perturbation theory)
International Nuclear Information System (INIS)
Mir-Kasimov, R.M.
1978-01-01
In the framework of the field-theoretical approach in which the off-the-mass shell extension proceeds in the p-space of constant curvature, the perburbation theory is developed. The configurational representation of the de Sitter space is introduced with the help of the Fourier transformation of the group of motions. On the basis of a natural generalization of the Bogolyubov causality condition to the case of the new configurational representation a perturbation theory is constructed with the local in xi space Lagrangian density fucntion. The obtained S matrix obeys the reguirement of translation invariance. The S matrix elements are given by convergent expressions
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Marta López-Marcos
2015-11-01
Full Text Available RESUMEN Durante las décadas de la Guerra Fría, el continente europeo se encuentra sumido en un complejo proceso de transformación, reconstrucción y planteamiento de nuevos proyectos políticos y territoriales. Esta situación es especialmente convulsa en la franja centroeuropea, donde en estados como Hungría, Polonia o la antigua Yugoslavia se daban profundos debates acerca de su identidad y su organización geopolítica. El progresivo aperturismo hacia los países occidentales, junto a la necesidad de modernizar en profundidad los sistemas e infraestructuras estatales, sirvieron como catalizadores para la proliferación de grandes proyectos territoriales y urbanos con el fin no solo de mejorar la calidad de vida de los habitantes, sino también de reforzar la posición de dichos estados en el continente y el resto del mundo. Este texto se centra en el caso de la República Popular de Polonia, donde estas cuestiones se trataron con gran profusión desde diversas ramas. Concretamente, la propuesta del arquitecto Oskar Hansen para un Sistema Lineal Continuo aúna la visión socialista del estado como agente productor del espacio con la participación individual dentro del colectivo –siguiendo su Teoría de la Forma Abierta y sus conexiones con el Team X- sobre un soporte arquitectónico : un modelo de “anti-ciudad” que abriría cuestiones que todavía hoy permanecen vigentes. SUMMARY During the decades of the Cold War, Europe was plunged into a complex process of transformation, reconstruction and the emergence of new political and territorial projects. This situation caused particular upheaval in the central European strip, where states such as Hungary, Poland and the former Yugoslavia were struck by a profound quandary as to their identity and their geopolitical organisation. As they gradually opened up towards western countries and understood the need to drastically modernise the states’ systems and infrastructures, this triggered
Spectral decomposition of model operators in de Branges spaces
International Nuclear Information System (INIS)
Gubreev, Gennady M; Tarasenko, Anna A
2011-01-01
The paper is devoted to studying a class of completely continuous nonselfadjoint operators in de Branges spaces of entire functions. Among other results, a class of unconditional bases of de Branges spaces consisting of values of their reproducing kernels is constructed. The operators that are studied are model operators in the class of completely continuous non-dissipative operators with two-dimensional imaginary parts. Bibliography: 22 titles.
ELISA cualitativo de IgA anti-Lipopolisacárido de Vibrio cholerae en saliva de humanos
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Judith Mónica del Campo
2002-03-01
Full Text Available Se estandarizó un ELISA para detectar el principal antígeno inductor de protección de Vibrio cholerae en saliva IgA contra el lipopolisacárido (LPS. El estudio se llevó a cabo en voluntarios que fueron inoculados por vía oral con dosis de 0, 107, 108, 109 unidades formadoras de colonias (ufc del candidato vacunal El Tor Ogawa, cepa 638. Las muestras de saliva fueron tomadas de forma seriada, a los 0, 7, 8, 9, 10 y 14 días postinoculación. Se consideró seroconversión si las densidades ópticas eran superiores al nivel de corte y si los incrementos después de inmunizar duplicaban los valores antes de la inmunización. Los resultados, al ser comparados con los grupos experimentales, condición individuos inoculados y los placebos, demostraron que la técnica tiene una sensibilidad del 93,3%, una especificidad del 96,0%, un valor predictivo positivo de 98,2% y negativo de 85,7%, y una eficiencia del 94,1%. Se demostró la presencia de IgA anti LPS en saliva de los individuos inoculados con el candidato vacunal, con una mayor concentración de anticuerpos con el inóculo de (109 ufc y se obtuvo la máxima positividad a los nueve días.
Produção de anticorpos policlonais anti-ricina Production of polyclonal anti-ricin antibodies
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Roselayne Ferro Furtado
2011-02-01
Full Text Available A ricina é uma proteína bastante tóxica presente nas sementes de mamona que impossibilita o uso da torta de mamona "in natura", como ração. A torta de mamona destoxificada necessita ainda de métodos de análise que garantam a ausência de traços dessa proteína. Objetivou-se, neste trabalho, produzir e avaliar a sensibilidade e especificidade de anticorpos policlonais anti-ricina, para serem empregados como possíveis componentes de métodos sorológicos na detecção de ricina em torta de mamona destoxificada. Foram avaliadas três doses da proteína: 400, 180 e 100 µg cada uma dividida em duas aplicações em coelhos. A primeira dose foi injetada no animal no início do experimento e a segunda após 21 dias. O método de ELISA indicou que as duas doses menores (100 e 180 µg induziram respostas imunológicas primária e secundária com produção de anticorpos específicos. Enquanto a dose maior (400 µg de ricina apresentou uma resposta primária com elevação dos títulos de anticorpos, seguida de uma supressão da resposta. Esse perfil é sugestivo de tolerância imunológica. Pela técnica de Western blotting verificou-se que os anticorpos policlonais produzidos são bastante específicos para a ricina, no entanto, por detectarem ricina na forma nativa e desnaturada não são recomendados para o monitoramento de ricina em torta de mamona destoxificada por tratamento térmico.Ricin is a very toxic protein found in castor bean plants, making it impossible to use natural castor cake as animal food. The detoxificated castor cake needs to be analyzed by methods that ensure the absence of traces of this protein. This work had the objective to produce and to evaluate the sensitivity and specificity of anti-ricin polyclonal antibodies, to be employed as component of sorologic methods as the ELISA in the detection of ricin in detoxificated castor cake. Three doses of protein, 400, 180 and 100 µg were evaluated each one injected twice into
Papel de las células nkt invariantes en la respuesta inmune anti-viral
Román, Alejandro; Rugeles, María Teresa; Montoya, Carlos Julio
2006-01-01
Las células T asesinas naturales con receptor de células T invariante y restringidas por la molécula CD1d (iNKT) son un subgrupo de linfocitos con potente actividad inmunorreguladora; su respuesta casi inmediata y la capacidad de producir citoquinas tanto Th1 como Th2 son factores determinantes en el desarrollo de la respuesta inmune innata y adaptativa. El papel fisiológico de las células iNKT se ha documentado ampliamente en la respuesta anti-tumoral, el desarrollo de la tolerancia en los ó...
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de Roodt, Adolfo Rafael
2010-06-01
Full Text Available Se estudió la reactividad inmunoquímica entre los sueros de distintas especies de reptiles frente a sueros hiperinmunes experimentales anti-suero de Caiman yacare y anti-suero de Caiman latirostris. Los sueros que se probaron fueron los homólogos de Caiman yacare, Caiman latirostris y los heterólogos de Alligator missisipiensis, Tupinambis merinae, Tupinambis rufescens, Chelonoidis chilensis, Clelia rustica, Waglerophis merremii, Lystrophys dorbignyi, Phyton molurus, Boa constrictor occidentalis, Eunectes notaeus, Crotalus durissus terrificus, Bothrops alternatus, Bothrops diporus, Bothrops jararaca, Bothrops jararacussu, Bothrops moojeni, Pitangus sulphuratus y Gallus gallus. La reactividad inmunoquímica se determinó mediante las técnicas de doble inmunodifusión y ELISA, mostrándose importante entre los sueros de los crocodrílidos y baja entre estos y los de las otras especies de reptiles estudiadas. Se observó mayor reactividad entre los antisueros anti-Caiman respecto a los sueros de Caiman latirostris y Caiman yacare que frente al suero de Alligator missisipiensis. Además, se encontró una fuerte reactividad entre ambos sueros anti-Caiman y el de Gallus gallus poniendo en evidencia la fuerte reactividad entre los sueros de arcosaurios. In order to study the immunochemical reactivity among sera from different species of reptiles regarding sera from Caiman, the immunoreactivity of sera from reptiles against antisera to Caiman yacare or anti-Caiman latirostris sera was studied. These hiperimmune sera were tested against sera from Alligator missisipiensis, Tupinambis merinae, Tupinambis rufescens, Chelonoidis chilensis, Clelia rustica, Waglerophis merremii, Lystrophys dorbignyi, Phyton molurus, Boa constrictor occidentalis, Eunectes notaeus, Crotalus durissus terrificus, Bothrops alternatus, Bothrops neuwiedii, Bothrops jararaca, Bothrops jararacussu, Bothrops moojeni, Pitangus sulphuratus and Gallus gallus. The immunochemical
Activités anti-radicalaires de l'huile essentielle et des extraits bruts ...
African Journals Online (AJOL)
une haute capacité de blocage du peroxyde d'hydrogène en comparaison avec les contrôles positifs de l'acide gallique et l'acide caféique. Mots-clés : Thymus numidicus, extraits bruts, activité antioxydante. Anti-radical activities of essential oil ...
La problemática de la epistemología anti-suerte
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Abel Wajnerman Paz
2017-01-01
Full Text Available D. Pritchard ha sostenido que el conocimiento requiere la satisfacción de una condición de habilidad y una anti-suerte que no guardan relación de implicación entre sí. Se sostiene que la satisfacción de una condición anti-suerte implica cumplir con la condición de habilidad, primero, porque, las características centrales del caso de D. Pritchard (TEMP en contra de esta implicación son compartidas con casos en los que hay habilidad; y segundo, el caso de A. Goldman del dios benevolente es más efectivo que TEMP, pero involucra un tipo de seguridad diferente a la requerida para el conocimiento. Por último, se muestra que la respuesta de D. Pritchard al problema de la generalidad bloquea la implicación de seguridad a habilidad. Se propone un contraejemplo, adaptando un caso tomado de la epistemología del testimonio.
Busca de sensação e condutas anti-sociais e delitivas em jovens
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Nilton Soares Formiga
Full Text Available O fenômeno das condutas juvenis tem sido alvo de interesse na ciência social e humana, principalmente aquelas que conduzem à delinqüência. Apesar de inúmeras variáveis conseguirem explicá-lo, o construto busca de sensações vem contribuindo muito para isso, pois ele enfatiza as diferenças individuais. A partir da perspectiva personalística, aponta a avaliação do grau com que os jovens pretendem viver experiências em correr riscos e sua predisposição a sensações de novidades e intensidades. 504 jovens, entre 11 e 20 anos, responderam o questionário de condutas anti-sociais e delitivas e de busca de sensação, de Arnett. Observou-se que a busca de intensidade e de novidades se relacionaram diretamente às condutas anti-sociais e delitivas. Esses resultados permitem supor que as variáveis personalísticas ainda têm bastante contribuição quando se pretende explicar a conduta juvenil delinqüente a partir da orientação de atitudes frente à excitação e ao investimento de atividades permeadoras de risco.
Busca de sensação e condutas anti-sociaise delitivas em jovens
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Nilton Soares Formiga
Full Text Available O fenômeno das condutas juvenis tem sido alvo de interesse na ciência social e humana, principalmente aquelas que conduzem à delinqüência. Apesar de inúmeras variáveis conseguirem explicá-lo, o construto busca de sensações vem contribuindo muito para isso, pois ele enfatiza as diferenças individuais. A partir da perspectiva personalística, aponta a avaliação do grau com que os jovens pretendem viver experiências em correr riscos e sua predisposição a sensações de novidades e intensidades. 504 jovens, entre 11 e 20 anos, responderam o questionário de condutas anti-sociais e delitivas e de busca de sensação, de Arnett. Observou-se que a busca de intensidade e de novidades se relacionaram diretamente às condutas anti-sociais e delitivas. Esses resultados permitem supor que as variáveis personalísticas ainda têm bastante contribuição quando se pretende explicar a conduta juvenil delinqüente a partir da orientação de atitudes frente à excitação e ao investimento de atividades permeadoras de risco.
AdS-like spectrum of the asymptotically Goedel space-times
International Nuclear Information System (INIS)
Konoplya, R. A.; Zhidenko, A.
2011-01-01
A black hole immersed in a rotating universe, described by the Gimon-Hashimoto solution, is tested on stability against scalar field perturbations. Unlike the previous studies on perturbations of this solution, which dealt only with the limit of slow universe rotation j, we managed to separate variables in the perturbation equation for the general case of arbitrary rotation. This leads to qualitatively different dynamics of perturbations, because the exact effective potential does not allow for Schwarzschild-like asymptotic of the wave function in the form of purely outgoing waves. The Dirichlet boundary conditions are allowed instead, which result in a totally different spectrum of asymptotically Goedel black holes: the spectrum of quasinormal frequencies is similar to the one of asymptotically anti-de Sitter black holes. At large and intermediate overtones N, the spectrum is equidistant in N. In the limit of small black holes, quasinormal modes (QNMs) approach the normal modes of the empty Goedel space-time. There is no evidence of instability in the found frequencies, which supports the idea that the existence of closed timelike curves (CTCs) and the onset of instability correlate (if at all) not in a straightforward way.
Reconstructing 1/2 BPS space-time metrics from matrix models and spin chains
International Nuclear Information System (INIS)
Vazquez, Samuel E.
2007-01-01
Using the anti-de Sitter/conformal field theories (AdS/CFT) correspondence, we address the question of how to measure complicated space-time metrics using gauge theory probes. In particular, we consider the case of the 1/2 Bogomol'nyi-Prasad-Sommerfield geometries of type IIB supergravity. These geometries are classified by certain droplets in a two-dimensional spacelike hypersurface. We show how to reconstruct the full metric inside these droplets using the one-loop N=4 super Yang-Mills theory dilatation operator. This is done by considering long operators in the SU(2) sector, which are dual to fast rotating strings on the droplets. We develop new powerful techniques for large N complex matrix models that allow us to construct the Hamiltonian for these strings. We find that the Hamiltonian can be mapped to a dynamical spin chain. That is, the length of the chain is not fixed. Moreover, all of these spin chains can be explicitly constructed using an interesting algebra which is derived from the matrix model. Our techniques work for general droplet configurations. As an example, we study a single elliptical droplet and the hypotrochoid
Space Debris Elimination (SpaDE)
National Aeronautics and Space Administration — The amount of debris in low Earth orbit (LEO) has increased rapidly over the last twenty years. This prevalence of debris increases the likelihood of cascading...
Quantum de Finetti theorem in phase-space representation
International Nuclear Information System (INIS)
Leverrier, Anthony; Cerf, Nicolas J.
2009-01-01
The quantum versions of de Finetti's theorem derived so far express the convergence of n-partite symmetric states, i.e., states that are invariant under permutations of their n parties, toward probabilistic mixtures of independent and identically distributed (IID) states of the form σ xn . Unfortunately, these theorems only hold in finite-dimensional Hilbert spaces, and their direct generalization to infinite-dimensional Hilbert spaces is known to fail. Here, we address this problem by considering invariance under orthogonal transformations in phase space instead of permutations in state space, which leads to a quantum de Finetti theorem particularly relevant to continuous-variable systems. Specifically, an n-mode bosonic state that is invariant with respect to this continuous symmetry in phase space is proven to converge toward a probabilistic mixture of IID Gaussian states (actually, n identical thermal states).
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Cesar Nobuo Shiratori
2011-02-01
Full Text Available OBJETIVOS: Traçar o perfil dos doadores de tecidos oculares humanos na região de atuação do Banco de Olhos de Cascavel - Paraná (PR e verificar o impacto da positividade da sorologia positiva para hepatite B (anti-HBc no descartes dos tecidos oculares. MÉTODOS: Estudo do tipo transversal de dados do Banco de Olhos de Cascavel do período de março de 2006 a abril de 2007. Informações como idade, sexo, causa de óbito, tempo entre óbito e enucleação e resultados sorológicos de doadores foram coletadas. Dados foram agrupados para caracterização da população de estudo e distribuídos segundo positividade da sorologia para hepatite B (anti-HBc. RESULTADOS: A média de idade dos doadores foi de 54,2 ± 20,6 anos e a maioria era do sexo masculino (64,7%. Tempo médio entre óbito e enucleação foi de 3,8 ± 2,4 horas, a principal causa de óbito foram doenças cardiovasculares (34,5%. Positividade para os marcadores anti-HBc e HBsAg foi de 47,4% e 1,5%, respectivamente, sendo os exames sorológicos para hepatite B a maior causa de descarte dos tecidos oculares doados. Doadores com sorologia positiva para anti-HBc apresentaram maior média de idade comparados com doadores com sorologia negativa (p<0,001. Somente 0,8% das doações apresentaram sorologia positiva para hepatite C. Não houve doações com sorologia para HIV positiva no período do estudo. CONCLUSÕES: Implementação do Banco de Olhos de Cascavel aumentou significativamente a disponibilização de córneas para transplante no Estado do Paraná. A principal contraindicação para disponibilização de tecidos oculares foi a positividade na sorologia para anti-HBc. Estudos de biosegurança devem ser realizados a fim de investigar o potencial de transmissão da hepatite B de doadores positivos para esse marcador. A inclusão desses doadores como doações efetivas acarretaria maior disponibilização de tecidos para transplantes.
O uso de drogas anti-reumáticas na gravidez Use of anti-rheumatic drugs during pregnancy
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Roger A. Levy
2005-06-01
Full Text Available A prescrição de drogas anti-reumáticas em pacientes férteis deve ter em conta o conhecimento atual sobre os efeitos na concepção, gestação e lactação. Um aconselhamento que levasse em consideração os riscos e benefícios do planejamento da gravidez, quando possível, seria o ideal. Com a incorporação de novas substâncias e o aparecimento constante de novos dados na literatura, esse assunto deve ser continuamente atualizado. O estagiamento de acordo com o fator de risco estabelecido pelo FDA é algumas vezes contraditório em relação a nossa prática, em parte porque os estudos em modelos animais podem não ser diretamente aplicáveis a humanos. A terapia com agentes modificadores da resposta biológica é aparentemente segura durante a gestação, considerando-se que tais agentes sejam compostos por moléculas grandes, incapazes de atravessar a placenta. Antiinflamatórios não-esteroidais (incluindo os inibidores específicos de COX-2 podem prejudicar a implantação do óvulo, mas o seu uso é possível no caso da gestação estar em curso, devendo ser evitados após 32 semanas do início da gravidez, quando estão relacionados com complicações fetais. Os inibidores específicos de COX-2 devem ser evitados pelo risco de malformação renal. Aspirina em baixa dose pode ser usada seguramente, quando indicada durante a gravidez. Há preferência pelas heparinas de baixo peso molecular, desde que a não fracionada apresente maior risco de induzir trombocitopenia e sangramento. A hidroxicloroquina é usada e de fato recomendada em gestantes com lúpus, com benefícios para a paciente e sem risco fetal. Varfarina é teratogênica se usada da 6ª a 9ª semana de gestação, mas pode ser usada durante o segundo e terceiro trimestres até a 34ª semana, quando deve ser interrompida com o intuito de evitar sangramento fetal. A imunoglobulina endovenosa é recomendada em casos difíceis de síndrome do anticorpo antifosfolipídeo e vem
On the quantum field theory in the momentum space with the constant curvature
International Nuclear Information System (INIS)
Gadzhiev, S.A.; Petrosyan, V.A.
1981-01-01
Model of polarization operator in the approximation of ''opalescent'' diagrams in the momentum space of constant curvature is investigated. Integral equation for an absorptive part of the hadron polarization operator has been obtained in stereographic parametrization of the de Sitter space. Integral equation for the case of zero mass of an exchange particle has been solved, cross section and mean multiplicity of hadron production in the e + e - annihilation have been calculated. Infrared divergences arising during exact summation of the considered diagram class are separated to a multiplicative constant of renormalization [ru
Efeito do anti-TNF-α em implantes endometriais no peritônio de ratas
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William Kondo
Full Text Available OBJETIVO: Avaliar o efeito da terapia anti-TNF-α no tratamento de implantes endometriais no peritônio de ratas. MÉTODOS: Os implantes endometrióticos foram induzidos cirurgicamente em 120 ratas Wistar-Albino. Os animais foram aleatoriamente distribuídos em 4 grupos. O grupo C (n=36 recebeu uma injeção intraperitoneal de 0,2ml de solução salina. O grupo L (n=41 recebeu uma injeção subcutânea de 1mg/kg de leuprolide. O grupo I5 (n=20 recebeu uma injeção subcutânea de 5mg/kg de anticorpo monoclonal anti-fator de necrose tumoral (TNF a (infliximab. O grupo I10 (n=20 recebeu uma injeção subcutânea de 10mg/kg de infliximab. As ratas foram sacrificadas após 21 dias para se avaliar o tamanho dos implantes e a expressão do TNF-α. RESULTADOS: O tratamento com leuprolide promoveu uma redução absoluta na área de superfície do implante comparado com o grupo C (+14mm vs. 0mm; p=0,013 e com o grupo I10 (+14mm vs. +5mm; p=0,018. Da mesma forma, uma redução percentual da area de superfície do implante foi observada comparando o grupo L com o grupo C (+33,3% vs. 0%; p=0,005 e com o grupo I10 (+33,3% vs. +18,3%; p=0,027. O tratamento com infliximab não foi capaz de diminuir a área de superfície do implante comparado com o grupo C. A expressão de TNF-α reduziu nos grupos L, I5 e I10 comparado com o grupo C (505,6µm² vs. 660,5µm² vs. 317,2µm² vs. 2519,3µm², respectivamente; p<0,001. CONCLUSÃO: A terapia anti-TNF-α reduziu a expressão de TNF-α nos implantes endometrióticos mas não reduziu a área de superfície da lesão.
Black holes in a box: Toward the numerical evolution of black holes in AdS space-times
International Nuclear Information System (INIS)
Witek, Helvi; Nerozzi, Andrea; Cardoso, Vitor; Herdeiro, Carlos; Sperhake, Ulrich; Zilhao, Miguel
2010-01-01
The evolution of black holes in ''confining boxes'' is interesting for a number of reasons, particularly because it mimics the global structure of anti-de Sitter geometries. These are nonglobally hyperbolic space-times and the Cauchy problem may only be well defined if the initial data are supplemented by boundary conditions at the timelike conformal boundary. Here, we explore the active role that boundary conditions play in the evolution of a bulk black hole system, by imprisoning a black hole binary in a box with mirrorlike boundary conditions. We are able to follow the post-merger dynamics for up to two reflections off the boundary of the gravitational radiation produced in the merger. We estimate that about 15% of the radiation energy is absorbed by the black hole per interaction, whereas transfer of angular momentum from the radiation to the black hole is observed only in the first interaction. We discuss the possible role of superradiant scattering for this result. Unlike the studies with outgoing boundary conditions, both of the Newman-Penrose scalars Ψ 4 and Ψ 0 are nontrivial in our setup, and we show that the numerical data verifies the expected relations between them.
O gerente de vendas no Brasil e a intenção de comportamento antiético - 1ª Parte
Urdan, André Torres
2004-01-01
O objetivo geral desta pesquisa é analisar a Intenção de Comportamento Antiético do executivo de vendas e alguns de seus possíveis determinantes, fruto de lacunas relevantes de conhecimento na realidade brasileira. Trata-se de uma replicação de estudo realizado nos Estados Unidos por SCHWEPKER Jr. (1999). Nesta linha, dois são os objetivos específicos. O primeiro, já cumprido na primeira parte do projeto, é descrever o perfil dos construtos Intenção de Comportamento Antiético, Julgamento Mora...
Exact Solutions of the Field Equations for Empty Space in the Nash Gravitational Theory
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Matthew T. Aadne
2017-02-01
Full Text Available John Nash has proposed a new theory of gravity. We define a Nash-tensor equal to the curvature tensor appearing in the Nash field equations for empty space, and calculate its components for two cases: 1. A static, spherically symmetric space; and 2. The expanding, homogeneous and isotropic space of the Friedmann-Lemaitre-Robertson-Walker (FLRW universe models. We find the general, exact solution of Nash’s field equations for empty space in the static case. The line element turns out to represent the Schwarzschild-de Sitter spacetime. Also we find the simplest non-trivial solution of the field equations in the cosmological case, which gives the scale factor corresponding to the de Sitter spacetime. Hence empty space in the Nash theory corresponds to a space with Lorentz Invariant Vacuum Energy (LIVE in the Einstein theory. This suggests that dark energy may be superfluous according to the Nash theory. We also consider a radiation filled universe model in an effort to find out how energy and matter may be incorporated into the Nash theory. A tentative interpretation of the Nash theory as a unified theory of gravity and electromagnetism leads to a very simple form of the field equations in the presence of matter. It should be noted, however, that the Nash theory is still unfinished. A satisfying way of including energy momentum into the theory has yet to be found.
Estado actual y futuro de la terapia anti-leishmaniásica en Colombia
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Jaime Soto
2006-10-01
Full Text Available Los antimoniales pentavalentes son la primera elección para el tratamiento de la leishmaniasis en Colombia pero la dosis ha tenido que incrementarse en mas de 600% para mantener su eficacia que en distintos reportes varía entre 93 y 25%, lo cual puede reflejar diferencias en la sensibilidad de los parásitos pero más probablemente incumplimiento de los esquemas recomendados. Los resultados de su empleo, así como la situación actual de pentamidina, anfotericina B y miltefosina son revisados y se hace una proyección sobre el desarrollo de la terapia en los próximos años. Para definir el real estado de la respuesta a los medicamentos anti-leishmaniásicos y prolongarles su vida útil, es indispensable establecer mecanismos de vigilancia de los factores implicados en el manejo de la enfermedad por lo que se plantea una estrategia de sitios centinela que permitan observaciones puntuales en el tiempo, en áreas específicas y sobre situaciones particulares.
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Ana Elisa Bauer de Camargo Silva
2013-02-01
Full Text Available OBJECTIVE: The objective of this study was to analyze the potential risks involved in the administration process of intravenous anti-infective medication at a medical clinic, using the Failure Mode and Effect Analysis. METHOD: This exploratory study was conducted at the medical clinic of a hospital in the State of Goiás. For data collection we convened a team comprised of six professionals involved in medication treatment: a doctor, nurse, nursing technician, pharmacist, a nursing and a risk manager. A total of 24 meetings were held, for a total of 56 hours. The data were transcribed into an electronic database within Microsoft Excel®, and the Xfmea4 software was used. RESULT: The results indicated 52 failure modes, 79 effects of failure, and 285 causes of failure. The causes were related to: the management of organizational processes, human resources, physical and material structure. A total of 298 actions for improvement were recommended for 215 causes of high and average priority, 81.9% of which were short-term priorities. The simulation of the impact of the proposed interventions revealed a 79.7% reduction of the high-priority failure modes. CONCLUSION: It was concluded that the study identified potential risks to patients and recommended proactive actions, of rapid application and low cost, evaluated positively in the reduction of risk of occurrence of avoidable incidents, increasing reliability and safety of the medication administration process. Studies like this demonstrate that, with the application of a method of risk analysis, nurses can effectively assist in preventing medication incidents.OBJETIVO: Este estudio objetivó analizar los riesgos potenciales de administración de medicamentos anti-infecciosos por vía endovenosa en una unidad de Clínica Médica, utilizando el Método de Análisis del Modo y Efecto de Falla. MÉTODO: De naturaleza exploratoria, se realizó en la Clínica Médica de un Hospital del Estado de Goi
Sidelines and Separate Spaces: Making Education Anti-Racist for Students of Color
Blackwell, Deanna M.
2010-01-01
The way in which anti-racist education is currently conceptualized and practiced holds very few benefits for students of color. By using whiteness theory and the politics of identity and difference, many educators have developed pedagogical interventions that are concerned with bringing white students into a consciousness about racism and white…
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Celina Maria Turchi Martelli
1999-07-01
Full Text Available En otros estudios se ha evaluado el menor riesgo de infecciones transmitidas por transfusión sanguínea que acarrea el tamizaje de anticuerpos contra los antígenos nucleares de la hepatitis B (anti-HBc, sumado a la prueba detectora de antígenos de superficie (HbsAg. No obstante, la mayoría de estos estudios se basaron en datos procedentes de zonas con baja endemicidad por hepatitis B o de bancos de sangre de países desarrollados, donde la mayoría de la sangre proviene de personas que han donado previamente. A fin de examinar los pros y los contras del tamizaje de anticuerpos anti-HBc en el Brasil, los autores describen los antecedentes y la interpretación de las pruebas de tamizaje para prevenir la hepatitis postransfusión. También presentan los datos sobre el tamizaje de la hepatitis B en todas las regiones del Brasil. No hay pruebas suficientes para suspender el tamizaje de los anticuerpos anti-HBc en el país. Debe darse alta prioridad a comparar el costo-efectividad de un marcador basado en la biología molecular con el de la actual prueba detectora de anticuerpos anti-HBc aplicada comúnmente, a fin de mejorar las medidas de tamizaje que garantizan la inocuidad de la sangre.
Botta Serrano, Marianella
2012-01-01
La aplicación de la ley anti maras en El Salvador no tuvo los resultados esperados por el gobierno en el momento de su implementación, la reducción del fenómeno no se vio afectada por la aplicación de esta ley que al contrario produjo una serie de efectos negativos que demostraron tanto la inefectividad de dicha ley, como la capacidad de las maras para adaptarse y evolucionar frente a las adversidades que les presentó una medida represiva como la tomada por el gobierno salvadoreño.
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Maria Luiza Dias Fraga Peron
2010-07-01
Full Text Available Paracoccidioidomycosis (PCM is an important systemic mycosis in LatinAmerica that occurs as active disease in 1-2% of Paracoccidioides brasiliensis infected people. Like PCM, tuberculosis (TB affects mainly the lungs and the clinical and radiological aspects do notalways allow differentiation between them. The aim of this study was to carry out serological investigation for detecting anti-P. brasiliensis antibodies, by three serological methods, in patientswith symptoms suggestive of pulmonary TB. From August 2005 to September 2006, 76 patients with pulmonary symptoms suspected for TB were attended at the Regional Specialties Center Laboratory in the city of Paranavaí, Paraná, Brazil and submitted to microbiological TB research, ELISA, immunodiffusion and immunoblotting for PCM. Of all the individuals, 21 (27.63% were reactive to P. brasiliensis by ELISA and 11 (14.47% showed a laboratory diagnosis of pulmonary TB. Of all the individuals serologically reactive to P. brasiliensis, by ELISA, none had positive results by immunodiffusion and one reacted with antigen 43 kDa when Immunobloting was carried out. Our results lead us to reflect a necessity to obtain a more specific serologic test for diagnosis of PCM disease in patients with respiratory symptoms considering the high number of individuals reactive to P. brasiliensis especially in endemic areas.Paracoccidioidomicose (PCM é importante micose sistêmica na América Latina, que ocorre como doença ativa em 1-2% dos indivíduos infectados com Paracoccidioides brasiliensis. Assim como a PCM, a tuberculose (TB afeta principalmente os pulmões, porém os aspectos clínicos e radiológicos nem sempre permitem a diferenciação entreessas doenças. O objetivo deste estudo foi realizar um inquérito sorológico para a detecção de anticorpos anti-P. brasiliensis, utilizando três métodos sorológicos, em pacientes com sintomassugestivos de tuberculose pulmonar. De agosto de 2005 a setembro de
O uso de anti-retrovirais em gestantes modifica o perfil lipídico?
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El Beitune Patrícia
2003-01-01
Full Text Available OBJETIVO: avaliar o efeito das medicações anti-retrovirais sobre o metabolismo lipídico em gestantes portadoras do HIV. MÉTODOS: estudo prospectivo realizado em 57 gestantes que foram divididas em três grupos: grupo AZT, com 20 pacientes portadoras do HIV em uso de AZT; grupo TT, com 25 pacientes portadoras do HIV em uso de esquemas contendo três anti-retrovirais (AZT + 3TC + NFV e grupo controle, com 12 pacientes. Os dados demográficos e antropométricos foram homogêneos entre os grupos estudados. Foram excluídas as pacientes com antecedentes pessoais ou familiares de hiperlipidemia. Amostras sanguíneas foram obtidas para avaliação dos lipídeos (colesterol total, frações LDL e HDL-colesterol e triglicerídeos em quatro oportunidades durante a gravidez (1º = 14-20 semanas; 2º = 21-26 semanas; 3º = 27-32 semanas e 4º = 33-38 semanas. Os dados foram analisados utilizando-se os testes não paramétricos do chi², teste de Friedman e teste de Kruskal-Wallis. RESULTADOS: o uso de anti-retrovirais durante a gestação não induziu diferenças nas taxas do colesterol total e HDL, no entanto, o uso destes agentes esteve associado a elevação de 76,5 mg/dL e 84 mg/dL para 96 mg/dL e 105 mg/dL na concentração da fração LDL-colesterol para os grupos AZT e TT, respectivamente (p<0,01. Observou-se associação positiva significante entre os triglicerídeos e a carga viral nas gestantes do grupo AZT (r = 0,53; p = 0,015. CONCLUSÃO: a utilização dos anti-retrovirais durante a gestação eleva significativamente a concentração da lipoproteína LDL. Persistem as dúvidas se a gestação potencializa a longo prazo os efeitos dos anti-retrovirais sobre o metabolismo lipídico.
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Claudia Mora
2015-12-01
Full Text Available Perante a importância do aconselhamento na testagem anti-HIV, analisamos as diretrizes institucionais, as competências privilegiadas no treinamento profissional e os saberes/práticas de aconselhadores. Trata-se de estudo qualitativo centrado na análise documental, observação e entrevista com aconselhadores de Centros de Testagem e Aconselhamento (CTA do estado do Rio de Janeiro. A análise foi orientada pela teoria de Pierre Bourdieu. Foi evidenciado que o habitus profissional dos aconselhadores resulta da articulação dos treinamentos, da graduação e de experiências e interesses pessoais. A operacionalização de competências, como a escuta ativa, é limitada pela rotina dos serviços e escassez de espaços de reflexão. Para incrementar a prática do aconselhamento, é importante desenvolver competências no treinamento, manter a educação continuada e fazer adequações na rotina do serviço. Tais ajustes podem fortalecer a passagem das diretrizes à ação e o aprimoramento da organização e gestão dos CTA.
Eikonal Approximation in AdS/CFT From Shock Waves to Four-Point Functions
Cornalba, L; Costa, Miguel S; Penedones, Joao; Cornalba, Lorenzo; Costa, M S; Penedones, J; Schiappa, Ricardo
2007-01-01
We initiate a program to generalize the standard eikonal approximation to compute amplitudes in Anti-de Sitter spacetimes. Inspired by the shock wave derivation of the eikonal amplitude in flat space, we study the two-point function E ~ _{shock} in the presence of a shock wave in Anti-de Sitter, where O_1 is a scalar primary operator in the dual conformal field theory. At tree level in the gravitational coupling, we relate the shock two-point function E to the discontinuity across a kinematical branch cut of the conformal field theory four-point function A ~ , where O_2 creates the shock geometry in Anti-de Sitter. Finally, we extend the above results by computing E in the presence of shock waves along the horizon of Schwarzschild BTZ black holes. This work gives new tools for the study of Planckian physics in Anti-de Sitter spacetimes.
Desenvolvimento e análise de filme anti-reflexo de sulfeto de zinco para células solares
Ly, Moussa
2007-01-01
O aproveitamento da energia gerada pelo Sol, renovável e limpa é hoje, uma das alternativas energéticas mais promissoras para enfrentar o desafio energético do mundo. Para se fabricar uma célula solar de alta eficiência, precisa-se reduzir a refletância da superfície. O objetivo deste trabalho é estudar o desenvolvimento e análise de filmes anti-reflexo (AR) de sulfeto de zinco (ZnS) para células solares. Inicialmente, foi implementado e otimizado um processo de deposição por aquecimento resi...
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Morella Bouchard Pereira
2014-07-01
Full Text Available El objetivo de este estudio fue evaluar en muestras de suero y humor acuoso los niveles de anticuerpos anti-toxoplasma a través del Coeficiente de Goldmann y Witmer (CGW y el patrón de reconocimiento antigénico a través del immunoblotting (IB, en pacientes con serología positiva con y sin lesiones de toxoplasmosis ocular. Se recogieron simultáneamente muestras de suero y humor acuoso de 26 pacientes: un grupo de casos que poseían lesiones retinales de toxoplasmosis ocular en fase activa e inactiva (n=17 y un grupo control que requería cirugía ocular por presencia de cataratas (n=9. Las determinación de IgM e IgG específicas se realizó por ELISA de inmunocaptura e indirecto, respectivamente. Se utilizó la inmunodifusión radial para la cuantificación de la IgG total. El CGW resultó >2, indicativo de producción local de anticuerpos específicos en 12/17 de los casos, mientras que en los controles no se observó, esto evidenció una sensibilidad del 71% y una especificidad de 100%. En IB, la aparición de bandas diferentes en humor acuoso, indicativo de producción local de anticuerpos específicos se observaron en 11/17 de los casos y 1/9 de los controles, reflejando una sensibilidad de 65% y una especificidad de 89%. Al considerar las dos pruebas la sensibilidad se incrementó a un 73%, pero la especificidad disminuyó a 89%. En conclusión el IB es útil como prueba confirmatoria para diagnóstico de toxoplasmosis ocular, pero sólo como un complemento del coeficiente de GW especialmente en pacientes con lesiones atípicas donde el diagnóstico clínico es difícil. Aqueous humor and serum immunoblotting profiles and anti–toxoplasma gondii antibodies in patients with toxoplasmosis-induced retinal lesions Abstract The purpose of this study was to analize the anti-Toxoplasma gondii antibodies levels in serum and aqueous humor samples in patients with ocular toxoplasmosis by using Goldman and Witmer Coefficient (GWC and the
Potencial anti-Sporothrix spp. de plantas da família lamiaceae
Stefanie Bressan Waller
2015-01-01
As propriedades terapêuticas das plantas medicinais são cada vez mais estudadas, principalmente devido aos crescentes casos de resistência antimicrobiana, como observado em cepas do Complexo Sporothrix. As plantas da família Lamiaceae são conhecidas por suas propriedades antifúngicas, entretanto, são escassos seus estudos contra agentes causadores da esporotricose. Devido ao potencial promissor dessas plantas, objetivou-se (1) avaliar a atividade anti-Sporothrix spp. in vitro de Origanum vulg...
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Juliana M. Fachinetto
Full Text Available Achyrocline satureioides (marcela é utilizada na medicina popular brasileira, na forma de chá, como tratamento de patologias digestivas e inflamatórias. O efeito anti-proliferativo de infusões de marcela sobre o ciclo celular da cebola foi avaliado, utilizando-se inflorescências de marcela recém coletadas (2005 e após armazenamento por 30 meses (2003. Preparou-se as infusões em duas concentrações: 5,0 mg/mL (concentração usual como chá e 20 mg/mL. Utilizaram-se 3 grupos de 6 bulbos de cebola para cada população de marcela. Retirou-se um grupo de bulbos controle de cada população. Todos os bulbos enraizados em água destilada foram transferidos para os extratos de marcela e permaneceram por 24 horas, (os bulbos controle permaneceram em água. As radículas foram coletadas, fixadas em etanol-ácido acético (3:1 por 24 h e estocadas em álcool 70%. Foram analisadas 6000 células por grupo de bulbos, e os índices mitóticos calculados submetidos a análise estatística pelo teste chi2 a 5%. Conclui-se que as infusões de marcela possuem ação antiproliferativa sobre o ciclo celular da cebola e que essa ação inibitória da divisão celular aumenta conforme aumento da concentração, bem como após o armazenamento.
Directory of Open Access Journals (Sweden)
Ananidia Rivero
2000-12-01
Full Text Available Se describe un estudio realizado con los hemoclasificadores monoclonales cubanos Hemo CIM anti-A y anti-B producidos por el Centro de Inmunología Molecular (CIM y comercializados por CIMAB S.A, para ser evaluados en pacientes VIH/SIDA. Se analizaron un total de 130 pacientes en el Servicio de Transfusiones del Instituto "Pedro Kourí". Se utilizaron en paralelo los antisueros policlonales de producción nacional (Laboratorios Betera y los reactivos monoclonales comerciales producidos y donados por International Blood Group Reference Laboratory; Bristol, UK. Se demostró que los reactivos Hemo CIM anti-A y Hemo CIM anti-B se comportaron de forma similar a sus homólogos comerciales y policlonales. Al comparar la efectividad de la aglutinación para los 3 reactivos pudimos comprobar que con el reactivo monoclonal, Hemo CIM anti-A y anti-B se obtuvieron los mejores resultados expresados en crucesA study conducted with the Cuban anti-A and anti-B Hemo CIM monoclonal hemoclassifiers produced by the Center of Molecular Immunology (CMI and commercialized by CIMAB S.A. to be evaluated in HIV/AIDS patients is described. 130 patients were analyzed at the Service of Transfusions of "Pedro Kouri" Institute. The polyclonal antisera of national production (Betera Laboratories and the commercial monoclonal reagents produced and donated by the International Blood Group Reference Laboratory; Bristol, UK, were used at the same time. It was proved that the anti-A Hemo CIM and anti-B Hemo CIM reagents behaved similarly to their commercial and polyclonal homologues. On comparing the effectiveness of the agglutination for the 3 reagents, we were able to verify that the best results expressed in crosses were obtained with the anti-A and anti-B Hemo CIM monoclonal reagents
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Daniela Martins Luciano
2011-12-01
Full Text Available This study aimed to estimate the occurrence of anti-Toxoplasma gondii antibodies by means of the Indirect Immunufluorescent Antibody Assay (IFAT in cattle and pigs from slaughterhouses in two municipalities in the State of Rio de Janeiro. IgG anti-T. gondii antibodies was found in 1.96% (9/459 of the cattle and 7.64% (31/406 of the pigs, without any positive association (p > 0.05 with risk factors for transmission and seropositivity. Taking the cutoff point of IFAT ³ 1:64, titers of 64 and 256 were detected, suggesting chronic infection. Despite the low prevalence rates found for cattle and pigs, these indicated environmental contamination in the municipalities investigated, biosafety failures at the technified pig farm evaluated and the possibility of human and animal infection through eating raw or undercooked meat from these animals.Este trabalho objetivou estimar a ocorrência de anticorpos anti-Toxoplasma gondii por meio da Reação de Imunofluorescência Indireta (RIFI em bovinos e suínos de abatedouros de dois municípios do Estado do Rio de Janeiro. Anticorpos IgG anti-T. gondii foram encontrados em 1,96% (9/459 dos bovinos e em 7,64% (31/406 dos suínos, sem associação positiva (p > 0,05 em relação aos fatores de risco de transmissão e a soropositividade. Considerando-se o ponto de corte (RIFI ³ 1:64, foram detectados os títulos de 64 e 256, sugestivos de infecção crônica. Apesar de baixas, as prevalências encontradas para bovinos e suínos indicaram contaminação ambiental nos municípios avaliados, falhas na biossegurança da granja tecnificada de suínos e a possibilidade de infecção humana e animal pela ingestão da carne crua ou mal passada desses animais.
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Vázquez-Corzo Sara
2003-01-01
Full Text Available OBJETIVO: Determinar si anticuerpos séricos contra E4, E7 y Ras pueden ser utilizados como marcadores de lesiones tempranas del cérvix uterino asociadas al virus del papiloma humano. MATERIAL Y MÉTODOS: Entre marzo de 1999 y abril de 2000 se realizó un estudio sero-epidemiológico de casos y controles en la clínica de displasias del Hospital General Doctor Gea González, en la Ciudad de México, en 116 muestras de suero para evaluar la presencia de anticuerpos anti-E4, E7 y Ras utilizando un ELISA de captura. Se estimaron razones de momios e intervalos de confianza de 95% RESULTADOS: Anticuerpos anti-E7 se asociaron a mujeres con lesiones NIC III, mientras que anticuerpos anti-E4 y anti-Ras fueron más frecuentes en lesiones NIC I-II. Al evaluar el perfil de anticuerpos que presentaron las mujeres, encontramos que a anticuerpos contra dos proteínas predicen la existencia de una lesión NIC I-II, y b la presencia de tres anticuerpos predicen una lesión NIC III. CONCLUSIONES: La detección de anticuerpos séricos contra E4, E7 y Ras en combinación con otras técnicas de diagnóstico, podrían ser de utilidad para detectar oportunamente a mujeres con lesiones tempranas asociadas al Virus del Papiloma Humano y en riesgo de desarrollar cáncer.
Coalescing black hole solution in the De-Sitter universe
International Nuclear Information System (INIS)
Ahmed, Mainuddin
2005-01-01
A new coalescing black hole solution of Einstein-Maxwell equation in general relativity is given. The new solution is also found to support the 'Nerst Theorem' of thermodynamics in the case of black hole. Thus this solution poses to solve an outstanding problem of thermodynamics and black hole physics. (author)
Spaced Seed Data Structures for De Novo Assembly
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Inanç Birol
2015-01-01
Full Text Available De novo assembly of the genome of a species is essential in the absence of a reference genome sequence. Many scalable assembly algorithms use the de Bruijn graph (DBG paradigm to reconstruct genomes, where a table of subsequences of a certain length is derived from the reads, and their overlaps are analyzed to assemble sequences. Despite longer subsequences unlocking longer genomic features for assembly, associated increase in compute resources limits the practicability of DBG over other assembly archetypes already designed for longer reads. Here, we revisit the DBG paradigm to adapt it to the changing sequencing technology landscape and introduce three data structure designs for spaced seeds in the form of paired subsequences. These data structures address memory and run time constraints imposed by longer reads. We observe that when a fixed distance separates seed pairs, it provides increased sequence specificity with increased gap length. Further, we note that Bloom filters would be suitable to implicitly store spaced seeds and be tolerant to sequencing errors. Building on this concept, we describe a data structure for tracking the frequencies of observed spaced seeds. These data structure designs will have applications in genome, transcriptome and metagenome assemblies, and read error correction.
An Assessment of China’s Anti-Satellite and Space Warfare Programs, Policies and Doctrines
2008-01-19
Zhu Rinzhong, “The Theory of GPS and Methods of Countering It,” Junshi xueshu, May 1999, pp. 5859, in Dean Cheng, “The Chinese Space Program: A 21st...Haijun Xueshu Yanjiu 海军学术研究 Military Economics Research Junshi Jingji Yanjiu 军事经济研究 Modern Military Branches Xiandai Bingzhong 现代兵种 Air Force Logistics
Chemical Space of FLT3 Inhibitors as Potential Anti-AML Drugs.
Lan, Qing-Yuan; Zhi, Yan-Le; Heng, Hao; Tian, Jie-Yi; Guo, Xiao-Xing; Liu, Hai-Chun; Chen, Ya-Dong; Lu, Tao; Lu, Shuai
2017-11-20
FLT3 is a member of receptor tyrosine kinase III family, mainly expressed in hematopoietic cells. The aberrant expression and function of FLT3 are strongly related to leukemia, especially acute myeloid leukemia. Its varieties of amino-acid residues mutations, such as FLT3-ITDs and -TKDs, can induce constant proliferation of hematological tumor cells with poor prognosis. Hence FLT3 serves as a promising target in AML chemotherapy. This review focused on the progress of FLT3 inhibitors study including those that have entered clinical trials or were reported in numerous patents all over the world. Thus, we provided a useful reference for the development of new anti-leukemia drugs. Through a comprehensive retrospective study, FLT3 inhibitors in several patent applications were identified and classified into five categories, including quinolone-related, indole-related, ureas, pyrimidines and other compounds. For each category of compounds, the structural feature, SAR, biological activity and current research status were thoroughly reviewed and analyzed. Although some of those compounds expressed potent bioactivities and have reached the advanced clinical trials for the treatment of leukemia, there are still several problems need to be faced before they enter the market eventually, especially the drug resistance issue. The improvement of therapeutic potency for FLT3 inhibitors might depend on the useful combination therapy and further refinement of the intrinsic properties of FLT3 inhibitors. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.
Energy Technology Data Exchange (ETDEWEB)
Delaunay, C
2008-10-15
The Higgs boson appears as the corner stone of high energy physics, it might be the cause of the excess of matter that led to the formation of the structures of the universe and it seems that it drives the breaking of the electroweak symmetry. Moreover, when the stability at low energies of the Higgs boson is assured by an extra space dimension, it appears that this extra dimension can explain most issues in the flavor physics that are not understood by the standard model. The first chapter presents the main tools of effective field theories, the role of experimental data in the construction of theories valid beyond the standard model is discussed. The second chapter focuses on the electroweak baryogenesis that allows the testing of new physics via the electroweak phase transition. We detail the calculation of a Higgs potential at finite temperature. We follow the dynamics of the phase transition including nucleation an supercooling. Finally we investigate the prospects of gravity wave detection to see the effects of a strong electroweak phase transition. The 2 last chapters are dedicated to the physics of extra-dimension. The properties of the dynamics of scalar, vector fields with a 1/2 spin plunged in a 5 d. Anti de Sitter geometry are reviewed. We present a model of lepton masses and mixings based on the A{sub 4} non-Abelian discrete symmetry. It is shown that this model does not contradict the tests of electroweak precision. (A.C.)
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Osnir de Sá Viana
2006-12-01
Full Text Available O efavirenz é uma das mais recentes classes de agentes anti-retrovirais aplicados no tratamento de infecções por HIV. Está entre os medicamentos de primeira escolha no tratamento da AIDS. Como o efavirenz possui característica hidrofóbica, baixa densidade e oferece grande resistência ao escoamento, a escolha de uma formulação adequada deste fármaco é essencial no desenvolvimento dos comprimidos e para garantir melhor disponibilização no trato gastrointestinal, de forma a alcançar a biodisponibilidade e o efeito terapêutico desejados. Neste trabalho, apresentamos, de forma lógica, o desenvolvimento tecnológico de comprimidos revestidos de efavirenz, levando em consideração suas características físicas e físico-químicas. Os núcleos (comprimidos de efavirenz foram obtidos utilizando-se a técnica de granulação por via úmida. No revestimento por película utilizou-se Opadry® Y-1-7000 em sistema aquoso. Os parâmetros adotados para avaliação física dos comprimidos seguiram as especificações farmacopéicas oficiais e a determinação quantitativa foi realizada mediante método analítico desenvolvido e validado.Efavirenz is one of the most recent classes of anti-retroviral drugs used in the treatment of HIV infections. It is the first choice therapy for AIDS treatment. As efavirenz detains hydrofobic characteristic, low density and offers great resistance to draining, it has been essential to choose an adequated formulation for it, in order to guarantee drug's availability in gastro-intestinal tract, achieving bioavailability and expected therapeutical effects. This work presents efavirez coated tablets thecnological development, considering the physics and physico-chemical characteristics of this drug. The efavirez nucleus (tablets has been obtained employing granulation technics by humid via. In the coating by film, Opadry Y-1-7000 in aquous system was used. The adopted parameters to tablet phisics evaluation
Perfil de utilización de los anti-factor de necrosis tumoral en pacientes de Colombia
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Jorge Machado
2011-03-01
Conclusiones. Los anti-TNF se emplearon a las dosis recomendadas, principalmente en artritis reumatoide y en combinación con otros antirreumáticos. El costo directo del tratamiento se consideró elevado para el sistema sanitario del país.
Phase transitions and critical behaviour for charged black holes
International Nuclear Information System (INIS)
Carlip, S; Vaidya, S
2003-01-01
We investigate the thermodynamics of a four-dimensional charged black hole in a finite cavity in asymptotically flat and asymptotically de Sitter spaces. In each case, we find a Hawking-Page-like phase transition between a black hole and a thermal gas very much like the known transition in asymptotically anti-de Sitter space. For a 'supercooled' black hole - a thermodynamically unstable black hole below the critical temperature for the Hawking-Page phase transition - the phase diagram has a line of first-order phase transitions that terminates in a second-order point. For the asymptotically flat case, we calculate the critical exponents at the second-order phase transition and find that they exactly match the known results for a charged black hole in anti-de Sitter space. We find strong evidence for similar phase transitions for the de Sitter black hole as well. Thus many of the thermodynamic features of charged anti-de Sitter black holes do not really depend on asymptotically anti-de Sitter boundary conditions; the thermodynamics of charged black holes is surprisingly universal
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Sara Vázquez-Corzo
2003-10-01
Full Text Available OBJETIVO: Determinar si anticuerpos séricos contra E4, E7 y Ras pueden ser utilizados como marcadores de lesiones tempranas del cérvix uterino asociadas al virus del papiloma humano. MATERIAL Y MÉTODOS: Entre marzo de 1999 y abril de 2000 se realizó un estudio sero-epidemiológico de casos y controles en la clínica de displasias del Hospital General Doctor Gea González, en la Ciudad de México, en 116 muestras de suero para evaluar la presencia de anticuerpos anti-E4, E7 y Ras utilizando un ELISA de captura. Se estimaron razones de momios e intervalos de confianza de 95% RESULTADOS: Anticuerpos anti-E7 se asociaron a mujeres con lesiones NIC III, mientras que anticuerpos anti-E4 y anti-Ras fueron más frecuentes en lesiones NIC I-II. Al evaluar el perfil de anticuerpos que presentaron las mujeres, encontramos que a anticuerpos contra dos proteínas predicen la existencia de una lesión NIC I-II, y b la presencia de tres anticuerpos predicen una lesión NIC III. CONCLUSIONES: La detección de anticuerpos séricos contra E4, E7 y Ras en combinación con otras técnicas de diagnóstico, podrían ser de utilidad para detectar oportunamente a mujeres con lesiones tempranas asociadas al Virus del Papiloma Humano y en riesgo de desarrollar cáncer.OBJECTIVE: To evaluate whether serum antibodies anti-E4, E7 and Ras could be used as markers for early cervical lesions associated with HPV (human papillomavirus. MATERIAL AND METHODS: A seroepidemiological case-control study was conducted between March 1999 and April 2000 at the dysplasia clinic of Hospital General Doctor Gea Gonzalez, in Mexico City, to evaluate the presence of antibodies anti-E4, E7, and Ras through a sandwich ELISA. Analysis was done using odds ratios and 95% confidence intervals. RESULTS: Anti-E7 antibodies were associated to women with CIN III lesions, while anti-E4 and Ras antibodies were strongly associated with CIN I-II lesions. The antibody profile of women with different
Design Space Approach for Preservative System Optimization of an Anti-Aging Eye Fluid Emulsion.
Lourenço, Felipe Rebello; Francisco, Fabiane Lacerda; Ferreira, Márcia Regina Spuri; Andreoli, Terezinha De Jesus; Löbenberg, Raimar; Bou-Chacra, Nádia
2015-01-01
The use of preservatives must be optimized in order to ensure the efficacy of an antimicrobial system as well as the product safety. Despite the wide variety of preservatives, the synergistic or antagonistic effects of their combinations are not well established and it is still an issue in the development of pharmaceutical and cosmetic products. The purpose of this paper was to establish a space design using a simplex-centroid approach to achieve the lowest effective concentration of 3 preservatives (methylparaben, propylparaben, and imidazolidinyl urea) and EDTA for an emulsion cosmetic product. Twenty-two formulae of emulsion differing only by imidazolidinyl urea (A: 0.00 to 0.30% w/w), methylparaben (B: 0.00 to 0.20% w/w), propylparaben (C: 0.00 to 0.10% w/w) and EDTA (D: 0.00 to 0.10% w/w) concentrations were prepared. They were tested alone and in binary, ternary and quaternary combinations. Aliquots of these formulae were inoculated with several microorganisms. An electrochemical method was used to determine microbial burden immediately after inoculation and after 2, 4, 8, 12, 24, 48, and 168 h. An optimization strategy was used to obtain the concentrations of preservatives and EDTA resulting in a most effective preservative system of all microorganisms simultaneously. The use of preservatives and EDTA in combination has the advantage of exhibiting a potential synergistic effect against a wider spectrum of microorganisms. Based on graphic and optimization strategies, we proposed a new formula containing a quaternary combination (A: 55%; B: 30%; C: 5% and D: 10% w/w), which complies with the specification of a conventional challenge test. A design space approach was successfully employed in the optimization of concentrations of preservatives and EDTA in an emulsion cosmetic product.
Prevalência de não adesão à farmacoterapia anti-hipertensiva e fatores associados
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Mayckel da Silva Barreto
2015-02-01
Full Text Available Objetivo: verificar a prevalência da não adesão ao tratamento medicamentoso anti-hipertensivo e sua associação com fatores biosócio-econômicos e assistenciais. Método: pesquisa descritiva de corte transversal, realizada com 422 indivíduos hipertensos. As informações foram coletadas, por meio de entrevistas domiciliares realizadas entre dezembro de 2011 e março de 2012. Resultados: os resultados demonstraram que os entrevistados eram, em sua maioria, do sexo feminino, casados, idosos, com baixa renda familiar e pouco tempo de diagnóstico. Foram considerados não aderentes ao tratamento medicamentoso 42.65% dos participantes. Os hipertensos não brancos, com menos de oito anos de estudo, que não frequentavam as consultas médicas; utilizavam mais de duas medicações anti-hipertensivas e que não possuíam plano de saúde apresentaram maiores chances de não aderirem à farmacoterapia. Conclusão: esses achados reforçam que hipertensos com características socioeconômicas desfavoráveis e dificuldade de acesso ao serviço necessitam de intervenções diferenciadas, a fim de estimulá-los a aderirem ao tratamento medicamentoso.
Notes on teleportation in an expanding space
Energy Technology Data Exchange (ETDEWEB)
Feng, Jun, E-mail: tsunfeng@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Yang, Wen-Li [Institute of Modern Physics, Northwest University, Xian 710069 (China); Zhang, Yao-Zhong [School of Mathematics and Physics, The University of Queensland, Brisbane, QLD 4072 (Australia); Fan, Heng, E-mail: hfan@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)
2013-02-26
We investigate the quantum teleportation between a conformal detector Alice and an inertial detector Bob in de Sitter space in two schemes, (i) one uses free scalar modes and (ii) one utilizes cavity to store qubit. We show that the fidelity of the teleportation is degraded for Bob in both cases. While the fidelity-loss is due to the Gibbons–Hawking effect associated with his cosmological horizon in the scheme (i), the entanglement decreases in the scheme (ii) because the ability to entangle the cavities is reduced by the spacetime curvature. With a cutoff at Planck-scale, comparing with the standard Bunch–Davies choice, we also show that the possible Planckian physics cause extra modifications to the fidelity of the teleportation protocol in both schemes.
MÉTODO DE ESCOLHA DE MEDICAMENTOS ANTI-HIPERTENSIVOS POR GESTORES DA ÁREA DE SAÚDE
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Rondinelli de Carvalho LADEIRA
2016-06-01
Full Text Available Um problema enfrentado pelos gestores de saúde é a aquisição de medicamentos que, para o abastecimento do SUS, deve-se levar em consideração a efetividade, os custos e a segurança dos mesmos. A análise farmacoeconômica pode ser vista como a descrição e a análise dos custos da terapia farmacêutica para os sistemas de assistência à saúde e para a sociedade. O presente trabalho faz a análise de custo-efetividade de cinco betabloqueadores adrenérgicos usados no tratamento de hipertensão arterial (atenolol, carvedilol, metoprolol, propranolol e sotalol através de auxílio multicritério à decisão. Tendo em vista gestores de saúde como agentes da decisão, foram testados os métodos de Borda para definição dos pesos dos critérios por especialistas e AHP para escolha do medicamento através do software IPE 1.0. Questionários foram aplicados a sete profissionais médicos especialistas em cardiologia para a comparação dos critérios (efetividade, custo, experiência com o fármaco e segurança, sub-critérios (agravamento da insuficiência cardíaca congestiva, agravamento da doença arterial periférica, broncoespasmo, bradicardia e alterações metabólicas, relativos ao critério segurança e alternativas à luz dos critérios estudados. O betabloqueador que se apresentou como melhor escolha foi o atenolol (32,38%.
Meditaciones anti-cartesianas: sobre el origen del anti-discurso filosófico de la modernidad
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ENRIQUE DUSSEL
2008-01-01
Full Text Available Descartes pasa por ser el primer filósofo moderno. Si se interpreta la Modernidad tal como lo hace el pensamiento decolonial o la filosofía de la liberación habría que resituar el siglo XVI, y los filósofos de ese siglo, como el origen de la filosofía moderna y no a Descartes. Además, Descartes fue alumno de los filósofos hispanos del siglo XVI contra los que se opina. El antidiscurso de la Modernidad no surge en la Ilustración sino al inicio del proceso de la conquista. Hay entonces que replantear completamente la historia filosófica de la Modernidad. Por último, la crítica de la Modernidad más radical debe buscarse en aquellos que la sufrieron como Guamán Poma de Ayala en el Perú.
Gonçalves,C.A.P.; Botteon,P.T.L.; Alves,G. E.S.; Faleiros,R.R.; Paes Leme,F.O.; Mendes,H.M.F.; Vasconcelos,A.C.
2013-01-01
O objetivo deste trabalho foi avaliar a influência da administração dos anti-inflamatórios não esteroidais (AINEs) cetoprofeno, fenilbutazona e flunixin meglumine sobre o índice apoptótico de células epiteliais do tecido lamelar de cavalos com laminite induzida por administração de amido. Foram empregados 20 equinos hígidos, divididos em quatro grupos experimentais (n=5): solução salina, cetoprofeno, fenilbutazona e flunixin meglumine. O tecido lamelar foi coletado por biópsia, fixado e corad...
Mobile app for human-interaction with sitter robots
Das, Sumit Kumar; Sahu, Ankita; Popa, Dan O.
2017-05-01
Human environments are often unstructured and unpredictable, thus making the autonomous operation of robots in such environments is very difficult. Despite many remaining challenges in perception, learning, and manipulation, more and more studies involving assistive robots have been carried out in recent years. In hospital environments, and in particular in patient rooms, there are well-established practices with respect to the type of furniture, patient services, and schedule of interventions. As a result, adding a robot into semi-structured hospital environments is an easier problem to tackle, with results that could have positive benefits to the quality of patient care and the help that robots can offer to nursing staff. When working in a healthcare facility, robots need to interact with patients and nurses through Human-Machine Interfaces (HMIs) that are intuitive to use, they should maintain awareness of surroundings, and offer safety guarantees for humans. While fully autonomous operation for robots is not yet technically feasible, direct teleoperation control of the robot would also be extremely cumbersome, as it requires expert user skills, and levels of concentration not available to many patients. Therefore, in our current study we present a traded control scheme, in which the robot and human both perform expert tasks. The human-robot communication and control scheme is realized through a mobile tablet app that can be customized for robot sitters in hospital environments. The role of the mobile app is to augment the verbal commands given to a robot through natural speech, camera and other native interfaces, while providing failure mode recovery options for users. Our app can access video feed and sensor data from robots, assist the user with decision making during pick and place operations, monitor the user health over time, and provides conversational dialogue during sitting sessions. In this paper, we present the software and hardware framework that
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Guilherme Nunes
2010-06-01
Full Text Available O objetivo deste estudo é descrever as características clínicas e as respostas às intervenções terapêuticas, incluindo a terapia antifator de necrose tumoral (TNF, em uma série de casos brasileiros de arterite de Takayasu (AT. Foi realizado um estudo observacional, retrospectivo, com base na revisão de prontuários, incluindo todos os pacientes com AT, de acordo com os critérios de classificação do American College of Rheumatology, em acompanhamento no Serviço de Reumatologia do Hospital Universitário da Universidade Federal de Santa Catarina (UFSC, Brasil. Foram incluídos 15 pacientes, sendo 14 (93,3% mulheres, com idade média ao diagnóstico de 29,6 anos. Hipertensão arterial sistêmica (60,0% e ausência de pulsos em membros superiores (53,3% foram os achados clínicos mais comuns ao diagnóstico. As artérias subclávias e carotídeas foram os vasos mais frequentemente acometidos. Doze pacientes (80,0% não obtiveram remissão sustentada em terapia isolada com corticosteroide, tendo sido empregada terapia imunossupressora, sendo metotrexato, azatioprina e ciclofosfamida as drogas utilizadas. Intervenções cirúrgicas foram necessárias em 53,3% dos casos. Três casos (20,0% foram refratários à terapia com corticoides e imunossupressores e foram tratados com agentes anti-TNF, com subsequente remissão da doença. Em conclusão, observou-se que uma parcela importante dos casos de AT é refratária à terapia tradicional e os agentes anti-TNF podem representar uma opção promissora para o controle da doença nesses casos.The aim of this study was to describe clinical features and response to different therapeutic interventions, including anti-tumor necrosis factor (TNF agents, in a case series of Takayasu arteritis (TA from Brazil. A retrospective observational chart-review study was performed including all patients meeting the American College of Rheumatology TA classification criteria followed at the rheumatology
Modelo matemático para estructura tubular de edifico antisísmico
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Mazzeo, Agustin
1972-02-01
Full Text Available This mathematical model was worked out when seeking a structural pattern for a building with a main steel structure, apt for the seismic circumstances of the city of Caracas. Of the various possibilities that were considered, it was decided the one which best met the conditions of the project involved the use of the so called external flexible tube, to withstand horizontal thrusts. The analysis of the space properties of the perimetral tube, through the use of a plane image of the structure, constitutes the mathematical model described in this article.El modelo matemático objeto del artículo fue desarrollado al estudiar la solución estructural para un edificio con estructura principal de acero, proyectado para las condiciones sísmicas de la ciudad de Caracas. De las varias alternativas analizadas, se concluyó que la que mejor permitía cumplir con las exigencias del proyecto consistía en utilizar como solución, para resistir los efectos horizontales, el sistema estructural conocido como tubo exterior flexible. El análisis de las características espaciales del tubo perimetral mediante el uso de una imagen plana de la estructura, constituye el modelo matemático que se describe en el artículo.
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Fernando Lopes Gonçales Júnior
1993-02-01
Full Text Available Pesquisamos os anticorpos anti-HBc e anti-HCV em amostras de soros provenientes de 799 candidatos a doadores, que tiveram suas unidades de sangue ou derivados transfundidas a 111 receptores. O anti-HBc e o anti-HCV foram reagentes, em respectivamente 9 e 2,1% dos doadores testados. Observamos que entre os 111 receptores, 44 haviam recebido pelo menos uma unidade anti-HBc positiva e 67 haviam sido transfundidos somente com unidades anti-HBc negativas. Houve um risco 4,5 vezes maior de aquisição de hepatite por vírus C pelos receptores que receberam pelo menos uma unidade anti-HBc positiva Se a pesquisa do anti-HBc fosse realizada na triagem sorológica dos doadores de sangue, cerca de 56% dos casos de HVC nos receptores saiam evitados. A população de receptores que recebeu pelo menos uma unidade anti-HCV reagente, apresentou um risco 29 vezes maior de adquirir esta hepatite, quando comparada aos receptores transfundidos com todas as unidades anti-HCV negativas. A realização do teste para a pesquisa do anti-HCV na triagem dos doadores de sangue, preveniria 79% dos casos de HVC pós-transfusionais. Os candidatos a doadores brasileiros parecem ser acometidos simultânea ou sequencialmente, pelos vírus B e C das hepatites, pois, 44,4% dos doadores anti-HCV positivos, também foram anti-HBc positivos. A realização dos testes para as pesquisas dos anticorpos anti-HBc e anti-HCV, nas triagens hemoterápicas, está indicada para prevenir a transmissão de hepatites pós-transfusionais, em nosso meio.We have analysed anti-HBc and anti-HCV antibodies in serum samples from 799 donors which had their blood or derivates transfused to 111 recipients. Anti-HBc and anti-HCV were reactive in respectively 9 and 2.1% of the donors tested. We have observed that among the 111 recipients, 44 had received at least one positive anti-HBc unit and 67 had been transfused only with negative anti-HBc, units. The risk of developing hepatitis C virus was 4.5 times
Produção e purificação de imunoglobulinas Y policlonais anti-Leptospira spp.
Directory of Open Access Journals (Sweden)
Tatiane C.F. Tavares
2013-09-01
Full Text Available Objetivou-se verificar se galinhas imunizadas com uma solução de Leptospira interrogans inativadas e proteínas de membrana externa do sorovar Hardjo, poderiam produzir anticorpos policlonais específicos anti-leptospiras, detectáveis em testes ELISA. Foram imunizados oito galinhas com 25 semanas de idade, da raça White Leghorn, sendo três imunizadas com uma suspensão de leptospiras inativadas, três com uma solução de proteínas de membrana externa extraída do sorovar Hardjo e duas controle. Coletas de sangue foram realizadas quinzenalmente e de ovos diariamente. A IgY foi purificada a partir da gema dos ovos utilizando para a delipidação o método de diluição em água ácida e a precipitação com sulfato de amônio. Nos testes ELISA realizados para verificar a especificidade da IgY, foi demonstrada a produção de anticorpos anti-Leptospira, tanto no soro quanto nas gemas purificadas. O pico de produção de anticorpos específicos ocorreu na 5º semana após a primeira imunização. Ficou demonstrada a possibilidade da indução da produção de anticorpos específicos em galinhas imunizadas com leptospiras do sorovar Hardjo inativadas, bem como, com proteínas de membrana externa (PME extraidas desse sorovar. As galinhas imunizadas com uma suspensão de leptospiras inativadas ou com PME de Leptospira interrogans do sorovar Hardjo produziram anticorpos reativos a PME Hardjo detectáves por teste ELISA.
Regulating public space on the beachfronts of Rio de Janeiro.
Godfrey, Brian J; Arguinzoni, Olivia M
2012-01-01
Despite the fortification of buildings, streets, and public squares, Rio de Janeiro's beaches remain widely regarded as democratic spaces of social diversity and accessibility. Our study revisits the question of Rio's “democratic” beachfronts, based on local interviews, field observations, official reports, and newspaper accounts. We focus on historical and contemporary perceptions of planning, privatization, and public-order programs on the city's southern seaside. Institutional discourses have justified increasing regulation to combat threats of disorder and insecurity. While residents value the relative openness of beachfronts, they also acknowledge issues of safety, social segmentation, and subtle forms of bias. The public generally applauds recent “Shock of Order” policing and commercial revitalization, although critics lament the loss of traditional freedoms for informal beach vendors and casual sports. These paradoxes highlight enduring tensions between social order and hierarchy on one hand, and democratic rights and equality on the other.
Intertwined Hamiltonians in two-dimensional curved spaces
International Nuclear Information System (INIS)
Aghababaei Samani, Keivan; Zarei, Mina
2005-01-01
The problem of intertwined Hamiltonians in two-dimensional curved spaces is investigated. Explicit results are obtained for Euclidean plane, Minkowski plane, Poincare half plane (AdS 2 ), de Sitter plane (dS 2 ), sphere, and torus. It is shown that the intertwining operator is related to the Killing vector fields and the isometry group of corresponding space. It is shown that the intertwined potentials are closely connected to the integral curves of the Killing vector fields. Two problems are considered as applications of the formalism presented in the paper. The first one is the problem of Hamiltonians with equispaced energy levels and the second one is the problem of Hamiltonians whose spectrum is like the spectrum of a free particle