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Black string in dRGT massive gravity

NASA Astrophysics Data System (ADS)

Tannukij, Lunchakorn; Wongjun, Pitayuth; Ghosh, Suchant G.

2017-12-01

We present a cylindrically symmetric solution, both charged and uncharged, which is known as a black string solution to the nonlinear ghost-free massive gravity found by de Rham, Gabadadze, and Tolley (dRGT). This "dRGT black string" can be thought of as a generalization of the black string solution found by Lemos. Moreover, the dRGT black string solution includes other classes of black string solution such as the monopole-black string ones since the graviton mass contributes to the global monopole term as well as the cosmological-constant term. To investigate the solution, we compute mass, temperature, and entropy of the dRGT black string. We found that the existence of the graviton mass drastically affects the thermodynamics of the black string. Furthermore, the Hawking-Page phase transition is found to be possible for the dRGT black string as well as the charged dRGT black string. The dRGT black string solution is thermodynamically stable for r>r_c with negative thermodynamical potential and positive heat capacity while it is unstable for r
Evolution and End Point of the Black String Instability: Large D Solution.

PubMed

Emparan, Roberto; Suzuki, Ryotaku; Tanabe, Kentaro

2015-08-28

We derive a simple set of nonlinear, (1+1)-dimensional partial differential equations that describe the dynamical evolution of black strings and branes to leading order in the expansion in the inverse of the number of dimensions D. These equations are easily solved numerically. Their solution shows that thin enough black strings are unstable to developing inhomogeneities along their length, and at late times they asymptote to stable nonuniform black strings. This proves an earlier conjecture about the end point of the instability of black strings in a large enough number of dimensions. If the initial black string is very thin, the final configuration is highly nonuniform and resembles a periodic array of localized black holes joined by short necks. We also present the equations that describe the nonlinear dynamics of anti-de Sitter black branes at large D.
Black holes and black strings of N = 2, d = 5 supergravity in the H-FGK formalism

NASA Astrophysics Data System (ADS)

Meessen, Patrick; Ortín, Tomás; Perz, Jan; Shahbazi, C. S.

2012-09-01

We study general classes and properties of extremal and non-extremal static black-hole solutions of N = 2, d = 5 supergravity coupled to vector multiplets using the recently proposed H-FGK formalism, which we also extend to static black strings. We explain how to determine the integration constants and physical parameters of the blackhole and black-string solutions. We derive some model-independent statements, including the transformation of non-extremal flow equations to the form of those for the extremal flow. We apply our methods to the construction of example solutions (among others a new extremal string solution of heterotic string theory on K 3 × S 1). In the cases where we have calculated it explicitly, the product of areas of the inner and outer horizon of a non-extremal solution coincides with the square of the moduli-independent area of the horizon of the extremal solution with the same charges.
Stationary black holes with stringy hair

NASA Astrophysics Data System (ADS)

Boos, Jens; Frolov, Valeri P.

2018-01-01

We discuss properties of black holes which are pierced by special configurations of cosmic strings. For static black holes, we consider radial strings in the limit when the number of strings grows to infinity while the tension of each single string tends to zero. In a properly taken limit, the stress-energy tensor of the string distribution is finite. We call such matter stringy matter. We present a solution of the Einstein equations for an electrically charged static black hole with the stringy matter, with and without a cosmological constant. This solution is a warped product of two metrics. One of them is a deformed 2-sphere, whose Gaussian curvature is determined by the energy density of the stringy matter. We discuss the embedding of a corresponding distorted sphere into a three-dimensional Euclidean space and formulate consistency conditions. We also found a relation between the square of the Weyl tensor invariant of the four-dimensional spacetime of the stringy black holes and the energy density of the stringy matter. In the second part of the paper, we discuss test stationary strings in the Kerr geometry and in its Kerr-NUT-(anti-)de Sitter generalizations. Explicit solutions for strings that are regular at the event horizon are obtained. Using these solutions, the stress-energy tensor of the stringy matter in these geometries is calculated. Extraction of the angular momentum from rotating black holes by such strings is also discussed.
Black String and Velocity Frame Dragging

NASA Astrophysics Data System (ADS)

Lee, Jungjai; Kim, Hyeong-Chan

We investigate velocity frame dragging with the boosted Schwarzschild black string solution and the boosted Kaluza-Klein bubble solution, in which a translational symmetry along the boosted z-coordinate is implemented. The velocity frame dragging effect can be nullified by the motion of an observer using the boost symmetry along the z-coordinate if it is not compact. However, in spacetime with the compact z-coordinate, we show that the effect cannot be removed since the compactification breaks the global Lorentz boost symmetry. As a result, the comoving velocity depends on r and the momentum parameter along the z-coordinate becomes an observer independent characteristic quantity of the black string and bubble solutions. The dragging induces a spherical ergo-region around the black string.
Black holes, anti de Sitter space, and topological strings

NASA Astrophysics Data System (ADS)

Yin, Xi

This thesis is devoted to the study of black holes in string theory, their connection to two and three dimensional anti de-Sitter space, and topological strings. We start by proposing a relation between supersymmetric black holes in four and five dimensions, as well as connections between multi-centered black holes in four dimensions and black rings in five dimensions. This connection is then applied to counting supersymmetric dyonic black holes in four dimensional string compactifications with 16 and 32 supersymmetries, respectively. We then turn to the near horizon attractor geometry AdS 2 x S2 x CY 3, and study the classical supersymmetric D-branes in this background. We also find supersymmetric black hole solutions in supergravity in AdS2 x S2, although the solutions have regions of closed timelike curves. Finally we consider the M-theory attractor geometry AdS3 x S2 x CY3, and compute the elliptic genus of the dual (0, 4) CFT by counting wrapped M2-brane states in the bulk in a dilute gas approximation. This leads to a derivation of the conjectured relation between black hole partition function and topological string amplitudes.
Phases and stability of non-uniform black strings

NASA Astrophysics Data System (ADS)

Emparan, Roberto; Luna, Raimon; Martínez, Marina; Suzuki, Ryotaku; Tanabe, Kentaro

2018-05-01

We construct solutions of non-uniform black strings in dimensions from D ≈ 9 all the way up to D = ∞, and investigate their thermodynamics and dynamical stability. Our approach employs the large- D perturbative expansion beyond the leading order, including corrections up to 1 /D 4. Combining both analytical techniques and relatively simple numerical solution of ODEs, we map out the ranges of parameters in which non-uniform black strings exist in each dimension and compute their thermodynamics and quasinormal modes with accuracy. We establish with very good precision the existence of Sorkin's critical dimension and we prove that not only the thermodynamic stability, but also the dynamic stability of the solutions changes at it.
Closed timelike curves produced by pairs of moving cosmic strings - Exact solutions

NASA Technical Reports Server (NTRS)

Gott, J. Richard, III

1991-01-01

Exact solutions of Einstein's field equations are presented for the general case of two moving straight cosmic strings that do not intersect. The solutions for parallel cosmic strings moving in opposite directions show closed timelike curves (CTCs) that circle the two strings as they pass, allowing observers to visit their own past. Similar results occur for nonparallel strings, and for masses in (2+1)-dimensional spacetime. For finite string loops the possibility that black-hole formation may prevent the formation of CTCs is discussed.
Cosmic string loops as the seeds of super-massive black holes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bramberger, Sebastian F.; Brandenberger, Robert H.; Jreidini, Paul

2015-06-01

Recent discoveries of super-massive black holes at high redshifts indicate a possible tension with the standard ΛCDM paradigm of early universe cosmology which has difficulties in explaining the origin of the required nonlinear compact seeds which trigger the formation of these super-massive black holes. Here we show that cosmic string loops which result from a scaling solution of strings formed during a phase transition in the very early universe lead to an additional source of compact seeds. The number density of string-induced seeds dominates at high redshifts and can help trigger the formation of the observed super-massive black holes.
Black holes as beads on cosmic strings

NASA Astrophysics Data System (ADS)

Ashoorioon, Amjad; Mann, Robert B.

2014-11-01

We consider the possibility of the formation of cosmic strings with black holes as beads. We focus on the simplest setup where two black holes are formed on a long cosmic string. It turns out that in the absence of a background magnetic field and for observationally viable values for cosmic string tensions, μ \\lt 2× {{10}-7}, the tension of the strut in between the black holes has to be less than the ones that run into infinity. This result does not change if a cosmological constant is present. However, if a background magnetic field is turned on, we can have stable setups where the tensions of all cosmic strings are equal. We derive the equilibrium conditions in each of these setups depending on whether the black holes are extremal or non-extremal. We obtain cosmologically acceptable solutions with solar mass black holes and an intragalactic-strength cosmic magnetic field.
A black hole quartet: New solutions and applications to string theory

NASA Astrophysics Data System (ADS)

Padi, Megha

In this thesis, we study a zoo of black hole solutions which help us connect string theory to the universe we live in. The intuition for how to attack fundamental problems can often be found in a toy model. In Chapter 2, we show that three-dimensional topologically massive gravity with a negative cosmological constant -ℓ -2 and coupling constant has "warped AdS3" solutions with SL(2, R ) x U(1) isometry. For muℓ > 3, we show that certain discrete quotients of warped AdS3 lead to black holes. Their thermodynamics is consistent with the existence of a holographic dual CFT with central charges cR = 15mℓ 2+81Gmm ℓ2+27 and cL = 12mℓ 2Gmm ℓ2+27 . The entropy of many supersymmetric black holes have been accounted for, but more realistic non-supersymmetric black holes have been largely overlooked. In Chapter 3, we derive new single-centered and multi-centered non-BPS black hole solutions for several four dimensional models which, after Kaluza-Klein reduction, admit a description in terms of a sigma model with symmetric target space. In particular, we provide the exact solution with generic charges and asymptotic moduli in N=2 supergravity coupled to one vector multiplet. As it stands, the current formulation of string theory allows for an extremely large number of possible solutions (or vacua). We first analyze this landscape by looking for universal characteristics. In Chapter 4, we provide evidence for the conjecture that gravity is always the weakest force in any string compactification. We show that, in several examples arising in string theory, higher-derivative corrections always make extremal non-supersymmetric black holes lighter than the classical bound M/Q = 1. In Chapter 5, we construct novel black hole bound states, called orientiholes, that are T-dual to IIB orientifold compactifications. The gravitational entropy of such orientiholes provides an "experimental" estimate of the number of vacua in various sectors of the IIB landscape. Furthermore, basic physical properties of orientiholes map to (sometimes subtle) microscopic features, thus providing a useful alternative viewpoint on a number of issues arising in D-brane model building. We also suggest a relation to the topological string analogous to the OSV conjecture.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Vieira, H.S., E-mail: horacio.santana.vieira@hotmail.com; Centro de Ciências, Tecnologia e Saúde, Universidade Estadual da Paraíba, CEP 58233-000, Araruna, PB; Bezerra, V.B., E-mail: valdir@fisica.ufpb.br

Charged massive scalar fields are considered in the gravitational and electromagnetic field produced by a dyonic black hole with a cosmic string along its axis of symmetry. Exact solutions of both angular and radial parts of the covariant Klein–Gordon equation in this background are obtained, and are given in terms of the confluent Heun functions. The role of the presence of the cosmic string in these solutions is showed up. From the radial solution, we obtain the exact wave solutions near the exterior horizon of the black hole, and discuss the Hawking radiation spectrum and the energy flux. -- Highlights:more » •A cosmic string is introduced along the axis of symmetry of the dyonic black hole. •The covariant Klein–Gordon equation for a charged massive scalar field in this background is analyzed. •Both angular and radial parts are transformed to a confluent Heun equation. •The resulting Hawking radiation spectrum and the energy flux are obtained.« less
Validity of black hole complementarity in the BTZ black hole

NASA Astrophysics Data System (ADS)

Gim, Yongwan; Kim, Wontae

2018-01-01

Based on the gedanken experiment for black hole complementarity in the Schwarzschild black hole, we calculate the energy required to duplicate information in the BTZ black hole under the assumption of absorbing boundary condition and its dual solution of the black string, respectively, in order to justify the validity of the no-cloning theorem in quantum mechanics. For the BTZ black hole, the required energy for the duplication of information can be made fairly small, whereas for the black string it exceeds the total mass of the black string, although they are related to each other under the dual transformation. So, the duplication of information might be possible in the BTZ black hole in contrast to the case of the black string, so that the no-cloning theorem could be violated for the former case. To save the duplication of information for the BTZ black hole, we perform an improved gedanken experiment by using the local thermodynamic quantities near the horizon rather than those defined at infinity, and show that the no-cloning theorem could be made valid even in the BTZ black hole. We also discuss how this local treatment for the no-cloning theorem can be applied to the black string as well as the Schwarzschild black hole innocuously.
Nonspherically symmetric black string perturbations in the large dimension limit

NASA Astrophysics Data System (ADS)

Sadhu, Amruta; Suneeta, Vardarajan

2016-06-01

We consider nonspherically symmetric perturbations of the uncharged black string/flat black brane in the large dimension (D) limit of general relativity. We express the perturbations in a simplified form using variables introduced by Ishibashi and Kodama. We apply the large D limit to the equations and show that this leads to decoupling of the equations in the near-horizon and asymptotic regions. It also enables use of matched asymptotic expansions to obtain approximate analytical solutions and to analyze stability of the black string/brane. For a large class of nonspherically symmetric perturbations, we prove that there are no instabilities in the large D limit. For the rest, we provide additional matching arguments that indicate that the black string/brane is stable. In the static limit, we show that for all nonspherically symmetric perturbations, there is no instability. This is proof that the Gross-Perry-Yaffe mode for semiclassical black hole perturbations is the unique unstable mode even in the large D limit. This work is also a direct analytical indication that the only instability of the black string is the Gregory-Laflamme instability.
Principal Killing strings in higher-dimensional Kerr-NUT-(A)dS spacetimes

NASA Astrophysics Data System (ADS)

Boos, Jens; Frolov, Valeri P.

2018-04-01

We construct special solutions of the Nambu-Goto equations for stationary strings in a general Kerr-NUT-(A)dS spacetime in any number of dimensions. This construction is based on the existence of explicit and hidden symmetries generated by the principal tensor which exists for these metrics. The characteristic property of these string configurations, which we call "principal Killing strings," is that they are stretched out from "infinity" to the horizon of the Kerr-NUT-(A)dS black hole and remain regular at the latter. We also demonstrate that principal Killing strings extract angular momentum from higher-dimensional rotating black holes and interpret this as the action of an asymptotic torque.
Physics from geometry: Non-Kahler compactifications, black rings anddS/CFT

NASA Astrophysics Data System (ADS)

Cyrier, Michelle

The spectrum that arises in four dimensions from compactification of ten dimensional string theory onto six dimensional manifolds is determined entirely by the geometry of the compactification manifold. The massless spectrum for compactifications on Calabi-Yau threefolds, which are Kahler and have complex structure, is well understood. In chapter 2 of this thesis, We study the compactification of heterotic string theory on manifolds that are non-Kahler. Such manifolds arise as a solution for compactifications of heterotic string theory with nonzero H-flux. We begin the study of the massless spectrum arising from compactification using this construction by counting zero modes of the linearized equations of motion for the gaugino in the supergravity approximation. We rephrase the question in terms of a cohomology problem and show that for a trivial gauge bundle, this cohomology reduces to the Dolbeault cohomology of the 3-fold, which we then compute. Another check of string theory is to study the entropy of black holes made in string theory. In Chapter 3, We review the microstate counting of four dimensional black holes made from M theory. We then describe a new solution in five dimensions, the supersymmetric black ring, and describe its microscopic entropy using a similar counting. These agree with the semi-classical Bekenstein-Hawking entropy for these black holes. Finally, one powerful tool for quantum gravity is the holographic duality of string theory in an Anti de Sitter background and a theory living on its conformal boundary. Strominger conjectured a similar duality between quantum gravity in a de Sitter background and the corresponding theory on its boundary. In chapter 4 we examine issues with different representations of the conformal field theory on the boundary for a massive quantum field theory living in the bulk and try to write down a sensible CFT.
Cloud of strings in {{f}}({{R}}) gravity

NASA Astrophysics Data System (ADS)

Morais Graça, J. P.; Lobo, Iarley P.; Salako, Ines G.

2018-05-01

We derive the solution for a spherically symmetric string cloud configuration in a d-dimensional spacetime in the framework of f(R) theories of gravity. We also analyze some thermodynamic properties of the joint black hole - cloud of strings solution. For its Hawking temperature, we found that the dependence of the mass with the horizon is significantly different in both theories. For the interaction of a black hole with thermal radiation, we found that the shapes of the curves are similar, but shifted. Our analysis generalizes some known results in the literature. IPL is Supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq-Brazil) (150384/2017-3), JPMG and IPL thank Coordenaç ao de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for Financial Support
Kerr-Newman black holes with string corrections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Charles, Anthony M.; Larsen, Finn

We study N = 2 supergravity with higher-derivative corrections that preserve the N = 2 supersymmetry and show that Kerr-Newman black holes are solutions to these theories. Modifications of the black hole entropy due to the higher derivatives are universal and apply even in the BPS and Schwarzschild limits. Our solutions and their entropy are greatly simplified by supersymmetry of the theory even though the black holes generally do not preserve any of the supersymmetry.
Kerr-Newman black holes with string corrections

DOE PAGES

Charles, Anthony M.; Larsen, Finn

2016-10-26

We study N = 2 supergravity with higher-derivative corrections that preserve the N = 2 supersymmetry and show that Kerr-Newman black holes are solutions to these theories. Modifications of the black hole entropy due to the higher derivatives are universal and apply even in the BPS and Schwarzschild limits. Our solutions and their entropy are greatly simplified by supersymmetry of the theory even though the black holes generally do not preserve any of the supersymmetry.
α '-corrected black holes in String Theory

NASA Astrophysics Data System (ADS)

Cano, Pablo A.; Meessen, Patrick; Ortín, Tomás; Ramírez, Pedro F.

2018-05-01

We consider the well-known solution of the Heterotic Superstring effective action to zeroth order in α ' that describes the intersection of a fundamental string with momentum and a solitonic 5-brane and which gives a 3-charge, static, extremal, supersymmetric black hole in 5 dimensions upon dimensional reduction on T5. We compute explicitly the first-order in α ' corrections to this solution, including SU(2) Yang-Mills fields which can be used to cancel some of these corrections and we study the main properties of this α '-corrected solution: supersymmetry, values of the near-horizon and asymptotic charges, behavior under α '-corrected T-duality, value of the entropy (using Wald formula directly in 10 dimensions), existence of small black holes etc. The value obtained for the entropy agrees, within the limits of approximation, with that obtained by microscopic methods. The α ' corrections coming from Wald's formula prove crucial for this result.

Thermodynamic properties of charged three-dimensional black holes in the scalar-tensor gravity theory

NASA Astrophysics Data System (ADS)

Dehghani, M.

2018-02-01

Making use of the suitable transformation relations, the action of three-dimensional Einstein-Maxwell-dilaton gravity theory has been obtained from that of scalar-tensor modified gravity theory coupled to the Maxwell's electrodynamics as the matter field. Two new classes of the static three-dimensional charged dilatonic black holes, as the exact solutions to the coupled scalar, electromagnetic and gravitational field equations, have been obtained in the Einstein frame. Also, it has been found that the scalar potential can be written in the form of a generalized Liouville-type potential. The conserved black hole charge and masses as well as the black entropy, temperature, and electric potential have been calculated from the geometrical and thermodynamical approaches, separately. Through comparison of the results arisen from these two alternative approaches, the validity of the thermodynamical first law has been proved for both of the new black hole solutions in the Einstein frame. Making use of the canonical ensemble method, a black hole stability or phase transition analysis has been performed. Regarding the black hole heat capacity, with the black hole charge as a constant, the points of type-1 and type-2 phase transitions have been determined. Also, the ranges of the black hole horizon radius at which the Einstein black holes are thermally stable have been obtained for both of the new black hole solutions. Then making use of the inverse transformation relations, two new classes of the string black hole solutions have been obtained from their Einstein counterpart. The thermodynamics and thermal stability of the new string black hole solutions have been investigated. It has been found that thermodynamic properties of the new charged black holes are identical in the Einstein and Jordan frames.
Non-Abelian black string solutions of N = (2,0) , d = 6 supergravity

NASA Astrophysics Data System (ADS)

Cano, Pablo A.; Ortín, Tomás; Santoli, Camilla

2016-12-01

We show that, when compactified on a circle, N = (2, 0), d = 6 supergravity coupled to 1 tensor multiplet and n V vector multiplets is dual to N = (2 , 0) , d = 6 supergravity coupled to just n T = n V + 1 tensor multiplets and no vector multiplets. Both theories reduce to the same models of N = 2 , d = 5 supergravity coupled to n V 5 = n V + 2 vector fields. We derive Buscher rules that relate solutions of these theories (and of the theory that one obtains by dualizing the 3-form field strength) admitting an isometry. Since the relations between the fields of N = 2 , d = 5 supergravity and those of the 6-dimensional theories are the same with or without gaugings, we construct supersymmetric non-Abelian solutions of the 6-dimensional gauged theories by uplifting the recently found 5-dimensional supersymmetric non-Abelian black-hole solutions. The solutions describe the usual superpositions of strings and waves supplemented by a BPST instanton in the transverse directions, similar to the gauge dyonic string of Duff, Lü and Pope. One of the solutions obtained interpolates smoothly between two AdS3× S3 geometries with different radii.
Dynamical black holes in low-energy string theory

NASA Astrophysics Data System (ADS)

Aniceto, Pedro; Rocha, Jorge V.

2017-05-01

We investigate time-dependent spherically symmetric solutions of the four-dimensional Einstein-Maxwell-axion-dilaton system, with the dilaton coupling that occurs in low-energy effective heterotic string theory. A class of dilaton-electrovacuum radiating solutions with a trivial axion, previously found by Güven and Yörük, is re-derived in a simpler manner and its causal structure is clarified. It is shown that such dynamical spacetimes featuring apparent horizons do not possess a regular light-like past null infinity or future null infinity, depending on whether they are radiating or accreting. These solutions are then extended in two ways. First we consider a Vaidya-like generalisation, which introduces a null dust source. Such spacetimes are used to test the status of cosmic censorship in the context of low-energy string theory. We prove that — within this family of solutions — regular black holes cannot evolve into naked singularities by accreting null dust, unless standard energy conditions are violated. Secondly, we employ S-duality to derive new time-dependent dyon solutions with a nontrivial axion turned on. Although they share the same causal structure as their Einstein-Maxwell-dilaton counterparts, these solutions possess both electric and magnetic charges.
String Theory Methods for Condensed Matter Physics

NASA Astrophysics Data System (ADS)

Nastase, Horatiu

2017-09-01

Preface; Acknowledgments; Introduction; Part I. Condensed Matter Models and Problems: 1. Lightning review of statistical mechanics, thermodynamics, phases and phase transitions; 2. Magnetism in solids; 3. Electrons in solids: Fermi gas vs. Fermi liquid; 4. Bosonic quasi-particles: phonons and plasmons; 5. Spin-charge separation in 1+1 dimensional solids: spinons and holons; 6. The Ising model and the Heisenberg spin chain; 7. Spin chains and integrable systems; 8. The thermodynamic Bethe ansatz; 9. Conformal field theories and quantum phase transitions; 10. Classical vs. quantum Hall effect; 11. Superconductivity: Landau-Ginzburg, London and BCS; 12. Topology and statistics: Berry and Chern-Simons, anyons and nonabelions; 13. Insulators; 14. The Kondo effect and the Kondo problem; 15. Hydrodynamics and transport properties: from Boltzmann to Navier-Stokes; Part II. Elements of General Relativity and String Theory: 16. The Einstein equation and the Schwarzschild solution; 17. The Reissner-Nordstrom and Kerr-Newman solutions and thermodynamic properties of black holes; 18. Extra dimensions and Kaluza-Klein; 19. Electromagnetism and gravity in various dimensions. Consistent truncations; 20. Gravity plus matter: black holes and p-branes in various dimensions; 21. Weak/strong coupling dualities in 1+1, 2+1, 3+1 and d+1 dimensions; 22. The relativistic point particle and the relativistic string; 23. Lightcone strings and quantization; 24. D-branes and gauge fields; 25. Electromagnetic fields on D-branes. Supersymmetry and N = 4 SYM. T-duality of closed strings; 26. Dualities and M theory; 27. The AdS/CFT correspondence: definition and motivation; Part III. Applying String Theory to Condensed Matter Problems: 28. The pp wave correspondence: string Hamiltonian from N = 4 SYM; 29. Spin chains from N = 4 SYM; 30. The Bethe ansatz: Bethe strings from classical strings in AdS; 31. Integrability and AdS/CFT; 32. AdS/CFT phenomenology: Lifshitz, Galilean and Schrodinger symmetries and their gravity duals; 33. Finite temperature and black holes; 34. Hot plasma equilibrium thermodynamics: entropy, charge density and chemical potential of strongly coupled theories; 35. Spectral functions and transport properties; 36. Dynamic and nonequilibrium properties of plasmas: electric transport, Langevin diffusion and thermalization via black hole quasi-normal modes; 37. The holographic superconductor; 38. The fluid-gravity correspondence: conformal relativistic fluids from black hole horizons; 39. Nonrelativistic fluids: from Einstein to Navier-Stokes and back; Part IV. Advanced Applications: 40. Fermi gas and liquid in AdS/CFT; 41. Quantum Hall effect from string theory; 42. Quantum critical systems and AdS/CFT; 43. Particle-vortex duality and ABJM vs. AdS4 X CP3 duality; 44. Topology and non-standard statistics from AdS/CFT; 45. DBI scalar model for QGP/black hole hydro- and thermo-dynamics; 46. Holographic entanglement entropy in condensed matter; 47. Holographic insulators; 48. Holographic strange metals and the Kondo problem; References; Index.
Classical and quantum production of cornucopions at energies below 1018 GeV

NASA Astrophysics Data System (ADS)

Banks, T.; O'loughlin, M.

1993-01-01

We argue that the paradoxes associated with infinitely degenerate states, which plague relic particle scenarios for the end point of black hole evaporation, may be absent when the relics are horned particles. Most of our arguments are based on simple observations about the classical geometry of extremal dilaton black holes, but at a crucial point we are forced to speculate about classical solutions to string theory in which the infinite coupling singularity of the extremal dilaton solution is shielded by a condensate of massless modes propagating in its infinite horn. We use the nonsingular c=1 solution of (1+1)-dimensional string theory as a crude model for the properties of the condensate. We also present a brief discussion of more general relic scenarios based on large relics of low mass.
New black holes in D =5 minimal gauged supergravity: Deformed boundaries and frozen horizons

NASA Astrophysics Data System (ADS)

Blázquez-Salcedo, Jose Luis; Kunz, Jutta; Navarro-Lérida, Francisco; Radu, Eugen

2018-04-01

A new class of black hole solutions of the five-dimensional minimal gauged supergravity is presented. They are characterized by the mass, the electric charge, two equal magnitude angular momenta and the magnitude of the magnetic potential at infinity. These black holes possess a horizon of spherical topology; however, both the horizon and the sphere at infinity can be arbitrarily squashed, with nonextremal solutions interpolating between black strings and black branes. A particular set of extremal configurations corresponds to a new one-parameter family of supersymmetric black holes. While their conserved charges are determined by the squashing of the sphere at infinity, these supersymmetric solutions possess the same horizon geometry.
On static black holes solutions in Einstein and Einstein-Gauss-Bonnet gravity with topology [Formula: see text].

PubMed

Dadhich, Naresh; Pons, Josep M

We study static black hole solutions in Einstein and Einstein-Gauss-Bonnet gravity with the topology of the product of two spheres, [Formula: see text], in higher dimensions. There is an unusual new feature of the Gauss-Bonnet black hole: the avoidance of a non-central naked singularity prescribes a mass range for the black hole in terms of [Formula: see text]. For an Einstein-Gauss-Bonnet black hole a limited window of negative values for [Formula: see text] is also permitted. This topology encompasses black strings, branes, and generalized Nariai metrics. We also give new solutions with the product of two spheres of constant curvature.
Four-qubit systems and dyonic black Hole-Black branes in superstring theory

NASA Astrophysics Data System (ADS)

Belhaj, A.; Bensed, M.; Benslimane, Z.; Sedra, M. B.; Segui, A.

Using dyonic solutions in the type IIA superstring theory on Calabi-Yau (CY) manifolds, we reconsider the study of black objects and quantum information theory using string/string duality in six dimensions. Concretely, we relate four-qubits with a stringy quaternionic moduli space of type IIA compactification associated with a dyonic black solution formed by black holes (BHs) and black 2-branes (B2B) carrying eight electric charges and eight magnetic charges. This connection is made by associating the cohomology classes of the heterotic superstring on T4 to four-qubit states. These states are interpreted in terms of such dyonic charges resulting from the quaternionic symmetric space SO(4,4) SO(4)×SO(4) corresponding to a N = 4 sigma model superpotential in two dimensions. The superpotential is considered as a functional depending on four quaternionic fields mapped to a class of Clifford algebras denoted as Cl0,4. A link between such an algebra and the cohomology classes of T4 in heterotic superstring theory is also given.
(Compactified) black branes in four dimensional f(R)-gravity

NASA Astrophysics Data System (ADS)

Dimakis, N.; Giacomini, Alex; Paliathanasis, Andronikos

2018-02-01

A new family of analytical solutions in a four dimensional static spacetime is presented for f (R) -gravity. In contrast to General Relativity, we find that a non trivial black brane/string solution is supported in vacuum power law f (R) -gravity for appropriate values of the parameters characterizing the model and when axisymmetry is introduced in the line element. For the aforementioned solution, we perform a brief investigation over its basic thermodynamic quantities.
An Exact Solution of Einstein-Maxwell Gravity Coupled to a Scalar Field

NASA Technical Reports Server (NTRS)

Turyshev, S. G.

1995-01-01

The general solution to low-energy string theory representing static spherically symmetric solution of the Einstein-Maxwell gravity with a massless scalar field has been found. Some of the partial cases appear to coincide with known solutions to black holes, naked singularities, and gravity and electromagnetic fields.
Brane - Anti-Brane Democracy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rajaraman, Arvind

2003-06-02

We suggest a duality invariant formula for the entropy and temperature of nonextreme black holes in supersymmetric string theory. The entropy is given in terms of the duality invariant parameter of the deviation from extremality and 56 SU(8) covariant central charges. It interpolates between the entropies of Schwarzschild solution and extremal solutions with various amount of unbroken supersymmetries and therefore serves for classification of black holes in supersymmetric string theories. We introduce the second auxiliary 56 via E(7) symmetric constraint. The symmetric and antisymmetric combinations of these two multiplets are related via moduli to the corresponding two fundamental representations ofmore » E(7): brane and anti-brane ''numbers.'' Using the CPT as well as C symmetry of the entropy formula and duality one can explain the mysterious simplicity of the non-extreme black hole area formula in terms of branes and anti-branes.« less
Black holes in higher derivative gravity.

PubMed

Lü, H; Perkins, A; Pope, C N; Stelle, K S

2015-05-01

Extensions of Einstein gravity with higher-order derivative terms arise in string theory and other effective theories, as well as being of interest in their own right. In this Letter we study static black-hole solutions in the example of Einstein gravity with additional quadratic curvature terms. A Lichnerowicz-type theorem simplifies the analysis by establishing that they must have vanishing Ricci scalar curvature. By numerical methods we then demonstrate the existence of further black-hole solutions over and above the Schwarzschild solution. We discuss some of their thermodynamic properties, and show that they obey the first law of thermodynamics.
Black branes and black strings in the astrophysical and cosmological context

NASA Astrophysics Data System (ADS)

Akarsu, Özgür; Chopovsky, Alexey; Zhuk, Alexander

2018-03-01

We consider Kaluza-Klein models where internal spaces are compact flat or curved Einstein spaces. This background is perturbed by a compact gravitating body with the dust-like equation of state (EoS) in the external/our space and an arbitrary EoS parameter Ω in the internal space. Without imposing any restrictions on the form of the perturbed metric and the distribution of the perturbed energy densities, we perform the general analysis of the Einstein and conservation equations in the weak-field limit. All conclusions follow from this analysis. For example, we demonstrate that the perturbed model is static and perturbed metric preserves the block-diagonal form. In a particular case Ω = - 1 / 2, the found solution corresponds to the weak-field limit of the black strings/branes. The black strings/branes are compact gravitating objects which have the topology (four-dimensional Schwarzschild spacetime) × (d-dimensional internal space) with d ≥ 1. We present the arguments in favour of these objects. First, they satisfy the gravitational tests for the parameterized post-Newtonian parameter γ at the same level of accuracy as General Relativity. Second, they are preferable from the thermodynamical point of view. Third, averaging over the Universe, they do not destroy the stabilization of the internal space. These are the astrophysical and cosmological aspects of the black strings/branes.
Nonminimally coupled massive scalar field in a 2D black hole: Exactly solvable model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frolov, V.; Zelnikov, A.

2001-06-15

We study a nonminimal massive scalar field in the background of a two-dimensional black hole spacetime. We consider the black hole which is the solution of the 2D dilaton gravity derived from string-theoretical models. We find an explicit solution in a closed form for all modes and the Green function of the scalar field with an arbitrary mass and a nonminimal coupling to the curvature. Greybody factors, the Hawking radiation, and 2>{sup ren} are calculated explicitly for this exactly solvable model.
Black hole solutions in d = 5 Chern-Simons gravity

NASA Astrophysics Data System (ADS)

Brihaye, Yves; Radu, Eugen

2013-11-01

The five dimensional Einstein-Gauss-Bonnet gravity with a negative cosmological constant becomes, for a special value of the Gauss-Bonnet coupling constant, a Chern-Simons (CS) theory of gravity. In this work we discuss the properties of several different types of black object solutions of this model. Special attention is paid to the case of spinning black holes with equal-magnitude angular momenta which posses a regular horizon of spherical topology. Closed form solutions are obtained in the small angular momentum limit. Nonperturbative solutions are constructed by solving numerically the equations of the model. Apart from that, new exact solutions describing static squashed black holes and black strings are also discussed. The action and global charges of all configurations studied in this work are obtained by using the quasilocal formalism with boundary counterterms generalized for the case of a d = 5 CS theory.
Constraints on cosmic strings due to black holes formed from collapsed cosmic string loops

NASA Technical Reports Server (NTRS)

Caldwell, R. R.; Gates, Evalyn

1993-01-01

The cosmological features of primordial black holes formed from collapsed cosmic string loops are studied. Observational restrictions on a population of primordial black holes are used to restrict f, the fraction of cosmic string loops which collapse to form black holes, and mu, the cosmic string mass-per-unit length. Using a realistic model of cosmic strings, we find the strongest restriction on the parameters f and mu is due to the energy density in 100MeV photons radiated by the black holes. We also find that inert black hole remnants cannot serve as the dark matter. If earlier, crude estimates of f are reliable, our results severely restrict mu, and therefore limit the viability of the cosmic string large-scale structure scenario.
Scattering of Cosmic Strings by Black Holes:. Loop Formation

NASA Astrophysics Data System (ADS)

Dubath, Florian; Sakellariadou, Mairi; Viallet, Claude Michel

We study the deformation of a long cosmic string by a nearby rotating black hole. We examine whether the deformation of a cosmic string, induced by the gravitational field of a Kerr black hole, may lead to the formation of a string loop. The segment of the string which enters the ergo-sphere of a rotating black hole gets deformed and, if it is sufficiently twisted, it can self-intersect, chopping off a loop. We find that the formation of a loop, via such a mechanism, is a rare event. It will only arise in a small region of the collision phase space, which depends on the string velocity, the impact parameter and the black hole angular momentum. We conclude that, generically, a long cosmic string is simply scattered, or captured, by a nearby rotating black hole.
Modern Quantum Field Theory II - Proceeeings of the International Colloquium

NASA Astrophysics Data System (ADS)

Das, S. R.; Mandal, G.; Mukhi, S.; Wadia, S. R.

1995-08-01

The Table of Contents for the book is as follows: * Foreword * 1. Black Holes and Quantum Gravity * Quantum Black Holes and the Problem of Time * Black Hole Entropy and the Semiclassical Approximation * Entropy and Information Loss in Two Dimensions * Strings on a Cone and Black Hole Entropy (Abstract) * Boundary Dynamics, Black Holes and Spacetime Fluctuations in Dilation Gravity (Abstract) * Pair Creation of Black Holes (Abstract) * A Brief View of 2-Dim. String Theory and Black Holes (Abstract) * 2. String Theory * Non-Abelian Duality in WZW Models * Operators and Correlation Functions in c ≤ 1 String Theory * New Symmetries in String Theory * A Look at the Discretized Superstring Using Random Matrices * The Nested BRST Structure of Wn-Symmetries * Landau-Ginzburg Model for a Critical Topological String (Abstract) * On the Geometry of Wn Gravity (Abstract) * O(d, d) Tranformations, Marginal Deformations and the Coset Construction in WZNW Models (Abstract) * Nonperturbative Effects and Multicritical Behaviour of c = 1 Matrix Model (Abstract) * Singular Limits and String Solutions (Abstract) * BV Algebra on the Moduli Spaces of Riemann Surfaces and String Field Theory (Abstract) * 3. Condensed Matter and Statistical Mechanics * Stochastic Dynamics in a Deposition-Evaporation Model on a Line * Models with Inverse-Square Interactions: Conjectured Dynamical Correlation Functions of the Calogero-Sutherland Model at Rational Couplings * Turbulence and Generic Scale Invariance * Singular Perturbation Approach to Phase Ordering Dynamics * Kinetics of Diffusion-Controlled and Ballistically-Controlled Reactions * Field Theory of a Frustrated Heisenberg Spin Chain * FQHE Physics in Relativistic Field Theories * Importance of Initial Conditions in Determining the Dynamical Class of Cellular Automata (Abstract) * Do Hard-Core Bosons Exhibit Quantum Hall Effect? (Abstract) * Hysteresis in Ferromagnets * 4. Fundamental Aspects of Quantum Mechanics and Quantum Field Theory * Finite Quantum Physics and Noncommutative Geometry * Higgs as Gauge Field and the Standard Model * Canonical Quantisation of an Off-Conformal Theory * Deterministic Quantum Mechanics in One Dimension * Spin-Statistics Relations for Topological Geons in 2+1 Quantum Gravity * Generalized Fock Spaces * Geometrical Expression for Short Distance Singularities in Field Theory * 5. Mathematics and Quantum Field Theory * Knot Invariants from Quantum Field Theories * Infinite Grassmannians and Moduli Spaces of G-Bundles * A Review of an Algebraic Geometry Approach to a Model Quantum Field Theory on a Curve (Abstract) * 6. Integrable Models * Spectral Representation of Correlation Functions in Two-Dimensional Quantum Field Theories * On Various Avatars of the Pasquier Algebra * Supersymmetric Integrable Field Theories and Eight Vertex Free Fermion Models (Abstract) * 7. Lattice Field Theory * From Kondo Model and Strong Coupling Lattice QCD to the Isgur-Wise Function * Effective Confinement from a Logarithmically Running Coupling (Abstract)
“Kerrr” black hole: The lord of the string

NASA Astrophysics Data System (ADS)

Smailagic, Anais; Spallucci, Euro

2010-04-01

Kerrr in the title is not a typo. The third “r” stands for regular, in the sense of pathology-free rotating black hole. We exhibit a long search-for, exact, Kerr-like, solution of the Einstein equations with novel features: (i) no curvature ring singularity; (ii) no “anti-gravity” universe with causality violating time-like closed world-lines; (iii) no “super-luminal” matter disk. The ring singularity is replaced by a classical, circular, rotating string with Planck tension representing the inner engine driving the rotation of all the surrounding matter. The resulting geometry is regular and smoothly interpolates among inner Minkowski space, borderline de Sitter and outer Kerr universe. The key ingredient to cure all unphysical features of the ordinary Kerr black hole is the choice of a “non-commutative geometry inspired” matter source as the input for the Einstein equations, in analogy with spherically symmetric black holes described in earlier works.
Charged black rings at large D

NASA Astrophysics Data System (ADS)

Chen, Bin; Li, Peng-Cheng; Wang, Zi-zhi

2017-04-01

We study the charged slowly rotating black holes in the Einstein-Maxwell theory in the large dimensions ( D). By using the 1 /D expansion in the near regions of the black holes we obtain the effective equations for the charged slowly rotating black holes. The effective equations capture the dynamics of various stationary solutions, including the charged black ring, the charged slowly rotating Myers-Perry black hole and the charged slowly boosted black string. Via different embeddings we construct these stationary solutions explicitly. For the charged black ring at large D, we find that the charge lowers the angular momentum due to the regularity condition on the solution. By performing the perturbation analysis of the effective equations, we obtain the quasinormal modes of the charge perturbation and the gravitational perturbation analytically. Like the neutral case the charged thin black ring suffers from the Gregory-Laflamme-like instability under the non-axisymmetric perturbations, but the charge weakens the instability. Besides, we find that the large D analysis always respects the cosmic censorship.

Hidden Symmetries in String Theory

NASA Astrophysics Data System (ADS)

Chervonyi, Iurii

In this thesis we study hidden symmetries within the framework of string theory. Symmetries play a very important role in physics: they lead to drastic simplifications, which allow one to compute various physical quantities without relying on perturbative techniques. There are two kinds of hidden symmetries investigated in this work: the first type is associated with dynamics of quantum fields and the second type is related to integrability of strings on various backgrounds. Integrability is a remarkable property of some theories that allows one to determine all dynamical properties of the system using purely analytical methods. The goals of this thesis are twofold: extension of hidden symmetries known in General Relativity to stringy backgrounds in higher dimensions and construction of new integrable string theories. In the context of the first goal we study hidden symmetries of stringy backgrounds, with and without supersymmetry. For supersymmetric geometries produced by D-branes we identify the backgrounds with solvable equations for geodesics, which can potentially give rise to integrable string theories. Relaxing the requirement of supersymmetry, we also study charged black holes in higher dimensions and identify their hidden symmetries encoded in so-called Killing(-Yano) tensors. We construct the explicit form of the Killing(-Yano) tensors for the charged rotating black hole in arbitrary number of dimensions, study behavior of such tensors under string dualities, and use the analysis of hidden symmetries to explain why exact solutions for black rings (black holes with non-spherical event horizons) in more than five dimensions remain elusive. As a byproduct we identify the standard parameterization of AdSp x Sq backgrounds with elliptic coordinates on a flat base. The second goal of this work is construction of new integrable string theories by applying continuous deformations of known examples. We use the recent developments called (generalized) lambda-deformation to construct new integrable backgrounds depending on several continuous parameters and study analytical properties of the such deformations.
Large-D gravity and low-D strings.

PubMed

Emparan, Roberto; Grumiller, Daniel; Tanabe, Kentaro

2013-06-21

We show that in the limit of a large number of dimensions a wide class of nonextremal neutral black holes has a universal near-horizon limit. The limiting geometry is the two-dimensional black hole of string theory with a two-dimensional target space. Its conformal symmetry explains the properties of massless scalars found recently in the large-D limit. For black branes with string charges, the near-horizon geometry is that of the three-dimensional black strings of Horne and Horowitz. The analogies between the α' expansion in string theory and the large-D expansion in gravity suggest a possible effective string description of the large-D limit of black holes. We comment on applications to several subjects, in particular to the problem of critical collapse.
The fields of a naked singularity and a black hole in mutual equilibrium

NASA Astrophysics Data System (ADS)

Paolino, Armando; Pizzi, Marco

2008-01-01

Recently Alekseev and Belinski have presented a new exact solution of the Einstein-Maxwell equation which describes two Reissner-Nordstrom (RN) sources in reciprocal equilibrium (no struts nor strings) one source is a naked singularity, the other is a black hole. In this paper we use the Alekseev-Belinki solution in the special case in which the charge of the black hole is zero-therefore we have a naked singularity near a neutral black hole. We give the plots of the electric force lines in both the cases in which the naked singularity has a mass comparable with the black hole and in which it is much smaller. The analysis of this latter case confirm the goodness of the Hanni-Ruffini approximation.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Marolf, Donald; Palmer, Belkis Cabrera; Physics Department, Syracuse University, Syracuse, New York 13244

A thermodynamic argument is presented suggesting that near-extremal spinning D1-D5-P black strings become unstable when their angular momentum exceeds J{sub crit}=3Q{sub 1}Q{sub 5}/2{radical}(2). In contrast, the dimensionally reduced black holes are thermodynamically stable. The proposed instability involves a phase in which the spin angular momentum above J{sub crit} is transferred to gyration of the string in space, i.e., to orbital angular momentum of parts of the string about the mean location in space. Thus the string becomes a rotating helical coil. We note that an instability of this form would yield a counter-example to the Gubser-Mitra conjecture, which proposes amore » particular link between dynamic black string instabilities and the thermodynamics of black strings. There may also be other instabilities associated with radiation modes of various fields. Our arguments also apply to the D-brane bound states associated with these black strings in weakly coupled string theory.« less
String in AdS black hole: A thermo field dynamic approach

NASA Astrophysics Data System (ADS)

Cantcheff, M. Botta; Gadelha, Alexandre L.; Marchioro, Dáfni F. Z.; Nedel, Daniel Luiz

2012-10-01

Based on Maldacena’s description of an eternal anti-de Sitter (AdS) black hole, we reassess the thermo field dynamics (TFD) formalism in the context of the AdS/CFT correspondence. The model studied here involves the maximally extended AdS-Schwarschild solution and two (noninteracting) copies of the conformal field theory (CFT) associated to the global AdS spacetime, along with an extension of the string by imposing natural gluing conditions in the horizon. We show that the gluing conditions in the horizon define a string boundary state which is identified with the TFD thermal vacuum, globally defined in the Kruskal extension of the AdS black hole. We emphasize the connection of this picture with unitary SU(1,1) TFD formulation, and we show that information about the bulk and the conformal boundary is present in the SU(1,1) parameters. Using the unitary SU(1,1) TFD formulation, a canonical prescription for calculating the world sheet real time thermal Green’s function is made, and the entropy associated with the entanglement of the two CFT’s is calculated.
General polytropic self-gravitating cylinder free-fall and accreting mass string with a chain of collapsed objects

NASA Astrophysics Data System (ADS)

Lou, Yu-Qing; Hu, Xu-Yao

2016-06-01

We present a theoretical model framework for general polytropic (GP) hydrodynamic cylinder under self-gravity of infinite length with axial uniformity and axisymmetry. For self-similar dynamic solutions, we derive valuable integrals, analytic asymptotic solutions, sonic critical curves, shock conditions, and global numerical solutions with or without expansion shocks. Among others, we investigate various dynamic solutions featured with central free-fall asymptotic behaviours, corresponding to a collapsed mass string with a sustained dynamic accretion from a surrounding mass reservoir. Depending on the allowed ranges of a scaling index a < -1, such cylindrical dynamic mass accretion rate could be steady, increasing with time and decreasing with time. Physically, such a collapsed mass string or filament would break up into a sequence of sub-clumps and segments as induced by gravitational Jeans instabilities. Depending on the scales involved, such sub-clumps would evolve into collapsed objects or gravitationally bound systems. In diverse astrophysical and cosmological contexts, such a scenario can be adapted on various temporal, spatial and mass scales to form a chain of collapsed clumps and/or compact objects. Examples include the formation of chains of proto-stars, brown dwarfs and gaseous planets along molecular filaments; the formation of luminous massive stars along magnetized spiral arms and circum-nuclear starburst rings in barred spiral galaxies; the formation of chains of compact stellar objects such as white dwarfs, neutron stars, and black holes along a highly condensed mass string. On cosmological scales, one can perceive the formation of chains of galaxies, chains of galaxy clusters or even chains of supermassive and hypermassive black holes in the Universe including the early Universe. All these chains referred to above include possible binaries.
Pair creation of higher dimensional black holes on a de Sitter background

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dias, Oscar J.C.; Lemos, Jose P.S.; CENTRA, Departamento de Fisica, F.C.T., Universidade do Algarve, Campus de Gambelas, 8005-139 Faro

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 themore » 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.« less
Black strings, low viscosity fluids, and violation of cosmic censorship.

PubMed

Lehner, Luis; Pretorius, Frans

2010-09-03

We describe the behavior of 5-dimensional black strings, subject to the Gregory-Laflamme instability. Beyond the linear level, the evolving strings exhibit a rich dynamics, where at intermediate stages the horizon can be described as a sequence of 3-dimensional spherical black holes joined by black string segments. These segments are themselves subject to a Gregory-Laflamme instability, resulting in a self-similar cascade, where ever-smaller satellite black holes form connected by ever-thinner string segments. This behavior is akin to satellite formation in low-viscosity fluid streams subject to the Rayleigh-Plateau instability. The simulation results imply that the string segments will reach zero radius in finite asymptotic time, whence the classical space-time terminates in a naked singularity. Since no fine-tuning is required to excite the instability, this constitutes a generic violation of cosmic censorship.
Building cosmological frozen stars

NASA Astrophysics Data System (ADS)

Kastor, David; Traschen, Jennie

2017-02-01

Janis-Newman-Winicour (JNW) solutions generalize Schwarzschild to include a massless scalar field. While they share the familiar infinite redshift feature of Schwarzschild, they suffer from the presence of naked singularities. Cosmological versions of JNW spacetimes were discovered some years ago, in the most general case, by Fonarev. Fonarev solutions are also plagued by naked singularities, but have the virtue, unlike e.g. Schwarzschild-deSitter, of being dynamical. Given that exact dynamical cosmological black hole solutions are scarce, Fonarev solutions merit further study. We show how Fonarev solutions can be obtained via generalized dimensional reduction from simpler static vacuum solutions. These results may lead towards constructions of actual dynamical cosmological black holes. In particular, we note that cosmological versions of extremal charged dilaton black holes are known. JNW spacetimes represent a different limiting case of the family of charged dilaton black holes, which have been important in the context of string theory, and better understanding their cosmological versions of JNW spacetimes thus provides a second data point towards finding cosmological versions of the entire family.
Geometrodynamics: the nonlinear dynamics of curved spacetime

NASA Astrophysics Data System (ADS)

Scheel, M. A.; Thorne, K. S.

2014-04-01

We review discoveries in the nonlinear dynamics of curved spacetime, largely made possible by numerical solutions of Einstein's equations. We discuss critical phenomena and self-similarity in gravitational collapse, the behavior of spacetime curvature near singularities, the instability of black strings in five spacetime dimensions, and the collision of four-dimensional black holes. We also discuss the prospects for further discoveries in geometrodynamics via observations of gravitational waves.
Charged string loops in Reissner-Nordström black hole background

NASA Astrophysics Data System (ADS)

Oteev, Tursinbay; Kološ, Martin; Stuchlík, Zdeněk

2018-03-01

We study the motion of current carrying charged string loops in the Reissner-Nordström black hole background combining the gravitational and electromagnetic field. Introducing new electromagnetic interaction between central charge and charged string loop makes the string loop equations of motion to be non-integrable even in the flat spacetime limit, but it can be governed by an effective potential even in the black hole background. We classify different types of the string loop trajectories using effective potential approach, and we compare the innermost stable string loop positions with loci of the charged particle innermost stable orbits. We examine string loop small oscillations around minima of the string loop effective potential, and we plot radial profiles of the string loop oscillation frequencies for both the radial and vertical modes. We construct charged string loop quasi-periodic oscillations model and we compare it with observed data from microquasars GRO 1655-40, XTE 1550-564, and GRS 1915+105. We also study the acceleration of current carrying string loops along the vertical axis and the string loop ejection from RN black hole neighbourhood, taking also into account the electromagnetic interaction.
Hawking Radiation of Massive Bosons via Tunneling from Black Strings

NASA Astrophysics Data System (ADS)

Feng, Zhong-Wen

2017-12-01

In the present paper, the Hawking radiation of massive bosons from 4-dimensional and 5-dimensional black strings are studied in quantum tunneling formalism. First, we derive the Hamilton-Jacobi equation set via the Proca equation and WKB approximation. Then, the tunneling rates and Hawking temperatures of the black strings are obtained. Our calculations show that the tunneling rates and Hawking temperatures are related to the properties of black strings' spacetime. When compare our results with those of scalars and fermions cases, it finds that they are the same.
Hawking Radiation of Massive Bosons via Tunneling from Black Strings

NASA Astrophysics Data System (ADS)

Feng, Zhong-Wen

2018-03-01

In the present paper, the Hawking radiation of massive bosons from 4-dimensional and 5-dimensional black strings are studied in quantum tunneling formalism. First, we derive the Hamilton-Jacobi equation set via the Proca equation and WKB approximation. Then, the tunneling rates and Hawking temperatures of the black strings are obtained. Our calculations show that the tunneling rates and Hawking temperatures are related to the properties of black strings' spacetime. When compare our results with those of scalars and fermions cases, it finds that they are the same.
Semiclassical (qft) and Quantum (string) Rotating Black Holes and Their Evaporation:. New Results

NASA Astrophysics Data System (ADS)

Bouchareb, A.; Ramón Medrano, M.; Sánchez, N. G.

Combination of both quantum field theory (QFT) and string theory in curved backgrounds in a consistent framework, the string analogue model, allows us to provide a full picture of the Kerr-Newman black hole and its evaporation going beyond the current picture. We compute the quantum emission cross-section of strings by a Kerr-Newman black hole (KNbh). It shows the black hole emission at the Hawking temperature Tsem in the early stage of evaporation and the new string emission featuring a Hagedorn transition into a string state of temperature Ts at the last stages. New bounds on J and Q emerge in the quantum string regime (besides the known ones of the classical/semiclassical QFT regime). The last state of evaporation of a semiclassical Kerr-Newman black hole with mass M > mPl, angular momentum J and charge Q is a string state of temperature Ts, string mass Ms, J = 0 and Q = 0, decaying as usual quantum strings do into all kinds of particles. (Naturally, in this framework, there is no loss of information, (there is no paradox at all).) We compute the string entropy Ss(m, j) from the microscopic string density of states of mass m and spin mode j, ρ(m, j). (Besides the Hagedorn transition at Ts) we find for high j (extremal string states j → m2α‧c), a new phase transition at a temperature Tsj = √ {j/hbar }Ts, higher than Ts. By precisely identifying the semiclassical and quantum (string) gravity regimes, we find a new formula for the Kerr black hole entropy Ssem(M, J), as a function of the usual Bekenstein-Hawking entropy S sem(0). For M ≫ mPl and J < GM2/c, S sem(0) is the leading term, but for high angular momentum, (nearly extremal case J = GM2/c), a gravitational phase transition operates and the whole entropy Ssem is drastically different from the Bekenstein-Hawking entropy S sem(0). This new extremal black hole transition occurs at a temperature Tsem J = (J/ℏ)Tsem, higher than the Hawking temperature Tsem.
Thermodynamic instability of topological black holes in Gauss-Bonnet gravity with a generalized electrodynamics

NASA Astrophysics Data System (ADS)

Hendi, S. H.; Panahiyan, S.

2014-12-01

Motivated by the string corrections on the gravity and electrodynamics sides, we consider a quadratic Maxwell invariant term as a correction of the Maxwell Lagrangian to obtain exact solutions of higher dimensional topological black holes in Gauss-Bonnet gravity. We first investigate the asymptotically flat solutions and obtain conserved and thermodynamic quantities which satisfy the first law of thermodynamics. We also analyze thermodynamic stability of the solutions by calculating the heat capacity and the Hessian matrix. Then, we focus on horizon-flat solutions with an anti-de Sitter (AdS) asymptote and produce a rotating spacetime with a suitable transformation. In addition, we calculate the conserved and thermodynamic quantities for asymptotically AdS black branes which satisfy the first law of thermodynamics. Finally, we perform thermodynamic instability criterion to investigate the effects of nonlinear electrodynamics in canonical and grand canonical ensembles.
Source of the Kerr-Newman solution as a gravitating bag model: 50 years of the problem of the source of the Kerr solution

NASA Astrophysics Data System (ADS)

Burinskii, Alexander

2016-01-01

It is known that gravitational and electromagnetic fields of an electron are described by the ultra-extreme Kerr-Newman (KN) black hole solution with extremely high spin/mass ratio. This solution is singular and has a topological defect, the Kerr singular ring, which may be regularized by introducing the solitonic source based on the Higgs mechanism of symmetry breaking. The source represents a domain wall bubble interpolating between the flat region inside the bubble and external KN solution. It was shown recently that the source represents a supersymmetric bag model, and its structure is unambiguously determined by Bogomolnyi equations. The Dirac equation is embedded inside the bag consistently with twistor structure of the Kerr geometry, and acquires the mass from the Yukawa coupling with Higgs field. The KN bag turns out to be flexible, and for parameters of an electron, it takes the form of very thin disk with a circular string placed along sharp boundary of the disk. Excitation of this string by a traveling wave creates a circulating singular pole, indicating that the bag-like source of KN solution unifies the dressed and point-like electron in a single bag-string-quark system.
Hawking temperature of rotating charged black strings from tunneling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmed, Jamil; Saifullah, K., E-mail: jamil_051@yahoo.com, E-mail: saifullah@qau.edu.pk

2011-11-01

Thermal radiations from spherically symmetric black holes have been studied from the point of view of quantum tunneling. In this paper we extend this approach to study radiation of fermions from charged and rotating black strings. Using WKB approximation and Hamilton-Jacobi method we work out the tunneling probabilities of incoming and outgoing fermions and find the correct Hawking temperature for these objects. We show that in appropriate limits the results reduce to those for the uncharged and non-rotating black strings.
FAST TRACK COMMUNICATION Single-charge rotating black holes in four-dimensional gauged supergravity

NASA Astrophysics Data System (ADS)

Chow, David D. K.

2011-02-01

We consider four-dimensional U(1)4 gauged supergravity, and obtain asymptotically AdS4, non-extremal, charged, rotating black holes with one non-zero U(1) charge. The thermodynamic quantities are computed. We obtain a generalization that includes a NUT parameter. The general solution has a discrete symmetry involving inversion of the rotation parameter, and has a string frame metric that admits a rank-2 Killing-Stäckel tensor.
Entropy of N=2 black holes and their M-brane description

DOE Office of Scientific and Technical Information (OSTI.GOV)

Behrndt, K.; Mohaupt, T.

1997-08-01

In this paper we discuss the M-brane description for an N=2 black hole. This solution is a result of the compactification of M-5-brane configurations over a Calabi-Yau threefold with arbitrary intersection numbers C{sub ABC}. In analogy with the D-brane description where one counts open string states we count here open M-2-branes which end on the M-5-brane. {copyright} {ital 1997} {ital The American Physical Society}
Deformation of extremal black holes from stringy interactions

NASA Astrophysics Data System (ADS)

Chen, Baoyi; Stein, Leo C.

2018-04-01

Black holes are a powerful setting for studying general relativity and theories beyond GR. However, analytical solutions for rotating black holes in beyond-GR theories are difficult to find because of the complexity of such theories. In this paper, we solve for the deformation to the near-horizon extremal Kerr metric due to two example string-inspired beyond-GR theories: Einstein-dilaton-Gauss-Bonnet and dynamical Chern-Simons theory. We accomplish this by making use of the enhanced symmetry group of NHEK and the weak-coupling limit of EdGB and dCS. We find that the EdGB metric deformation has a curvature singularity, while the dCS metric is regular. From these solutions, we compute orbital frequencies, horizon areas, and entropies. This sets the stage for analytically understanding the microscopic origin of black hole entropy in beyond-GR theories.

String-theoretic breakdown of effective field theory near black hole horizons

NASA Astrophysics Data System (ADS)

Dodelson, Matthew; Silverstein, Eva

2017-09-01

We investigate the validity of the equivalence principle near horizons in string theory, analyzing the breakdown of effective field theory caused by longitudinal string spreading effects. An experiment is set up where a detector is thrown into a black hole a long time after an early infalling string. Light cone gauge calculations, taken at face value, indicate a detectable level of root-mean-square longitudinal spreading of the initial string as measured by the late infaller. This results from the large relative boost between the string and detector in the near-horizon region, which develops automatically despite their modest initial energies outside the black hole and the weak curvature in the geometry. We subject this scenario to basic consistency checks, using these to obtain a relatively conservative criterion for its detectability. In a companion paper, we exhibit longitudinal nonlocality in well-defined gauge-invariant S-matrix calculations, obtaining results consistent with the predicted spreading albeit not in a direct analog of the black hole process. We discuss applications of this effect to the firewall paradox, and estimate the time and distance scales it predicts for new physics near black hole and cosmological horizons.
Non-Schwarzschild black-hole metric in four dimensional higher derivative gravity: Analytical approximation

NASA Astrophysics Data System (ADS)

Kokkotas, K. D.; Konoplya, R. A.; Zhidenko, A.

2017-09-01

Higher derivative extensions of Einstein gravity are important within the string theory approach to gravity and as alternative and effective theories of gravity. H. Lü, A. Perkins, C. Pope, and K. Stelle [Phys. Rev. Lett. 114, 171601 (2015), 10.1103/PhysRevLett.114.171601] found a numerical solution describing a spherically symmetric non-Schwarzschild asymptotically flat black hole in Einstein gravity with added higher derivative terms. Using the general and quickly convergent parametrization in terms of the continued fractions, we represent this numerical solution in the analytical form, which is accurate not only near the event horizon or far from the black hole, but in the whole space. Thereby, the obtained analytical form of the metric allows one to study easily all the further properties of the black hole, such as thermodynamics, Hawking radiation, particle motion, accretion, perturbations, stability, quasinormal spectrum, etc. Thus, the found analytical approximate representation can serve in the same way as an exact solution.
Exact Solutions in Three-Dimensional Gravity

NASA Astrophysics Data System (ADS)

García-Díaz, Alberto A.

2017-09-01

Preface; 1. Introduction; 2. Point particles; 3. Dust solutions; 4. AdS cyclic symmetric stationary solutions; 5. Perfect fluid static stars; 6. Static perfect fluid stars with Λ; 7. Hydrodynamic equilibrium; 8. Stationary perfect fluid with Λ; 9. Friedmann–Robertson–Walker cosmologies; 10. Dilaton-inflaton FRW cosmologies; 11. Einstein–Maxwell solutions; 12. Nonlinear electrodynamics black hole; 13. Dilaton minimally coupled to gravity; 14. Dilaton non-minimally coupled to gravity; 15. Low energy 2+1 string gravity; 16. Topologically massive gravity; 17. Bianchi type spacetimes in TMG; 18. Petrov type N wave metrics; 19. Kundt spacetimes in TMG; 20. Cotton tensor in Riemannian spacetimes; References; Index.
Habemus superstratum! A constructive proof of the existence of superstrata

NASA Astrophysics Data System (ADS)

Bena, Iosif; Giusto, Stefano; Russo, Rodolfo; Shigemori, Masaki; Warner, Nicholas P.

2015-05-01

We construct the first example of a superstratum: a class of smooth horizonless supergravity solutions that are parameterized by arbitrary continuous functions of (at least) two variables and have the same charges as the supersymmetric D1-D5-P black hole. We work in Type IIB string theory on T 4 or K3 and our solutions involve a subset of fields that can be described by a six-dimensional supergravity with two tensor multiplets. The solutions can thus be constructed using a linear structure, and we give an explicit recipe to start from a superposition of modes specified by an arbitrary function of two variables and impose regularity to obtain the full horizonless solutions in closed form. We also give the precise CFT description of these solutions and show that they are not dual to descendants of chiral primaries. They are thus much more general than all the known solutions whose CFT dual is precisely understood. Hence our construction represents a substantial step toward the ultimate goal of constructing the fully generic superstratum that can account for a finite fraction of the entropy of the three-charge black hole in the regime of parameters where the classical black hole solution exists.
Low-energy dynamics of gravitation

NASA Astrophysics Data System (ADS)

Torma, Tibor

The present status of theories of quantum gravity are reviewed from the low energy point of view. String theory relates classical black-hole type solutions of Einstein- like equations (e.g. axidilaton gravity) to the string vacuum. Several such solutions are proposed and their properties are investigated, including their behavior under supersymmetry transformations. A general feature of all possible quantum theories of gravitation is that they lead to a field theory description at low (as compared to the Planck mass) energies. The theoretical consistency, uniqueness and consequences of such an effective theory are investigated. I show that a power counting theorem allows for the momentum expansion that defines the effective theory even in the presence of large masses. I also show that graviton-graviton scattering is free of potential infrared and collinear divergencies that plague perturbative discussions of Yang-Mills theories.
Instability of black strings in the third-order Lovelock theory

NASA Astrophysics Data System (ADS)

Giacomini, Alex; Henríquez-Báez, Carla; Lagos, Marcela; Oliva, Julio; Vera, Aldo

2016-05-01

We show that homogeneous black strings of third-order Lovelock theory are unstable under s-wave perturbations. This analysis is done in dimension D =9 , which is the lowest dimension that allows the existence of homogeneous black strings in a theory that contains only the third-order Lovelock term in the Lagrangian. As is the case in general relativity, the instability is produced by long wavelength perturbations and it stands for the perturbative counterpart of a thermal instability. We also provide a comparative analysis of the instabilities of black strings at a fixed radius in general relativity, Gauss-Bonnet, and third-order Lovelock theories. We show that the minimum critical wavelength that triggers the instability grows with the power of the curvature defined in the Lagrangian. The maximum exponential growth during the time of the perturbation is the largest in general relativity and it decreases with the number of curvatures involved in the Lagrangian.
Supersymmetric attractors, topological strings, and the M5-brane CFT

NASA Astrophysics Data System (ADS)

Guica, Monica M.

One of the purposes of this thesis is to present the consistent and unifying picture that emerges in string and M-theory with eight supercharges. On one hand, this involves classifying and relating supersymmetric objects that occur in N = 2 compactifications of string and M-theory on a Calabi-Yau manifold. These come in a surprisingly wide variety of four and five-dimensional black holes, black rings and their sometimes very complicated bound states. On the other hand, the topological string also makes its appearance in theories with eight supercharges, and turns out to compute certain black hole degeneracies. We dedicate the introduction and the first chapter to summarizing and reviewing the beautiful relationships between black holes, black rings, their dual conformal field theory and the topological string, and we also outline the remaining puzzles and issues. Some of the black holes in question can be obtained by multiply-wrapping an M-theory M5-brane on a self-intersecting four-cycle in the Calabi-Yau manifold. Their dual microscopic description is known, and consists of a two-dimensional conformal field theory (CFT) which is the low-energy limit of the gauge theory that resides on the worldvolume of the M5 brane. We show that in a certain limit the M5-brane CFT is - perhaps surprisingly - able to reproduce the entropy of a completely different type of black holes, those obtained from wrapped M2-branes, whose microscopic description has not yet been understood. We also argue that certain black hole bound states should also be described by the same CFT, which suggests a unifying description of the various black objects in eight-supercharge supergravity theories. Finally, we describe and present a proof of the so-called OSV conjecture, which states that the mixed partition function of N = 2 four-dimensional BPS black holes equals the modulus square of the type A topological string partition function. We also attempt to use this relationship to better understand corrections to the entropy of supersymmetric black holes and rings in five dimensions.
(Non-adiabatic) string creation on nice slices in Schwarzschild black holes

NASA Astrophysics Data System (ADS)

Puhm, Andrea; Rojas, Francisco; Ugajin, Tomonori

2017-04-01

Nice slices have played a pivotal role in the discussion of the black hole information paradox as they avoid regions of strong spacetime curvature and yet smoothly cut through the infalling matter and the outgoing Hawking radiation, thus, justifying the use of low energy field theory. To avoid information loss it has been argued recently, however, that local effective field theory has to break down at the horizon. To assess the extent of this breakdown in a UV complete framework we study string-theoretic effects on nice slices in Schwarzschild black holes. Our purpose is two-fold. First, we use nice slices to address various open questions and caveats of [1] where it was argued that boost-enhanced non-adiabatic string-theoretic effects at the horizon could provide a dynamical mechanism for the firewall. Second, we identify two non-adiabatic effects on nice slices in Schwarzschild black holes: pair production of open strings near the horizon enhanced by the presence of the infinite tower of highly excited string states and a late-time non-adiabatic effect intrinsic to nice slices.
(Non-adiabatic) string creation on nice slices in Schwarzschild black holes

DOE PAGES

Puhm, Andrea; Rojas, Francisco; Ugajin, Tomonori

2017-04-27

Nice slices have played a pivotal role in the discussion of the black hole information paradox as they avoid regions of strong spacetime curvature and yet smoothly cut through the infalling matter and the outgoing Hawking radiation, thus, justifying the use of low energy field theory. To avoid information loss it has been argued recently, however, that local effective field theory has to break down at the horizon. To assess the extent of this breakdown in a UV complete framework we study string-theoretic effects on nice slices in Schwarzschild black holes. Here, our purpose is two-fold. First, we use nicemore » slices to address various open questions and caveats of [1] where it was argued that boost-enhanced non-adiabatic string-theoretic effects at the horizon could provide a dynamical mechanism for the firewall. Second, we identify two non-adiabatic effects on nice slices in Schwarzschild black holes: pair production of open strings near the horizon enhanced by the presence of the infinite tower of highly excited string states and a late-time non-adiabatic effect intrinsic to nice slices.« less
(Non-adiabatic) string creation on nice slices in Schwarzschild black holes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Puhm, Andrea; Rojas, Francisco; Ugajin, Tomonori

Nice slices have played a pivotal role in the discussion of the black hole information paradox as they avoid regions of strong spacetime curvature and yet smoothly cut through the infalling matter and the outgoing Hawking radiation, thus, justifying the use of low energy field theory. To avoid information loss it has been argued recently, however, that local effective field theory has to break down at the horizon. To assess the extent of this breakdown in a UV complete framework we study string-theoretic effects on nice slices in Schwarzschild black holes. Here, our purpose is two-fold. First, we use nicemore » slices to address various open questions and caveats of [1] where it was argued that boost-enhanced non-adiabatic string-theoretic effects at the horizon could provide a dynamical mechanism for the firewall. Second, we identify two non-adiabatic effects on nice slices in Schwarzschild black holes: pair production of open strings near the horizon enhanced by the presence of the infinite tower of highly excited string states and a late-time non-adiabatic effect intrinsic to nice slices.« less
Black string corrections in variable tension braneworld scenarios

NASA Astrophysics Data System (ADS)

Da Rocha, Roldão; Hoff da Silva, J. M.

2012-02-01

Braneworld models with variable tension are investigated, and the corrections on the black string horizon along the extra dimension are provided. Such corrections are encrypted in additional terms involving the covariant derivatives of the variable tension on the brane, providing profound consequences concerning the black string horizon variation along the extra dimension, near the brane. The black string horizon behavior is shown to be drastically modified by the terms corrected by the brane variable tension. In particular, a model motivated by the phenomenological interesting case regarding Eötvös branes is investigated. It forthwith provides further physical features regarding variable tension braneworld scenarios, heretofore concealed in all previous analysis in the literature. All precedent analysis considered uniquely the expansion of the metric up to the second order along the extra dimension, which is able to evince solely the brane variable tension absolute value. Notwithstanding, the expansion terms aftermath, further accomplished in this paper from the third order on, elicits the successive covariant derivatives of the brane variable tension, and their respective coupling with the extrinsic curvature, the Weyl tensor, and the Riemann and Ricci tensors, as well as the scalar curvature. Such additional terms are shown to provide sudden modifications in the black string horizon in a variable tension braneworld scenario.
A universal counting of black hole microstates in AdS4

NASA Astrophysics Data System (ADS)

Azzurli, Francesco; Bobev, Nikolay; Crichigno, P. Marcos; Min, Vincent S.; Zaffaroni, Alberto

2018-02-01

Many three-dimensional N=2 SCFTs admit a universal partial topological twist when placed on hyperbolic Riemann surfaces. We exploit this fact to derive a universal formula which relates the planar limit of the topologically twisted index of these SCFTs and their three-sphere partition function. We then utilize this to account for the entropy of a large class of supersymmetric asymptotically AdS4 magnetically charged black holes in M-theory and massive type IIA string theory. In this context we also discuss novel AdS2 solutions of eleven-dimensional supergravity which describe the near horizon region of large new families of supersymmetric black holes arising from M2-branes wrapping Riemann surfaces.
String loops in the field of braneworld spherically symmetric black holes and naked singularities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stuchlík, Z.; Kološ, M., E-mail: zdenek.stuchlik@fpf.slu.cz, E-mail: martin.kolos@fpf.slu.cz

We study motion of current-carrying string loops in the field of braneworld spherically symmetric black holes and naked singularities. The spacetime is described by the Reissner-Nordström geometry with tidal charge b reflecting the non-local tidal effects coming from the external dimension; both positive and negative values of the spacetime parameter b are considered. We restrict attention to the axisymmetric motion of string loops when the motion can be fully governed by an appropriately defined effective potential related to the energy and angular momentum of the string loops. In dependence on these two constants of the motion, the string loops canmore » be captured, trapped, or can escape to infinity. In close vicinity of stable equilibrium points at the centre of trapped states the motion is regular. We describe how it is transformed to chaotic motion with growing energy of the string loop. In the field of naked singularities the trapped states located off the equatorial plane of the system exist and trajectories unable to cross the equatorial plane occur, contrary to the trajectories in the field of black holes where crossing the equatorial plane is always admitted. We concentrate our attention to the so called transmutation effect when the string loops are accelerated in the deep gravitational field near the black hole or naked singularity by transforming the oscillatory energy to the energy of the transitional motion. We demonstrate that the influence of the tidal charge can be substantial especially in the naked singularity spacetimes with b > 1 where the acceleration to ultrarelativistic velocities with Lorentz factor γ ∼ 100 can be reached, being more than one order higher in comparison with those obtained in the black hole spacetimes.« less
String theory and aspects of higher dimensional gravity

NASA Astrophysics Data System (ADS)

Copsey, Keith

2007-05-01

String theory generically requires that there are more than the four dimensions easily observable. It has become clear in recent years that gravity in more than four dimensions presents qualitative new features and this thesis is dedicated to exploring some of these phenomena. I discuss the thermodynamics of new types of black holes with new types of charges and study aspects of the AdS-CFT correspondence dual to gravitational phenomena unique to higher dimensions. I further describe the construction of a broad new class of solutions in more than four dimensions containing dynamical minimal spheres ("bubbles of nothing") in asymptotically flat and AdS space without any asymptotic Kaluza-Klein direction.
Habemus superstratum! A constructive proof of the existence of superstrata

DOE PAGES

Bena, Iosif; Giusto, Stefano; Russo, Rodolfo; ...

2015-05-21

Here, we construct the first example of a superstratum: a class of smooth horizonless supergravity solutions that are parameterized by arbitrary continuous functions of (at least) two variables and have the same charges as the supersymmetric D1-D5-P black hole. We work in Type IIB string theory on T 4 or K 3 and our solutions involve a subset of fields that can be described by a six-dimensional supergravity with two tensor multiplets. The solutions can thus be constructed using a linear structure, and we give an explicit recipe to start from a superposition of modes specified by an arbitrary functionmore » of two variables and impose regularity to obtain the full horizonless solutions in closed form. We also give the precise CFT description of these solutions and show that they are not dual to descendants of chiral primaries. They are thus much more general than all the known solutions whose CFT dual is precisely understood. Hence our construction represents a substantial step toward the ultimate goal of constructing the fully generic superstratum that can account for a finite fraction of the entropy of the three-charge black hole in the regime of parameters where the classical black hole solution exists.« less
Mass and angular momentum of black holes in low-energy heterotic string theory

NASA Astrophysics Data System (ADS)

Peng, Jun-Jin

2016-04-01

We investigate conserved charges in the low-energy effective field theory describing heterotic string theory. Starting with a general Lagrangian that consists of a metric, a scalar field, a vector gauge field, together with a two-form potential, we derive off-shell Noether potentials of the Lagrangian and generalize the Abbott-Deser-Tekin (ADT) formalism to the off-shell level by establishing one-to-one correspondence between the ADT potential and the off-shell Noether potential. It is proved that the off-shell generalized ADT formalism is conformally invariant. Then, we apply the formulation to compute mass and angular momentum of the four-dimensional Kerr-Sen black hole and the five-dimensional rotating charged black string in the string frame without a necessity to transform the metrics into the Einstein frame.
Charged black holes and the AdS/CFT correspondence

NASA Astrophysics Data System (ADS)

Tesileanu, Tiberiu

The AdS/CFT duality is an equivalence between string theory and gauge theory. The duality allows one to use calculations done in classical gravity to derive results in strongly-coupled field theories. This thesis explores several applications of the duality that have some relevance to condensed matter physics. In the first of these applications, it is shown that a large class of strongly-coupled (3 + 1)-dimensional conformal field theories undergo a superfluid phase transition in which a certain chiral primary operator develops a non-zero expectation value at low temperatures. A suggestion is made for the identity of the condensing operator in the field theory. In a different application, the conifold theory, an SU(N) x SU(N) gauge theory, is studied at nonzero chemical potential for baryon number density. In the low-temperature limit, the near-horizon geometry of the dual supergravity solution becomes a warped product AdS 2 x R3 x T1,1, with logarithmic warp factors. This encodes a type of emergent quantum near-criticality in the field theory. A similar construction is analyzed in the context of M theory. This construction is based on branes wrapped around topologically nontrivial cycles of the geometry. Several non-supersymmetric solutions are found, which pass a number of stability checks. Reducing one of the solutions to type IIA string theory, and T-dualizing to type IIB yields a product of a squashed Sasaki-Einstein manifold with an extremal BTZ black hole. Possible field theory interpretations are discussed.
Noncommutative geometry inspired Einstein–Gauss–Bonnet black holes

NASA Astrophysics Data System (ADS)

Ghosh, Sushant G.

2018-04-01

Low energy limits of a string theory suggests that the gravity action should include quadratic and higher-order curvature terms, in the form of dimensionally continued Gauss–Bonnet densities. Einstein–Gauss–Bonnet is a natural extension of the general relativity to higher dimensions in which the first and second-order terms correspond, respectively, to general relativity and Einstein–Gauss–Bonnet gravity. We obtain five-dimensional (5D) black hole solutions, inspired by a noncommutative geometry, with a static spherically symmetric, Gaussian mass distribution as a source both in the general relativity and Einstein–Gauss–Bonnet gravity cases, and we also analyzes their thermodynamical properties. Owing the noncommutative corrected black hole, the thermodynamic quantities have also been modified, and phase transition is shown to be achievable. The phase transitions for the thermodynamic stability, in both the theories, are characterized by a discontinuity in the specific heat at r_+=rC , with the stable (unstable) branch for r < (>) rC . The metric of the noncommutative inspired black holes smoothly goes over to the Boulware–Deser solution at large distance. The paper has been appended with a calculation of black hole mass using holographic renormalization.
Cosmic censorship conjecture in Kerr-Sen black hole

NASA Astrophysics Data System (ADS)

Gwak, Bogeun

2017-06-01

The validity of the cosmic censorship conjecture for the Kerr-Sen black hole, which is a solution to the low-energy effective field theory for four-dimensional heterotic string theory, is investigated using charged particle absorption. When the black hole absorbs the particle, the charge on it changes owing to the conserved quantities of the particle. Changes in the black hole are constrained to the equation for the motion of the particle and are consistent with the laws of thermodynamics. Particle absorption increases the mass of the Kerr-Sen black hole to more than that of the absorbed charges such as angular momentum and electric charge; hence, the black hole cannot be overcharged. In the near-extremal black hole, we observe a violation of the cosmic censorship conjecture for the angular momentum in the first order of expansion and the electric charge in the second order. However, considering an adiabatic process carrying the conserved quantities as those of the black hole, we prove the stability of the black hole horizon. Thus, we resolve the violation. This is consistent with the third law of thermodynamics.
Black-Hole Solutions to Einstein's Equations in the Presence of Matter and Modifications of Gravitation in Extra Dimensions

NASA Astrophysics Data System (ADS)

Goutéraux, B.

2010-11-01

In this thesis, we wish to examine the black-hole solutions of modified gravity theories inspired by String Theory or Cosmology. Namely, these modifications will take the guise of additional gauge and scalar fields for the so-called Einstein-Maxwell-Dilaton theories with an exponential Liouville potential; and of extra spatial dimensions for Einstein-Gauss-Bonnet theories. The black-hole solutions of EMD theories as well as their integrability are reviewed. One of the main results is that a master equation is obtained in the case of planar horizon topology, which allows to completely integrate the problem for s special relationship between the couplings. We also classify existing solutions. We move on to the study of Gauss-Bonnet black holes, focusing on the six-dimensional case. It is found that the Gauss-Bonnet coupling exposes the Weyl tensor of the horizon to the dynamics, severely restricting the Einstein spaces admissible and effectively lifting some of the degeneracy on the horizon topology. We then turn to the study of the thermodynamic properties of black holes, in General Relativity as well as in EMD theories. For the latter, phase transitions may be found in the canonical ensemble, which resemble the phase transitions for Reissner-Nordström black holes. Generically, we find that the thermodynamic properties (stability, order of phase transitions) depend crucially on the values of the EMD coupling constants. Finally, we interpret our planar EMD solutions holographically as Infra-Red geometries through the AdS/CFT correspondence, taking into account various validity constraints. We also compute AC and DC conductivities as applications to Condensed Matter Systems, and find some properties characteristic of strange metal behaviour.

Equivalence of emergent de Sitter spaces from conformal field theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asplund, Curtis T.; Callebaut, Nele; Zukowski, Claire

Recently, two groups have made distinct proposals for a de Sitter space that is emergent from conformal field theory (CFT). The first proposal is that, for two-dimensional holographic CFTs, the kinematic space of geodesics on a space-like slice of the asymptotically anti-de Sitter bulk is two-dimensional de Sitter space (dS 2), with a metric that can be derived from the entanglement entropy of intervals in the CFT. In the second proposal, de Sitter dynamics emerges naturally from the first law of entanglement entropy for perturbations around the vacuum state of CFTs. We provide support for the equivalence of these twomore » emergent spacetimes in the vacuum case and beyond. In particular, we study the kinematic spaces of nontrivial solutions of 3d gravity, including the BTZ black string, BTZ black hole, and conical singularities. We argue that the resulting spaces are generically globally hyperbolic spacetimes that support dynamics given boundary conditions at future infinity. For the BTZ black string, corresponding to a thermal state of the CFT, we show that both prescriptions lead to an emergent hyperbolic patch of dS 2. As a result, we offer a general method for relating kinematic space and the auxiliary de Sitter space that is valid in the vacuum and thermal cases.« less
Equivalence of emergent de Sitter spaces from conformal field theory

DOE PAGES

Asplund, Curtis T.; Callebaut, Nele; Zukowski, Claire

2016-09-27

Recently, two groups have made distinct proposals for a de Sitter space that is emergent from conformal field theory (CFT). The first proposal is that, for two-dimensional holographic CFTs, the kinematic space of geodesics on a space-like slice of the asymptotically anti-de Sitter bulk is two-dimensional de Sitter space (dS 2), with a metric that can be derived from the entanglement entropy of intervals in the CFT. In the second proposal, de Sitter dynamics emerges naturally from the first law of entanglement entropy for perturbations around the vacuum state of CFTs. We provide support for the equivalence of these twomore » emergent spacetimes in the vacuum case and beyond. In particular, we study the kinematic spaces of nontrivial solutions of 3d gravity, including the BTZ black string, BTZ black hole, and conical singularities. We argue that the resulting spaces are generically globally hyperbolic spacetimes that support dynamics given boundary conditions at future infinity. For the BTZ black string, corresponding to a thermal state of the CFT, we show that both prescriptions lead to an emergent hyperbolic patch of dS 2. As a result, we offer a general method for relating kinematic space and the auxiliary de Sitter space that is valid in the vacuum and thermal cases.« less
Rotating elastic string loops in flat and black hole spacetimes: stability, cosmic censorship and the Penrose process

NASA Astrophysics Data System (ADS)

Natário, José; Queimada, Leonel; Vicente, Rodrigo

2018-04-01

We rederive the equations of motion for relativistic strings, that is, one-dimensional elastic bodies whose internal energy depends only on their stretching, and use them to study circular string loops rotating in the equatorial plane of flat and black hole spacetimes. We start by obtaining the conditions for equilibrium, and find that: (i) if the string’s longitudinal speed of sound does not exceed the speed of light then its radius when rotating in Minkowski’s spacetime is always larger than its radius when at rest; (ii) in Minkowski’s spacetime, equilibria are linearly stable for rotation speeds below a certain threshold, higher than the string’s longitudinal speed of sound, and linearly unstable for some rotation speeds above it; (iii) equilibria are always linearly unstable in Schwarzschild’s spacetime. Moreover, we study interactions of a rotating string loop with a Kerr black hole, namely in the context of the weak cosmic censorship conjecture and the Penrose process. We find that: (i) elastic string loops that satisfy the null energy condition cannot overspin extremal black holes; (ii) elastic string loops that satisfy the dominant energy condition cannot increase the maximum efficiency of the usual particle Penrose process; (iii) if the dominant energy condition (but not the weak energy condition) is violated then the efficiency can be increased. This last result hints at the interesting possibility that the dominant energy condition may underlie the well known upper bounds for the efficiencies of energy extraction processes (including, for example, superradiance).
Self-Gravitating Fundamental Strings and Black Holes

NASA Technical Reports Server (NTRS)

Damour, T.; Veneziano, G.

1999-01-01

The configuration of typically highly excited M much greater than M(sub s) which is approximately equal to alpha(prime) to the 1/2 power string states is considered as the string coupling g is adiabatically increased. The size distribution of very massive single string states is studied and the mass shift, due to a long-range gravitational, dilatonic, and axionic attraction, is estimated.
Black hole attractors and gauge theories

NASA Astrophysics Data System (ADS)

Huang, Lisa Li Fang

2007-12-01

This thesis is devoted to the study of supersymmetric black holes that arise from string compactifications. We begin by studying the R 2 corrections to the entropy of two solutions of five dimensional supergravity, the supersymmetric black ring and the spinning black hole. Using Wald's formula we compute the R2 corrections to the entropy of the black ring and BMPV black hole. We study N D4-branes wrapping a 4 cycle and M DO-branes on the quintic. For N D4-branes, we resolve the naive mismatch between the moduli space of the Higgs branch of the gauge theory and the moduli of a degree N hypersurface which the D4-brane wraps. The degree N surface must admit a holomorphic divisor and is a determinantal variety. Adding a single DO brane to probe the deformed geometry, we recover the determinant equation from F and D flatness condition which was previously discovered from a classical geometry approach. We next generalize the qunitic story for Calabi-Yau manifolds arising from complete intersections in toric varieties. We recover the moduli space of N D4-branes in terms of the moduli space of a U( N) x U(N) gauge theory with bi-fundamentals com ing from a D6 - D6 system. We also recast the tachyon condensation of the D6 - D6 system in the language of open string gauged linear sigma model. We obtain the determinant equation from F-term constraints arising from a boundary coupling. We set out to understand the Ooguri-Strominger-Vafa conjecture directly in the D4-DO black hole attractor geometry. We show that the lift to the euclidean IIA attractor geometry gives a complexified M-theory geometry whose asymptotic boundary is a torus. Employing AdS3/CFT 2 duality, we argue that the string partition function computes the elliptic genus of the Maldacena-Strominger-Witten conformal field theory. We evaluate the IIA partition function using the Green-Schwarz formalism and show that it gives ZtopZ top, coming from instantons and anti-instantons respectively. Finally, we determine the spectrum of free, large N, SU( N) Yang Mills theory on S3 by decomposing its thermal partition function into characters of the irreducible representations of the conformal group SO(4, 2).
Thermodynamic properties of asymptotically Reissner–Nordström black holes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hendi, S.H., E-mail: hendi@shirazu.ac.ir

2014-07-15

Motivated by possible relation between Born–Infeld type nonlinear electrodynamics and an effective low-energy action of open string theory, asymptotically Reissner–Nordström black holes whose electric field is described by a nonlinear electrodynamics (NLED) are studied. We take into account a four dimensional topological static black hole ansatz and solve the field equations, exactly, in terms of the NLED as a matter field. The main goal of this paper is investigation of thermodynamic properties of the obtained black holes. Moreover, we calculate the heat capacity and find that the nonlinearity affects the minimum size of stable black holes. We also use Legendre-invariantmore » metric proposed by Quevedo to obtain scalar curvature divergences. We find that the singularities of the Ricci scalar in Geometrothermodynamics (GTD) method take place at the Davies points. -- Highlights: •We examine the thermodynamical properties of black holes in Einstein gravity with nonlinear electrodynamics. •We investigate thermodynamic stability and discuss about the size of stable black holes. •We obtain analytical solutions of higher dimensional theory.« less
Classical probes of string/gauge theory duality

NASA Astrophysics Data System (ADS)

Ishizeki, Riei

The AdS/CFT correspondence has played an important role in the recent development of string theory. The reason is that it proposes a description of certain gauge theories in terms of string theory. It is such that simple string theory computations give information about the strong coupling regime of the gauge theory. Vice versa, gauge theory computations give information about string theory and quantum gravity. Although much is known about AdS/CFT, the precise map between the two sides of the correspondence is not completely understood. In the unraveling of such map classical string solutions play a vital role. In this thesis, several classical string solutions are proposed to help understand the AdS/CFT duality. First, rigidly rotating strings on a two-sphere are studied. Taking special limits of such solutions leads to two cases: the already known giant magnon solution, and a new solution which we call the single spike solution. Next, we compute the scattering phase shift of the single spike solutions and compare the result with the giant magnon solutions. Intriguingly, the results are the same up to non-logarithmic terms, indicating that the single spike solution should have the same rich spin chain structure as the giant magnon solution. Afterward, we consider open string solutions ending on the boundary of AdS5. The lines traced by the ends of such open strings can be viewed as Wilson loops in N = 4 SYM theory. After applying an inversion transformation, the open Wilson loops become closed Wilson loops whose expectation value is consistent with previously conjectured results. Next, several Wilson loops for N = 4 SYM in an AdS5 pp-wave background are considered and translated to the pure AdS 5 background and their interpretation as forward quark-gluon scattering is suggested. In the last part of this thesis, a class of classical solutions for closed strings moving in AdS3 x S 1 ⊂ AdS5 x S5 with energy E and spin S in AdS3 and angular momentum J and winding m in S1 is explained. The relation between different limits of the spiky string solution with the Landau-Lifshitz model is of particular interest. The presented solutions provide new classes of string motion that are used to better understand the AdS/CFT correspondence, including the single spike solution and previously unknown examples of supersymmetric Wilson loops.
Vertex Operator Formulation of Scattering around Black-Hole

NASA Astrophysics Data System (ADS)

Park, I. Y.

We propose a full-fledged open string framework that seems suited to study the black hole information paradox. We set up a configuration to compute the scattering amplitude of a IIB open string around a D5-brane. The D5-brane is situated at the origin of a transverse D3-brane. A string perturbation theory is employed where the geometry of the D5-brane is treated as a potential. We reason that the setup is capable of reconciling the unitary evolution of states and information loss that is measured by an observer on the D3 brane. With the configurations of these kinds, the information loss is an apparent phenomenon: it is just a manifestation of the fact that the D3-observer does not have access to the "hair" of the D5 black brane.
Gravitational lensing effects of vacuum strings - Exact solutions

NASA Technical Reports Server (NTRS)

Gott, J. R., III

1985-01-01

Exact interior and exterior solutions to Einstein's field equations are derived for vacuum strings. The exterior solution for a uniform density vacuum string corresponds to a conical space while the interior solution is that of a spherical cap. For Mu equals 0-1/4 the external metric is ds-squared = -dt-squared + dr-squared + (1-4 Mu)-squared r-squared dphi-squared + dz-squared, where Mu is the mass per unit length in the string in Planck masses per Planck length. A maximum mass per unit length for a string is 6.73 x 10 to the 27th g/cm. It is shown that strings cause temperature fluctuations in the cosmic microwave background and produce equal brightness double QSO images separated by up to several minutes of arc. Formulae for lensing probabilities, image splittings, and time delays are derived for strings in a realistic cosmological setting. String searches using ST, the VLA, and the COBE satellite are discussed.
Separability of black holes in string theory

NASA Astrophysics Data System (ADS)

Keeler, Cynthia; Larsen, Finn

2012-10-01

We analyze the origin of separability for rotating black holes in string theory, considering both massless and massive geodesic equations as well as the corresponding wave equations. We construct a conformal Killing-Stackel tensor for a general class of black holes with four independent charges, then identify two-charge configurations where enhancement to an exact Killing-Stackel tensor is possible. We show that further enhancement to a conserved Killing-Yano tensor is possible only for the special case of Kerr-Newman black holes. We construct natural null congruences for all these black holes and use the results to show that only the Kerr-Newman black holes are algebraically special in the sense of Petrov. Modifying the asymptotic behavior by the subtraction procedure that induces an exact SL(2)2 also preserves only the conformal Killing-Stackel tensor. Similarly, we find that a rotating Kaluza-Klein black hole possesses a conformal Killing-Stackel tensor but has no further enhancements.
String theory, gauge theory and quantum gravity. Proceedings. Trieste Spring School and Workshop on String Theory, Gauge Theory and Quantum Gravity, Trieste (Italy), 11 - 22 Apr 1994.

NASA Astrophysics Data System (ADS)

1995-04-01

The following topics were dealt with: string theory, gauge theory, quantum gravity, quantum geometry, black hole physics and information loss, second quantisation of the Wilson loop, 2D Yang-Mills theory, topological field theories, equivariant cohomology, superstring theory and fermion masses, supergravity, topological gravity, waves in string cosmology, superstring theories, 4D space-time.
The Future of Theoretical Physics and Cosmology

NASA Astrophysics Data System (ADS)

Gibbons, G. W.; Shellard, E. P. S.; Rankin, S. J.

2009-08-01

Preface; List of contributors; 1. Introduction; Part I. Popular Symposium: 2. Our complex cosmos and its future Martin J. Rees; 3. Theories of everything and Hawking's wave function of the Universe James B. Hartle; 4. The problem of space-time singularities: implications for quantum gravity? Roger Penrose; 5. Warping spacetime Kip Thorne; 6. 60 years in a nutshell Stephen W. Hawking; Part II. Spacetime Singularities: 7. Cosmological perturbations and singularities George F. R. Ellis; 8. The quantum physics of chronology protection Matt Visser; 9. Energy dominance and the Hawking-Ellis vacuum conservation theorem Brandon Carter; 10. On the instability of extra space dimensions Roger Penrose; Part III. Black Holes: 11. Black hole uniqueness and the inner horizon stability problem Werner Israel; 12. Black holes in the real universe and their prospects as probes of relativistic gravity Martin J. Rees; 13. Primordial black holes Bernard Carr; 14. Black hole pair creation Simon F. Ross; 15. Black holes as accelerators Steven Giddings; Part IV. Hawking Radiation: 16. Black holes and string theory Malcolm Perry; 17. M theory and black hole quantum mechanics Joe Polchinski; 18. Playing with black strings Gary Horowitz; 19. Twenty years of debate with Stephen Leonard Susskind; Part V. Quantum Gravity: 20. Euclidean quantum gravity: the view from 2002 Gary Gibbons; 21. Zeta functions, anomalies and stable branes Ian Moss; 22. Some reflections on the status of conventional quantum theory when applied to quantum gravity Chris Isham; 23. Quantum geometry and its ramifications Abhay Ashtekar; 24. Topology change in quantum gravity Fay Dowker; Part VI. M Theory and Beyond: 25. The past and future of string theory Edward Witten; 26. String theory David Gross; 27. A brief description of string theory Michael Green; 28. The story of M Paul Townsend; 29. Gauged supergravity and holographic field theory Nick Warner; 30. 57 varieties in a NUTshell Chris Pope; Part VII. de Sitter Space: 31. Adventures in de Sitter space Raphael Bousso; 32. de Sitter space in non-critical string theory Andrew Strominger; 33. Supergravity, M theory and cosmology Renata Kallosh; Part VIII. Quantum Cosmology: 34. The state of the universe James B. Hartle; 35. Quantum cosmology Don Page; 36. Quantum cosmology and eternal inflation A. Vilenkin; 37. Probability in the deterministic theory known as quantum mechanics Bryce de Witt; 38. The interpretation of quantum cosmology and the problem of time J. Halliwell; 39. What local supersymmetry can do for quantum cosmology Peter D'Eath; Part IX. Cosmology: 40. Inflation and cosmological perturbations Alan Guth; 41. The future of cosmology: observational and computational prospects Paul Shellard; 42. The ekpyrotic universe and its cyclic extension Neil Turok; 43. Inflationary theory versus the ekpyrotic/cyclic scenario Andrei Linde; 44. Brane (new) worlds Pierre Binetruy; 45. Publications of Stephen Hawking; Index.
Charting the landscape of supercritical string theory.

PubMed

Hellerman, Simeon; Swanson, Ian

2007-10-26

Special solutions of string theory in supercritical dimensions can interpolate in time between theories with different numbers of spacetime dimensions and different amounts of world sheet supersymmetry. These solutions connect supercritical string theories to the more familiar string duality web in ten dimensions and provide a precise link between supersymmetric and purely bosonic string theories. Dimension quenching and c duality appear to be natural concepts in string theory, giving rise to large networks of interconnected theories.
Black holes in many dimensions at the CERN Large Hadron Collider: testing critical string theory.

PubMed

Hewett, JoAnne L; Lillie, Ben; Rizzo, Thomas G

2005-12-31

We consider black hole production at the CERN Large Hadron Collider (LHC) in a generic scenario with many extra dimensions where the standard model fields are confined to a brane. With approximately 20 dimensions the hierarchy problem is shown to be naturally solved without the need for large compactification radii. We find that in such a scenario the properties of black holes can be used to determine the number of extra dimensions, . In particular, we demonstrate that measurements of the decay distributions of such black holes at the LHC can determine if is significantly larger than 6 or 7 with high confidence and thus can probe one of the critical properties of string theory compactifications.
Gravitating lepton bag model

NASA Astrophysics Data System (ADS)

Burinskii, A.

2015-08-01

The Kerr-Newman (KN) black hole (BH) solution exhibits the external gravitational and electromagnetic field corresponding to that of the Dirac electron. For the large spin/mass ratio, a ≫ m, the BH loses horizons and acquires a naked singular ring creating two-sheeted topology. This space is regularized by the Higgs mechanism of symmetry breaking, leading to an extended particle that has a regular spinning core compatible with the external KN solution. We show that this core has much in common with the known MIT and SLAC bag models, but has the important advantage of being in accordance with the external gravitational and electromagnetic fields of the KN solution. A peculiar two-sheeted structure of Kerr's gravity provides a framework for the implementation of the Higgs mechanism of symmetry breaking in configuration space in accordance with the concept of the electroweak sector of the Standard Model. Similar to other bag models, the KN bag is flexible and pliant to deformations. For parameters of a spinning electron, the bag takes the shape of a thin rotating disk of the Compton radius, with a ring-string structure and a quark-like singular pole formed at the sharp edge of this disk, indicating that the considered lepton bag forms a single bag-string-quark system.
Evidence for a scaling solution in cosmic-string evolution

NASA Technical Reports Server (NTRS)

Bennett, David P.; Bouchet, Francois R.

1988-01-01

Numerical simulations are used to study the most fundamental issue of cosmic-string evolution: the existence of a scaling solution. Strong evidence is found that a scaling solution does indeed exist. This justifies the main assumption on which the cosmic-string theories of galaxy formation is based. The main conclusion coincides with that of Albrecht and Turok (1985) but the results are not consistent with theirs. In fact, the results indicate that the details of string evolution are very different from the standard dogma.
Non-BPS attractors in 5 d and 6 d extended supergravity

NASA Astrophysics Data System (ADS)

Andrianopoli, L.; Ferrara, S.; Marrani, A.; Trigiante, M.

2008-05-01

We connect the attractor equations of a certain class of N=2, d=5 supergravities with their (1,0), d=6 counterparts, by relating the moduli space of non-BPS d=5 black hole/black string attractors to the moduli space of extremal dyonic black string d=6 non-BPS attractors. For d=5 real special symmetric spaces and for N=4,6,8 theories, we explicitly compute the flat directions of the black object potential corresponding to vanishing eigenvalues of its Hessian matrix. In the case N=4, we study the relation to the (2,0), d=6 theory. We finally describe the embedding of the N=2, d=5 magic models in N=8, d=5 supergravity as well as the interconnection among the corresponding charge orbits.
Non-perturbative String Theory from Water Waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iyer, Ramakrishnan; Johnson, Clifford V.; /Southern California U.

2012-06-14

We use a combination of a 't Hooft limit and numerical methods to find non-perturbative solutions of exactly solvable string theories, showing that perturbative solutions in different asymptotic regimes are connected by smooth interpolating functions. Our earlier perturbative work showed that a large class of minimal string theories arise as special limits of a Painleve IV hierarchy of string equations that can be derived by a similarity reduction of the dispersive water wave hierarchy of differential equations. The hierarchy of string equations contains new perturbative solutions, some of which were conjectured to be the type IIA and IIB string theoriesmore » coupled to (4, 4k ? 2) superconformal minimal models of type (A, D). Our present paper shows that these new theories have smooth non-perturbative extensions. We also find evidence for putative new string theories that were not apparent in the perturbative analysis.« less
Pre-Big-Bang bubbles from the gravitational instability of generic string vacua

NASA Astrophysics Data System (ADS)

Buonanno, A.; Damour, T.; Veneziano, G.

1999-03-01

We formulate the basic postulate of pre-Big-Bang cosmology as one of ``asymptotic past triviality", by which we mean that the initial state is a generic perturbative solution of the tree-level low-energy effective action. Such a past-trivial ``string vacuum'' is made of an arbitrary ensemble of incoming gravitational and dilatonic waves, and is generically prone to gravitational instability, leading to the possible formation of many black holes hiding singular space-like hypersurfaces. Each such singular space-like hypersurface of gravitational collapse becomes, in the string-frame metric, the usual Big-Bang t=0 hypersurface, i.e. the place of birth of a baby Friedmann universe after a period of dilaton-driven inflation. Specializing to the spherically symmetric case, we review and reinterpret previous work on the subject, and propose a simple, scale-invariant criterion for collapse/inflation in terms of asymptotic data at past null infinity. Those data should determine whether, when, and where collapse/inflation occurs, and, when it does, fix its characteristics, including anisotropies on the Big-Bang hypersurface whose imprint could have survived till now. Using Bayesian probability concepts, we finally attempt to answer some fine-tuning objections recently moved to the pre-Big-Bang scenario.
String solutions in spherically-symmetric f(R) gravity vacuum

NASA Astrophysics Data System (ADS)

Dil, Emre

Dynamical evolution of the cosmic string in a spherically symmetric f(R) gravity vacuum is studied for a closed and straight string. We first set the background spacetime metric for a constant curvature scalar R = R0, and obtain the Killing fields for it. Using the standard gauge coordinates and constraints for both closed and straight strings, we present the equation of motions and find the solutions of them. We then analyze the dynamics of the string by studying the behavior of the string radius and periastron radius, with respect to both proper time and azimuthal angle, for various values of f(R) functions. Consequently, we conclude that the value of f(R) dramatically affects the closed string collapse time and the straight string angular deviation.

Tilted string cosmologies

NASA Astrophysics Data System (ADS)

Clancy, Dominic; Feinstein, Alexander; Lidsey, James E.; Tavakol, Reza

1999-04-01

Global symmetries of the string effective action are employed to generate tilted, homogeneous Bianchi type VIh string cosmologies from a previously known stiff perfect fluid solution to Einstein gravity. The dilaton field is not constant on the surfaces of homogeneity. The future asymptotic state of the models is interpreted as a plane wave and is itself an exact solution to the string equations of motion to all orders in the inverse string tension. An inhomogeneous generalization of the Bianchi type III model is also found.
Deforming baryons into confining strings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hartnoll, Sean A.; Portugues, Ruben

2004-09-15

We find explicit probe D3-brane solutions in the infrared of the Maldacena-Nunez background. The solutions describe deformed baryon vertices: q external quarks are separated in spacetime from the remaining N-q. As the separation is taken to infinity we recover known solutions describing infinite confining strings in N=1 gauge theory. We present results for the mass of finite confining strings as a function of length. We also find probe D2-brane solutions in a confining type IIA geometry, the reduction of a G{sub 2} holonomy M theory background. The relation between these deformed baryons and confining strings is not as straightforward.
The Matter-Gravity Entanglement Hypothesis

NASA Astrophysics Data System (ADS)

Kay, Bernard S.

2018-03-01

I outline some of my work and results (some dating back to 1998, some more recent) on my matter-gravity entanglement hypothesis, according to which the entropy of a closed quantum gravitational system is equal to the system's matter-gravity entanglement entropy. The main arguments presented are: (1) that this hypothesis is capable of resolving what I call the second-law puzzle, i.e. the puzzle as to how the entropy increase of a closed system can be reconciled with the asssumption of unitary time-evolution; (2) that the black hole information loss puzzle may be regarded as a special case of this second law puzzle and that therefore the same resolution applies to it; (3) that the black hole thermal atmosphere puzzle (which I recall) can be resolved by adopting a radically different-from-usual description of quantum black hole equilibrium states, according to which they are total pure states, entangled between matter and gravity in such a way that the partial states of matter and gravity are each approximately thermal equilibrium states (at the Hawking temperature); (4) that the Susskind-Horowitz-Polchinski string-theoretic understanding of black hole entropy as the logarithm of the degeneracy of a long string (which is the weak string coupling limit of a black hole) cannot be quite correct but should be replaced by a modified understanding according to which it is the entanglement entropy between a long string and its stringy atmosphere, when in a total pure equilibrium state in a suitable box, which (in line with (3)) goes over, at strong-coupling, to a black hole in equilibrium with its thermal atmosphere. The modified understanding in (4) is based on a general result, which I also describe, which concerns the likely state of a quantum system when it is weakly coupled to an energy-bath and the total state is a random pure state with a given energy. This result generalizes Goldstein et al.'s `canonical typicality' result to systems which are not necessarily small.
The Matter-Gravity Entanglement Hypothesis

NASA Astrophysics Data System (ADS)

Kay, Bernard S.

2018-05-01

I outline some of my work and results (some dating back to 1998, some more recent) on my matter-gravity entanglement hypothesis, according to which the entropy of a closed quantum gravitational system is equal to the system's matter-gravity entanglement entropy. The main arguments presented are: (1) that this hypothesis is capable of resolving what I call the second-law puzzle, i.e. the puzzle as to how the entropy increase of a closed system can be reconciled with the asssumption of unitary time-evolution; (2) that the black hole information loss puzzle may be regarded as a special case of this second law puzzle and that therefore the same resolution applies to it; (3) that the black hole thermal atmosphere puzzle (which I recall) can be resolved by adopting a radically different-from-usual description of quantum black hole equilibrium states, according to which they are total pure states, entangled between matter and gravity in such a way that the partial states of matter and gravity are each approximately thermal equilibrium states (at the Hawking temperature); (4) that the Susskind-Horowitz-Polchinski string-theoretic understanding of black hole entropy as the logarithm of the degeneracy of a long string (which is the weak string coupling limit of a black hole) cannot be quite correct but should be replaced by a modified understanding according to which it is the entanglement entropy between a long string and its stringy atmosphere, when in a total pure equilibrium state in a suitable box, which (in line with (3)) goes over, at strong-coupling, to a black hole in equilibrium with its thermal atmosphere. The modified understanding in (4) is based on a general result, which I also describe, which concerns the likely state of a quantum system when it is weakly coupled to an energy-bath and the total state is a random pure state with a given energy. This result generalizes Goldstein et al.'s `canonical typicality' result to systems which are not necessarily small.
Four-qubit entanglement classification from string theory.

PubMed

Borsten, L; Dahanayake, D; Duff, M J; Marrani, A; Rubens, W

2010-09-03

We invoke the black-hole-qubit correspondence to derive the classification of four-qubit entanglement. The U-duality orbits resulting from timelike reduction of string theory from D=4 to D=3 yield 31 entanglement families, which reduce to nine up to permutation of the four qubits.
Solutions on a brane in a bulk spacetime with Kalb–Ramond field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chakraborty, Sumanta, E-mail: sumanta@iucaa.in; SenGupta, Soumitra, E-mail: tpssg@iacs.res.in

Effective gravitational field equations on a brane have been derived, when the bulk spacetime is endowed with the second rank antisymmetric Kalb–Ramond field. Since both the graviton and the Kalb–Ramond field are closed string excitations, they can propagate in the bulk. After deriving the effective gravitational field equations on the brane, we solve them for a static spherically symmetric solution. It turns out that the solution so obtained represents a black hole or naked singularity depending on the parameter space of the model. The stability of this model is also discussed. Cosmological solutions to the gravitational field equations have beenmore » obtained, where the Kalb–Ramond field is found to behave as normal pressure free matter. For certain specific choices of the parameters in the cosmological solution, the solution exhibits a transition in the behaviour of the scale factor and hence a transition in the expansion history of the universe. The possibility of accelerated expansion of the universe in this scenario is also discussed.« less
Lectures from the European RTN Winter School on Strings, Supergravity and Gauge Theories, CERN, 16 20 January, 2006

NASA Astrophysics Data System (ADS)

Derendinger, J.-P.; Scrucca, C. A.; Uranga, A. M.

2006-11-01

This special issue is devoted to the proceedings of the conference 'Winter School on Strings, Supergravity and Gauge Theories', which took place at CERN, the European Centre for Nuclear Research, in Geneva, Switzerland, from the 16 to the 20 of January 2006. This event was organized in the framework of the European Mobility Research and Training Network entitled 'Constituents, Fundamental Forces and Symmetries of the Universe'. It is part of a yearly series of scientific schools which have become a traditional rendezvous for young researchers of the community. The previous one was held at SISSA, in Trieste, Italy, in February 2005, and the next one will take place again at CERN, in January 2007. The school was primarily meant for young doctoral students and postdoctoral researchers working in the area of string theory. It consisted of five general lectures of four hours each, whose notes are published in the present proceedings, and five working group discussion sessions, focused on specific topics of the network research program. It was attended by approximately 250 participants. The topics of the lectures were chosen to provide an introduction to some of the areas of recent progress and to the open problems in string theory. String theory is expected to provide insights into the description of systems where the role of gravity is crucial. One prominent example of such systems are time-dependent backgrounds with big bang singularities, whose status in string theory is reviewed in the lecture notes by Ben Craps. In another main problem in quantum gravity, string theory gives a fascinating microscopic description of black holes and their properties. The lectures by Shiraz Minwalla review the thermal properties of black holes from their microscopic description in terms of a holographically dual large N field theory. Progress in the description of black hole microstates, and its interplay with the macroscopic description in terms of supergravity solutions via the attractor mechanism, are covered by the lectures by Atish Dabholkar and Boris Pioline. A final important mainstream topic in string theory, being a higher-dimensional theory, is its compactification to four dimensions, and the computation of four-dimensional physical properties in terms of the properties of the internal space. The lectures by Mariana Graña review recent progress in the classification of the most general supersymmetric backgrounds describing the compactified dimensions, and their role in determining the number of massless scalar moduli fields in four dimensions. The conference was financially supported by the European Commission under contract MRTN-CT-2004-005104 and by CERN. It was jointly organized by the Physics Institute of the University of Neuchâtel and the Theory Unit of the Physics Division of CERN. It is a great pleasure for us to warmly thank the Theory Unit of CERN for its very kind hospitality and for the high quality of the services and infrastructure that it has provided. We also acknowledge helpful administrative assistance from the Physics Institute of the University of Neuchâtel. Special thanks go finally to Denis Frank for his very valuable help in preparing the conference web pages, and to J Rostant, A-M Perrin and M-S Vascotto for their continuous and very reliable assistance.
Self-similar motion of a Nambu-Goto string

NASA Astrophysics Data System (ADS)

Igata, Takahisa; Houri, Tsuyoshi; Harada, Tomohiro

2016-09-01

We study the self-similar motion of a string in a self-similar spacetime by introducing the concept of a self-similar string, which is defined as the world sheet to which a homothetic vector field is tangent. It is shown that in Nambu-Goto theory, the equations of motion for a self-similar string reduce to those for a particle. Moreover, under certain conditions such as the hypersurface orthogonality of the homothetic vector field, the equations of motion for a self-similar string simplify to the geodesic equations on a (pseudo)Riemannian space. As a concrete example, we investigate a self-similar Nambu-Goto string in a spatially flat Friedmann-Lemaître-Robertson-Walker expanding universe with self-similarity and obtain solutions of open and closed strings, which have various nontrivial configurations depending on the rate of the cosmic expansion. For instance, we obtain a circular solution that evolves linearly in the cosmic time while keeping its configuration by the balance between the effects of the cosmic expansion and string tension. We also show the instability for linear radial perturbation of the circular solutions.
Gödel universes in string theory

NASA Astrophysics Data System (ADS)

Barrow, John D.; Dabrowski, Mariusz P.

1998-11-01

We show that homogeneous Gödel spacetimes need not contain closed timelike curves in low-energy-effective string theories. We find exact solutions for the Gödel metric in string theory for the full O(α') action including both dilaton and axion fields. The results are valid for bosonic, heterotic and super-strings. To first order in the inverse string tension α', these solutions display a simple relation between the angular velocity of the Gödel universe, Ω, and the inverse string tension of the form α'=1/Ω2 in the absence of the axion field. The generalization of this relationship is also found when the axion field is present.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Dijkgraaf, Robbert; Gopakumar, Rajesh; Ooguri, Hirosi

We argue that the holographic description of four-dimensional Bogomol'nyi-Prasad-Sommerfield black holes naturally includes multicenter solutions. This suggests that the holographic dual to the gauge theory is not a single AdS{sub 2}xS{sup 2} but a coherent ensemble of them. We verify this in a particular class of examples, where the two-dimensional Yang-Mills theory gives a holographic description of the black holes obtained by branes wrapping Calabi-Yau cycles. Using the free fermionic formulation, we show that O(e{sup -N}) nonperturbative effects entangle the two Fermi surfaces. In an Euclidean description, the wave function of the multicenter black holes gets mapped to the Hartle-Hawkingmore » wave function of baby universes. This provides a concrete realization, within string theory, of effects that can be interpreted as the creation of baby universes. We find that, at least in the case we study, the baby universes do not lead to a loss of quantum coherence, in accord with general arguments.« less
Black branes as piezoelectrics.

PubMed

Armas, Jay; Gath, Jakob; Obers, Niels A

2012-12-14

We find a realization of linear electroelasticity theory in gravitational physics by uncovering a new response coefficient of charged black branes, exhibiting their piezoelectric behavior. Taking charged dilatonic black strings as an example and using the blackfold approach we measure their elastic and piezolectric moduli. We also use our results to draw predictions about the equilibrium condition of charged dilatonic black rings in dimensions higher than six.
Lattice black branes: sphere packing in general relativity

NASA Astrophysics Data System (ADS)

Dias, Óscar J. C.; Santos, Jorge E.; Way, Benson

2018-05-01

We perturbatively construct asymptotically R^{1,3}× T^2 black branes with multiple inhomogeneous directions and show that some of them are thermodynamically preferred over uniform branes in both the microcanonical and canonical ensembles. This demonstrates that, unlike five-dimensional black strings, the instability of some unstable black branes has a plausible endpoint that does not require a violation of cosmic censorship.
Search for microscopic black holes in pp collisions at $$ \\sqrt{s}=8 $$ TeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.

2013-07-01

A search for microscopic black holes and string balls is presented, based on a data sample of pp collisions at sqrt(s) = 8 TeV recorded by the CMS experiment at the Large Hadron Collider and corresponding to an integrated luminosity of 12 inverse femtobarns. No excess of events with energetic multiparticle final states, typical of black hole production or of similar new physics processes, is observed. Given the agreement of the observations with the expected standard model background, which is dominated by QCD multijet production, 95% confidence limits are set on the production of semiclassical or quantum black holes, ormore » of string balls, corresponding to the exclusions of masses below 4.3 to 6.2 TeV, depending on model assumptions. In addition, model-independent limits are set on new physics processes resulting in energetic multiparticle final states.« less
Using 4th order Runge-Kutta method for solving a twisted Skyrme string equation

NASA Astrophysics Data System (ADS)

Hadi, Miftachul; Anderson, Malcolm; Husein, Andri

2016-03-01

We study numerical solution, especially using 4th order Runge-Kutta method, for solving a twisted Skyrme string equation. We find numerically that the value of minimum energy per unit length of vortex solution for a twisted Skyrmion string is 20.37 × 1060 eV/m.
Rapidly moving cosmic strings and chronology protection

NASA Astrophysics Data System (ADS)

Ori, Amos

1991-10-01

Recently, Gott has provided a family of solutions of the Einstein equations describing pairs of parallel cosmic strings in motion. He has shown that if the strings' relative velocity is sufficiently high, there exist closed timelike curves (CTC's) in the spacetime. Here we show that if there are CTC's in such a solution, then every t=const hypersurface in the spacetime intersects CTC's. Therefore, these solutions do not contradict the chronology protection conjecture of Hawking.
String limit of the isotropic Heisenberg chain in the four-particle sector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Antipov, A. G., E-mail: aga2@csa.ru; Komarov, I. V., E-mail: ivkoma@rambler.r

2008-05-15

The quantum method of variable separation is applied to the spectral problem of the isotropic Heisenberg model. The Baxter difference equation is resolved by means of a special quasiclassical asymptotic expansion. States are identified by multiplicities of limiting values of the Bethe parameters. The string limit of the four-particle sector is investigated. String solutions are singled out and classified. It is shown that only a minor fraction of solutions demonstrate string behavior.
From fractals to wormholes via string theory

NASA Astrophysics Data System (ADS)

Felce, Andrew George

The thesis is in two parts. The first part is devoted to a study of the definition of mass for soliton solutions in string theory. In the context of the low-energy effective field theory, there are three distinct quantities from which one can extract the mass of a soliton: the ADM mass, the static action and the kinetic energy. The three corresponding masses are carefully defined and shown to be equal for a representative class of string solitons, the so-called 'black fivebranes'. Along the way a potential confusion in the definition of the action is cleared up, and it is shown that the kinetic energy of a moving soliton is given in terms of a surface integral at spacelike infinity. This result for the kinetic energy is used to motivate a conjecture about the exact value of soliton masses in string theory: That in conformal field theory the kinetic mass is realized as the norm of the (1,1) deformation induced by the collective coordinate. Such deformations are usually treated as unphysical because they appear to be pure gauge and have zero norm. In a soliton conformal field theory, a finite number of these gauge transformations become physical because of a subtlety involving the boundary at spatial infinity. Some proposals for concrete exploration of this phenomenon are discussed. The second part of the thesis concerns the connection between string theory and an important problem in condensed matter physics. It has recently been shown that the dissipative Hofstadter model (dissipative quantum mechanics of an electron subject to uniform magnetic field and periodic potential in two dimensions) exhibits critical behavior on a network of lines in the dissipation/magnetic field plane. Apart from their obvious condensed matter interest, the corresponding critical theories represent non-trivial solutions of open string field theory containing a tachyon and gauge field background. A detailed account of their properties would be interesting from several points of view. The thesis reports the results of an initial investigation of the free energy, N-point functions and boundary state for this type of critical theory. Although the primary goal is to study the magnetic field dependence of these quantities, some new results are presented which bear on the zero magnetic field case as well.
Causal Structure around Spinning 5-DIMENSIONAL Cosmic Strings

NASA Astrophysics Data System (ADS)

Slagter, Reinoud Jan

2008-09-01

We present a numerical solution of a stationary 5-dimensional spinning cosmic string in the Einstein-Yang-Mills (EYM) model, where the extra bulk coordinate ψ is periodic. It turns out that when gψψ approaches zero, i.e., a closed time-like curve (CTC) would appear, the solution becomes singular. We also investigated the geometrical structure of the static 5D cosmic string. Two opposite moving 5D strings could, in contrast with the 4D case, fulfil the Gott condition for CTC formation.
Killing(-Yano) tensors in string theory

NASA Astrophysics Data System (ADS)

Chervonyi, Yuri; Lunin, Oleg

2015-09-01

We construct the Killing(-Yano) tensors for a large class of charged black holes in higher dimensions and study general properties of such tensors, in particular, their behavior under string dualities. Killing(-Yano) tensors encode the symmetries beyond isometries, which lead to insights into dynamics of particles and fields on a given geometry by providing a set of conserved quantities. By analyzing the eigenvalues of the Killing tensor, we provide a prescription for constructing several conserved quantities starting from a single object, and we demonstrate that Killing tensors in higher dimensions are always associated with ellipsoidal coordinates. We also determine the transformations of the Killing(-Yano) tensors under string dualities, and find the unique modification of the Killing-Yano equation consistent with these symmetries. These results are used to construct the explicit form of the Killing(-Yano) tensors for the Myers-Perry black hole in arbitrary number of dimensions and for its charged version.
The Weak Gravity Conjecture and the axionic black hole paradox

NASA Astrophysics Data System (ADS)

Hebecker, Arthur; Soler, Pablo

2017-09-01

In theories with a perturbatively massless 2-form (dual to an axion), a paradox may arise in the process of black hole evaporation. Schwarzschild black holes can support a non-trivial Wilson-line-type field, the integral of the 2-form around their horizon. After such an `axionic black hole' evaporates, the Wilson line must be supported by the corresponding 3-form field strength in the region formerly occupied by the black hole. In the limit of small axion decay-constant f, the energy required for this field configuration is too large. Thus, energy cannot be conserved in the process of black hole evaporation. The natural resolution of this paradox is through the presence of light strings, which allow the black hole to "shed" its axionic hair sufficiently early. This gives rise to a new Weak-Gravity-type argument in the 2-form context: small coupling, in this case f , enforces the presence of light strings or a low cutoff. We also discuss how this argument may be modified in situations where the weak coupling regime is achieved in the low-energy effective theory through an appropriate gauging of a model with a vector field and two 2-forms.

Gauge/Gravity correspondence and black hole attractors in various dimensions

NASA Astrophysics Data System (ADS)

Li, Wei

This thesis investigates several topics on Gauge/Gravity correspondence and black hole attractors in various dimensions. The first chapter contains a brief review and summary of main results. Chapters 2 and 3 aim at a microscopic description of black objects in five dimensions. Chapter 2 studies higher-derivative corrections for 5D black rings and spinning black holes. It shows that certain R 2 terms found in Calabi-Yau compactifications of M-theory yield macroscopic corrections to the entropies that match the microscopic corrections. Chapter 3 constructs probe brane configurations that preserve half of the enhanced near-horizon supersymmetry of 5D spinning black holes, whose near-horizon geometry is squashed AdS2 x S 3. There are supersymmetric zero-brane probes stabilized by orbital angular momentum on S3 and one-brane probes with momentum and winding around a U(1)L x U(1)R torus in S3. Chapter 4 constructs and analyzes generic single-centered and multi-centered black hole attractor solutions in various four-dimensional models which, after Kaluza-Klein reduction, admit a description in terms of 3D gravity coupled to a sigma model whose target space is symmetric coset space. The solutions correspond to certain nilpotent generators of the coset algebra. The non-BPS black hole attractors are found to be drastically different from their BPS counterparts. Chapter 5 examines three-dimensional topologically massive gravity with negative cosmological constant in asymptotically AdS 3 spacetimes. It proves that the theory is unitary and stable only at a special value of Chern-Simons coupling, where the theory becomes chiral. This suggests the existence of a stable, consistent quantum gravity theory at the chiral point which is dual to a holomorphic boundary CFT 2. Finally, Chapter 6 studies the two-dimensional N = 1 critical string theory with a linear dilaton background. It constructs time-dependent boundary state solutions that correspond to D0-branes falling toward the Liouville wall. It also shows that there exist four types of stable, falling D0-branes (two branes and two anti-branes) in Type 0A projection and two unstable ones in Type 0B projection.
Solvability of a Nonlinear Integral Equation in Dynamical String Theory

NASA Astrophysics Data System (ADS)

Khachatryan, A. Kh.; Khachatryan, Kh. A.

2018-04-01

We investigate an integral equation of the convolution type with a cubic nonlinearity on the entire real line. This equation has a direct application in open-string field theory and in p-adic string theory and describes nonlocal interactions. We prove that there exists a one-parameter family of bounded monotonic solutions and calculate the limits of solutions constructed at infinity.
Brane Physics in M-theory

NASA Astrophysics Data System (ADS)

Argurio, Riccardo

1998-07-01

The thesis begins with an introduction to M-theory (at a graduate student's level), starting from perturbative string theory and proceeding to dualities, D-branes and finally Matrix theory. The following chapter treats, in a self-contained way, of general classical p-brane solutions. Black and extremal branes are reviewed, along with their semi-classical thermodynamics. We then focus on intersecting extremal branes, the intersection rules being derived both with and without the explicit use of supersymmetry. The last three chapters comprise more advanced aspects of brane physics, such as the dynamics of open branes, the little theories on the world-volume of branes and how the four dimensional Schwarzschild black hole can be mapped to an extremal configuration of branes, thus allowing for a statistical interpretation of its entropy. The original results were already reported in hep-th/9701042, hep-th/9704190, hep-th/9710027 and hep-th/9801053.
Iron line spectroscopy with Einstein-dilaton-Gauss-Bonnet black holes

NASA Astrophysics Data System (ADS)

Nampalliwar, Sourabh; Bambi, Cosimo; Kokkotas, Kostas D.; Konoplya, Roman A.

2018-06-01

Einstein-dilaton-Gauss-Bonnet gravity is a well-motivated alternative theory of gravity that emerges naturally from string theory. While black hole solutions have been known in this theory in numerical form for a while, an approximate analytical metric was obtained recently by some of us, which allows for faster and more detailed analysis. Here we test the accuracy of the analytical metric in the context of X-ray reflection spectroscopy. We analyze innermost stable circular orbits (ISCO) and relativistically broadened iron lines and find that both the ISCO and iron lines are determined sufficiently accurately up to the limit of the approximation. We also find that, though the ISCO increases by about 7% as dilaton coupling increases from zero to extremal values, the redshift at ISCO changes by less than 1%. Consequently, the shape of the iron line is much less sensitive to the dilaton charge than expected.
Eventful horizons: String theory in de Sitter and anti-de Sitter

NASA Astrophysics Data System (ADS)

Kleban, Matthew Benjamin

String theory purports to be a theory of quantum gravity. As such, it should have much to say about the deep mysteries surrounding the very early stages of our universe. For this reason, although the theory is notoriously difficult to directly test, data from experimental cosmology may provide a way to probe the high energy physics of string theory. In the first part of this thesis, I will address the important issue of the testability of string theory using observations of the cosmic microwave background radiation. In the second part, I will study some formal difficulties that arise in attempting to understand string theory in de Sitter spacetime. In the third part, I will study the singularity of an eternal anti de Sitter Schwarzschild black hole, using the AdS/CFT correspondence.
Search for black holes and sphalerons in high-multiplicity final states in proton-proton collisions at $$\\sqrt{s} =$$ 13 TeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sirunyan, Albert M; et al.

A search in energetic, high-multiplicity final states for evidence of physics beyond the standard model, such as black holes, string balls, and electroweak sphalerons, is presented. The data sample corresponds to an integrated luminosity of 35.9 fbmore » $$^{-1}$$ collected with the CMS experiment at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV in 2016. Standard model backgrounds, dominated by multijet production, are determined from control regions in data without any reliance on simulation. No evidence for excesses above the predicted background is observed. Model-independent 95% confidence level upper limits on the cross section of beyond the standard model signals in these final states are set and further interpreted in terms of limits on semiclassical black hole, string ball, and sphaleron production. In the context of models with large extra dimensions, semiclassical black holes with minimum masses as high as 10.1 TeV and string balls with masses as high as 9.5 TeV are excluded by this search. Results of the first dedicated search for electroweak sphalerons are presented. An upper limit of 0.021 is set on the fraction of all quark-quark interactions above the nominal threshold energy of 9 TeV resulting in the sphaleron transition.« less
Momentum fractionation on superstrata

DOE PAGES

Bena, Iosif; Martinec, Emil; Turton, David; ...

2016-05-11

Superstrata are bound states in string theory that carry D1, D5, and momentum charges, and whose supergravity descriptions are parameterized by arbitrary functions of (at least) two variables. In the D1-D5 CFT, typical three-charge states reside in highdegree twisted sectors, and their momentum charge is carried by modes that individually have fractional momentum. Understanding this momentum fractionation holographically is crucial for understanding typical black-hole microstates in this system. We use solution-generating techniques to add momentum to a multi-wound supertube and thereby construct the first examples of asymptotically-flat superstrata. The resulting supergravity solutions are horizonless and smooth up to well-understood orbifoldmore » singularities. Upon taking the AdS3 decoupling limit, our solutions are dual to CFT states with momentum fractionation. We give a precise proposal for these dual CFT states. Lastly, our construction establishes the very nontrivial fact that large classes of CFT states with momentum fractionation can be realized in the bulk as smooth horizonless supergravity solutions.« less
Dilatonic imprints on exact gravitational wave signatures

NASA Astrophysics Data System (ADS)

McCarthy, Fiona; KubizÅák, David; Mann, Robert B.

2018-05-01

By employing the moduli space approximation, we analytically calculate the gravitational wave signatures emitted upon the merger of two extremally charged dilatonic black holes. We probe several values of the dilatonic coupling constant a , and find significant departures from the Einstein-Maxwell (a =0 ) counterpart studied in [Phys. Rev. D 96, 061501 (2017), 10.1103/PhysRevD.96.061501]. For (low-energy) string theory black holes (a =1 ) there are no coalescence orbits and only a memory effect is observed, whereas for an intermediate value of the coupling (a =1 /√{3 } ) the late-time merger signature becomes exponentially suppressed, compared to the polynomial decay in the a =0 case without a dilaton. Such an imprint shows a clear difference between the case with and without a scalar field (as, for example, predicted by string theory) in black hole mergers.
Self-assembly of a nanotube from a black phosphorus nanoribbon on a string of fullerenes at low temperature.

PubMed

Cai, Kun; Shi, Jiao; Liu, Ling-Nan; Qin, Qing-Hua

2017-09-13

A string of fullerenes is used for generating a nanotube by self-assembly of a black phosphorus (BP) nanoribbon at a temperature of 8 K. Among the fullerenes in the string, there are at least two fixed fullerenes placed along the edge of the BP ribbon for keeping its configuration stability during winding. By way of molecular dynamics simulations, it is found that successful generation of a BP nanotube depends on the bending stiffness of the ribbon and the attraction between the fullerenes and the ribbon. When the attraction is strong enough, the two edges (along the zigzag direction) of the BP ribbon will be able to bond covalently to form a nanotube. By the molecular dynamics approach, the maximum width of the BP ribbon capable of forming a nanotube with a perfect length is investigated in three typical models. The maximum width of the BP ribbon becomes larger with the string containing more fullerenes. This finding reveals a way to control the width of the BP ribbon which forms a nanotube. It provides guidance for fabricating a BP nanotube with a specified length, the same as to the width of the ribbon.
Holographic hierarchy in the Gaussian matrix model via the fuzzy sphere

NASA Astrophysics Data System (ADS)

Garner, David; Ramgoolam, Sanjaye

2013-10-01

The Gaussian Hermitian matrix model was recently proposed to have a dual string description with worldsheets mapping to a sphere target space. The correlators were written as sums over holomorphic (Belyi) maps from worldsheets to the two-dimensional sphere, branched over three points. We express the matrix model correlators by using the fuzzy sphere construction of matrix algebras, which can be interpreted as a string field theory description of the Belyi strings. This gives the correlators in terms of trivalent ribbon graphs that represent the couplings of irreducible representations of su(2), which can be evaluated in terms of 3j and 6j symbols. The Gaussian model perturbed by a cubic potential is then recognised as a generating function for Ponzano-Regge partition functions for 3-manifolds having the worldsheet as boundary, and equipped with boundary data determined by the ribbon graphs. This can be viewed as a holographic extension of the Belyi string worldsheets to membrane worldvolumes, forming part of a holographic hierarchy linking, via the large N expansion, the zero-dimensional QFT of the Matrix model to 2D strings and 3D membranes. Note that if, after removing the white vertices, the graph contains a blue edge connecting to the same black vertex at both ends, then the triangulation generated from the black edges will contain faces that resemble cut discs. These faces are triangles with two of the edges identified.
Hawking radiation of Dirac particles from black strings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmed, Jamil; Saifullah, K., E-mail: jamil_051@yahoo.com, E-mail: saifullah@qau.edu.pk

2011-08-01

Hawking radiation has been studied as a phenomenon of quantum tunneling in different black holes. In this paper we extend this semi-classical approach to cylindrically symmetric black holes. Using the Hamilton-Jacobi method and WKB approximation we calculate the tunneling probabilities of incoming and outgoing Dirac particles from the event horizon and find the Hawking temperature of these black holes. We obtain results both for uncharged as well as charged particles.
Wormhole at the core of an infinite cosmic string

NASA Astrophysics Data System (ADS)

Aros, Rodrigo O.; Zamorano, Nelson

1997-11-01

We study a solution of Einstein's equations that describes a straight cosmic string with a variable angular deficit, starting with a 2π deficit at the core. We show that the coordinate singularity associated with this defect can be interpreted as a traversable wormhole lodging at the core of the string. A negative energy density gradually decreases the angular deficit as the distance from the core increases, ending, at radial infinity, in a Minkowski spacetime. The negative energy density can be confined to a small transversal section of the string by gluing to it an exterior Gott-like solution that freezes the angular deficit existing at the matching border. The equation of state of the string is such that any massive particle may stay at rest anywhere in this spacetime. In this sense this is a 2+1 spacetime solution. A generalization that includes the existence of two interacting parallel wormholes is displayed. These wormholes are not traversable. Finally, we point out that a similar result, flat at infinity and with a 2π defect (or excess) at the core, has been recently published by Dyer and Marleau. Even though theirs is a local string fully coupled to gravity, our toy model captures important aspects of this solution.
Superradiant instabilities of rotating black branes and strings

NASA Astrophysics Data System (ADS)

Cardoso, Vitor; Yoshida, Shijun

2005-07-01

Black branes and strings are generally unstable against a certain sector of gravitational perturbations. This is known as the Gregory-Laflamme instability. It has been recently argued [1], [2] that there exists another general instability affecting many rotating extended black objects. This instability is in a sense universal, in that it is triggered by any massless field, and not just gravitational perturbations. Here we investigate this novel mechanism in detail. For this instability to work, two ingredients are necessary: (i) an ergo-region, which gives rise to superradiant amplification of waves, and (ii) ``bound'' states in the effective potential governing the evolution of the particular mode under study. We show that the black brane Kerr4×Rp is unstable against this mechanism, and we present numerical results for instability timescales for this case. On the other hand, and quite surprisingly, black branes of the form Kerrd×Rp are all stable against this mechanism for d > 4. This is quite an unexpected result, and it stems from the fact that there are no stable circular orbits in higher dimensional black hole spacetimes, or in a wave picture, that there are no bound states in the effective potential. We also show that it is quite easy to simulate this instability in the laboratory with acoustic black branes.
Closed string tachyon driving f(R) cosmology

NASA Astrophysics Data System (ADS)

Wang, Peng; Wu, Houwen; Yang, Haitang

2018-05-01

To study quantum effects on the bulk tachyon dynamics, we replace R with f(R) in the low-energy effective action that couples gravity, the dilaton, and the bulk closed string tachyon of bosonic closed string theory and study properties of their classical solutions. The α' corrections of the graviton-dilaton-tachyon system are implemented in the f(R). We obtain the tachyon-induced rolling solutions and show that the string metric does not need to remain fixed in some cases. In the case with H( t=‑∞ ) = , only the R and R2 terms in f(R) play a role in obtaining the rolling solutions with nontrivial metric. The singular behavior of more classical solutions are investigated and found to be modified by quantum effects. In particular, there could exist some classical solutions, in which the tachyon field rolls down from a maximum of the tachyon potential while the dilaton expectation value is always bounded from above during the rolling process.
Dark solitons, D-branes and noncommutative tachyon field theory

NASA Astrophysics Data System (ADS)

Giaccari, Stefano; Nian, Jun

2017-11-01

In this paper we discuss the boson/vortex duality by mapping the (3+1)D Gross-Pitaevskii theory into an effective string theory in the presence of boundaries. Via the effective string theory, we find the Seiberg-Witten map between the commutative and the noncommutative tachyon field theories, and consequently identify their soliton solutions with D-branes in the effective string theory. We perform various checks of the duality map and the identification of soliton solutions. This new insight between the Gross-Pitaevskii theory and the effective string theory explains the similarity of these two systems at quantitative level.
Exact solutions of the Schrödinger equation with a coulomb ring-shaped potential in the cosmic string spacetime

NASA Astrophysics Data System (ADS)

Wang, Zhi; Long, Zheng-wen; Long, Chao-yun; Teng, Jing

2015-05-01

We study the Schrödinger equation with a Coulomb ring-shaped potential in the spacetime of a cosmic string, and the solutions of the system are obtained by using the generalized parametric Nikiforov-Uvarov (NU) method. They show that the quantum dynamics of a physical system depend on the non-trivial topological features of the cosmic string spacetime and the energy levels of the considered quantum system depend explicitly on the angular deficit α which characterizes the global structure of the metric in the cosmic string spacetime.
Is it really naked? On cosmic censorship in string theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frolov, Andrei V.

We investigate the possibility of cosmic censorship violation in string theory using a characteristic double-null code, which penetrates horizons and is capable of resolving the spacetime all the way to the singularity. We perform high-resolution numerical simulations of the evolution of negative mass initial scalar field profiles, which were argued to provide a counterexample to cosmic censorship conjecture for AdS-asymptotic spacetimes in five-dimensional supergravity. In no instances formation of naked singularity is seen. Instead, numerical evidence indicates that black holes form in the collapse. Our results are consistent with earlier numerical studies, and explicitly show where the 'no black hole'more » argument breaks.« less
Inhomogeneous Einstein-Rosen string cosmology

NASA Astrophysics Data System (ADS)

Clancy, Dominic; Feinstein, Alexander; Lidsey, James E.; Tavakol, Reza

1999-08-01

Families of anisotropic and inhomogeneous string cosmologies containing non-trivial dilaton and axion fields are derived by applying the global symmetries of the string effective action to a generalized Einstein-Rosen metric. The models exhibit a two-dimensional group of Abelian isometries. In particular, two classes of exact solutions are found that represent inhomogeneous generalizations of the Bianchi type VIh cosmology. The asymptotic behavior of the solutions is investigated and further applications are briefly discussed.
Strings Attached? Linking Historically Black Colleges and Universities Public Revenue Sources with Efficiency

ERIC Educational Resources Information Center

Coupet, Jason

2017-01-01

Historically Black Colleges and Universities (HBCUs), a set of US higher education institutions historically tasked with educating African-American students, receive both state and federal funding. However, state governments often assert operational control through the political process, potentially influencing how key resources are used. Do these…
Hairy strings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sahakian, Vatche

Zero modes of the world-sheet spinors of a closed string can source higher order moments of the bulk supergravity fields. In this work, we analyze various configurations of closed strings focusing on the imprints of the quantized spinor vacuum expectation values onto the tails of bulk fields. We identify supersymmetric arrangements for which all multipole charges vanish; while for others, we find that one is left with Neveu-Schwarz-Neveu-Schwarz, and Ramond-Ramond dipole and quadrupole moments. Our analysis is exhaustive with respect to all the bosonic fields of the bulk and to all higher order moments. We comment on the relevance ofmore » these results to entropy computations of hairy black holes of a single charge or more, and to open/closed string duality.« less

Holographic anisotropic background with confinement-deconfinement phase transition

NASA Astrophysics Data System (ADS)

Aref'eva, Irina; Rannu, Kristina

2018-05-01

We present new anisotropic black brane solutions in 5D Einstein-dilaton-two-Maxwell system. The anisotropic background is specified by an arbitrary dynamical exponent ν, a nontrivial warp factor, a non-zero dilaton field, a non-zero time component of the first Maxwell field and a non-zero longitudinal magnetic component of the second Maxwell field. The blackening function supports the Van der Waals-like phase transition between small and large black holes for a suitable first Maxwell field charge. The isotropic case corresponding to ν = 1 and zero magnetic field reproduces previously known solutions. We investigate the anisotropy influence on the thermodynamic properties of our background, in particular, on the small/large black holes phase transition diagram. We discuss applications of the model to the bottom-up holographic QCD. The RG flow interpolates between the UV section with two suppressed transversal coordinates and the IR section with the suppressed time and longitudinal coordinates due to anisotropic character of our solution. We study the temporal Wilson loops, extended in longitudinal and transversal directions, by calculating the minimal surfaces of the corresponding probing open string world-sheet in anisotropic backgrounds with various temperatures and chemical potentials. We find that dynamical wall locations depend on the orientation of the quark pairs, that gives a crossover transition line between confinement/deconfinement phases in the dual gauge theory. Instability of the background leads to the appearance of the critical points ( μ ϑ,b , T ϑ,b ) depending on the orientation ϑ of quark-antiquark pairs in respect to the heavy ions collision line.
Tachyon solutions in boundary and open string field theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Calcagni, Gianluca; Nardelli, Giuseppe; Dipartimento di Matematica e Fisica, Universita Cattolica, via Musei 41, 25121 Brescia

2008-12-15

We construct rolling tachyon solutions of open and boundary string field theory (OSFT and BSFT, respectively), in the bosonic and supersymmetric (susy) case. The wildly oscillating solution of susy OSFT is recovered, together with a family of time-dependent BSFT solutions, for the bosonic and susy string. These are parametrized by an arbitrary constant r involved in solving the Green equation of the target fields. When r=0 we recover previous results in BSFT, whereas for r attaining the value predicted by OSFT it is shown that the bosonic OSFT solution is the derivative of the boundary one; in the supersymmetric casemore » the relation between the two solutions is more complicated. This technical correspondence sheds some light on the nature of wild oscillations, which appear in both theories whenever r>0.« less
Higher dimensional strange quark matter solutions in self creation cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Şen, R., E-mail: ramazansen-1991@hotmail.com; Aygün, S., E-mail: saygun@comu.edu.tr

In this study, we have generalized the higher dimensional flat Friedmann-Robertson-Walker (FRW) universe solutions for a cloud of string with perfect fluid attached strange quark matter (SQM) in Self Creation Cosmology (SCC). We have obtained that the cloud of string with perfect fluid does not survive and the string tension density vanishes for this model. However, we get dark energy model for strange quark matter with positive density and negative pressure in self creation cosmology.
Global structure of Gott's two-string spacetime

NASA Astrophysics Data System (ADS)

Cutler, Curt

1992-01-01

Gott has recently obtained exact solutions to Einstein's equation representing two infinitely long, straight cosmic strings that gravitationally scatter off each other. A remarkable feature of these solutions is that they contain closed timelike curves when the relative velocity of the strings is sufficiently high. In this paper we elucidate the global structure of Gott's two-string spacetime. In particular, we prove that the closed timelike curves are confined to a certain region of the spacetime, and that the spacetime contains complete spacelike, edgeless, achronal hypersurfaces, from which the causality-violating regions may be said to evolve. We then explicitly determine the boundary of the region containing closed timelike curves.
AdS/CFT, Black Holes, And Fuzzballs

NASA Astrophysics Data System (ADS)

Zadeh, Ida G.

In this thesis we investigate two different aspects of the AdS/CFT correspondence. We first investigate the holographic AdS/CMT correspondence. Gravitational backgrounds in d + 2 dimensions have been proposed as holographic duals to Lifshitz-like theories describing critical phenomena in d + 1 dimensions with critical exponent z ≥ 1. We numerically explore a dilaton-Einstein-Maxwell model admitting such backgrounds as solutions. We show how to embed these solutions into AdS space for a range of values of z and d. We next investigate the AdS3/CFT2 correspondence and focus on the microscopic CFT description of the D1--D5 system on T4 x S1. In the context of the fuzzball programme, we investigate deforming the CFT away from the orbifold point and study lifting of the low-lying string states. We start by considering general 2D orbifold CFTs of the form M N/SN, with M a target space manifold and SN the symmetric group. The Lunin-Mathur covering space technique provides a way to compute correlators in these orbifold theories, and we generalize this technique in two ways. First, we consider excitations of twist operators by modes of fields that are not twisted by that operator, and show how to account for these excitations when computing correlation functions in the covering space. Second, we consider non-twist sector operators and show how to include the effects of these insertions in the covering space. Using the generalization of the Lunin-Mathur symmetric orbifold technology and conformal perturbation theory, we initiate a program to compute the anomalous dimensions of low-lying string states in the D1--D5 superconformal field theory. Our method entails finding four-point functions involving a string operator O of interest and the deformation operator, taking coincidence limits to identify which other operators mix with O, subtracting conformal families of these operators, and computing their mixing coefficients. We find evidence of operator mixing at first order in the deformation parameter, which means that the string state acquires an anomalous dimension. After diagonalization this will mean that anomalous dimensions of some string states in the D1--D5 SCFT must decrease away from the orbifold point while others increase. Finally, we summarize our results and discuss some future directions of research.
Black holes and beyond

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mathur, Samir D., E-mail: mathur.16@osu.edu

The black hole information paradox forces us into a strange situation: we must find a way to break the semiclassical approximation in a domain where no quantum gravity effects would normally be expected. Traditional quantizations of gravity do not exhibit any such breakdown, and this forces us into a difficult corner: either we must give up quantum mechanics or we must accept the existence of troublesome 'remnants'. In string theory, however, the fundamental quanta are extended objects, and it turns out that the bound states of such objects acquire a size that grows with the number of quanta in themore » bound state. The interior of the black hole gets completely altered to a 'fuzzball' structure, and information is able to escape in radiation from the hole. The semiclassical approximation can break at macroscopic scales due to the large entropy of the hole: the measure in the path integral competes with the classical action, instead of giving a subleading correction. Putting this picture of black hole microstates together with ideas about entangled states leads to a natural set of conjectures on many long-standing questions in gravity: the significance of Rindler and de Sitter entropies, the notion of black hole complementarity, and the fate of an observer falling into a black hole. - Highlights: Black-Right-Pointing-Pointer The information paradox is a serious problem. Black-Right-Pointing-Pointer To solve it we need to find 'hair' on black holes. Black-Right-Pointing-Pointer In string theory we find 'hair' by the fuzzball construction. Black-Right-Pointing-Pointer Fuzzballs help to resolve many other issues in gravity.« less
Thermodynamics and luminosities of rainbow black holes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mu, Benrong; Wang, Peng; Yang, Haitang, E-mail: mubenrong@uestc.edu.cn, E-mail: pengw@scu.edu.cn, E-mail: hyanga@scu.edu.cn

2015-11-01

Doubly special relativity (DSR) is an effective model for encoding quantum gravity in flat spacetime. As result of the nonlinearity of the Lorentz transformation, the energy-momentum dispersion relation is modified. One simple way to import DSR to curved spacetime is ''Gravity's rainbow'', where the spacetime background felt by a test particle would depend on its energy. Focusing on the ''Amelino-Camelia dispersion relation'' which is E{sup 2} = m{sup 2}+p{sup 2}[1−η(E/m{sub p}){sup n}] with n > 0, we investigate the thermodynamical properties of a Schwarzschild black hole and a static uncharged black string for all possible values of η and n in the framework ofmore » rainbow gravity. It shows that there are non-vanishing minimum masses for these two black holes in the cases with η < 0 and n ≥ 2. Considering effects of rainbow gravity on both the Hawking temperature and radius of the event horizon, we use the geometric optics approximation to compute luminosities of a 2D black hole, a Schwarzschild one and a static uncharged black string. It is found that the luminosities can be significantly suppressed or boosted depending on the values of η and n.« less
Remember to blink: Reduced attentional blink following instructions to forget.

PubMed

Taylor, Tracy L

2018-04-24

This study used rapid serial visual presentation (RSVP) to determine whether, in an item-method directed forgetting task, study word processing ends earlier for forget words than for remember words. The critical manipulation required participants to monitor an RSVP stream of black nonsense strings in which a single blue word was embedded. The next item to follow the word was a string of red fs that instructed the participant to forget the word or green rs that instructed the participant to remember the word. After the memory instruction, a probe string of black xs or os appeared at postinstruction positions 1-8. Accuracy in reporting the identity of the probe string revealed an attenuated attentional blink following instructions to forget. A yes-no recognition task that followed the study trials confirmed a directed forgetting effect, with better recognition of remember words than forget words. Considered in the context of control conditions that required participants to commit either all or none of the study words to memory, the pattern of probe identification accuracy following the directed forgetting task argues that an intention to forget releases limited-capacity attentional resources sooner than an instruction to remember-despite participants needing to maintain an ongoing rehearsal set in both cases.
Holographic cosmology from BIonic solutions

NASA Astrophysics Data System (ADS)

Sepehri, Alireza; Faizal, Mir; Setare, Mohammad Reza; Ali, Ahmed Farag

2017-02-01

In this paper, we will use a BIonic solution for analyzing the holographic cosmology. A BIonic solution is a configuration of a D3-brane and an anti-D3-brane connected by a wormhole, and holographic cosmology is a recent proposal to explain cosmic expansion by using the holographic principle. In our model, a BIonic configuration will be produced by the transition of fundamental black strings. The formation of a BIonic configuration will cause inflation. As the D3-brane moves away from the anti-D3-brane, the wormhole will get annihilated, and the inflation will end with the annihilation of this wormhole. However, it is possible for a D3-brane to collide with an anti-D3-brane. Such a collision will occur if the distance between the D3-brane and the anti-D3-brane reduces, and this will create tachyonic states. We will demonstrate that these tachyonic states will lead to the formation of a new wormhole, and this will cause acceleration of the universe before such a collision.
Tachyon condensation and black hole entropy.

PubMed

Dabholkar, Atish

2002-03-04

String propagation on a cone with deficit angle 2pi(1-1 / N) is considered for the purpose of computing the entropy of a large mass black hole. The entropy computed using the recent results on condensation of twisted-sector tachyons in this theory is found to be in precise agreement with the Bekenstein-Hawking entropy.
Aspects of black holes and the information paradox

NASA Astrophysics Data System (ADS)

Levi, Thomas S.

In this thesis we explore various aspects of string theory and the black hole information paradox. The thesis is divided into two parts. In the first part, we examine black holes in the context of the AdS/CFT correspondence and holography. We show how the correspondence is formulated in a time dependent background when multiple vacua exist. We explain how particle production and Hawking radiation is expressed in the dual field theory. We then investigate the rotating BTZ black hole using AdS/CFT. We show how to compute field theory correlation functions in two ways. The first involves integration over the region up to and including the inner (Cauchy) horizon. The second integrates over only the region outside the outer (event) horizon, but over a contour in the complex time plane. We then show that the inner horizon is unstable to generic perturbations and how this instability can be detected in the dual field theory. We conjecture that signatures in the complex time plane might encode information behind the horizon in the dual field theory. In the second part of the thesis we turn to the "fuzzball" conjecture where black holes are seen as emergent phenomena that arise from a coarse-graining over many smooth microstates. We present a solution generating technique for general three-charge spacetimes that are candidate microstates for finite area black holes and rings. We show these microstates have the same asymptotic behavior as black holes or black rings, but in the interior are characterized by an intricate geometry of 2-cycles we call spacetime foam.
Dynamics of cosmic strings with higher-dimensional windings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamauchi, Daisuke; Lake, Matthew J.; Thailand Center of Excellence in Physics, Ministry of Education,Bangkok 10400

2015-06-11

We consider F-strings with arbitrary configurations in the Minkowski directions of a higher-dimensional spacetime, which also wrap and spin around S{sup 1} subcycles of constant radius in an arbitrary internal manifold, and determine the relation between the higher-dimensional and the effective four-dimensional quantities that govern the string dynamics. We show that, for any such configuration, the motion of the windings in the compact space may render the string effectively tensionless from a four-dimensional perspective, so that it remains static with respect to the large dimensions. Such a critical configuration occurs when (locally) exactly half the square of the string lengthmore » lies in the large dimensions and half lies in the compact space. The critical solution is then seen to arise as a special case, in which the wavelength of the windings is equal to their circumference. As examples, long straight strings and circular loops are considered in detail, and the solutions to the equations of motion that satisfy the tensionless condition are presented. These solutions are then generalized to planar loops and arbitrary three-dimensional configurations. Under the process of dimensional reduction, in which higher-dimensional motion is equivalent to an effective worldsheet current (giving rise to a conserved charge), this phenomenon may be seen as the analogue of the tensionless condition which arises for superconducting and chiral-current carrying cosmic strings.« less
Dynamics of cosmic strings with higher-dimensional windings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamauchi, Daisuke; Lake, Matthew J., E-mail: yamauchi@resceu.s.u-tokyo.ac.jp, E-mail: matthewj@nu.ac.th

2015-06-01

We consider F-strings with arbitrary configurations in the Minkowski directions of a higher-dimensional spacetime, which also wrap and spin around S{sup 1} subcycles of constant radius in an arbitrary internal manifold, and determine the relation between the higher-dimensional and the effective four-dimensional quantities that govern the string dynamics. We show that, for any such configuration, the motion of the windings in the compact space may render the string effectively tensionless from a four-dimensional perspective, so that it remains static with respect to the large dimensions. Such a critical configuration occurs when (locally) exactly half the square of the string lengthmore » lies in the large dimensions and half lies in the compact space. The critical solution is then seen to arise as a special case, in which the wavelength of the windings is equal to their circumference. As examples, long straight strings and circular loops are considered in detail, and the solutions to the equations of motion that satisfy the tensionless condition are presented. These solutions are then generalized to planar loops and arbitrary three-dimensional configurations. Under the process of dimensional reduction, in which higher-dimensional motion is equivalent to an effective worldsheet current (giving rise to a conserved charge), this phenomenon may be seen as the analogue of the tensionless condition which arises for superconducting and chiral-current carrying cosmic strings.« less
Cosmic strings - A problem or a solution?

NASA Technical Reports Server (NTRS)

Bennett, David P.; Bouchet, Francois R.

1988-01-01

The most fundamental issue in the theory of cosmic strings is addressed by means of Numerical Simulations: the existence of a scaling solution. The resolution of this question will determine whether cosmic strings can form the basis of an attractive theory of galaxy formation or prove to be a cosmological disaster like magnetic monopoles or domain walls. After a brief discussion of our numerical technique, results are presented which, though still preliminary, offer the best support to date of this scaling hypothesis.
Linear perturbations of black holes: stability, quasi-normal modes and tails

NASA Astrophysics Data System (ADS)

Zhidenko, Alexander

2009-03-01

Black holes have their proper oscillations, which are called the quasi-normal modes. The proper oscillations of astrophysical black holes can be observed in the nearest future with the help of gravitational wave detectors. Quasi-normal modes are also very important in the context of testing of the stability of black objects, the anti-de Sitter/Conformal Field Theory (AdS/CFT) correspondence and in higher dimensional theories, such as the brane-world scenarios and string theory. This dissertation reviews a number of works, which provide a thorough study of the quasi-normal spectrum of a wide class of black holes in four and higher dimensions for fields of various spin and gravitational perturbations. We have studied numerically the dependance of the quasi-normal modes on a number of factors, such as the presence of the cosmological constant, the Gauss-Bonnet parameter or the aether in the space-time, the dependance of the spectrum on parameters of the black hole and fields under consideration. By the analysis of the quasi-normal spectrum, we have studied the stability of higher dimensional Reissner-Nordstrom-de Sitter black holes, Kaluza-Klein black holes with squashed horizons, Gauss-Bonnet black holes and black strings. Special attention is paid to the evolution of massive fields in the background of various black holes. We have considered their quasi-normal ringing and the late-time tails. In addition, we present two new numerical techniques: a generalisation of the Nollert improvement of the Frobenius method for higher dimensional problems and a qualitatively new method, which allows to calculate quasi-normal frequencies for black holes, which metrics are not known analytically.
THE FLOW AROUND A COSMIC STRING. I. HYDRODYNAMIC SOLUTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beresnyak, Andrey; Nordita, KTH Royal Institute of Technology and Stockholm University, SE-10691

2015-05-10

Cosmic strings are linear topological defects which are hypothesized to be produced during inflation. Most searches for strings have relied on the string’s lensing of background galaxies or the cosmic microwave background. In this paper, I obtained a solution for the supersonic flow of collisional gas past the cosmic string which has two planar shocks with a shock compression ratio that depends on the angle defect of the string and its speed. The shocks result in the compression and heating of the gas and, given favorable conditions, particle acceleration. Gas heating and over-density in an unusual wedge shape can bemore » detected by observing the Hi line at high redshifts. Particle acceleration can occur in the present-day universe when the string crosses the hot gas contained in galaxy clusters and, since the consequences of such a collision persist for cosmological timescales, could be located by looking at unusual large-scale radio sources situated on a single spatial plane.« less
D1 string dynamics in curved backgrounds with fluxes

NASA Astrophysics Data System (ADS)

Banerjee, Aritra; Biswas, Sagar; Nayak, Rashmi R.

2016-04-01

We study various rotating and oscillating D-string configurations in some general backgrounds with fluxes. In particular, we look for solutions to the equations of motion of various rigidly rotating D-strings in AdS3 background with mixed flux, and in the intersecting D-brane geometries. We find out relations among various conserved charges corresponding to the breathing and rotating D-string configurations.
High-fiber foods

MedlinePlus

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Holographic duality: Stealing dimensions from metals

NASA Astrophysics Data System (ADS)

Zaanen, Jan

2013-10-01

Although electrically charged black holes seem remote from superconductors and strange metals in the laboratory, they might be intimately related by the holographic dualities discovered in string theory.
Second order perturbations of a macroscopic string: Covariant approach

NASA Astrophysics Data System (ADS)

Larsen, A. L.; Nicolaidis, A.

2001-06-01

Using a world-sheet covariant formalism, we derive the equations of motion for second order perturbations of a generic macroscopic string, thus generalizing previous results for first order perturbations. We give the explicit results for the first and second order perturbations of a contracting near-circular string; these results are relevant for the understanding of the possible outcome when a cosmic string contracts under its own tension, as discussed in a series of papers by Vilenkin and Garriga. In particular, second order perturbations are necessary for a consistent computation of the energy. We also quantize the perturbations and derive the mass formula up to second order in perturbations for an observer using world-sheet time τ. The high frequency modes give the standard Minkowski result while, interestingly enough, the Hamiltonian turns out to be nondiagonal in oscillators for low-frequency modes. Using an alternative definition of the vacuum, it is possible to diagonalize the Hamiltonian, and the standard string mass spectrum appears for all frequencies. We finally discuss how our results are also relevant for the problems concerning string-spreading near a black hole horizon, as originally discussed by Susskind.

Quantum criticality and black holes.

PubMed

Sachdev, Subir; Müller, Markus

2009-04-22

Many condensed matter experiments explore the finite temperature dynamics of systems near quantum critical points. Often, there are no well-defined quasiparticle excitations, and so quantum kinetic equations do not describe the transport properties completely. The theory shows that the transport coefficients are not proportional to a mean free scattering time (as is the case in the Boltzmann theory of quasiparticles), but are completely determined by the absolute temperature and by equilibrium thermodynamic observables. Recently, explicit solutions of this quantum critical dynamics have become possible via the anti-de Sitter/conformal field theory duality discovered in string theory. This shows that the quantum critical theory provides a holographic description of the quantum theory of black holes in a negatively curved anti-de Sitter space, and relates its transport coefficients to properties of the Hawking radiation from the black hole. We review how insights from this connection have led to new results for experimental systems: (i) the vicinity of the superfluid-insulator transition in the presence of an applied magnetic field, and its possible application to measurements of the Nernst effect in the cuprates, (ii) the magnetohydrodynamics of the plasma of Dirac electrons in graphene and the prediction of a hydrodynamic cyclotron resonance.
Gravitoelectromagnetic perturbations of Kerr-Newman black holes: stability and isospectrality in the slow-rotation limit.

PubMed

Pani, Paolo; Berti, Emanuele; Gualtieri, Leonardo

2013-06-14

The most general stationary black-hole solution of Einstein-Maxwell theory in vacuum is the Kerr-Newman metric, specified by three parameters: mass M, spin J, and charge Q. Within classical general relativity, one of the most important and challenging open problems in black-hole perturbation theory is the study of gravitational and electromagnetic fields in the Kerr-Newman geometry, because of the indissoluble coupling of the perturbation functions. Here we circumvent this long-standing problem by working in the slow-rotation limit. We compute the quasinormal modes up to linear order in J for any value of Q and provide the first, fully consistent stability analysis of the Kerr-Newman metric. For scalar perturbations the quasinormal modes can be computed exactly, and we demonstrate that the method is accurate within 3% for spins J/J(max) ≲ 0.5, where J(max) is the maximum allowed spin for any value of Q. Quite remarkably, we find numerical evidence that the axial and polar sectors of the gravitoelectromagnetic perturbations are isospectral to linear order in the spin. The extension of our results to nonasymptotically flat space-times could be useful in the context of gauge-gravity dualities and string theory.
Spontaneous symmetry breaking and phase coexistence in two-color networks

NASA Astrophysics Data System (ADS)

Avetisov, V.; Gorsky, A.; Nechaev, S.; Valba, O.

2016-01-01

We consider an equilibrium ensemble of large Erdős-Renyi topological random networks with fixed vertex degree and two types of vertices, black and white, prepared randomly with the bond connection probability p . The network energy is a sum of all unicolor triples (either black or white), weighted with chemical potential of triples μ . Minimizing the system energy, we see for some positive μ the formation of two predominantly unicolor clusters, linked by a string of Nb w black-white bonds. We have demonstrated that the system exhibits critical behavior manifested in the emergence of a wide plateau on the Nb w(μ ) curve, which is relevant to a spinodal decomposition in first-order phase transitions. In terms of a string theory, the plateau formation can be interpreted as an entanglement between baby universes in two-dimensional gravity. We conjecture that the observed classical phenomenon can be considered as a toy model for the chiral condensate formation in quantum chromodynamics.
Spontaneous symmetry breaking and phase coexistence in two-color networks.

PubMed

Avetisov, V; Gorsky, A; Nechaev, S; Valba, O

2016-01-01

We consider an equilibrium ensemble of large Erdős-Renyi topological random networks with fixed vertex degree and two types of vertices, black and white, prepared randomly with the bond connection probability p. The network energy is a sum of all unicolor triples (either black or white), weighted with chemical potential of triples μ. Minimizing the system energy, we see for some positive μ the formation of two predominantly unicolor clusters, linked by a string of N_{bw} black-white bonds. We have demonstrated that the system exhibits critical behavior manifested in the emergence of a wide plateau on the N_{bw}(μ) curve, which is relevant to a spinodal decomposition in first-order phase transitions. In terms of a string theory, the plateau formation can be interpreted as an entanglement between baby universes in two-dimensional gravity. We conjecture that the observed classical phenomenon can be considered as a toy model for the chiral condensate formation in quantum chromodynamics.
End Point of Black Ring Instabilities and the Weak Cosmic Censorship Conjecture.

PubMed

Figueras, Pau; Kunesch, Markus; Tunyasuvunakool, Saran

2016-02-19

We produce the first concrete evidence that violation of the weak cosmic censorship conjecture can occur in asymptotically flat spaces of five dimensions by numerically evolving perturbed black rings. For certain thin rings, we identify a new, elastic-type instability dominating the evolution, causing the system to settle to a spherical black hole. However, for sufficiently thin rings the Gregory-Laflamme mode is dominant, and the instability unfolds similarly to that of black strings, where the horizon develops a structure of bulges connected by necks which become ever thinner over time.
A class of exact classical solutions to string theory.

PubMed

Coley, A A

2002-12-31

We show that the recently obtained class of spacetimes for which all of the scalar curvature invariants vanish (which can be regarded as generalizations of pp-wave spacetimes) are exact solutions in string theory to all perturbative orders in the string tension scale. As a result the spectrum of the theory can be explicitly obtained, and these spacetimes are expected to provide some hints for the study of superstrings on more general backgrounds. Since these Lorentzian spacetimes suffer no quantum corrections to all loop orders they may also offer insights into quantum gravity.
On the motion of a quantum particle in the spinning cosmic string space–time

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hassanabadi, H., E-mail: h.hasanabadi@shahroodut.ac.ir; Afshardoost, A.; Zarrinkamar, S.

2015-05-15

We analyze the energy spectrum and the wave function of a particle subjected to magnetic field in the spinning cosmic string space–time and investigate the influence of the spinning reference frame and topological defect on the system. To do this we solve Schrödinger equation in the spinning cosmic string background. In our work, instead of using an approximation in the calculations, we use the quasi-exact ansatz approach which gives the exact solutions for some primary levels. - Highlights: • Solving the Schrödinger equation in the spinning cosmic string space time. • Proposing a quasi-exact analytical solution to the general formmore » of the corresponding equation. • Generalizing the previous works.« less
Exact solutions of bulk viscous with string cloud attached to strange quark matter for higher dimensional FRW universe in Lyra geometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Çağlar, Halife, E-mail: hlfcglr@gmail.com; Aygün, Sezgin, E-mail: saygun@comu.edu.tr

In this study, we have investigated bulk viscous with strange quark matter attached to the string cloud for higher dimensional Friedman-Robertson-Walker (FRW) universe in Lyra geometry. By using varying deceleration parameter and conservation equations we have solved Einstein Field Equations (EFE’s) and obtained generalized exact solutions for our model. Also we have found that string is not survived for bulk viscous with strange quark matter attached to the string cloud in framework higher dimensional FRW universe in Lyra geometry. This result agrees with Kiran and Reddy, Krori et al, Sahoo and Mishra and Mohanty et al. in four and fivemore » dimensions.« less
Moving heavy quarkonium entropy, effective string tension, and the QCD phase diagram

NASA Astrophysics Data System (ADS)

Chen, Xun; Feng, Sheng-Qin; Shi, Ya-Fei; Zhong, Yang

2018-03-01

The entropy and effective string tension of the moving heavy quark-antiquark pair in the strongly coupled plasmas are calculated by using a deformed an anti-de Sitter/Reissner-Nordström black hole metric. A sharp peak of the heavy-quarkonium entropy around the deconfinement transition can be realized in our model, which is consistent with the lattice QCD result. The effective string tension of the heavy quark-antiquark pair is related to the deconfinement phase transition. Thus, we investigate the deconfinement phase transition by analyzing the characteristics of the effective string tension with different temperatures, chemical potentials, and rapidities. It is found that the results of phase diagram calculated through effective string tension are in agreement with results calculated through a Polyakov loop. We argue that a moving system will reach the phase transition point at a lower temperature and chemical potential than a stationary system. It means that the lifetime of the moving quark-gluon plasma become longer than the static one.
Holographic Spherically Symmetric Metrics

NASA Astrophysics Data System (ADS)

Petri, Michael

The holographic principle (HP) conjectures, that the maximum number of degrees of freedom of any realistic physical system is proportional to the system's boundary area. The HP has its roots in the study of black holes. It has recently been applied to cosmological solutions. In this article we apply the HP to spherically symmetric static space-times. We find that any regular spherically symmetric object saturating the HP is subject to tight constraints on the (interior) metric, energy-density, temperature and entropy-density. Whenever gravity can be described by a metric theory, gravity is macroscopically scale invariant and the laws of thermodynamics hold locally and globally, the (interior) metric of a regular holographic object is uniquely determined up to a constant factor and the interior matter-state must follow well defined scaling relations. When the metric theory of gravity is general relativity, the interior matter has an overall string equation of state (EOS) and a unique total energy-density. Thus the holographic metric derived in this article can serve as simple interior 4D realization of Mathur's string fuzzball proposal. Some properties of the holographic metric and its possible experimental verification are discussed. The geodesics of the holographic metric describe an isotropically expanding (or contracting) universe with a nearly homogeneous matter-distribution within the local Hubble volume. Due to the overall string EOS the active gravitational mass-density is zero, resulting in a coasting expansion with Ht = 1, which is compatible with the recent GRB-data.
Singular gauge transformation and the Erler-Maccaferri solution in bosonic open string field theory

NASA Astrophysics Data System (ADS)

Miwa, Akitsugu; Sugita, Kazuhiro

2017-09-01

We study candidate multiple-brane solutions of bosonic open string field theory. They are constructed by performing a singular gauge transformation n times for the Erler-Maccaferri solution. We check the equation of motion in the strong sense, and find that it is satisfied only when we perform the gauge transformation once. We calculate the energy for that case and obtain a support that the solution is a multiple-brane solution. We also check the tachyon profile for a specific solution that we interpret as describing a D24-brane placed on a D25-brane.
'Black universe' epoch in string cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buchel, Alex; Perimeter Institute for Theoretical Physics, Waterloo, Ontario, N2J 2W9; Kofman, Lev

2008-10-15

String theory compactification involves manifolds with multiple warp factors. For cosmological applications, we often introduce a short, high-energy inflationary throat, and a long, low-energy standard model (SM) throat. It is assumed that at the end of inflation, the excited Kaluza-Klein modes from the inflationary throat tunnel to the SM throat and reheat standard model degrees of freedom, which are attached to probe brane(s). However, the huge hierarchy of energy scales can result in a highly dynamic transition of the throat geometry. We point out that in such a cosmological scenario the standard model throat (together with SM brane) will bemore » cloaked by a Schwarzschild horizon, produced by the Kaluza-Klein modes tunneling from the short throat. The black brane formation is dual to the first order chiral phase transition of the cascading gauge theory. We calculate the critical energy density corresponding the formation of the black hole (BH) horizon in the long throat. We discuss the duality between 'black universe' cosmology and an expanding universe driven by the hot gauge theory radiation. We address the new problem of the hierarchical multiple-throat scenarios: SM brane disappearance after the decay of the BH horizon.« less
At the end of a moving string

NASA Astrophysics Data System (ADS)

Hanna, James; Santangelo, Christian

2012-11-01

We address a basic problem in the dynamics of flexible bodies: the propagation of a shape along a string and its reflection at a free boundary. Although the string equations - inertia balancing stress in an inextensible curve - are quite old, the only exact solutions known for non-trivial geometries are traveling waves with spatially uniform stress. Suitable for closed ``lariats,'' these solutions are incompatible with a free end, where the stress must vanish. It is impossible to drag an open, flexible, curved string along its tangents. This is reflected in the unwrapping motion of a string or chain as it is pulled around an object, and has strong implications for slender structures in passive locomotion, whether industrial cables or the ribbons of rhythmic gymnastics. We consider planar dynamics restricted to time-independent, but spatially varying, stress. We find a new exact solution at a distance ~t4/3 from the free end; continuation to the end requires introduction of a secular error into the positions and velocities and a singularity in acceleration ~t-2/3 at the end, which appears to have a physical basis. This work is an early step towards understanding the dynamics of a wide class of industrial and natural thin-object systems.
BOOK REVIEW: String Theory in a Nutshell

NASA Astrophysics Data System (ADS)

Skenderis, Kostas

2007-11-01

The book 'String Theory in a Nutshell' by Elias Kiritsis provides a comprehensive introduction to modern string theory. String theory is the leading candidate for a theory that successfully unifies all fundamental forces of nature, including gravity. The subject has been continuously developing since the early 1970s, with classic textbooks on the subject being those of Green, Schwarz and Witten (1987) and Polchinski (1998). Since the latter was published there have been substantial developments, in particular in understanding black holes and gravity/gauge theory dualities. A textbook treatment of this important material is clearly needed, both by students and researchers in string theory and by mathematicians and physicists working in related fields. This book has a good selection of material, starting from basics and moving into classic and modern topics. In particular, Kiritsis' presentation of the basic material is complementary to that of the earlier textbooks and he includes a number of topics which are not easily found or covered adequately elsewhere, for example, loop corrections to string effective couplings. Overall the book nicely covers the major advances of the last ten years, including (non-perturbative) string dualities, black hole physics, AdS/CFT and matrix models. It provides a concise but fairly complete introduction to these subjects which can be used both by students and by researchers. Moreover the emphasis is on results that are reasonably established, as is appropriate for a textbook; concise summaries are given for subjects which are still in flux, with references to relevant reviews and papers. A positive feature of the book is that the bibliography sections at the end of each chapter provide a comprehensive guide to the literature. The bibliographies point to reviews and pedagogical papers on subjects covered in this book as well as those that were omitted. It is rare for a textbook to contain such a self-contained and detailed guide to the literature. In all, the book contains nearly five hundred exercises for the graduate-level student, which are useful both in teaching courses on string theory and for those who are studying by themselves. A nice feature of this book is that references are made to specific pages earlier in the book, rather than to chapters, which is helpful for students working through the book on their own. In summary,'String Theory in a Nutshell'is a valuable addition to the existing string theory textbooks; it is complementary to the previous books and gives a good treatment of subsequent developments. It is likely to become a staple reference on the subject, used both by students and researchers.
Integrable subsectors from holography

NASA Astrophysics Data System (ADS)

de Mello Koch, Robert; Kim, Minkyoo; Van Zyl, Hendrik J. R.

2018-05-01

We consider operators in N=4 super Yang-Mills theory dual to closed string states propagating on a class of LLM geometries. The LLM geometries we consider are specified by a boundary condition that is a set of black rings on the LLM plane. When projected to the LLM plane, the closed strings are polygons with all corners lying on the outer edge of a single ring. The large N limit of correlators of these operators receives contributions from non-planar diagrams even for the leading large N dynamics. Our interest in these fluctuations is because a previous weak coupling analysis argues that the net effect of summing the huge set of non-planar diagrams, is a simple rescaling of the 't Hooft coupling. We carry out some nontrivial checks of this proposal. Using the su(2|2)2 symmetry we determine the two magnon S-matrix and demonstrate that it agrees, up to two loops, with a weak coupling computation performed in the CFT. We also compute the first finite size corrections to both the magnon and the dyonic magnon by constructing solutions to the Nambu-Goto action that carry finite angular momentum. These finite size computations constitute a strong coupling confirmation of the proposal.
Aspects of some dualities in string theory

NASA Astrophysics Data System (ADS)

Kim, Bom Soo

AdS/CFT correspondence in string theory has changed landscape of the theoretical physics. Through this celebrated duality between gravity theory and field theory, one can investigate analytically strongly coupled gauge theories such as Quantum Chromodynamics (QCD) in terms of weakly coupled string theory such as supergravity theory and vice versa. In the first part of this thesis we used this duality to construct a new type of nonlocal field theory, called Puff Field Theory, in terms of D3 branes in type IIB string theory with a geometric twist. In addition to the strong-weak duality of AdS/CFT, there also exists a weak-weak duality, called Twistor String Theory. Twistor technique is successfully used to calculate the SYM scattering amplitude in an elegant fashion. Yet, the progress in the string theory side was hindered by a non-unitary conformal gravity. We extend the Twistor string theory by introducing mass terms, in the second part of the thesis. A chiral mass term is identified as a vacuum expectation value of a conformal supergravity field and is tied with the breaking of the conformal symmetry of gravity. As a prime candidate for a quantum theory of gravity, string theory revealed many promising successes such as counting the number of microstates in supersymmetric Black Holes thermodynamics and resolution of timelike and null singularities, to name a few. Yet, the fundamental string and M-theroy formulations are not yet available. Various string theories without gravity, such as Non-Commutative Open String (NCOS) and Open Membrane (OM) theories, are very nice playground to investigate the fundamental structure of string and M-theory without the complication of gravity. In the last part of the thesis, simpler Non-Relativistic String Theories are constructed and investigated. One important motivation for those theories is related to the connection between Non-Relativistic String Theories and Non-critical String Theories through the bosonization of betagamma CFT.
Black hole thermodynamics from Euclidean horizon constraints.

PubMed

Carlip, S

2007-07-13

To explain black hole thermodynamics in quantum gravity, one must introduce constraints to ensure that a black hole is actually present. I show that for a large class of black holes, such "horizon constraints" allow the use of conformal field theory techniques to compute the density of states, reproducing the Bekenstein-Hawking entropy in a nearly model-independent manner. One standard string theory approach to black hole entropy arises as a special case, lending support to the claim that the mechanism may be "universal." I argue that the relevant degrees of freedom are Goldstone-boson-like excitations arising from the weak breaking of symmetry by the constraints.
Finite-g Strings

NASA Astrophysics Data System (ADS)

Vicedo, Benoit

2008-10-01

In view of one day proving the AdS/CFT correspondence, a deeper understanding of string theory on certain curved backgrounds such as AdS_5xS^5 is required. In this dissertation we make a step in this direction by focusing on RxS^3. It was discovered in recent years that string theory on AdS_5xS^5 admits a Lax formulation. However, the complete statement of integrability requires not only the existence of a Lax formulation, but also that the resulting integrals of motion are in pairwise involution. This idea is central to the first part of this thesis. Exploiting this integrability we apply algebro-geometric methods to string theory on RxS^3 and obtain the general finite-gap solution. The construction is based on an invariant algebraic curve previously found in the AdS_5xS^5 case. However, encoding the dynamics of the solution requires specification of additional marked points. By restricting the symplectic structure of the string to this algebro-geometric data we derive the action-angle variables of the system. We then perform a first-principle semiclassical quantisation of string theory on RxS^3 as a toy model for strings on AdS_5xS^5. The result is exactly what one expects from the dual gauge theory perspective, namely the underlying algebraic curve discretises in a natural way. We also derive a general formula for the fluctuation energies around the generic finite-gap solution. The ideas used can be generalised to AdS_5xS^5.
Dark matter cosmic string in the gravitational field of a black hole

NASA Astrophysics Data System (ADS)

Nakonieczny, Łukasz; Nakonieczna, Anna; Rogatko, Marek

2018-03-01

We examined analytically and proposed a numerical model of an Abelian Higgs dark matter vortex in the spacetime of a stationary axisymmetric Kerr black hole. In analytical calculations the dark matter sector was modeled by an addition of a U(1)-gauge field coupled to the visible sector. The backreaction analysis revealed that the impact of the dark vortex presence is far more complicated than causing only a deficit angle. The vortex causes an ergosphere shift and the event horizon velocity is also influenced by its presence. These phenomena are more significant than in the case of a visible vortex sector. The area of the event horizon of a black hole is diminished and this decline is larger in comparison to the Kerr black hole with an Abelian Higgs vortex case. After analyzing the gravitational properties for the general setup, we focused on the subset of models that are motivated by particle physics. We retained the Abelian Higgs model as a description of the dark matter sector (this sector contained a heavy dark photon and an additional complex scalar) and added a real scalar representing the real component of the Higgs doublet in the unitary gauge, as well as an additional U(1)-gauge field representing an ordinary electromagnetic field. Moreover, we considered two coupling channels between the visible and dark sectors, which were the kinetic mixing between the gauge fields and a quartic coupling between the scalar fields. After solving the equations of motion for the matter fields numerically we analyzed properties of the cosmic string in the dark matter sector and its influence on the visible sector fields that are directly coupled to it. We found out that the presence of the cosmic string induced spatial variation in the vacuum expectation value of the Higgs field and a nonzero electromagnetic field around the black hole.
The string soundscape at gravitational wave detectors

NASA Astrophysics Data System (ADS)

Garcia Garcia, Isabel; Krippendorf, Sven; March-Russell, John

2018-04-01

We argue that gravitational wave signals due to collisions of ultra-relativistic bubble walls may be common in string theory. This occurs due to a process of post-inflationary vacuum decay via quantum tunnelling. Though we study a specific string construction involving warped throats, we argue that our conclusions are more general. Many such transitions could have occurred in the post-inflationary Universe, as a large number of throats with exponentially different mass scales can be present in the string landscape, leading to several signals of widely different frequencies - a soundscape connected to the landscape of vacua. Detectors such as aLIGO/VIRGO, LISA, and pulsar timing observations with SKA and EPTA have the sensitivity to detect such signals. A distribution of primordial black holes is also a likely consequence, though reliable estimates of masses and their abundance require dedicated numerical simulations, as do the fine details of the gravitational wave spectrum due to the unusual nature of the transition.

Propagating stress-pulses and wiggling transition revealed in string dynamics

NASA Astrophysics Data System (ADS)

Yao, Zhenwei

2018-02-01

Understanding string dynamics yields insights into the intricate dynamic behaviors of various filamentary thin structures in nature and industry covering multiple length scales. In this work, we investigate the planar dynamics of a flexible string where one end is free and the other end is subject to transverse and longitudinal motions. Under transverse harmonic motion, we reveal the propagating pulse structure in the stress profile over the string, and analyze its role in bringing the system into a chaotic state. For a string where one end is under longitudinal uniform acceleration, we identify the wiggling transition, derive the analytical wiggling solution from the string equations, and present the phase diagram.
Information as the Fifth Dimension of the Universe which Fundamental Particles (strings), Dark Matter/Energy and Space-time are Floating in it While they are Listening to its Whispering for Getting Order

NASA Astrophysics Data System (ADS)

Gholibeigian, Hassan; Gholibeigian, Ghasem; Amirshahkarami, Azim; Gholibeigian, Kazem

2017-01-01

Four animated sub-particles (sub-strings) as origin of the life and generator of momentum (vibration) of elementary particles (strings) are communicated for transferring information for processing and preparing fundamental particles for the next step. It means that information may be a ``dimension'' of the nature which fundamental particles, dark matter/energy and space-time are floating in it and listening to its whispering and getting quantum information packages about their conditions and laws. So, communication of information which began before the spark to B.B. (Convection Bang), may be a ``Fundamental symmetry'' in the nature because leads other symmetries and supersymmetry as well as other phenomena. The processed information are always carried by fundamental particles as the preserved history and entropy of Universe. So, information wouldn't be destroyed, lost or released by black hole. But the involved fundamental particles of thermal radiation, electromagnetic and gravitational fields carry processed information during emitting from black hole, while they are communicated from fifth dimension for their new movement. AmirKabir University of Technology, Tehran, Iran.
Pulsating strings with mixed three-form flux

NASA Astrophysics Data System (ADS)

Hernández, Rafael; Nieto, Juan Miguel; Ruiz, Roberto

2018-04-01

Circular strings pulsating in AdS 3 × S 3 × T 4 with mixed R-R and NS-NS three-form fluxes can be described by an integrable deformation of the one-dimensional Neumann-Rosochatius mechanical model. In this article we find a general class of pulsating solutions to this integrable system that can be expressed in terms of elliptic functions. In the limit of strings moving in AdS 3 with pure NS-NS three-form flux, where the action reduces to the SL(2, ℝ) WZW model, we find agreement with the analysis of the classical solutions of the system performed using spectral flow by Maldacena and Ooguri. We use our elliptic solutions in AdS 3 to extend the dispersion relation beyond the limit of pure NS-NS flux.
Holographic screening length in a hot plasma of two sphere

NASA Astrophysics Data System (ADS)

Atmaja, A. Nata; Kassim, H. Abu; Yusof, N.

2015-11-01

We study the screening length L_{max} of a moving quark-antiquark pair in a hot plasma, which lives in a two sphere, S^2, using the AdS/CFT correspondence in which the corresponding background metric is the four-dimensional Schwarzschild-AdS black hole. The geodesic of both ends of the string at the boundary, interpreted as the quark-antiquark pair, is given by a stationary motion in the equatorial plane by which the separation length L of both ends of the string is parallel to the angular velocity ω . The screening length and total energy H of the quark-antiquark pair are computed numerically and show that the plots are bounded from below by some functions related to the momentum transfer P_c of the drag force configuration. We compare the result by computing the screening length in the reference frame of the moving quark-antiquark pair, in which the background metrics are "Boost-AdS" and Kerr-AdS black holes. Comparing both black holes, we argue that the mass parameters M_{Sch} of the Schwarzschild-AdS black hole and M_{Kerr} of the Kerr-AdS black hole are related at high temperature by M_{Kerr}=M_{Sch}(1-a^2l^2)^{3/2}, where a is the angular momentum parameter and l is the AdS curvature.
Computer Corner: Computer Graphics for the Vibrating String.

ERIC Educational Resources Information Center

Smith, David A.; Cunningham, R. Stephen

1986-01-01

Computer graphics are used to display the sum of the first few terms of the series solution for the problem of the vibrating string frequently discussed in introductory courses on differential equations. (MNS)
Cosmic R-string, R-tube and vacuum instability

NASA Astrophysics Data System (ADS)

Eto, Minoru; Hamada, Yuta; Kamada, Kohei; Kobayashi, Tatsuo; Ohashi, Keisuke; Ookouchi, Yutaka

2013-03-01

We show that a cosmic string associated with spontaneous U(1) R symmetry breaking gives a constraint for supersymmetric model building. In some models, the string can be viewed as a tube-like domain wall with a winding number interpolating a false vacuum and a true vacuum. Such string causes inhomogeneous decay of the false vacuum to the true vacuum via rapid expansion of the radius of the tube and hence its formation would be inconsistent with the present Universe. However, we demonstrate that there exist metastable solutions which do not expand rapidly. Furthermore, when the true vacua are degenerate, the structure inside the tube becomes involved. As an example, we show a "bamboo"-like solution, which suggests a possibility observing an information of true vacua from outside of the tube through the shape and the tension of the tube.
Non-Abelian supertubes

NASA Astrophysics Data System (ADS)

Fernández-Melgarejo, José J.; Park, Minkyu; Shigemori, Masaki

2017-12-01

A supertube is a supersymmetric configuration in string theory which occurs when a pair of branes spontaneously polarizes and generates a new dipole charge extended along a closed curve. The dipole charge of a codimension-2 supertube is characterized by the U-duality monodromy as one goes around the supertube. For multiple codimension-2 supertubes, their monodromies do not commute in general. In this paper, we construct a supersymmetric solution of five-dimensional supergravity that describes two supertubes with such non-Abelian monodromies, in a certain perturbative expansion. In supergravity, the monodromies are realized as the multi-valuedness of the scalar fields, while in higher dimensions they correspond to non-geometric duality twists of the internal space. The supertubes in our solution carry NS5 and 5 2 2 dipole charges and exhibit the same monodromy structure as the SU(2) Seiberg-Witten geometry. The perturbative solution has AdS2 × S 2 asymptotics and vanishing four-dimensional angular momentum. We argue that this solution represents a microstate of four-dimensional black holes with a finite horizon and that it provides a clue for the gravity realization of a pure-Higgs branch state in the dual quiver quantum mechanics.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, I.Y.; Tirziu, A.; Tseytlin, A.A.

We consider circular strings rotating with equal spins S{sub 1}=S{sub 2}=S in two orthogonal planes in AdS{sub 5} and suggest that they may be dual to long gauge-theory operators built out of self-dual components of gauge field strength. As was found in hep-th/0404187, the one-loop anomalous dimensions of the such gauge-theory operators are described by an antiferromagnetic XXX{sub 1} spin chain and scale linearly with length L>>1. We find that in the case of rigid rotating string both the classical energy E{sub 0} and the 1-loop string correction E{sub 1} depend linearly on the spin S (within the stability regionmore » of the solution). This supports the identification of the rigid rotating string with the gauge-theory operator corresponding to the maximal-spin (ferromagnetic) state of the XXX{sub 1} spin chain. The energy of more general rotating and pulsating strings also happens to scale linearly with both the spin and the oscillation number. Such solutions should be dual to other lower-spin states of the spin chain, with the antiferromagnetic ground state presumably corresponding to the string pulsating in two planes with no rotation.« less
Bianchi type-II String Cosmological Model with Magnetic Field in Scale-Covariant Theory of Gravitation

NASA Astrophysics Data System (ADS)

Sharma, N. K.; Singh, J. K.

2014-12-01

The spatially homogeneous and totally anisotropic Bianchi type-II cosmological solutions of massive strings have been investigated in the presence of the magnetic field in the framework of scale-covariant theory of gravitation formulated by Canuto et al. (Phys. Rev. Lett. 39, 429, 1977). With the help of special law of variation for Hubble's parameter proposed by Berman (Nuovo Cimento 74, 182, 1983) string cosmological model is obtained in this theory. We use the power law relation between scalar field ϕ and scale factor R to find the solutions. Some physical and kinematical properties of the model are also discussed.
Dilatonic BTZ black holes with power-law field

NASA Astrophysics Data System (ADS)

Hendi, S. H.; Eslam Panah, B.; Panahiyan, S.; Sheykhi, A.

2017-04-01

Motivated by low energy effective action of string theory and numerous applications of BTZ black holes, we will consider minimal coupling between dilaton and nonlinear electromagnetic fields in three dimensions. The main goal is studying thermodynamical structure of black holes in this set up. Temperature and heat capacity of these black holes are investigated and a picture regarding their phase transitions is given. In addition, the role and importance of studying the mass of black holes is highlighted. We will see how different parameters modify thermodynamical quantities, hence thermodynamical structure of these black holes. In addition, geometrical thermodynamics is used to investigate thermodynamical properties of these black holes. In this regard, the successful method is presented and the nature of interaction around bound and phase transition points is studied.
New solutions with accelerated expansion in string theory

DOE PAGES

Dodelson, Matthew; Dong, Xi; Silverstein, Eva; ...

2014-12-05

We present concrete solutions with accelerated expansion in string theory, requiring a small, tractable list of stress energy sources. We explain how this construction (and others in progress) evades previous no go theorems for simple accelerating solutions. Our solutions respect an approximate scaling symmetry and realize discrete sequences of values for the equation of state, including one with an accumulation point at w = –1 and another accumulating near w = –1/3 from below. In another class of models, a density of defects generates scaling solutions with accelerated expansion. Here, we briefly discuss potential applications to dark energy phenomenology, andmore » to holography for cosmology.« less
QCD triple Pomeron coupling from string amplitudes

NASA Astrophysics Data System (ADS)

Bialas, A.; Navelet, H.; Peschanski, R.

1998-06-01

Using the recent solution of the triple Pomeron coupling in the QCD dipole picture as a closed string amplitude with six legs, its analytical form in terms of hypergeometric functions and numerical value are derived.
Analytical Solutions to Backreaction on Cosmic Strings

NASA Astrophysics Data System (ADS)

Wachter, Jeremy M.

2017-08-01

We present analytical studies of gravitational and electromagnetic backreaction on cosmic strings. For oscillating loops of cosmic string, we present a general argument for how kinks must change; additionally, we apply this general argument to the geometrically simple case of the Garfinkle-Vachaspati loop. Our results suggest that the formation of cusps on loops is delayed, and so we should expect fewer cuspy signatures to be seen in gravitational wave observations. Electromagnetic backreaction we show to reduce currents on a string at least as rapidly as necessary to avoid a paradox, and currents induced on a superconducting straight string will be asymptotically reduced to zero.
Emission of fermions in little string theory

NASA Astrophysics Data System (ADS)

Lorente-Espín, Oscar

2013-03-01

It is well known that little string theory (LST) black holes radiate a purely thermal spectrum of scalar particles. This theory lives in a Hagedorn phase with a fixed Hagedorn temperature that does not depend on its mass. Therefore, the theory keeps a thermal profile even taking into account self-gravitating effects and the backreaction of the metric. This has implications concerning the information loss paradox; one would not be able to recover any information from the LST black hole since the emission of scalar particles is totally uncorrelated. Several studies of the emission spectrum in LST concern scalar fields; it is our aim in this work to extend the study to the emission of fermions in order to verify that the most relevant conclusion for the scalar field remains valid for the fermion fields. Thus, we have calculated the emission probability, the flux, and also the greybody factor corresponding to a fermion field in LST background.
Development of inquiry behavior in concept identification.

PubMed

Vassilopoulos, C A; Dickerson, D J

1992-08-01

We studied inquiry behavior in concept identification in first-, fifth-, eighth-grade, and college students with problems involving eight four-letter strings. The task was to identify the correct string by asking questions related to either one letter or four letters that were answered by yes or no. Processing demands were manipulated by comparing (a) a condition in which letter strings were removed from view as feedback eliminated them as possible solutions with a condition in which strings remained in view and (b) problems that were structured so that relevant letter categories were easy to identify with problems that were not. Problem solving generally improved with age. First graders tended to ask questions that eliminated solutions one by one, whereas the older groups asked more informative questions. At the three upper grade levels, strategies for selecting queries were adapted to situations, with less demanding strategies being used when processing demands were higher.
Isometry group orbit quantization of spinning strings in AdS3 × S3

NASA Astrophysics Data System (ADS)

Heinze, Martin; Jorjadze, George; Megrelidze, Luka

2015-03-01

Describing the bosonic AdS3 × S3 particle and string in SU(1,1) × SU(2) group variables, we provide a Hamiltonian treatment of the isometry group orbits of solutions via analysis of the pre-symplectic form. For the particle we obtain a one-parameter family of orbits parameterized by creation-annihilation variables, which leads to the Holstein-Primakoff realization of the isometry group generators. The scheme is then applied to spinning string solutions characterized by one winding number in AdS3 and two winding numbers in S3. We find a two-parameter family of orbits, where quantization again provides the Holstein-Primakoff realization of the symmetry generators with an oscillator-type energy spectrum. Analyzing the minimal energy at strong coupling, we verify the spectrum of short strings at special values of winding numbers.
Exact closed-form solution of the hyperbolic equation of string vibrations with material relaxation properties taken into account

NASA Astrophysics Data System (ADS)

Kudinov, I. V.; Kudinov, V. A.

2014-09-01

The differential equation of damped string vibrations was obtained with the finite speed of extension and strain propagation in the Hooke's law formula taken into account. In contrast to the well-known equations, the obtained equation contains the first and third time derivatives of the displacement and the mixed derivative with respect to the space and time variables. Separation of variables was used to obtain its exact closed-form solution, whose analysis showed that, for large values of the relaxation coefficient, the string return to the initial state after its escape from equilibrium is accompanied by high-frequency low-amplitude damped vibrations, which occur on the initial time interval only in the region of positive displacements. And in the limit, for some large values of the relaxation coefficient, the string return to the initial state occurs practically without any oscillatory process.
Existence of topological multi-string solutions in Abelian gauge field theories

NASA Astrophysics Data System (ADS)

Han, Jongmin; Sohn, Juhee

2017-11-01

In this paper, we consider a general form of self-dual equations arising from Abelian gauge field theories coupled with the Einstein equations. By applying the super/subsolution method, we prove that topological multi-string solutions exist for any coupling constant, which improves previously known results. We provide two examples for application: the self-dual Einstein-Maxwell-Higgs model and the gravitational Maxwell gauged O(3) sigma model.
Evolution of perturbations of squashed Kaluza-Klein black holes: Escape from instability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ishihara, Hideki; Kimura, Masashi; Konoplya, Roman A.

2008-04-15

The squashed Kaluza-Klien (KK) black holes differ from the Schwarzschild black holes with asymptotic flatness or the black strings even at energies for which the KK modes are not excited yet, so that squashed KK black holes open a window in higher dimensions. Another important feature is that the squashed KK black holes are apparently stable and, thereby, let us avoid the Gregory-Laflamme instability. In the present paper, the evolution of scalar and gravitational perturbations in time and frequency domains is considered for these squashed KK black holes. The scalar field perturbations are analyzed for general rotating squashed KK blackmore » holes. Gravitational perturbations for the so-called zero mode are shown to be decayed for nonrotating black holes, in concordance with the stability of the squashed KK black holes. The correlation of quasinormal frequencies with the size of extra dimension is discussed.« less
Bethe Ansatz solutions for highest states in Script N = 4 SYM and AdS/CFT duality

NASA Astrophysics Data System (ADS)

Beccaria, Matteo; DelDebbio, Luigi

2006-09-01

We consider the operators with highest anomalous dimension Δ in the compact rank-one sectors fraktur sfraktur u(1|1) and fraktur sfraktur u(2) of Script N = 4 super Yang-Mills. We study the flow of Δ from weak to strong 't Hooft coupling λ by solving (i) the all-loop gauge Bethe Ansatz, (ii) the quantum string Bethe Ansatz. The two calculations are carefully compared in the strong coupling limit and exhibit different exponents ν in the leading order expansion Δ ~ λν. We find ν = 1/2 and ν = 1/4 for the gauge or string solution. This strong coupling discrepancy is not unexpected, and it provides an explicit example where the gauge Bethe Ansatz solution cannot be trusted at large λ. Instead, the string solution perfectly reproduces the Gubser-Klebanov-Polyakov law Δ = 2n1/2 λ1/4. In particular, we provide an analytic expression for the integer level n as a function of the U(1) charge in both sectors.

Giant magnons and spiky strings in the Schrödinger/dipole-deformed CFT correspondence

NASA Astrophysics Data System (ADS)

Georgiou, George; Zoakos, Dimitrios

2018-02-01

We construct semi-classical string solutions of the Schrödinger Sch 5 × S 5 spacetime, which is conjectured to be the gravity dual of a non-local dipole-deformed CFT. They are the counterparts of the giant magnon and spiky string solutions of the undeformed AdS 5 × S 5 to which they flow when the deformation parameter is turned off. They live in an S 3 subspace of the five-sphere along the directions of which the B-field has non-zero components, having also extent in the Sch 5 part of the metric. Finally, we speculate on the form of the dual field theory operators.
Rotating black holes in higher dimensions with a cosmological constant.

PubMed

Gibbons, G W; Lü, H; Page, Don N; Pope, C N

2004-10-22

We present the metric for a rotating black hole with a cosmological constant and with arbitrary angular momenta in all higher dimensions. The metric is given in both Kerr-Schild and the Boyer-Lindquist form. In the Euclidean-signature case, we also obtain smooth compact Einstein spaces on associated S(D-2) bundles over S2, infinitely many for each odd D>/=5. Applications to string theory and M-theory are indicated.
On the emergence of classical gravity

NASA Astrophysics Data System (ADS)

Larjo, Klaus

In this thesis I will discuss how certain black holes arise as an effective, thermodynamical description from non-singular microstates in string theory. This provides a possible solution to the information paradox, and strengthens the case for treating black holes as thermodynamical objects. I will characterize the data defining a microstate of a black hole in several settings, and demonstrate that most of the data is unmeasurable for a classical observer. I will further show that the data that is measurable is universal for nearly all microstates, making it impossible for a classical observer to distinguish between microstates, thus giving rise to an effective statistical description for the black hole. In the first half of the thesis I will work with two specific systems: the half-BPS sector of [Special characters omitted.] = 4 super Yang-Mills the and the conformal field theory corresponding to the D1/D5 system; in both cases the high degree of symmetry present provides great control over potentially intractable computations. For these systems, I will further specify the conditions a quantum mechanical microstate must satisfy in order to have a classical description in terms of a unique metric, and define a 'metric operator' whose eigenstates correspond to classical geometries. In the second half of the thesis I will consider a much broader setting, general [Special characters omitted.] = I superconformal quiver gauge the= ories and their dual gravity theories, and demonstrate that a similar effective description arises also in this setting.
Teaching: the Wave Mechanics of McLeods' Stringy Electron, Explicit Nucleons, and Through-the-Earth Projections of Constellations' Stick Figures

NASA Astrophysics Data System (ADS)

McLeod, Roger David; McLeod, David Matthew

2012-02-01

This shows how Hooke's law, for electron, proton and neutron, 2D and 3D, strings, builds electromagnetic string-waves, extending, and pleasing, Schr"odinger. These are composed of spirally linked, parallel, north-pole oriented, neutrino and antineutrino strings, stable by magnetic repulsions. Their Dumbo Proton is antineutrino-scissor cut, and compressed in the vicinity of a neutron star, where electrostatic marriage occurs with a neutrino-scissor cut, and compressed, electron, so a Mickey Neutron emerges. Strings predict: electron charge is - 1/3 e, Dumbo P is 25 % longer than Mickey N, and Hooke says relaxing springs fuel three, separate, non-eternal, inflations, after Big Bangs. Gravity is strings, longitudinally linked. Einstein says Herman Grid's black diagonals prove human vision reads its information from algebraically-signed electromagnetic field distributions, (diffraction) patterns, easily known by ray-tracing, not requiring difficult Spatial Fourier Transformation. High-schoolers understand its application to Wave Mechanics, agreeing that positive-numbered probabilities do not enter, to possibly displease God. Detected stick-figure forms of constellations: like Phoenix, Leo, Canis Major, and especially Orion, fool some observers into false beliefs in things like UFHumanoids, or Kokopelli, Pele and Pamola!
Toward holographic reconstruction of bulk geometry from lattice simulations

NASA Astrophysics Data System (ADS)

Rinaldi, Enrico; Berkowitz, Evan; Hanada, Masanori; Maltz, Jonathan; Vranas, Pavlos

2018-02-01

A black hole described in SU( N ) gauge theory consists of N D-branes. By separating one of the D-branes from others and studying the interaction between them, the black hole geometry can be probed. In order to obtain quantitative results, we employ the lattice Monte Carlo simulation. As a proof of the concept, we perform an explicit calculation in the matrix model dual to the black zero-brane in type IIA string theory. We demonstrate this method actually works in the high temperature region, where the stringy correction is large. We argue possible dual gravity interpretations.
Searches for Kaluza-Klein graviton excitations and microscopic black holes with the aid of the CMS detector at the LHC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Savina, M. V., E-mail: savina@cern.ch

2015-06-15

A survey of the results of the Compact Muon Solenoid (CMS) experiment that concern searches for massive Kaluza-Klein graviton excitations and microscopic black holes, quantum black holes, and string balls within models of low-energy multidimensional gravity is presented on behalf of the CMS Collaboration. The analysis in question is performed on the basis of a complete sample of data accumulated for proton-proton collisions at the c.m. energies of 7 and 8 TeV at the Large Hadron Collider (LHC) over the period spanning 2010 and 2012.
Toward holographic reconstruction of bulk geometry from lattice simulations

DOE PAGES

Rinaldi, Enrico; Berkowitz, Evan; Hanada, Masanori; ...

2018-02-07

A black hole described in SU(N ) gauge theory consists of N D-branes. By separating one of the D-branes from others and studying the interaction between them, the black hole geometry can be probed. In order to obtain quantitative results, we employ the lattice Monte Carlo simulation. As a proof of the concept, we perform an explicit calculation in the matrix model dual to the black zero-brane in type IIA string theory. We demonstrate this method actually works in the high temperature region, where the stringy correction is large. We argue possible dual gravity interpretations.
Interaction of solitons with a string of coupled quantum dots

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Vijendra, E-mail: vsmedphysics@gmail.com; Swami, O. P., E-mail: omg1789@gmail.com; Nagar, A. K., E-mail: ajaya.nagar@gmail.com

2016-05-06

In this paper, we develop a theory for discrete solitons interaction with a string of coupled quantum dots in view of the local field effects. Discrete nonlinear Schrodinger (DNLS) equations are used to describe the dynamics of the string. Numerical calculations are carried out and results are analyzed with the help of matlab software. With the help of numerical solutions we demonstrate that in the quantum dots string, Rabi oscillations (RO) are self trapped into stable bright Rabi solitons. The Rabi oscillations in different types of nanostructures have potential applications to the elements of quantum logic and quantum memory.
A hybrid metaheuristic for closest string problem.

PubMed

Mousavi, Sayyed Rasoul

2011-01-01

The Closest String Problem (CSP) is an optimisation problem, which is to obtain a string with the minimum distance from a number of given strings. In this paper, a new metaheuristic algorithm is investigated for the problem, whose main feature is relatively high speed in obtaining good solutions, which is essential when the input size is large. The proposed algorithm is compared with four recent algorithms suggested for the problem, outperforming them in more than 98% of the cases. It is also remarkably faster than all of them, running within 1 s in most of the experimental cases.
Local structure of Rb{sub 2}Li{sub 4}(SeO{sub 4}){sub 3}{center_dot}2H{sub 2}O by the modeling of X-ray diffuse scattering - from average-structure to microdomain model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Komornicka, Dorota; Wolcyrz, Marek, E-mail: m.wolcyrz@int.pan.wroc.pl; Pietraszko, Adam

2012-08-15

Local structure of dirubidium tetralithium tris(selenate(VI)) dihydrate - Rb{sub 2}Li{sub 4}(SeO{sub 4}){sub 3}{center_dot} 2H{sub 2}O has been determined basing on the modeling of X-ray diffuse scattering. The origin of observed structured diffuse streaks is SeO{sub 4} tetrahedra switching between two alternative positions in two quasi-planar layers existing in each unit cell and formation of domains with specific SeO{sub 4} tetrahedra configuration locally fulfilling condition for C-centering in the 2a Multiplication-Sign 2b Multiplication-Sign c superstructure cell. The local structure solution is characterized by a uniform distribution of rather large domains (ca. thousand of unit cells) in two layers, but also monodomainsmore » can be taken into account. Inside a single domain SeO{sub 4} tetrahedra are ordered along ab-diagonal forming two-string ribbons. Inside the ribbons SeO{sub 4} and LiO{sub 4} tetrahedra share the oxygen corners, whereas ribbons are bound to each other by a net of hydrogen bonds and fastened by corner sharing SeO{sub 4} tetrahedra of the neighboring layers. - Graphical abstract: Experimental sections of the reciprocal space showing diffraction effects observed for RLSO. Bragg spots are visible on sections with integer indices (1 kl section - on the left), streaks - on sections with fractional ones (1.5 kl section - on the right). At the center: resulting local structure of the A package modeled as a microdomain: two-string ribbons of ordered oxygen-corners-sharing SeO{sub 4} and LiO{sub 4} terahedra extended along ab-diagonal are seen; ribbons are bound by hydrogen bonds (shown in pink); the multiplied 2a Multiplication-Sign 2b unit cell is shown. Highlights: Black-Right-Pointing-Pointer X-ray diffuse scattering in RLSO was registered and modeled. Black-Right-Pointing-Pointer The origin of diffuse streaks is SeO{sub 4} tetrahedra switching in two structure layers. Black-Right-Pointing-Pointer The local structure is characterized by a uniform distribution of microdomains. Black-Right-Pointing-Pointer Inside a single domain SeO{sub 4} tetrahedra are ordered along ab-diagonal forming ribbons. Black-Right-Pointing-Pointer The ribbons are bound to each other by a net of hydrogen bonds.« less
Topological defects in open string field theory

NASA Astrophysics Data System (ADS)

Kojita, Toshiko; Maccaferri, Carlo; Masuda, Toru; Schnabl, Martin

2018-04-01

We show how conformal field theory topological defects can relate solutions of open string field theory for different boundary conditions. To this end we generalize the results of Graham and Watts to include the action of defects on boundary condition changing fields. Special care is devoted to the general case when nontrivial multiplicities arise upon defect action. Surprisingly the fusion algebra of defects is realized on open string fields only up to a (star algebra) isomorphism.
Termination of String Rewriting Rules that have One Pair of Overlaps

NASA Technical Reports Server (NTRS)

Geser, Alfons; Bushnell, Dennis M. (Technical Monitor)

2002-01-01

This paper presents a partial solution to the long standing open problem of termination of one-rule string rewriting. Overlaps between the two sides of the rule play a central role in existing termination criteria. We characterize termination of all one-rule string rewriting systems that have one such overlap at either end. This both completes a result of Kurth and generalizes a result of Shikishima-Tsuji et al.
Pitch glide effect induced by a nonlinear string-barrier interaction

NASA Astrophysics Data System (ADS)

Kartofelev, Dmitri; Stulov, Anatoli; Välimäki, Vesa

2015-10-01

Interactions of a vibrating string with its supports and other spatially distributed barriers play a significant role in the physics of many stringed musical instruments. It is well known that the tone of the string vibrations is determined by the string supports, and that the boundary conditions of the string termination may cause a short-lasting initial fundamental frequency shifting. Generally, this phenomenon is associated with the nonlinear modulation of the stiff string tension. The aim of this paper is to study the initial frequency glide phenomenon that is induced only by the string-barrier interaction, apart from other possible physical causes, and without the interfering effects of dissipation and dispersion. From a numerical simulation perspective, this highly nonlinear problem may present various difficulties, not the least of which is the risk of numerical instability. We propose a numerically stable and a purely kinematic model of the string-barrier interaction, which is based on the travelling wave solution of the ideal string vibration. The model is capable of reproducing the motion of the vibrating string exhibiting the initial fundamental frequency glide, which is caused solely by the complex nonlinear interaction of the string with its termination. The results presented in this paper can expand our knowledge and understanding of the timbre evolution and the physical principles of sound generation of numerous stringed instruments, such as lutes called the tambura, sitar and biwa.
String duality transformations in f(R) gravity from Noether symmetry approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Capozziello, Salvatore; Gionti, Gabriele S.J.; Vernieri, Daniele, E-mail: capozziello@na.inf.it, E-mail: ggionti@as.arizona.edu, E-mail: vernieri@iap.fr

2016-01-01

We select f(R) gravity models that undergo scale factor duality transformations. As a starting point, we consider the tree-level effective gravitational action of bosonic String Theory coupled with the dilaton field. This theory inherits the Busher's duality of its parent String Theory. Using conformal transformations of the metric tensor, it is possible to map the tree-level dilaton-graviton string effective action into f(R) gravity, relating the dilaton field to the Ricci scalar curvature. Furthermore, the duality can be framed under the standard of Noether symmetries and exact cosmological solutions are derived. Using suitable changes of variables, the string-based f(R) Lagrangians aremore » shown in cases where the duality transformation becomes a parity inversion.« less
Excited cosmic strings with superconducting currents

NASA Astrophysics Data System (ADS)

Hartmann, Betti; Michel, Florent; Peter, Patrick

2017-12-01

We present a detailed analysis of excited cosmic string solutions that possess superconducting currents. These currents can be excited inside the string core, and—if the condensate is large enough—can lead to the excitations of the Higgs field. Next to the case with global unbroken symmetry, we discuss also the effects of the gauging of this symmetry and show that excited condensates persist when coupled to an electromagnetic field. The space-time of such strings is also constructed by solving the Einstein equations numerically and we show how the local scalar curvature is modified by the excitation. We consider the relevance of our results on the cosmic string network evolution as well as observations of primordial gravitational waves and cosmic rays.
Cosmology of the closed string tachyon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swanson, Ian

2008-09-15

The spacetime physics of bulk closed string tachyon condensation is studied at the level of a two-derivative effective action. We derive the unique perturbative tachyon potential consistent with a full class of linearized tachyonic deformations of supercritical string theory. The solutions of interest deform a general linear dilaton background by the insertion of purely exponential tachyon vertex operators. In spacetime, the evolution of the tachyon drives an accelerated contraction of the universe and, absent higher-order corrections, the theory collapses to a cosmological singularity in finite time, at arbitrarily weak string coupling. When the tachyon exhibits a null symmetry, the worldsheetmore » dynamics is known to be exact and well defined at tree level. We prove that if the two-derivative effective action is free of nongravitational singularities, higher-order corrections always resolve the spacetime curvature singularity of the null tachyon. The resulting theory provides an explicit mechanism by which tachyon condensation can generate or terminate the flow of cosmological time in string theory. Additional particular solutions can resolve an initial singularity with a tachyonic phase at weak coupling, or yield solitonic configurations that localize the universe along spatial directions.« less
Deformed D1D5 CFT: A Holographic Probe of Quantum Gravity

NASA Astrophysics Data System (ADS)

Jardine, Ian Theodore

One of the big unsolved questions in gravity research is the black hole information problem. This problem, which pits the unitarity of quantum field theory against smooth classical spacetime, must have a solution in a complete theory of quantum gravity. This thesis will explore aspects of one approach to this problem in the context of string theory. The approach imagines black hole microstates as string theoretic objects. We look at a prototype system, the D1D5 system, and exploit holography to examine the dual conformal field theory (CFT). Specifically, we examine the CFT deformed from the free orbifold point, dual to a very stringy bulk, using a twisted operator that will take us towards the point with the supergravity description. The effects of twisted operators in the CFT are key to understanding physical processes such as emission and thermalization in black hole microstates. We will propose a component twist method for examining the effects of bare twist operators for higher twists in the continuum limit. Our method builds higher twists from simple 2-cycle twists, whose effects are known. We will find that, in this limit, the coefficients describing general states will follow a conjectured general functional form. We then explore the deformed CFT directly by examining operator mixing for untwisted operators. We will exploit the operator product expansion on the covering space, where twist operators of the orbifold are resolved. We use this to examine the mixing of a general supergravity operator, specifically examine the dilaton, and finish with the mixing of a non-supersymmetric candidate operator. We conjecture that this method could be extended to include twisted operators. We will also examine the mixing of the non-supersymmetric candidate operator by examining three point functions. To automate the lengthy and repetitive computations, we wrote a Mathematica package to compute correlation functions and OPEs in the D1D5 CFT. We will explain some of the main functions of this package and how it can be applied to computations. Finally, we will end with a short discussion on future directions.
Comments on new multiple-brane solutions based on Hata-Kojita duality in open string field theory

NASA Astrophysics Data System (ADS)

Masuda, Toru

2014-05-01

Recently, Hata and Kojita proposed a new energy formula for a class of solutions in Witten's open string field theory based on a novel symmetry of correlation functions they found. Their energy formula can be regarded as a generalization of the conventional energy formula by Murata and Schnabl. Following their proposal, we investigate their new ansatz for the classical solution representing double D-branes. We present a regularized definition of this solution and show that the solution satisfies the equation of motion when it is contracted with the solution itself and when it is contracted with any states in the Fock space. However, the Ellwood invariant and the boundary state of the solution are the same as those for the perturbative vacuum. This result disagrees with an expectation from the Ellwood conjecture.
Quantum gravity inde Sitter space and anti-de Sitter space

NASA Astrophysics Data System (ADS)

Lippert, Matthew S.

In this thesis, we consider two aspects of quantum gravity---the nature of holography in anti-de Sitter space and string theory models of de Sitter space. Searching for a holographic resolution of the black hole information paradox, we pursue the identity of precursors in the context of AdS/CFT. We consider precursors that encode bulk information causally disconnected from the boundary and whose measurement involves nonlocal bulk processes. Previous arguments that these precursors are large, undecorated Wilson loops are found to be flawed. We construct a toy model of holography which encapsulates the expected properties of precursors and compare it with previous such discussions. The information contained in precursors is argued to be encoded in the high-energy sector of the theory and not observable by low-energy measurements. These considerations lead us to propose a locality bound, which indicates where locality breaks down due to black hole or stringy effects. We apply the locality bound to Hawking's argument for information loss in black hole evaporation. We argue that independence of internal and external Hilbert spaces cannot be established without incorporating strong gravitational effects that undermine locality and invalidate the use of quantum field theory in a semiclassical background geometry. We then turn to the investigation of the landscape of string theory vacua, and investigate a recently constructed de Sitter compactification of IIB string theory, which was shown to be metastable in agreement with general arguments about de Sitter spacetimes in quantum gravity. We describe how discrete flux choices lead to a closely-spaced set of vacua and explore various decay channels. We find that in many situations NS5-brane meditated decays which exchange NSNS 3-form flux for D3-branes are comparatively extremely fast.
Logarithmic corrections to black hole entropy: the non-BPS branch

NASA Astrophysics Data System (ADS)

Castro, Alejandra; Godet, Victor; Larsen, Finn; Zeng, Yangwenxiao

2018-05-01

We compute the leading logarithmic correction to black hole entropy on the non-BPS branch of 4D N≥2 supergravity theories. This branch corresponds to finite temperature black holes whose extremal limit does not preserve supersymmetry, such as the D0 - D6 system in string theory. Starting from a black hole in minimal Kaluza-Klein theory, we discuss in detail its embedding into N=8 , 6, 4, 2 supergravity, its spectrum of quadratic fluctuations in all these environments, and the resulting quantum corrections. We find that the c-anomaly vanishes only when N≥6 , in contrast to the BPS branch where c vanishes for all N≥2 . We briefly discuss potential repercussions this feature could have in a microscopic description of these black holes.

Purely cubic action for string field theory

NASA Technical Reports Server (NTRS)

Horowitz, G. T.; Lykken, J.; Rohm, R.; Strominger, A.

1986-01-01

It is shown that Witten's (1986) open-bosonic-string field-theory action and a closed-string analog can be written as a purely cubic interaction term. The conventional form of the action arises by expansion around particular solutions of the classical equations of motion. The explicit background dependence of the conventional action via the Becchi-Rouet-Stora-Tyutin operator is eliminated in the cubic formulation. A closed-form expression is found for the full nonlinear gauge-transformation law.
Segmented strings and the McMillan map

DOE PAGES

Gubser, Steven S.; Parikh, Sarthak; Witaszczyk, Przemek

2016-07-25

We present new exact solutions describing motions of closed segmented strings in AdS 3 in terms of elliptic functions. The existence of analytic expressions is due to the integrability of the classical equations of motion, which in our examples reduce to instances of the McMillan map. Here, we also obtain a discrete evolution rule for the motion in AdS 3 of arbitrary bound states of fundamental strings and D1-branes in the test approximation.
Self-gravitating strings in 2+1 dimensions

NASA Astrophysics Data System (ADS)

Ben-Menahem, Shahar

1993-05-01

We present a family of classical spacetimes in 2+1 dimensions. Such a spacetime is produced by a Nambu-Goto self-gravitating string. Because of the special properties of three-dimensional gravity, the metric is completely described as a Minkowski space with two identified world sheets. In the flat limit, the standard string is recovered. The formalism is developed for an open string with massive end points, but applies to other boundary conditions as well. We consider another limit, where the string tension vanishes in geometrical units but the end masses produce finite deficit angles. In this limit, our open string reduces to the free-masses solution of Gott, which possesses closed timelike curves when the relative motion of the two masses is sufficiently rapid. It is shown that the induced world sheet Liouville mode obeys (-classically)- a sinh- or cosh-Gordon differential equation, which reduces to the Liouville equation in the flat limit. A quadratic-action formulation of this system is presented. The possibility and significance of quantizing the self-gravitating string is discussed.
BRST-BFV analysis of anomalies in bosonic string theory interacting with background gravitational field

NASA Astrophysics Data System (ADS)

Buchbinder, I. L.; Mistchuk, B. R.; Pershin, V. D.

1995-02-01

A general BRST-BFV analysis of the anomaly in string theory coupled to background fields is carried out. An exact equation for the c-valued symbol of the anomaly operator is found and the structure of its solution is studied.
The effect of gas and fluid flows on nonlinear lateral vibrations of rotating drill strings

NASA Astrophysics Data System (ADS)

Khajiyeva, Lelya; Kudaibergenov, Askar; Kudaibergenov, Askat

2018-06-01

In this work we develop nonlinear mathematical models describing coupled lateral vibrations of a rotating drill string under the effect of external supersonic gas and internal fluid flows. An axial compressive load and a torque also affect the drill string. The mathematical models are derived by the use of Novozhilov's nonlinear theory of elasticity with implementation of Hamilton's variation principle. Expressions for the gas flow pressure are determined according to the piston theory. The fluid flow is considered as added mass inside the curved tube of the drill string. Using an algorithm developed in the Mathematica computation program on the basis of the Galerkin approach and the stiffness switching method the numerical solution of the obtained approximate differential equations is found. Influences of the external loads, drill string angular speed of rotation, parameters of the gas and fluid flows on the drill string vibrations are shown.
Pearling Instabilities of a Viscoelastic Thread

NASA Astrophysics Data System (ADS)

Deblais, A.; Velikov, K. P.; Bonn, D.

2018-05-01

Pearling instabilities of slender viscoelastic threads have received much attention, but remain incompletely understood. We study the instabilities in polymer solutions subject to uniaxial elongational flow. Two distinctly different instabilites are observed: beads on a string and blistering. The beads-on-a-string structure arises from a capillary instability whereas the blistering instability has a different origin: it is due to a coupling between stress and polymer concentration. By varying the temperature to change the solution properties we elucidate the interplay between flow and phase separation.
PREFACE: Lectures from the CERN Winter School on Strings, Supergravity and Gauge Theories, CERN, 9-13 February 2009 Lectures from the CERN Winter School on Strings, Supergravity and Gauge Theories, CERN, 9-13 February 2009

NASA Astrophysics Data System (ADS)

Uranga, A. M.

2009-11-01

This special section is devoted to the proceedings of the conference `Winter School on Strings, Supergravity and Gauge Theories', which took place at CERN, the European Centre for Nuclear Research, in Geneva, Switzerland 9-13 February 2009. This event is part of a yearly series of scientific schools, which represents a well established tradition. Previous events have been held at SISSA, in Trieste, Italy, in February 2005 and at CERN in January 2006, January 2007 and January 2008, and were funded by the European Mobility Research and Training Network `Constituents, Fundamental Forces and Symmetries of the Universe'. The next event will take place again at CERN, in January 2010. The school was primarily meant for young doctoral students and postdoctoral researchers working in the area of string theory. It consisted of several general lectures of four hours each, whose notes are published in this special section, and six working group discussion sessions, focused on specific topics of the network research program. It was well attended by over 200 participants. The topics of the lectures were chosen to provide an introduction to some of the areas of recent progress, and to the open problems, in string theory. One of the most active areas in string theory in recent years has been the AdS/CFT or gauge/gravity correspondence, which proposes the complete equivalence of string theory on (asymptotically) anti de Sitter spacetimes with certain quantum (gauge) field theories. The duality has recently been applied to understanding the hydrodynamical properties of a hot plasma in gauge theories (like the quark-gluon plasma created in heavy ion collisions at the RHIC experiment at Brookhaven, and soon at the LHC at CERN) in terms of a dual gravitational AdS theory in the presence of a black hole. These developments were reviewed in the lecture notes by M Rangamani. In addition, the AdS/CFT duality has been proposed as a tool to study interesting physical properties in other physical systems described by quantum field theory, for instance in the context of a condensed matter system. The lectures by S Hartnoll provided an introduction to this recent development with an emphasis on the dual holographic description of superconductivity. Finally, ideas inspired by the AdS/CFT correspondence are yielding deep insights into fundamental questions of quantum gravity, like the entropy of black holes and its interpretation in terms of microstates. The lectures by S Mathur reviewed the black hole entropy and information paradox, and the proposal for its resolution in terms of `fuzzball' microstates. Further sets of lectures, not included in this special section, by F Zwirner and V Mukhanov, covered phenomenological aspects of high energy physics beyond the Standard Model and of cosmology. The coming experimental data in these two fields are expected to foster new developments in connecting string theory to the real world. The conference was financially supported by CERN and partially by the Arnold Sommerfeld Center for Theoretical Physics of the Ludwig Maximilians University of Munich. It is a great pleasure for us to warmly thank the Theory Unit of CERN for its very kind hospitality and for the high quality of the assistance and the infrastructures that it has provided. A M Uranga CERN, Switzerland Guest Editor
Charged black holes in string-inspired gravity II. Mass inflation and dependence on parameters and potentials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hansen, Jakob; Yeom, Dong-han, E-mail: hansen@kisti.re.kr, E-mail: innocent.yeom@gmail.com

2015-09-01

We investigate the relation between the existence of mass inflation and model parameters of string-inspired gravity models. In order to cover various models, we investigate a Brans-Dicke theory that is coupled to a U(1) gauge field. By tuning a model parameter that decides the coupling between the Brans-Dicke field and the electromagnetic field, we can make both of models such that the Brans-Dicke field is biased toward strong or weak coupling directions after gravitational collapses. We observe that as long as the Brans-Dicke field is biased toward any (strong or weak) directions, there is no Cauchy horizon and no massmore » inflation. Therefore, we conclude that to induce a Cauchy horizon and mass inflation inside a charged black hole, either there is no bias of the Brans-Dicke field as well as no Brans-Dicke hair outside the horizon or such a biased Brans-Dicke field should be well trapped and controlled by a potential.« less
Charged black holes in string-inspired gravity II. Mass inflation and dependence on parameters and potentials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hansen, Jakob; Yeom, Dong-han

2015-09-07

We investigate the relation between the existence of mass inflation and model parameters of string-inspired gravity models. In order to cover various models, we investigate a Brans-Dicke theory that is coupled to a U(1) gauge field. By tuning a model parameter that decides the coupling between the Brans-Dicke field and the electromagnetic field, we can make both of models such that the Brans-Dicke field is biased toward strong or weak coupling directions after gravitational collapses. We observe that as long as the Brans-Dicke field is biased toward any (strong or weak) directions, there is no Cauchy horizon and no massmore » inflation. Therefore, we conclude that to induce a Cauchy horizon and mass inflation inside a charged black hole, either there is no bias of the Brans-Dicke field as well as no Brans-Dicke hair outside the horizon or such a biased Brans-Dicke field should be well trapped and controlled by a potential.« less
Private randomness expansion with untrusted devices

NASA Astrophysics Data System (ADS)

Colbeck, Roger; Kent, Adrian

2011-03-01

Randomness is an important resource for many applications, from gambling to secure communication. However, guaranteeing that the output from a candidate random source could not have been predicted by an outside party is a challenging task, and many supposedly random sources used today provide no such guarantee. Quantum solutions to this problem exist, for example a device which internally sends a photon through a beamsplitter and observes on which side it emerges, but, presently, such solutions require the user to trust the internal workings of the device. Here, we seek to go beyond this limitation by asking whether randomness can be generated using untrusted devices—even ones created by an adversarial agent—while providing a guarantee that no outside party (including the agent) can predict it. Since this is easily seen to be impossible unless the user has an initially private random string, the task we investigate here is private randomness expansion. We introduce a protocol for private randomness expansion with untrusted devices which is designed to take as input an initially private random string and produce as output a longer private random string. We point out that private randomness expansion protocols are generally vulnerable to attacks that can render the initial string partially insecure, even though that string is used only inside a secure laboratory; our protocol is designed to remove this previously unconsidered vulnerability by privacy amplification. We also discuss extensions of our protocol designed to generate an arbitrarily long random string from a finite initially private random string. The security of these protocols against the most general attacks is left as an open question.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia-Compean, H.; Loaiza-Brito, O.; Departamento de Fisica, Universidad de Guanajuato, C.P. 37150, Leon, Guanajuato

The first steps towards a proposal for a description of the quantum hair in 4D supersymmetric black holes in string Calabi-Yau (CY) compactifications are given. The quantum hair consisting of electric and magnetic fractional charges in black holes are derived from periods of the CY's torsion cycles. In the process a K-theory interpretation of the quantum hair in terms of the Atiyah-Hirzebruch spectral sequence is carried out. Finally, the same procedure is considered for torsion cycles of certain generalized CY's threefolds such as half-flat manifolds.
Second quantization of a covariant relativistic spacetime string in Steuckelberg-Horwitz-Piron theory

NASA Astrophysics Data System (ADS)

Suleymanov, Michael; Horwitz, Lawrence; Yahalom, Asher

2017-06-01

A relativistic 4D string is described in the framework of the covariant quantum theory first introduced by Stueckelberg [ Helv. Phys. Acta 14, 588 (1941)], and further developed by Horwitz and Piron [ Helv. Phys. Acta 46, 316 (1973)], and discussed at length in the book of Horwitz [Relativistic Quantum Mechanics, Springer (2015)]. We describe the space-time string using the solutions of relativistic harmonic oscillator [ J. Math. Phys. 30, 66 (1989)]. We first study the problem of the discrete string, both classically and quantum mechanically, and then turn to a study of the continuum limit, which contains a basically new formalism for the quantization of an extended system. The mass and energy spectrum are derived. Some comparison is made with known string models.
No Strings Attached: Open Source Solutions

ERIC Educational Resources Information Center

Fredricks, Kathy

2009-01-01

Imagine downloading a new software application and not having to worry about licensing, finding dollars in the budget, or incurring additional maintenance costs. Imagine finding a Web design tool in the public domain--free for use. Imagine major universities that provide online courses with no strings attached. Imagine online textbooks without a…
Straight spinning cosmic strings in Brans-Dicke gravity

NASA Astrophysics Data System (ADS)

Dos Santos, S. Mittmann; da Silva, J. M. Hoff; Cindra, J. L.

2018-03-01

An exact solution of straight spinning cosmic strings in Brans-Dicke theory of gravitation is presented. The possibility of the existence of closed time-like curves around these cosmic strings is analyzed. Furthermore, the stability about the formation of the topological defect discussed here is checked. It is shown that the existence of a suitable choice for the integration constants in which closed time-like curves are not allowed. We also study the (im)possibility of using the obtained spacetime in the rotational curves problem.
Reduced-Size Integer Linear Programming Models for String Selection Problems: Application to the Farthest String Problem.

PubMed

Zörnig, Peter

2015-08-01

We present integer programming models for some variants of the farthest string problem. The number of variables and constraints is substantially less than that of the integer linear programming models known in the literature. Moreover, the solution of the linear programming-relaxation contains only a small proportion of noninteger values, which considerably simplifies the rounding process. Numerical tests have shown excellent results, especially when a small set of long sequences is given.
A swamp of non-SUSY vacua

NASA Astrophysics Data System (ADS)

Danielsson, U. H.; Dibitetto, G.; Vargas, S. C.

2017-11-01

We consider known examples of non-supersymmetric AdS7 and AdS4 solutions arising from compactifications of massive type IIA supergravity and study their stability, taking into account the coupling between closed- and open-string sector excitations. Generically, open strings are found to develop modes with masses below the Breitenlohner-Freedman (BF) bound. We comment on the relation with the Weak Gravity Conjecture, and how this analysis may play an important role in examining the validity of non-supersymmetric constructions in string theory.
Numerical relativity beyond astrophysics.

PubMed

Garfinkle, David

2017-01-01

Though the main applications of computer simulations in relativity are to astrophysical systems such as black holes and neutron stars, nonetheless there are important applications of numerical methods to the investigation of general relativity as a fundamental theory of the nature of space and time. This paper gives an overview of some of these applications. In particular we cover (i) investigations of the properties of spacetime singularities such as those that occur in the interior of black holes and in big bang cosmology. (ii) investigations of critical behavior at the threshold of black hole formation in gravitational collapse. (iii) investigations inspired by string theory, in particular analogs of black holes in more than 4 spacetime dimensions and gravitational collapse in spacetimes with a negative cosmological constant.
Numerical relativity beyond astrophysics

NASA Astrophysics Data System (ADS)

Garfinkle, David

2017-01-01

Though the main applications of computer simulations in relativity are to astrophysical systems such as black holes and neutron stars, nonetheless there are important applications of numerical methods to the investigation of general relativity as a fundamental theory of the nature of space and time. This paper gives an overview of some of these applications. In particular we cover (i) investigations of the properties of spacetime singularities such as those that occur in the interior of black holes and in big bang cosmology. (ii) investigations of critical behavior at the threshold of black hole formation in gravitational collapse. (iii) investigations inspired by string theory, in particular analogs of black holes in more than 4 spacetime dimensions and gravitational collapse in spacetimes with a negative cosmological constant.
Progress report for a research program in theoretical high energy physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feldman, D.; Fried, H.M.; Jevicki, A.

This year's research has dealt with: superstrings in the early universe; the invisible axion emissions from SN1987A; quartic interaction in Witten's superstring field theory; W-boson associated multiplicity and the dual parton model; cosmic strings and galaxy formation; cosmic strings and baryogenesis; quark flavor mixing; p -- /bar p/ scattering at TeV energies; random surfaces; ordered exponentials and differential equations; initial value and back-reaction problems in quantum field theory; string field theory and Weyl invariance; the renormalization group and string field theory; the evolution of scalar fields in an inflationary universe, with and without the effects of gravitational perturbations; cosmic stringmore » catalysis of skyrmion decay; inflation and cosmic strings from dynamical symmetry breaking; the physic of flavor mixing; string-inspired cosmology; strings at high-energy densities and complex temperatures; the problem of non-locality in string theory; string statistical mechanics; large-scale structures with cosmic strings and neutrinos; the delta expansion for stochastic quantization; high-energy neutrino flux from ordinary cosmic strings; a physical picture of loop bremsstrahlung; cylindrically-symmetric solutions of four-dimensional sigma models; large-scale structure with hot dark matter and cosmic strings; the unitarization of the odderon; string thermodynamics and conservation laws; the dependence of inflationary-universe models on initial conditions; the delta expansion and local gauge invariance; particle physics and galaxy formation; chaotic inflation with metric and matter perturbations; grand-unified theories, galaxy formation, and large-scale structure; neutrino clustering in cosmic-string-induced wakes; and infrared approximations to nonlinear differential equations. 17 refs.« less
Magnetic charge and photon mass: Physical string singularities, Dirac condition, and magnetic confinement

NASA Astrophysics Data System (ADS)

Evans, Timothy J.; Singleton, Douglas

2018-04-01

We find exact, simple solutions to the Proca version of Maxwell’s equations with magnetic sources. Several properties of these solutions differ from the usual case of magnetic charge with a massless photon: (i) the string singularities of the usual 3-vector potentials become real singularities in the magnetic fields; (ii) the different 3-vector potentials become gauge inequivalent and physically distinct solutions; (iii) the magnetic field depends on r and 𝜃 and thus is no longer rotationally symmetric; (iv) a combined system of electric and magnetic charge carries a field angular momentum even when the electric and magnetic charges are located at the same place (i.e. for dyons); (v) for these dyons, one recovers the standard Dirac condition despite the photon being massive. We discuss the reason for this. We conclude by proposing that the string singularity in the magnetic field of an isolated magnetic charge suggests a confinement mechanism for magnetic charge, similar to the flux tube confinement of quarks in QCD.

For AAPT: Teaching the Wave Mechanics of McLeods' Stringy Electron, Explicit Nucleons, and Through-the-Earth Projections of Constellations' Stick Figures

NASA Astrophysics Data System (ADS)

McLeod, David Matthew

2011-11-01

McLeods' NEF11#22 submission is from their same-title INVITED presentation at Frontiers in Optics 2011, San Jose, CA. It shows how Hooke's law for electron, proton and neutron strings build electromagnetic waves from strings. These are composed of spirally linked, parallel, north-pole oriented, neutrino and antineutrino strings, stable because of magnetic repulsions. Their Dumbo Proton is antineutrino-scissor cut, and compressed in the vicinity of a neutron star, where electrostatic marriage occurs with a neutrino-scissor cut, and compressed, electron, so a Mickey Neutron emerges. Strings then predict electron charge is -- 1/3 e, Dumbo P is 25 % longer than Mickey N, and Hooke says relaxing springs fuel three separate inflations after each Big Bang oscillation. Gravity can be strings longitudinally linked. Einstein says Herman Grid's black diagonals prove human vision reads its information from algebraically-signed electromagnetic field diffraction patterns known by ray-tracing, not difficult Spatial Fourier Transformation. High-schoolers understand its application to Wave Mechanics, and agree that positive-numbered probabilities do not enter to possibly displease God. Stick figure constellations detected, like Phoenix, Leo, Canis Major, and especially Orion, fool some observers into false beliefs in things like UFHumanoids, or Kokopelli, Pele and Pamola!
Renormalization group flows and continual Lie algebras

NASA Astrophysics Data System (ADS)

Bakas, Ioannis

2003-08-01

We study the renormalization group flows of two-dimensional metrics in sigma models using the one-loop beta functions, and demonstrate that they provide a continual analogue of the Toda field equations in conformally flat coordinates. In this algebraic setting, the logarithm of the world-sheet length scale, t, is interpreted as Dynkin parameter on the root system of a novel continual Lie algebra, denoted by Script G(d/dt;1), with anti-symmetric Cartan kernel K(t,t') = delta'(t-t'); as such, it coincides with the Cartan matrix of the superalgebra sl(N|N+1) in the large-N limit. The resulting Toda field equation is a non-linear generalization of the heat equation, which is integrable in target space and shares the same dissipative properties in time, t. We provide the general solution of the renormalization group flows in terms of free fields, via Bäcklund transformations, and present some simple examples that illustrate the validity of their formal power series expansion in terms of algebraic data. We study in detail the sausage model that arises as geometric deformation of the O(3) sigma model, and give a new interpretation to its ultra-violet limit by gluing together two copies of Witten's two-dimensional black hole in the asymptotic region. We also provide some new solutions that describe the renormalization group flow of negatively curved spaces in different patches, which look like a cane in the infra-red region. Finally, we revisit the transition of a flat cone C/Zn to the plane, as another special solution, and note that tachyon condensation in closed string theory exhibits a hidden relation to the infinite dimensional algebra Script G(d/dt;1) in the regime of gravity. Its exponential growth holds the key for the construction of conserved currents and their systematic interpretation in string theory, but they still remain unknown.
Analytical Tools for Investigating and Modeling Agent-Based Systems

DTIC Science & Technology

2005-06-01

of Black Holes Cluster 10 : Juan M. Maldacena (1924), Journal of High Energy Physics Field theory models for tachyon and gauge field string dy...namics; Super-Poincare Invariant Superstring Field The- ory; Level Four Approximation to the Tachyon Potential in Superstring Field Theory; SO(32) Spinors
Gravitational collapse of conventional polytropic cylinder

NASA Astrophysics Data System (ADS)

Lou, Yu-Qing; Hu, Xu-Yao

2017-07-01

In reference to general polytropic and conventional polytropic hydrodynamic cylinders of infinite length with axial uniformity and axisymmetry under self-gravity, the dynamic evolution of central collapsing mass string in free-fall dynamic accretion phase is re-examined in details. We compare the central mass accretion rate and the envelope mass infall rate at small radii. Among others, we correct mistakes and typos of Kawachi & Hanawa (KH hereafter) and in particular prove that their key asymptotic free-fall solution involving polytropic index γ in the two power exponents is erroneous by analytical analyses and numerical tests. The correct free-fall asymptotic solutions at sufficiently small \\hat{r} (the dimensionless independent self-similar variable) scale as {˜ } -|ln \\hat{r}|^{1/2} in contrast to KH's ˜ -|ln \\hat{r}|^{(2-γ )/2} for the reduced bulk radial flow velocity and as {˜ } \\hat{r}^{-1}|ln \\hat{r}|^{-1/2} in contrast to KH's {˜ } \\hat{r}^{-1} |ln \\hat{r}|^{-(2-γ )/2} for the reduced mass density. We offer consistent scenarios for numerical simulation code testing and theoretical study on dynamic filamentary structure formation and evolution as well as pertinent stability properties. Due to unavoidable Jeans instabilities along the cylinder, such collapsing massive filaments or strings can further break up into clumps and segments of various lengths as well as clumps embedded within segments and evolve into chains of gravitationally collapsed objects (such as gaseous planets, brown dwarfs, protostars, white dwarfs, neutron stars, black holes in a wide mass range, globular clusters, dwarf spheroidals, galaxies, galaxy clusters and even larger mass reservoirs etc.) in various astrophysical and cosmological contexts as articulated by Lou & Hu recently. As an example, we present a model scheme for comparing with observations of molecular filaments for forming protostars, brown dwarfs and gaseous planets and so forth.
TOPICAL REVIEW: TeV mini black hole decay at future colliders

NASA Astrophysics Data System (ADS)

Casanova, Alex; Spallucci, Euro

2006-02-01

It is generally believed that mini black holes decay by emitting elementary particles with a black body energy spectrum. The original calculation leads to the conclusion that about the 90% of the black hole mass is radiated away in the form of photons, neutrinos and light leptons, mainly electrons and muons. With the advent of string theory, such a scenario must be updated by including new effects coming from the stringy nature of particles and interactions. The main modifications with respect to the original picture of black hole evaporation come from recent developments in non-perturbative string theory globally referred to as TeV-scale gravity. By taking for granted that black holes can be produced in hadronic collisions, then their decay must take into account that: (i) we live in a D3 brane embedded into a higher dimensional bulk spacetime; (ii) fundamental interactions, including gravity, are unified at the TeV energy scale. Thus, the formal description of the Hawking radiation mechanism has to be extended to the case of more than four spacetime dimensions and includes the presence of D-branes. This kind of topological defect in the bulk spacetime fabric acts as a sort of 'cosmic fly-paper' trapping electro-weak standard model elementary particles in our (3 + 1)-dimensional universe. Furthermore, unification of fundamental interactions at an energy scale many orders of magnitude lower than the Planck energy implies that any kind of fundamental particle, not only leptons, is expected to be emitted. A detailed understanding of the new scenario is instrumental for optimal tuning of detectors at future colliders, where, hopefully, this exciting new physics will be tested. In this review, we study higher dimensional black hole decay, considering not only the emission of particles according to the Hawking mechanism, but also their near-horizon QED/QCD interactions. The ultimate motivation is to build up a phenomenologically reliable scenario, allowing a clear experimental signature of the event.
Appearance of Keplerian discs orbiting Kerr superspinars

NASA Astrophysics Data System (ADS)

Stuchlík, Zdeněk; Schee, Jan

2010-11-01

We study optical phenomena related to the appearance of Keplerian accretion discs orbiting Kerr superspinars predicted by string theory. The superspinar exterior is described by standard Kerr naked singularity geometry breaking the black hole limit on the internal angular momentum (spin). We construct local photon escape cones for a variety of orbiting sources that enable us to determine the superspinars silhouette in the case of distant observers. We show that the superspinar silhouette depends strongly on the assumed edge where the external Kerr spacetime is joined to the internal spacetime governed by string theory and significantly differs from the black hole silhouette. The appearance of the accretion disc is strongly dependent on the value of the superspinar spin in both their shape and frequency shift profile. Apparent extension of the disc grows significantly with the growing spin, while the frequency shift grows with the descending spin. This behaviour differs substantially from the appearance of discs orbiting black holes enabling thus, at least in principle, to distinguish clearly the Kerr superspinars and black holes. In vicinity of a Kerr superspinar the non-escaped photons have to be separated to those captured by the superspinar and those being trapped in its strong gravitational field leading to self-illumination of the disc that could even influence its structure and cause self-reflection effect of radiation of the disc. The amount of trapped photons grows with descending superspinar spin. We thus can expect significant self-illumination effects in the field of Kerr superspinars with near-extreme spin a ~ 1.
On coupling NEC-violating matter to gravity

DOE PAGES

Chatterjee, Saugata; Parikh, Maulik; van der Schaar, Jan Pieter

2015-03-16

We show that effective theories of matter that classically violate the null energy condition cannot be minimally coupled to Einstein gravity without being inconsistent with both string theory and black hole thermodynamics. We argue however that they could still be either non-minimally coupled or coupled to higher-curvature theories of gravity.
String Stability of a Linear Formation Flight Control System

NASA Technical Reports Server (NTRS)

Allen, Michael J.; Ryan, Jack; Hanson, Curtis E.; Parle, James F.

2002-01-01

String stability analysis of an autonomous formation flight system was performed using linear and nonlinear simulations. String stability is a measure of how position errors propagate from one vehicle to another in a cascaded system. In the formation flight system considered here, each i(sup th) aircraft uses information from itself and the preceding ((i-1)(sup th)) aircraft to track a commanded relative position. A possible solution for meeting performance requirements with such a system is to allow string instability. This paper explores two results of string instability and outlines analysis techniques for string unstable systems. The three analysis techniques presented here are: linear, nonlinear formation performance, and ride quality. The linear technique was developed from a worst-case scenario and could be applied to the design of a string unstable controller. The nonlinear formation performance and ride quality analysis techniques both use nonlinear formation simulation. Three of the four formation-controller gain-sets analyzed in this paper were limited more by ride quality than by performance. Formations of up to seven aircraft in a cascaded formation could be used in the presence of light gusts with this string unstable system.
Chern-Simons improved Hamiltonians for strings in three space dimensions

NASA Astrophysics Data System (ADS)

Gordeli, Ivan; Melnikov, Dmitry; Niemi, Antti J.; Sedrakyan, Ara

2016-07-01

In the case of a structureless string the extrinsic curvature and torsion determine uniquely its shape in three-dimensional ambient space, by way of solution of the Frenet equation. In many physical scenarios there are in addition symmetries that constrain the functional form of the ensuing energy function. For example, the energy of a structureless string should be independent of the way the string is framed in the Frenet equation. Thus the energy should only involve the curvature and torsion as dynamical variables, in a manner that resembles the Hamiltonian of the Abelian Higgs model. Here we investigate the effect of symmetry principles in the construction of Hamiltonians for structureless strings. We deduce from the concept of frame independence that in addition to extrinsic curvature and torsion, the string can also engage a three-dimensional Abelian bulk gauge field as a dynamical variable. We find that the presence of a bulk gauge field gives rise to a long-range interaction between different strings. Moreover, when this gauge field is subject to Chern-Simons self-interaction, it becomes plausible that interacting strings are subject to fractional statistics in three space dimensions.
Modeling and simulation performance of sucker rod beam pump

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aditsania, Annisa, E-mail: annisaaditsania@gmail.com; Rahmawati, Silvy Dewi, E-mail: silvyarahmawati@gmail.com; Sukarno, Pudjo, E-mail: psukarno@gmail.com

2015-09-30

Artificial lift is a mechanism to lift hydrocarbon, generally petroleum, from a well to surface. This is used in the case that the natural pressure from the reservoir has significantly decreased. Sucker rod beam pumping is a method of artificial lift. Sucker rod beam pump is modeled in this research as a function of geometry of the surface part, the size of sucker rod string, and fluid properties. Besides its length, sucker rod string also classified into tapered and un-tapered. At the beginning of this research, for easy modeling, the sucker rod string was assumed as un-tapered. The assumption provedmore » non-realistic to use. Therefore, the tapered sucker rod string modeling needs building. The numerical solution of this sucker rod beam pump model is computed using finite difference method. The numerical result shows that the peak of polished rod load for sucker rod beam pump unit C-456-D-256-120, for non-tapered sucker rod string is 38504.2 lb, while for tapered rod string is 25723.3 lb. For that reason, to avoid the sucker rod string breaks due to the overload, the use of tapered sucker rod beam string is suggested in this research.« less
Searching for cosmic strings in CMB anisotropy maps using wavelets and curvelets

NASA Astrophysics Data System (ADS)

Hergt, Lukas; Amara, Adam; Brandenberger, Robert; Kacprzak, Tomasz; Réfrégier, Alexandre

2017-06-01

We use wavelet and curvelet transforms to extract signals of cosmic strings from simulated cosmic microwave background (CMB) temperature anisotropy maps, and to study the limits on the cosmic string tension which various ongoing CMB temperature anisotropy experiments will be able to achieve. We construct sky maps with size and angular resolution corresponding to various experiments. These maps contain the signals of a scaling solution of long string segments with a given string tension G μ, the contribution of the dominant Gaussian primordial cosmological fluctuations, and pixel by pixel white noise with an amplitude corresponding to the instrumental noise of the various experiments. In the case that we include white noise, we find that using curvelets we obtain lower bounds on the string tension than with wavelets. For maps with Planck specification, we obtain bounds comparable to what was obtained by the Planck collaboration [1]. Experiments with better angular resolution such as the South Pole Telescope third generation (SPT-3G) survey will be able to yield stronger limits. For maps with a specification of SPT-3G we find that string signals will be visible down to a string tension of G μ = 1.4 × 10-7.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Svendsen, Harald G.

In this paper we study a solution of heterotic string theory corresponding to a rotating Kerr-Taub-NUT spacetime. It has an exact CFT description as a heterotic coset model, and a Lagrangian formulation as a gauged WZNW model. It is a generalization of a recently discussed stringy Taub-NUT solution, and is interesting as another laboratory for studying the fate of closed timelike curves and cosmological singularities in string theory. We extend the computation of the exact metric and dilaton to this rotating case, and then discuss some properties of the metric, with particular emphasis on the curvature singularities.
Classification of solutions of elliptic equations arising from a gravitational O(3) gauge field model

NASA Astrophysics Data System (ADS)

Choi, Nari; Han, Jongmin

2018-04-01

In this paper, we study an elliptic equation arising from the self-dual Maxwell gauged O (3) sigma model coupled with gravity. When the parameter τ equals 1 and there is only one singular source, we consider radially symmetric solutions. There appear three important constants: a positive parameter a representing a scaled gravitational constant, a nonnegative integer N1 representing the total string number, and a nonnegative integer N2 representing the total anti-string number. The values of the products aN1 , aN2 ∈ [ 0 , ∞) play a crucial role in classifying radial solutions. By using the decay rates of solutions at infinity, we provide a complete classification of solutions for all possible values of aN1 and aN2. This improves previously known results.
Free and forced vibrations of an eccentrically rotating string on a viscoelastic foundation

NASA Astrophysics Data System (ADS)

Soedel, S. M.; Soedel, W.

1989-12-01

Equations of motion of an eccentrically rotating cord on a viscoelastic foundation, derived by way of Hamilton's principle, are solved for free and forced vibrations. The natural frequencies during rotation are bifurcations of the stationary string values. The natural modes are complex and can be interpreted as mode pairs spinning with and against the string rotation. The general forced solution is expanded in terms of these complex modes. Results are given for an example of steady state harmonic response because of its practical significance to aircraft or automobile tire design.
Supersymmetric string waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bergshoeff, E.A.; Kallosh, R.; Ortin, T.

1993-06-15

We present plane-wave-type solutions of the lowest-order superstring effective action which have unbroken space-time supersymmetries. They are given by a stringy generalization of the Brinkmann metric, dialton, axion, and gauge fields. Some conspiracy between the metric and the axion field is required. The [alpha][prime] stringy corrections to the effective on-shell action, to the equations of motion (and therefore to the solutions themselves), and to the supersymmetry transformations are shown to vanish for a special class of these solutions that we call supersymmetric string waves (SSW's). In the SSW solutions, there exists a conspiracy not only between the metric and themore » axion field, but also between the gauge fields and the metric, since the embedding of the spin connection in the gauge group is required.« less
Aho-Corasick String Matching on Shared and Distributed Memory Parallel Architectures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tumeo, Antonino; Villa, Oreste; Chavarría-Miranda, Daniel

String matching is at the core of many critical applications, including network intrusion detection systems, search engines, virus scanners, spam filters, DNA and protein sequencing, and data mining. For all of these applications string matching requires a combination of (sometimes all) the following characteristics: high and/or predictable performance, support for large data sets and flexibility of integration and customization. Many software based implementations targeting conventional cache-based microprocessors fail to achieve high and predictable performance requirements, while Field-Programmable Gate Array (FPGA) implementations and dedicated hardware solutions fail to support large data sets (dictionary sizes) and are difficult to integrate and customize.more » The advent of multicore, multithreaded, and GPU-based systems is opening the possibility for software based solutions to reach very high performance at a sustained rate. This paper compares several software-based implementations of the Aho-Corasick string searching algorithm for high performance systems. We discuss the implementation of the algorithm on several types of shared-memory high-performance architectures (Niagara 2, large x86 SMPs and Cray XMT), distributed memory with homogeneous processing elements (InfiniBand cluster of x86 multicores) and heterogeneous processing elements (InfiniBand cluster of x86 multicores with NVIDIA Tesla C10 GPUs). We describe in detail how each solution achieves the objectives of supporting large dictionaries, sustaining high performance, and enabling customization and flexibility using various data sets.« less
Social interaction as a heuristic for combinatorial optimization problems

NASA Astrophysics Data System (ADS)

Fontanari, José F.

2010-11-01

We investigate the performance of a variant of Axelrod’s model for dissemination of culture—the Adaptive Culture Heuristic (ACH)—on solving an NP-Complete optimization problem, namely, the classification of binary input patterns of size F by a Boolean Binary Perceptron. In this heuristic, N agents, characterized by binary strings of length F which represent possible solutions to the optimization problem, are fixed at the sites of a square lattice and interact with their nearest neighbors only. The interactions are such that the agents’ strings (or cultures) become more similar to the low-cost strings of their neighbors resulting in the dissemination of these strings across the lattice. Eventually the dynamics freezes into a homogeneous absorbing configuration in which all agents exhibit identical solutions to the optimization problem. We find through extensive simulations that the probability of finding the optimal solution is a function of the reduced variable F/N1/4 so that the number of agents must increase with the fourth power of the problem size, N∝F4 , to guarantee a fixed probability of success. In this case, we find that the relaxation time to reach an absorbing configuration scales with F6 which can be interpreted as the overall computational cost of the ACH to find an optimal set of weights for a Boolean binary perceptron, given a fixed probability of success.
Concept Specification by PRECIS Role Operators: Some Technical Problems with Social Science and Humanities Literature.

ERIC Educational Resources Information Center

Mahapatra, M.; Biswas, S. C.

1985-01-01

Two hundred journal articles related to fields of taxation, genetic psychology, and Shakespearean drama published from 1970-1980 were analyzed and PRECIS input strings were drawn. Occasions when input string and index entries looked incomplete and unexpressive after losing context of document are provided with solutions. Role operator schema is…
Tensile strength and the mining of black holes.

PubMed

Brown, Adam R

2013-11-22

There are a number of important thought experiments that involve raising and lowering boxes full of radiation in the vicinity of black hole horizons. This Letter looks at the limitations placed on these thought experiments by the null energy condition, which imposes a fundamental bound on the tensile-strength-to-weight ratio of the materials involved, makes it impossible to build a box near the horizon that is wider than a single wavelength of the Hawking quanta, and puts a severe constraint on the operation of "space elevators" near black holes. In particular, it is shown that proposals for mining black holes by lowering boxes near the horizon, collecting some Hawking radiation, and dragging it out to infinity cannot proceed nearly as rapidly as has previously been claimed. As a consequence of this limitation, the boxes and all the moving parts are superfluous and black holes can be destroyed equally rapidly by threading the horizon with strings.
New dimensions for wound strings: The modular transformation of geometry to topology

DOE Office of Scientific and Technical Information (OSTI.GOV)

McGreevy, John; Silverstein, Eva; Starr, David

2007-02-15

We show, using a theorem of Milnor and Margulis, that string theory on compact negatively curved spaces grows new effective dimensions as the space shrinks, generalizing and contextualizing the results in E. Silverstein, Phys. Rev. D 73, 086004 (2006).. Milnor's theorem relates negative sectional curvature on a compact Riemannian manifold to exponential growth of its fundamental group, which translates in string theory to a higher effective central charge arising from winding strings. This exponential density of winding modes is related by modular invariance to the infrared small perturbation spectrum. Using self-consistent approximations valid at large radius, we analyze this correspondencemore » explicitly in a broad set of time-dependent solutions, finding precise agreement between the effective central charge and the corresponding infrared small perturbation spectrum. This indicates a basic relation between geometry, topology, and dimensionality in string theory.« less

Fast spinning strings on η deformed AdS 5 × S 5

NASA Astrophysics Data System (ADS)

Banerjee, Aritra; Bhattacharyya, Arpan; Roychowdhury, Dibakar

2018-02-01

In this paper, considering the correspondence between spin chains and string sigma models, we explore the rotating string solutions over η deformed AdS 5 × S 5 in the so-called fast spinning limit. In our analysis, we focus only on the bosonic part of the full superstring action and compute the relevant limits on both ( R × S 3) η and ( R × S 5) η models. The resulting system reveals that in the fast spinning limit, the sigma model on η deformed S 5 could be approximately thought of as the continuum limit of anisotropic SU(3) Heisenberg spin chain model. We compute the energy for a certain class of spinning strings in deformed S 5 and we show that this energy can be mapped to that of a similar spinning string in the purely imaginary β deformed background.
Gravitating lepton bag model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burinskii, A., E-mail: burinskii@mail.ru

The Kerr–Newman (KN) black hole (BH) solution exhibits the external gravitational and electromagnetic field corresponding to that of the Dirac electron. For the large spin/mass ratio, a ≫ m, the BH loses horizons and acquires a naked singular ring creating two-sheeted topology. This space is regularized by the Higgs mechanism of symmetry breaking, leading to an extended particle that has a regular spinning core compatible with the external KN solution. We show that this core has much in common with the known MIT and SLAC bag models, but has the important advantage of being in accordance with the external gravitationalmore » and electromagnetic fields of the KN solution. A peculiar two-sheeted structure of Kerr’s gravity provides a framework for the implementation of the Higgs mechanism of symmetry breaking in configuration space in accordance with the concept of the electroweak sector of the Standard Model. Similar to other bag models, the KN bag is flexible and pliant to deformations. For parameters of a spinning electron, the bag takes the shape of a thin rotating disk of the Compton radius, with a ring–string structure and a quark-like singular pole formed at the sharp edge of this disk, indicating that the considered lepton bag forms a single bag–string–quark system.« less
A simple model for the evolution of a non-Abelian cosmic string network

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cella, G.; Pieroni, M., E-mail: giancarlo.cella@pi.infn.it, E-mail: mauro.pieroni@apc.univ-paris7.fr

2016-06-01

In this paper we present the results of numerical simulations intended to study the behavior of non-Abelian cosmic strings networks. In particular we are interested in discussing the variations in the asymptotic behavior of the system as we variate the number of generators for the topological defects. A simple model which allows for cosmic strings is presented and its lattice discretization is discussed. The evolution of the generated cosmic string networks is then studied for different values for the number of generators for the topological defects. Scaling solution appears to be approached in most cases and we present an argumentmore » to justify the lack of scaling for the residual cases.« less
The effective supergravity of little string theory

NASA Astrophysics Data System (ADS)

Antoniadis, Ignatios; Delgado, Antonio; Markou, Chrysoula; Pokorski, Stefan

2018-02-01

In this work we present the minimal supersymmetric extension of the five-dimensional dilaton-gravity theory that captures the main properties of the holographic dual of little string theory. It is described by a particular gauging of N=2 supergravity coupled with one vector multiplet associated with the string dilaton, along the U(1) subgroup of SU(2) R-symmetry. The linear dilaton in the fifth coordinate solution of the equations of motion (with flat string frame metric) breaks half of the supersymmetries to N=1 in four dimensions. Interest in the linear dilaton model has lately been revived in the context of the clockwork mechanism, which has recently been proposed as a new source of exponential scale separation in field theory.
Semiclassical gravitational effects on the gravitational lensing in the spacetime of topological defects

NASA Astrophysics Data System (ADS)

Jusufi, Kimet; Rahaman, Farook; Banerjee, Ayan

2018-02-01

The theory of gravitational lensing has revealed many generic and fundamental properties of compact objects like black holes and wormholes. In this article, we utilize a recent formulation to compute the quantum effects on the deflection angle of a light ray, namely, the Gauss-Bonnet theorem (GBT) to explore the semiclassical gravitational effects in the spacetime of a point-like global monopole and a cosmic string. Previously, the Gauss-Bonnet theorem (Gibbons and Werner, 2008) was proposed as an alternative way to compute the deflection angle of light in a static, spherically symmetric and asymptotically flat spacetime. In the present article we have used the celebrated GBT that applied to the optical metric as well as the geodesic method in computing the deflection angle. Interestingly one can observe that we have found an exact result between GBT and the standard approach up to the third-order contributions terms by modifying the domain of integration for cosmic string and global monopole deflection angles. Finally we have considered the time delay in the cosmic string/global monopole spacetime and found that the delay in time is proportional to the linear mass density of the cosmic string and global monopole parameter, respectively.
String Theory: exact solutions, marginal deformations and hyperbolic spaces

NASA Astrophysics Data System (ADS)

Orlando, Domenico

2006-10-01

This thesis is almost entirely devoted to studying string theory backgrounds characterized by simple geometrical and integrability properties. The archetype of this type of system is given by Wess-Zumino-Witten models, describing string propagation in a group manifold or, equivalently, a class of conformal field theories with current algebras. We study the moduli space of such models by using truly marginal deformations. Particular emphasis is placed on asymmetric deformations that, together with the CFT description, enjoy a very nice spacetime interpretation in terms of the underlying Lie algebra. Then we take a slight detour so to deal with off-shell systems. Using a renormalization-group approach we describe the relaxation towards the symmetrical equilibrium situation. In he final chapter we consider backgrounds with Ramond-Ramond field and in particular we analyze direct products of constant-curvature spaces and find solutions with hyperbolic spaces.
Conformal twists, Yang–Baxter σ-models & holographic noncommutativity

NASA Astrophysics Data System (ADS)

Araujo, Thiago; Bakhmatov, Ilya; Colgáin, Eoin Ó.; Sakamoto, Jun-ichi; Sheikh-Jabbari, Mohammad M.; Yoshida, Kentaroh

2018-06-01

Expanding upon earlier results (Araujo et al 2017 Phys. Rev. D 95 105006), we present a compendium of σ-models associated with integrable deformations of AdS5 generated by solutions to homogenous classical Yang–Baxter equation. Each example we study from four viewpoints: conformal (Drinfeld) twists, closed string gravity backgrounds, open string parameters and proposed dual noncommutative (NC) gauge theory. Irrespective of whether the deformed background is a solution to supergravity or generalized supergravity, we show that the open string metric associated with each gravity background is undeformed AdS5 with constant open string coupling and the NC structure Θ is directly related to the conformal twist. One novel feature is that Θ exhibits ‘holographic noncommutativity’: while it may exhibit non-trivial dependence on the holographic direction, its value everywhere in the bulk is uniquely determined by its value at the boundary, thus facilitating introduction of a dual NC gauge theory. We show that the divergence of the NC structure Θ is directly related to the unimodularity of the twist. We discuss the implementation of an outer automorphism of the conformal algebra as a coordinate transformation in the AdS bulk and discuss its implications for Yang–Baxter σ-models and self-T-duality based on fermionic T-duality. Finally, we comment on implications of our results for the integrability of associated open strings and planar integrability of dual NC gauge theories.
Spacelike brane actions.

PubMed

Hashimoto, Koji; Ho, Pei-Ming; Wang, John E

2003-04-11

We derive effective actions for "spacelike branes" (S-branes) and find a solution describing the formation of fundamental strings in the rolling tachyon background. The S-brane action is a Dirac-Born-Infeld action for Euclidean world volumes defined in the context of time-dependent tachyon condensation of non-BPS (Bogomol'nyi-Prasad-Sommerfield) branes. It includes gauge fields and, in particular, a scalar field associated with translation along the time direction. We show that the BIon spike solutions constructed in this system correspond to the production of a confined electric flux tube (a fundamental string) at late time of the rolling tachyon.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Hergt, Lukas; Amara, Adam; Kacprzak, Tomasz

We use wavelet and curvelet transforms to extract signals of cosmic strings from simulated cosmic microwave background (CMB) temperature anisotropy maps, and to study the limits on the cosmic string tension which various ongoing CMB temperature anisotropy experiments will be able to achieve. We construct sky maps with size and angular resolution corresponding to various experiments. These maps contain the signals of a scaling solution of long string segments with a given string tension G μ, the contribution of the dominant Gaussian primordial cosmological fluctuations, and pixel by pixel white noise with an amplitude corresponding to the instrumental noise ofmore » the various experiments. In the case that we include white noise, we find that using curvelets we obtain lower bounds on the string tension than with wavelets. For maps with Planck specification, we obtain bounds comparable to what was obtained by the Planck collaboration [1]. Experiments with better angular resolution such as the South Pole Telescope third generation (SPT-3G) survey will be able to yield stronger limits. For maps with a specification of SPT-3G we find that string signals will be visible down to a string tension of G μ = 1.4 × 10{sup −7}.« less
Sexual Partner Type Taxonomy Use Among Black Adolescent Mothers in the United States.

PubMed

Nelson, LaRon E; Morrison-Beedy, Dianne; Kearney, Margaret H; Dozier, Ann

2011-01-01

Research on sexual-partner type focuses mostly on "main" and "casual" partner categories. The literature indicates that adolescent girls are less likely to use condoms with main partners, and more likely to use condoms with casual partners. Adolescent mothers may have different types of sexual partners than other adolescent girls. The purpose of this study was to explore and describe the range of male sexual partner types reported by Black adolescent mothers. This study was a qualitative description of the perspectives of Black, predominantly African-American, mothers (n=31). Data were generated using focus groups and interviews. The participants' ages ranged from 15-19 years. A semi-structured qualitative questioning guide was used to stimulate focused discussions. Transcribed data were analyzed using qualitative content analysis. The range of sexual partner types of the women were reflected in three themes (1) All main partners are not created equal; (2) They're not casual partners because there are strings attached; (3) "Wham, bam, thank you ma'am:" No strings attached. Nine partner types were identified under these three themes, including a "baby daddy" partner. The partner-types of Black adolescent mothers are more robust than the "main" and "casual" partner categories typically referenced in the research literature. The range of sex partners includes the birth fathers of their children. Clinicians and researchers must consider how co-parenthood status is used in the construction of the "baby daddy" partner and what implications this unique sexual partner type may have on risk reduction behaviors such as condom use.
A survey of solutions in a gravitational Born-Infeld theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chern, Jann-Long, E-mail: chern@math.ncu.edu.tw; Yang, Sze-Guang, E-mail: sgyang@math.ncu.edu.tw

2014-03-15

An elliptic equation that arises from a cosmic string model with the action of the Born-Infeld nonlinear electromagnetism, is considered. We classify and establish the uniqueness of radially symmetric solutions.
The dynamics of domain walls and strings

NASA Technical Reports Server (NTRS)

Gregory, Ruth; Haws, David; Garfinkle, David

1989-01-01

The leading order finite-width corrections to the equation of motion describing the motion of a domain wall are derived. The regime in which this equation of motion is invalid is discussed. Spherically and cylindrically symmetric solutions to this equation of motion are found. A misconception that has arisen in recent years regarding the rigidity (or otherwise) of cosmic strings is also clarified.
Non-Abelian cosmic string in the Starobinsky model of gravity

NASA Astrophysics Data System (ADS)

Morais Graça, J. P.; de Pádua Santos, A.; Bezerra de Mello, Eugênio R.; Bezerra, V. B.

In this paper, we analyze numerically the behavior of the solutions corresponding to a non-Abelian cosmic string in the framework of the Starobinsky model, i.e. where f(R) = R + ζR2. We perform the calculations for both an asymptotically flat and asymptotically (anti)-de Sitter spacetimes. We found that the angular deficit generated by the string decreases as the parameter ζ increases, in the case of a null cosmological constant. For a positive cosmological constant, we found that the cosmic horizon is affected in a nontrivial way by the parameter ζ.
An Integrated Theory of Everything (TOE)

NASA Astrophysics Data System (ADS)

Colella, Antonio

2014-03-01

An Integrated TOE unifies all known physical phenomena from the Planck cube to the Super Universe (multiverse). Each matter/force particle is represented by a Planck cube string. Any Super Universe object is a volume of contiguous Planck cubes. Super force Planck cube string singularities existed at the start of all universes. An Integrated TOE foundations are twenty independent existing theories and without sacrificing their integrities, are replaced by twenty interrelated amplified theories. Amplifications of Higgs force theory are key to an Integrated TOE and include: 64 supersymmetric Higgs particles; super force condensations to 17 matter particles/associated Higgs forces; spontaneous symmetry breaking is bidirectional; and the sum of 8 permanent Higgs force energies is dark energy. Stellar black hole theory was amplified to include a quark star (matter) with mass, volume, near zero temperature, and maximum entropy. A black hole (energy) has energy, minimal volume (singularity), near infinite temperature, and minimum entropy. Our precursor universe's super supermassive quark star (matter) evaporated to a super supermassive black hole (energy). This transferred total conserved energy/mass and transformed entropy from maximum to minimum. Integrated Theory of Everything Book Video: https://www.youtube.com/watch?v=4a1c9IvdoGY Research Article Video: http://www.youtube.com/watch?v=CD-QoLeVbSY Research Article: http://toncolella.files.wordpress.com/2012/07/m080112.pdf.
The Firewall Transformation for Black Holes and Some of Its Implications

NASA Astrophysics Data System (ADS)

't Hooft, Gerard

2017-12-01

A promising strategy for better understanding space and time at the Planck scale, is outlined and further pursued. It is explained in detail, how black hole unitarity demands the existence of transformations that can remove firewalls. This must then be combined with a continuity condition on the horizon, with antipodal identification as an inevitable consequence. The antipodal identification comes with a it{CPT} inversion. We claim to have arrived at `new physics', but rather than string theory, our `new physics' concerns new constraints on the topology and the boundary conditions of general coordinate transformations. The resulting theory is conceptually quite non trivial, and more analysis is needed. A strong entanglement between Hawking particles at opposite sides of the black hole is suspected, but questions remain. A few misconceptions concerning black holes, originating from older investigations, are discussed.
Frontiers in Numerical Relativity

NASA Astrophysics Data System (ADS)

Evans, Charles R.; Finn, Lee S.; Hobill, David W.

2011-06-01

Preface; Participants; Introduction; 1. Supercomputing and numerical relativity: a look at the past, present and future David W. Hobill and Larry L. Smarr; 2. Computational relativity in two and three dimensions Stuart L. Shapiro and Saul A. Teukolsky; 3. Slowly moving maximally charged black holes Robert C. Ferrell and Douglas M. Eardley; 4. Kepler's third law in general relativity Steven Detweiler; 5. Black hole spacetimes: testing numerical relativity David H. Bernstein, David W. Hobill and Larry L. Smarr; 6. Three dimensional initial data of numerical relativity Ken-ichi Oohara and Takashi Nakamura; 7. Initial data for collisions of black holes and other gravitational miscellany James W. York, Jr.; 8. Analytic-numerical matching for gravitational waveform extraction Andrew M. Abrahams; 9. Supernovae, gravitational radiation and the quadrupole formula L. S. Finn; 10. Gravitational radiation from perturbations of stellar core collapse models Edward Seidel and Thomas Moore; 11. General relativistic implicit radiation hydrodynamics in polar sliced space-time Paul J. Schinder; 12. General relativistic radiation hydrodynamics in spherically symmetric spacetimes A. Mezzacappa and R. A. Matzner; 13. Constraint preserving transport for magnetohydrodynamics John F. Hawley and Charles R. Evans; 14. Enforcing the momentum constraints during axisymmetric spacelike simulations Charles R. Evans; 15. Experiences with an adaptive mesh refinement algorithm in numerical relativity Matthew W. Choptuik; 16. The multigrid technique Gregory B. Cook; 17. Finite element methods in numerical relativity P. J. Mann; 18. Pseudo-spectral methods applied to gravitational collapse Silvano Bonazzola and Jean-Alain Marck; 19. Methods in 3D numerical relativity Takashi Nakamura and Ken-ichi Oohara; 20. Nonaxisymmetric rotating gravitational collapse and gravitational radiation Richard F. Stark; 21. Nonaxisymmetric neutron star collisions: initial results using smooth particle hydrodynamics Christopher S. Kochanek and Charles R. Evans; 22. Relativistic hydrodynamics James R. Wilson and Grant J. Mathews; 23. Computational dynamics of U(1) gauge strings: probability of reconnection of cosmic strings Richard A. Matzner; 24. Dynamically inhomogenous cosmic nucleosynthesis Hannu Kurki-Suonio; 25. Initial value solutions in planar cosmologies Peter Anninos, Joan Centrella and Richard Matzner; 26. An algorithmic overview of an Einstein solver Roger Ove; 27. A PDE compiler for full-metric numerical relativity Jonathan Thornburg; 28. Numerical evolution on null cones R. Gomez and J. Winicour; 29. Normal modes coupled to gravitational waves in a relativistic star Yasufumi Kojima; 30. Cosmic censorship and numerical relativity Dalia S. Goldwirth, Amos Ori and Tsvi Piran.
On the BV formalism of open superstring field theory in the large Hilbert space

NASA Astrophysics Data System (ADS)

Matsunaga, Hiroaki; Nomura, Mitsuru

2018-05-01

We construct several BV master actions for open superstring field theory in the large Hilbert space. First, we show that a naive use of the conventional BV approach breaks down at the third order of the antifield number expansion, although it enables us to define a simple "string antibracket" taking the Darboux form as spacetime antibrackets. This fact implies that in the large Hilbert space, "string fields-antifields" should be reassembled to obtain master actions in a simple manner. We determine the assembly of the string anti-fields on the basis of Berkovits' constrained BV approach, and give solutions to the master equation defined by Dirac antibrackets on the constrained string field-antifield space. It is expected that partial gauge-fixing enables us to relate superstring field theories based on the large and small Hilbert spaces directly: reassembling string fields-antifields is rather natural from this point of view. Finally, inspired by these results, we revisit the conventional BV approach and construct a BV master action based on the minimal set of string fields-antifields.
Psyche=singularity: A comparison of Carl Jung's transpersonal psychology and Leonard Susskind's holographic string theory

NASA Astrophysics Data System (ADS)

Desmond, Timothy

In this dissertation I discern what Carl Jung calls the mandala image of the ultimate archetype of unity underlying and structuring cosmos and psyche by pointing out parallels between his transpersonal psychology and Stanford physicist Leonard Susskind's string theory. Despite his atheistic, materialistically reductionist interpretation of it, I demonstrate how Susskind's string theory of holographic information conservation at the event horizons of black holes, and the cosmic horizon of the universe, corroborates the following four topics about which Jung wrote: (1) his near-death experience of the cosmic horizon after a heart attack in 1944; ( 2) his equation relating psychic energy to mass, "Psyche=highest intensity in the smallest space" (1997, 162), which I translate into the equation, Psyche=Singularity; (3) his theory that the mandala, a circle or sphere with a central point, is the symbolic image of the ultimate archetype of unity through the union of opposites, which structures both cosmos and psyche, and which rises spontaneously from the collective unconscious to compensate a conscious mind torn by irreconcilable demands (1989, 334-335, 396-397); and (4) his theory of synchronicity. I argue that Susskind's inside-out black hole model of our Big Bang universe forms a geometrically perfect mandala: a central Singularity encompassed by a two-dimensional sphere which serves as a universal memory bank. Moreover, in precise fulfillment of Jung's theory, Susskind used that mandala to reconcile the notoriously incommensurable paradigms of general relativity and quantum mechanics, providing in the process a mathematically plausible explanation for Jung's near-death experience of his past, present, and future life simultaneously at the cosmic horizon. Finally, Susskind's theory also provides a plausible cosmological model to explain Jung's theory of synchronicity--meaningful coincidences may be tied together by strings at the cosmic horizon, from which they radiate inward as the holographic "movie" of our three-dimensional world.
Small scale structure on cosmic strings

NASA Technical Reports Server (NTRS)

Albrecht, Andreas

1989-01-01

The current understanding of cosmic string evolution is discussed, and the focus placed on the question of small scale structure on strings, where most of the disagreements lie. A physical picture designed to put the role of the small scale structure into more intuitive terms is presented. In this picture it can be seen how the small scale structure can feed back in a major way on the overall scaling solution. It is also argued that it is easy for small scale numerical errors to feed back in just such a way. The intuitive discussion presented here may form the basis for an analytic treatment of the small scale structure, which argued in any case would be extremely valuable in filling the gaps in the present understanding of cosmic string evolution.
Integrated hydraulic booster/tool string technology for unfreezing of stuck downhole strings in horizontal wells

NASA Astrophysics Data System (ADS)

Tian, Q. Z.

2017-12-01

It is common to use a jarring tool to unfreeze stuck downhole string. However, in a horizontal well, influenced by the friction caused by the deviated section, jarring effect is poor; on the other hand, the forcing point can be located in the horizontal section by a hydraulic booster and the friction can be reduced, but it is time-consuming and easy to break downhole string using a large-tonnage and constant pull force. A hydraulic booster - jar tool string has been developed for unfreezing operation in horizontal wells. The technical solution involves three elements: a two-stage parallel spring cylinder structure for increasing the energy storage capacity of spring accelerators; multiple groups of spring accelerators connected in series to increase the working stroke; a hydraulic booster intensifying jarring force. The integrated unfreezing tool string based on these three elements can effectively overcome the friction caused by a deviated borehole, and thus unfreeze a stuck string with the interaction of the hydraulic booster and the mechanical jar which form an alternatively dynamic load. Experimental results show that the jarring performance parameters of the hydraulic booster-jar unfreezing tool string for the horizontal wells are in accordance with original design requirements. Then field technical parameters were developed based on numerical simulation and experimental data. Field application shows that the hydraulic booster-jar unfreezing tool string is effective to free stuck downhole tools in a horizontal well, and it reduces hook load by 80% and lessens the requirement of workover equipment. This provides a new technology to unfreeze stuck downhole string in a horizontal well.

Should Ethnicity "Matter" when Teaching about "Race" and Racism in the Classroom?

ERIC Educational Resources Information Center

Housee, Shirin

2008-01-01

Teaching about "race" and racism to a diverse student group can lead to some very interesting exchanges. Some of these moments are much to do with the subject content. Learning about racism often pulls on our emotional strings: black students sometimes express their hurt and anger, while white students sometimes remain silent or express…
12 healthy snacks with 200 calories or less

MedlinePlus

... of grapes or cherry tomatoes with a low-fat string cheese One cup (240 mL) raw carrots, broccoli, or bell peppers with 2 tbsp (30 mL) of hummus or black bean dip One cup (240 mL) tomato soup ... in 1 cup (240 mL) fat-free milk with cinnamon A hard-boiled egg ...
Tensionless Strings and Supersymmetric Sigma Models: Aspects of the Target Space Geometry

NASA Astrophysics Data System (ADS)

Bredthauer, Andreas

2007-01-01

In this thesis, two aspects of string theory are discussed, tensionless strings and supersymmetric sigma models. The equivalent to a massless particle in string theory is a tensionless string. Even almost 30 years after it was first mentioned, it is still quite poorly understood. We discuss how tensionless strings give rise to exact solutions to supergravity and solve closed tensionless string theory in the ten dimensional maximally supersymmetric plane wave background, a contraction of AdS(5)xS(5) where tensionless strings are of great interest due to their proposed relation to higher spin gauge theory via the AdS/CFT correspondence. For a sigma model, the amount of supersymmetry on its worldsheet restricts the geometry of the target space. For N=(2,2) supersymmetry, for example, the target space has to be bi-hermitian. Recently, with generalized complex geometry, a new mathematical framework was developed that is especially suited to discuss the target space geometry of sigma models in a Hamiltonian formulation. Bi-hermitian geometry is so-called generalized Kaehler geometry but the relation is involved. We discuss various amounts of supersymmetry in phase space and show that this relation can be established by considering the equivalence between the Hamilton and Lagrange formulation of the sigma model. In the study of generalized supersymmetric sigma models, we find objects that favor a geometrical interpretation beyond generalized complex geometry.
Document retrieval on repetitive string collections.

PubMed

Gagie, Travis; Hartikainen, Aleksi; Karhu, Kalle; Kärkkäinen, Juha; Navarro, Gonzalo; Puglisi, Simon J; Sirén, Jouni

2017-01-01

Most of the fastest-growing string collections today are repetitive, that is, most of the constituent documents are similar to many others. As these collections keep growing, a key approach to handling them is to exploit their repetitiveness, which can reduce their space usage by orders of magnitude. We study the problem of indexing repetitive string collections in order to perform efficient document retrieval operations on them. Document retrieval problems are routinely solved by search engines on large natural language collections, but the techniques are less developed on generic string collections. The case of repetitive string collections is even less understood, and there are very few existing solutions. We develop two novel ideas, interleaved LCPs and precomputed document lists , that yield highly compressed indexes solving the problem of document listing (find all the documents where a string appears), top- k document retrieval (find the k documents where a string appears most often), and document counting (count the number of documents where a string appears). We also show that a classical data structure supporting the latter query becomes highly compressible on repetitive data. Finally, we show how the tools we developed can be combined to solve ranked conjunctive and disjunctive multi-term queries under the simple [Formula: see text] model of relevance. We thoroughly evaluate the resulting techniques in various real-life repetitiveness scenarios, and recommend the best choices for each case.
Loss of locality in gravitational correlators with a large number of insertions

NASA Astrophysics Data System (ADS)

Ghosh, Sudip; Raju, Suvrat

2017-09-01

We review lessons from the AdS/CFT correspondence that indicate that the emergence of locality in quantum gravity is contingent upon considering observables with a small number of insertions. Correlation functions, where the number of insertions scales with a power of the central charge of the CFT, are sensitive to nonlocal effects in the bulk theory, which arise from a combination of the effects of the bulk Gauss law and a breakdown of perturbation theory. To examine whether a similar effect occurs in flat space, we consider the scattering of massless particles in the bosonic string and the superstring in the limit, where the number of external particles, n, becomes very large. We use estimates of the volume of the Weil-Petersson moduli space of punctured Riemann surfaces to argue that string amplitudes grow factorially in this limit. We verify this factorial behavior through an extensive numerical analysis of string amplitudes at large n. Our numerical calculations rely on the observation that, in the large n limit, the string scattering amplitude localizes on the Gross-Mende saddle points, even though individual particle energies are small. This factorial growth implies the breakdown of string perturbation theory for n ˜(M/plE ) d -2 in d dimensions, where E is the typical individual particle energy. We explore the implications of this breakdown for the black hole information paradox. We show that the loss of locality suggested by this breakdown is precisely sufficient to resolve the cloning and strong subadditivity paradoxes.
How far will a behaviourally flexible invasive bird go to innovate?

PubMed Central

Logan, Corina J.

2016-01-01

Behavioural flexibility is considered a key factor in the ability to adapt to changing environments. A traditional way of characterizing behavioural flexibility is to determine whether individuals invent solutions to novel problems, termed innovativeness. Great-tailed grackles are behaviourally flexible in that they can change their preferences when a task changes using existing behaviours; however, it is unknown how far they will go to invent solutions to novel problems. To begin to answer this question, I gave grackles two novel tests that a variety of other species can perform: stick tool use and string pulling. No grackle used a stick to access out-of-reach food, even after seeing a human demonstrate the solution. No grackle spontaneously pulled a vertically oriented string, but one did pull a horizontally oriented string twice. Additionally, a third novel test was previously conducted on these individuals and it was found that no grackle spontaneously dropped stones down a platform apparatus to release food, but six out of eight did become proficient after training. These results support the idea that behavioural flexibility is a multi-faceted trait because grackles are flexible, but not particularly innovative. This contradicts the idea that behavioural flexibility and innovativeness are interchangeable terms. PMID:27429781
U-folds as K3 fibrations

NASA Astrophysics Data System (ADS)

Braun, Andreas P.; Fucito, Francesco; Morales, Jose Francisco

2013-10-01

We study four-dimensional flux vacua describing intrinsic non- perturbative systems of 3 and 7 branes in type IIB string theory. The solutions are described as compactifications of a G(ravity) theory on a Calabi Yau threefold which consists of a fibration of an auxiliary K3 surface over an S 2 base. In the spirit of F-theory, the complex structure of the K3 surface varying over the base codifies the details of the fluxes, the dilaton and the warp factors in type IIB string theory. We discuss in detail some simple examples of geometric and non-geometric solutions where the precise flux/geometry dictionary can be explicitly worked out. In particular, we describe non-geometric T-fold solutions exhibiting non-trivial T-duality monodromies exchanging 3- and 7-branes.
Anisotropic Bianchi Type-I and Type-II Bulk Viscous String Cosmological Models Coupled with Zero Mass Scalar Field

NASA Astrophysics Data System (ADS)

Venkateswarlu, R.; Sreenivas, K.

2014-06-01

The LRS Bianchi type-I and type-II string cosmological models are studied when the source for the energy momentum tensor is a bulk viscous stiff fluid containing one dimensional strings together with zero-mass scalar field. We have obtained the solutions of the field equations assuming a functional relationship between metric coefficients when the metric is Bianchi type-I and constant deceleration parameter in case of Bianchi type-II metric. The physical and kinematical properties of the models are discussed in each case. The effects of Viscosity on the physical and kinematical properties are also studied.
Efficient parallel algorithms for string editing and related problems

NASA Technical Reports Server (NTRS)

Apostolico, Alberto; Atallah, Mikhail J.; Larmore, Lawrence; Mcfaddin, H. S.

1988-01-01

The string editing problem for input strings x and y consists of transforming x into y by performing a series of weighted edit operations on x of overall minimum cost. An edit operation on x can be the deletion of a symbol from x, the insertion of a symbol in x or the substitution of a symbol x with another symbol. This problem has a well known O((absolute value of x)(absolute value of y)) time sequential solution (25). The efficient Program Requirements Analysis Methods (PRAM) parallel algorithms for the string editing problem are given. If m = ((absolute value of x),(absolute value of y)) and n = max((absolute value of x),(absolute value of y)), then the CREW bound is O (log m log n) time with O (mn/log m) processors. In all algorithms, space is O (mn).
Minimal string theories and integrable hierarchies

NASA Astrophysics Data System (ADS)

Iyer, Ramakrishnan

Well-defined, non-perturbative formulations of the physics of string theories in specific minimal or superminimal model backgrounds can be obtained by solving matrix models in the double scaling limit. They provide us with the first examples of completely solvable string theories. Despite being relatively simple compared to higher dimensional critical string theories, they furnish non-perturbative descriptions of interesting physical phenomena such as geometrical transitions between D-branes and fluxes, tachyon condensation and holography. The physics of these theories in the minimal model backgrounds is succinctly encoded in a non-linear differential equation known as the string equation, along with an associated hierarchy of integrable partial differential equations (PDEs). The bosonic string in (2,2m-1) conformal minimal model backgrounds and the type 0A string in (2,4 m) superconformal minimal model backgrounds have the Korteweg-de Vries system, while type 0B in (2,4m) backgrounds has the Zakharov-Shabat system. The integrable PDE hierarchy governs flows between backgrounds with different m. In this thesis, we explore this interesting connection between minimal string theories and integrable hierarchies further. We uncover the remarkable role that an infinite hierarchy of non-linear differential equations plays in organizing and connecting certain minimal string theories non-perturbatively. We are able to embed the type 0A and 0B (A,A) minimal string theories into this single framework. The string theories arise as special limits of a rich system of equations underpinned by an integrable system known as the dispersive water wave hierarchy. We find that there are several other string-like limits of the system, and conjecture that some of them are type IIA and IIB (A,D) minimal string backgrounds. We explain how these and several other string-like special points arise and are connected. In some cases, the framework endows the theories with a non-perturbative definition for the first time. Notably, we discover that the Painleve IV equation plays a key role in organizing the string theory physics, joining its siblings, Painleve I and II, whose roles have previously been identified in this minimal string context. We then present evidence that the conjectured type II theories have smooth non-perturbative solutions, connecting two perturbative asymptotic regimes, in a 't Hooft limit. Our technique also demonstrates evidence for new minimal string theories that are not apparent in a perturbative analysis.
Quantum gravity in the Southern Cone Conference. Proceedings. Conference, Bariloche (Argentina), 7 - 10 Jan 1998.

NASA Astrophysics Data System (ADS)

1999-04-01

The following topics are discussed: Black hole formation by canonical dynamics of gravitating shells; canonical quantum gravity; Vassiliev invariants; midisuperspace models; quantum spacetime; large-N limit of superconformal field theories and supergravity; world-volume fields and background coupling of branes; gauge enhancement and chirality changes in nonperturbative orbifold models; chiral p-forms; formally renormalizable gravitationally self-interacting string models; gauge supergravities for all odd dimensions; black hole radiation and S-matrix; primordial black holes; fluctuations in a thermal field and dissipation of a black hole spacetime in far-field limit; adiabatic interpretation of particle creation in a de Sitter universe; nonequilibrium dynamics of quantum fields in inflationary cosmology; magnetic fields in the early Universe; classical regime of a quantum universe obtained through a functional method; decoherence and correlations in semiclassical cosmology; fluid of primordial fluctuations; causal statistical mechanics calculation of initial cosmic entropy and quantum gravity prospects and black hole-D-brane correspondence.
Meissner effect for axially symmetric charged black holes

NASA Astrophysics Data System (ADS)

Gürlebeck, Norman; Scholtz, Martin

2018-04-01

In our previous work [N. Gürlebeck and M. Scholtz, Phys. Rev. D 95, 064010 (2017), 10.1103/PhysRevD.95.064010], we have shown that electric and magnetic fields are expelled from the horizons of extremal, stationary and axially symmetric uncharged black holes; this is called the Meissner effect for black holes. Here, we generalize this result in several directions. First, we allow that the black hole carries charge, which requires a generalization of the definition of the Meissner effect. Next, we introduce the notion of almost isolated horizons, which is weaker than the usual notion of isolated horizons, since the geometry of the former is not necessarily completely time independent. Moreover, we allow the horizon to be pierced by strings, thereby violating the usual assumption on the spherical topology made in the definition of the weakly isolated horizon. Finally, we spell out in detail all assumptions entering the proof and show that the Meissner effect is an inherent property of black holes even in full nonlinear theory.
Black holes and fundamental fields: Hair, kicks, and a gravitational Magnus effect

NASA Astrophysics Data System (ADS)

Okawa, Hirotada; Cardoso, Vitor

2014-11-01

Scalar fields pervade theoretical physics and are a fundamental ingredient to solve the dark matter problem, to realize the Peccei-Quinn mechanism in QCD or the string-axiverse scenario. They are also a useful proxy for more complex matter interactions, such as accretion disks or matter in extreme conditions. Here, we study the collision between scalar "clouds" and rotating black holes. For the first time we are able to compare analytic estimates and strong field, nonlinear numerical calculations for this problem. As the black hole pierces through the cloud it accretes according to the Bondi-Hoyle prediction, but is deflected through a purely kinematic gravitational "anti-Magnus" effect, which we predict to be present also during the interaction of black holes with accretion disks. After the interaction is over, we find large recoil velocities in the transverse direction. The end-state of the process belongs to the vacuum Kerr family if the scalar is massless, but can be a hairy black hole when the scalar is massive.
Sexual Partner Type Taxonomy Use Among Black Adolescent Mothers in the United States

PubMed Central

Nelson, LaRon E.; Morrison-Beedy, Dianne; Kearney, Margaret H.; Dozier, Ann

2013-01-01

Purpose Research on sexual-partner type focuses mostly on “main” and “casual” partner categories. The literature indicates that adolescent girls are less likely to use condoms with main partners, and more likely to use condoms with casual partners. Adolescent mothers may have different types of sexual partners than other adolescent girls. The purpose of this study was to explore and describe the range of male sexual partner types reported by Black adolescent mothers. Design and Sample This study was a qualitative description of the perspectives of Black, predominantly African-American, mothers (n=31). Data were generated using focus groups and interviews. The participants' ages ranged from 15–19 years. Measures A semi-structured qualitative questioning guide was used to stimulate focused discussions. Transcribed data were analyzed using qualitative content analysis. Results The range of sexual partner types of the women were reflected in three themes (1) All main partners are not created equal; (2) They're not casual partners because there are strings attached; (3) “Wham, bam, thank you ma'am:” No strings attached. Nine partner types were identified under these three themes, including a “baby daddy” partner. Conclusion The partner-types of Black adolescent mothers are more robust than the “main” and “casual” partner categories typically referenced in the research literature. The range of sex partners includes the birth fathers of their children. Clinicians and researchers must consider how co-parenthood status is used in the construction of the “baby daddy” partner and what implications this unique sexual partner type may have on risk reduction behaviors such as condom use. PMID:25382990
Open/closed string duality and relativistic fluids

NASA Astrophysics Data System (ADS)

Niarchos, Vasilis

2016-07-01

We propose an open/closed string duality in general backgrounds extending previous ideas about open string completeness by Ashoke Sen. Our proposal sets up a general version of holography that works in gravity as a tomographic principle. We argue, in particular, that previous expectations of a supergravity/Dirac-Born-Infeld (DBI) correspondence are naturally embedded in this conjecture and can be tested in a well-defined manner. As an example, we consider the correspondence between open string field theories on extremal D-brane setups in flat space in the large-N , large 't Hooft limit, and asymptotically flat solutions in ten-dimensional type II supergravity. We focus on a convenient long-wavelength regime, where specific effects of higher-spin open string modes can be traced explicitly in the dual supergravity computation. For instance, in this regime we show how the full Abelian DBI action arises from supergravity as a straightforward reformulation of relativistic hydrodynamics. In the example of a (2 +1 )-dimensional open string theory this reformulation involves an Abelian Hodge duality. We also point out how different deformations of the DBI action, related to higher-derivative corrections and non-Abelian effects, can arise in this context as deformations in corresponding relativistic hydrodynamics.
Wormholes and Child Universes

NASA Astrophysics Data System (ADS)

Guendelman, E. I.

Evidence to the case that classical gravitation provides the clue to make sense out of quantum gravity is presented. The key observation is the existence in classical gravitation of child universe solutions or "almost" solutions, "almost" because of some singularity problems. The difficulties of these child universe solutions that are due to their generic singularity problems will be very likely be cured by quantum effects, just like for example "almost" instanton solutions are made relevant in gauge theories with the breaking of conformal invariance. Some well-motivated modifcations of general relativity where these singularity problems are absent even at the classical level are discussed. High energy density excitations, responsible for UV divergences in quantum field theories, including quantum gravity, are likely to be the source of child universes which carry them out of the original space-time. This decoupling could prevent these high UV excitations from having any influence on physical amplitudes. Child universe production could therefore be responsible for UV regularization in quantum field theories which take into account semiclassically gravitational effects. Child universe production in the last stages of black hole evaporation, the prediction of absence of trans-Planckian primordial perturbations, connection to the minimum length hypothesis, and in particular the connection to the maximal curvature hypothesis are discussed. Some discussion of superexcited states in the case these states such as Kaluza-Klein excitations are carried out. Finally, the possibility of obtaining "string like" effects from the wormholes associated with the child universes is discussed.
Arizona State's Origins Project Starts with a Big Bang

ERIC Educational Resources Information Center

Mangan, Katherine

2009-01-01

For 12 hours at Arizona State University, a sold-out crowd of 3,000 people gave a group of famous scientists a pop-star welcome, cheering their remarks and lining up for autographs after a day full of discussion about black holes, string theory, and evolutionary biology. At a time when program cuts and faculty layoffs dominate the headlines of…
Q&A: Brian Greene on music and string theory

NASA Astrophysics Data System (ADS)

Hoffman, Jascha

2010-05-01

Brian Greene, author of best-selling books The Elegant Universe and The Fabric of the Cosmos, is a theoretical physicist at Columbia University, New York. As an orchestral work based on his 2008 children's book, Icarus at the Edge of Time, premieres next week, Greene discusses black holes and how music might portray the physics of warped space-time.
Super-light baryo-photons, weak gravity conjecture and exotic instantons in neutron-antineutron transitions

NASA Astrophysics Data System (ADS)

Addazi, Andrea

2018-05-01

In companion papers (A. Addazi, Nuovo Cim. C, 38(1): 21 (2015); A. Addazi, Z. Berezhiani, and Y. Kamyshkov, arXiv:1607.00348), we have discussed current bounds on a new super-light baryo-photon, associated with a U(1) B-L gauge, from current neutron-antineutron data, which are competitive with Eötvös-type experiments. Here, we discuss the implications of possible baryo-photon detection in string theory and quantum gravity. The discovery of a very light gauge boson should imply violation of the weak gravity conjecture, carrying deep consequences for our understanding of holography, quantum gravity and black holes. We also show how the detection of a baryo-photon would exclude the generation of all B–L violating operators from exotic stringy instantons. We will argue against the common statement in the literature that neutron-antineutron data may indirectly test at least the 300–1000 TeV scale. Searches for baryo-photons can provide indirect information on the Planck (or string) scale (quantum black holes, holography and non-perturbative stringy effects). This strongly motivates new neutron-antineutron experiments with adjustable magnetic fields dedicated to the detection of super-light baryo-photons.
The 6D superswirl

NASA Astrophysics Data System (ADS)

Parameswaran, S. L.; Tasinato, G.; Zavala, I.

2006-03-01

We present a novel supersymmetric solution to a nonlinear sigma model coupled to supergravity. The solution represents a static, supersymmetric, codimension-two object, which is different to the familiar cosmic strings. In particular, we consider 6D chiral gauged supergravity, whose spectrum contains a number of hypermultiplets. The scalar components of the hypermultiplet are charged under a gauge field, and supersymmetry implies that they experience a simple paraboloid-like (or 2D infinite well) potential, which is minimised when they vanish. Unlike conventional vortices, the energy density of our configuration is not localized to a string-like core. The solutions have two timelike singularities in the internal manifold, which provide the necessary boundary conditions to ensure that the scalars do not lie at the minimum of their potential. The 4D spacetime is flat, and the solution is a continuous deformation of the so-called "rugby ball" solution, which has been studied in the context of the cosmological constant problem. It represents an unexpected class of supersymmetric solutions to the 6D theory, which have gravity, gauge fluxes and hyperscalars all active in the background.

Aspects of neutrino oscillation in alternative gravity theories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chakraborty, Sumanta, E-mail: sumantac.physics@gmail.com

2015-10-01

Neutrino spin and flavour oscillation in curved spacetime have been studied for the most general static spherically symmetric configuration. Having exploited the spherical symmetry we have confined ourselves to the equatorial plane in order to determine the spin and flavour oscillation frequency in this general set-up. Using the symmetry properties we have derived spin oscillation frequency for neutrino moving along a geodesic or in a circular orbit. Starting from the expression of neutrino spin oscillation frequency we have shown that even in this general context, in high energy limit the spin oscillation frequency for neutrino moving along circular orbit vanishes.more » We have verified previous results along this line by transforming to Schwarzschild coordinates under appropriate limit. This finally lends itself to the probability of neutrino helicity flip which turns out to be non-zero. While for neutrino flavour oscillation we have derived general results for oscillation phase, which subsequently have been applied to three different gravity theories. One, of them appears as low-energy approximation to string theory, where we have an additional field, namely, dilaton field coupled to Maxwell field tensor. This yields a realization of Reissner-Nordström solution in string theory at low-energy. Next one corresponds to generalization of Schwarzschild solution by introduction of quadratic curvature terms of all possible form to the Einstein-Hilbert action. Finally, we have also discussed regular black hole solutions. In all these cases the flavour oscillation probabilities can be determined for solar neutrinos and thus can be used to put bounds on the parameters of these gravity theories. While for spin oscillation probability, we have considered two cases, Gauss-Bonnet term added to the Einstein-Hilbert action and the f(R) gravity theory. In both these cases we could impose bounds on the parameters which are consistent with previous considerations. In a nutshell, in this work we have presented both spin and flavour oscillation frequency of neutrino in most general static spherically symmetric spacetime, encompassing a vast class of solutions, which when applied to three such instances in alternative theories for flavour oscillation and two alternative theories for spin oscillation put bounds on the parameters of these theories. Implications are also discussed.« less
Exact quantum numbers of collapsed and non-collapsed two-string solutions in the spin-1/2 Heisenberg spin chain

NASA Astrophysics Data System (ADS)

Deguchi, Tetsuo; Ranjan Giri, Pulak

2016-04-01

Every solution of the Bethe-ansatz equations (BAEs) is characterized by a set of quantum numbers, by which we can evaluate it numerically. However, no general rule is known how to give quantum numbers for the physical solutions of BAE. For the spin-1/2 XXX chain we rigorously derive all the quantum numbers for the complete set of the Bethe-ansatz eigenvectors in the two down-spin sector with any chain length N. Here we obtain them both for real and complex solutions. We also show that all the solutions associated with them are distinct. Consequently, we prove the completeness of the Bethe ansatz and give an exact expression for the number of real solutions which correspond to collapsed bound-state solutions (i.e., two-string solutions) in the sector: 2[(N-1)/2-(N/π ){{tan}}-1(\\sqrt{N-1})] in terms of Gauss’ symbol. Moreover, we prove in the sector the scheme conjectured by Takahashi for solving BAE systematically. We also suggest that by applying the present method we can derive the quantum numbers for the spin-1/2 XXZ chain.
Bifurcation analysis and phase diagram of a spin-string model with buckled states.

PubMed

Ruiz-Garcia, M; Bonilla, L L; Prados, A

2017-12-01

We analyze a one-dimensional spin-string model, in which string oscillators are linearly coupled to their two nearest neighbors and to Ising spins representing internal degrees of freedom. String-spin coupling induces a long-range ferromagnetic interaction among spins that competes with a spin-spin antiferromagnetic coupling. As a consequence, the complex phase diagram of the system exhibits different flat rippled and buckled states, with first or second order transition lines between states. This complexity translates to the two-dimensional version of the model, whose numerical solution has been recently used to explain qualitatively the rippled to buckled transition observed in scanning tunneling microscopy experiments with suspended graphene sheets. Here we describe in detail the phase diagram of the simpler one-dimensional model and phase stability using bifurcation theory. This gives additional insight into the physical mechanisms underlying the different phases and the behavior observed in experiments.
Hadronic density of states from string theory.

PubMed

Pando Zayas, Leopoldo A; Vaman, Diana

2003-09-12

We present an exact calculation of the finite temperature partition function for the hadronic states corresponding to a Penrose-Güven limit of the Maldacena-Nùñez embedding of the N=1 super Yang-Mills (SYM) into string theory. It is established that the theory exhibits a Hagedorn density of states. We propose a semiclassical string approximation to the finite temperature partition function for confining gauge theories admitting a supergravity dual, by performing an expansion around classical solutions characterized by temporal windings. This semiclassical approximation reveals a hadronic energy density of states of a Hagedorn type, with the coefficient determined by the gauge theory string tension as expected for confining theories. We argue that our proposal captures primarily information about states of pure N=1 SYM theory, given that this semiclassical approximation does not entail a projection onto states of large U(1) charge.
Automorphic properties of low energy string amplitudes in various dimensions

NASA Astrophysics Data System (ADS)

Green, Michael B.; Russo, Jorge G.; Vanhove, Pierre

2010-04-01

This paper explores the moduli-dependent coefficients of higher-derivative interactions that appear in the low-energy expansion of the four-supergraviton amplitude of maximally supersymmetric string theory compactified on a d torus. These automorphic functions are determined for terms up to order ∂6R4 and various values of d by imposing a variety of consistency conditions. They satisfy Laplace eigenvalue equations with or without source terms, whose solutions are given in terms of Eisenstein series, or more general automorphic functions, for certain parabolic subgroups of the relevant U-duality groups. The ultraviolet divergences of the corresponding supergravity field theory limits are encoded in various logarithms, although the string theory expressions are finite. This analysis includes intriguing representations of SL(d) and SO(d,d) Eisenstein series in terms of toroidally compactified one and two-loop string and supergravity amplitudes.
Ambitwistor Strings in Four Dimensions

NASA Astrophysics Data System (ADS)

Geyer, Yvonne; Lipstein, Arthur E.; Mason, Lionel

2014-08-01

We develop ambitwistor string theories for four dimensions to obtain new formulas for tree-level gauge and gravity amplitudes with arbitrary amounts of supersymmetry. Ambitwistor space is the space of complex null geodesics in complexified Minkowski space, and in contrast to earlier ambitwistor strings, we use twistors rather than vectors to represent this space. Although superficially similar to the original twistor string theories of Witten, Berkovits, and Skinner, these theories differ in the assignment of world sheet spins of the fields, rely on both twistor and dual twistor representatives for the vertex operators, and use the ambitwistor procedure for calculating correlation functions. Our models are much more flexible, no longer requiring maximal supersymmetry, and the resulting formulas for amplitudes are simpler, having substantially reduced moduli. These are supported on the solutions to the scattering equations refined according to helicity and can be checked by comparison with corresponding formulas of Witten and of Cachazo and Skinner.
Bifurcation analysis and phase diagram of a spin-string model with buckled states

NASA Astrophysics Data System (ADS)

Ruiz-Garcia, M.; Bonilla, L. L.; Prados, A.

2017-12-01

We analyze a one-dimensional spin-string model, in which string oscillators are linearly coupled to their two nearest neighbors and to Ising spins representing internal degrees of freedom. String-spin coupling induces a long-range ferromagnetic interaction among spins that competes with a spin-spin antiferromagnetic coupling. As a consequence, the complex phase diagram of the system exhibits different flat rippled and buckled states, with first or second order transition lines between states. This complexity translates to the two-dimensional version of the model, whose numerical solution has been recently used to explain qualitatively the rippled to buckled transition observed in scanning tunneling microscopy experiments with suspended graphene sheets. Here we describe in detail the phase diagram of the simpler one-dimensional model and phase stability using bifurcation theory. This gives additional insight into the physical mechanisms underlying the different phases and the behavior observed in experiments.
Dynamics with infinitely many time derivatives in Friedmann-Robertson-Walker background and rolling tachyons

NASA Astrophysics Data System (ADS)

Joukovskaya, Liudmila

2009-02-01

Dynamics with infinitely many time derivatives has place in string field theory and have been profoundly investigated there. Recently there has been considerable interest in theories with infinitely many derivatives in the cosmological context in view of new features which these theories might accommodate owing to nonlocal interaction. In present work we continue investigation of such models, as a concrete example we study the dynamics of unstable D-brane in the open string theory in the Friedmann-Robertson-Walker background. We construct numerical solutions describing dynamical interpolation between the perturbative and non-perturbative vacua. The obtained solutions have several interesting properties and might be of interest from the cosmological points of view.
BOOK REVIEW: Quantum Gravity (2nd edn)

NASA Astrophysics Data System (ADS)

Husain, Viqar

2008-06-01

There has been a flurry of books on quantum gravity in the past few years. The first edition of Kiefer's book appeared in 2004, about the same time as Carlo Rovelli's book with the same title. This was soon followed by Thomas Thiemann's 'Modern Canonical Quantum General Relativity'. Although the main focus of each of these books is non-perturbative and non-string approaches to the quantization of general relativity, they are quite orthogonal in temperament, style, subject matter and mathematical detail. Rovelli and Thiemann focus primarily on loop quantum gravity (LQG), whereas Kiefer attempts a broader introduction and review of the subject that includes chapters on string theory and decoherence. Kiefer's second edition attempts an even wider and somewhat ambitious sweep with 'new sections on asymptotic safety, dynamical triangulation, primordial black holes, the information-loss problem, loop quantum cosmology, and other topics'. The presentation of these current topics is necessarily brief given the size of the book, but effective in encapsulating the main ideas in some cases. For instance the few pages devoted to loop quantum cosmology describe how the mini-superspace reduction of the quantum Hamiltonian constraint of LQG becomes a difference equation, whereas the discussion of 'dynamical triangulations', an approach to defining a discretized Lorentzian path integral for quantum gravity, is less detailed. The first few chapters of the book provide, in a roughly historical sequence, the covariant and canonical metric variable approach to the subject developed in the 1960s and 70s. The problem(s) of time in quantum gravity are nicely summarized in the chapter on quantum geometrodynamics, followed by a detailed and effective introduction of the WKB approach and the semi-classical approximation. These topics form the traditional core of the subject. The next three chapters cover LQG, quantization of black holes, and quantum cosmology. Of these the chapter on LQG is the shortest at fourteen pages—a reflection perhaps of the fact that there are two books and a few long reviews of the subject available written by the main protagonists in the field. The chapters on black holes and cosmology provide a more or less standard introduction to black hole thermodynamics, Hawking and Unruh radiation, quantization of the Schwarzschild metric and mini-superspace collapse models, and the DeWitt, Hartle Hawking and Vilenkin wavefunctions. The chapter on string theory is an essay-like overview of its quantum gravitational aspects. It provides a nice introduction to selected ideas and a guide to the literature. Here a prescient student may be left wondering why there is no quantum cosmology in string theory, perhaps a deliberate omission to avoid the 'landscape' and its fauna. In summary, I think this book succeeds in its purpose of providing a broad introduction to quantum gravity, and nicely complements some of the other books on the subject.
Actions for particles and strings and Chern-Simons gravity

NASA Astrophysics Data System (ADS)

Jiusi, Lei; Nair, V. P.

2017-09-01

We consider actions for particles and strings, including twistorial descriptions on 4D Minkowski and AdS5 spacetimes from the point of view of coadjoint orbits for the isometry group. We also consider the collective coordinate dynamics of singular solutions in Chern-Simons (CS) theories and CS theories of gravity. This is a generalization of the work of Einstein, Infeld, and Hoffmann and also has potential points of contact with fluid-gravity correspondence.
Higher winding strings and confined monopoles in N=2 supersymmetric QCD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Auzzi, R.; Bolognesi, S.; Shifman, M.

2010-04-15

We consider composite string solutions in N=2 SQCD with the gauge group U(N), the Fayet-Iliopoulos term {xi}{ne}0 and N (s)quark flavors. These bulk theories support non-Abelian strings and confined monopoles identified with kinks in the two-dimensional world-sheet theory. Similar and more complicated kinks (corresponding to composite confined monopoles) must exist in the world-sheet theories on composite strings. In a bid to detect them we analyze the Hanany-Tong (HT) model, focusing on a particular example of N=2. Unequal quark mass terms in the bulk theory result in the twisted masses in the N=(2,2) HT model. For spatially coinciding 2-strings, we findmore » three distinct minima of potential energy, corresponding to three different 2-strings. Then we find BPS-saturated kinks interpolating between each pair of vacua. Two kinks can be called elementary. They emanate one unit of the magnetic flux and have the same mass as the conventional 't Hooft-Polyakov monopole on the Coulomb branch of the bulk theory ({xi}=0). The third kink represents a composite bimonopole, with twice the minimal magnetic flux. Its mass is twice the mass of the elementary confined monopole. We find instantons in the HT model, and discuss quantum effects in composite strings at strong coupling. In addition, we study the renormalization group flow in this model.« less
Singularity resolution in string theory and new quantum condensed matter phases

NASA Astrophysics Data System (ADS)

Fidkowski, Lukasz

2007-12-01

In the first part of this thesis (chapters 1 through 4) we study singularity resolution in string theory. We employ an array of techniques, including the AdS-CFT correspondence, exact solvability of low dimensional models, and supersymmetry. We are able to detect a signature of the black hole singularity by analytically continuing certain AdS-CFT correlators. Also in AdS-CFT, we are able to study a D-brane snapping transition on both sides of the correspondence. In the second part (chapters 5 through 7) we study topological phases in condensed matter systems. We investigate theoretical lattice models realizing such phases, use these to derive nontrivial mathematical physics results, and study an idealized quantum interferometer designed to detect such a phase in quantum Hall systems.
European Pulsar Timing Array limits on an isotropic stochastic gravitational-wave background

NASA Astrophysics Data System (ADS)

Lentati, L.; Taylor, S. R.; Mingarelli, C. M. F.; Sesana, A.; Sanidas, S. A.; Vecchio, A.; Caballero, R. N.; Lee, K. J.; van Haasteren, R.; Babak, S.; Bassa, C. G.; Brem, P.; Burgay, M.; Champion, D. J.; Cognard, I.; Desvignes, G.; Gair, J. R.; Guillemot, L.; Hessels, J. W. T.; Janssen, G. H.; Karuppusamy, R.; Kramer, M.; Lassus, A.; Lazarus, P.; Liu, K.; Osłowski, S.; Perrodin, D.; Petiteau, A.; Possenti, A.; Purver, M. B.; Rosado, P. A.; Smits, R.; Stappers, B.; Theureau, G.; Tiburzi, C.; Verbiest, J. P. W.

2015-11-01

We present new limits on an isotropic stochastic gravitational-wave background (GWB) using a six pulsar data set spanning 18 yr of observations from the 2015 European Pulsar Timing Array data release. Performing a Bayesian analysis, we fit simultaneously for the intrinsic noise parameters for each pulsar, along with common correlated signals including clock, and Solar system ephemeris errors, obtaining a robust 95 per cent upper limit on the dimensionless strain amplitude A of the background of A < 3.0 × 10-15 at a reference frequency of 1 yr-1 and a spectral index of 13/3, corresponding to a background from inspiralling supermassive black hole binaries, constraining the GW energy density to Ωgw(f)h2 < 1.1 × 10-9 at 2.8 nHz. We also present limits on the correlated power spectrum at a series of discrete frequencies, and show that our sensitivity to a fiducial isotropic GWB is highest at a frequency of ˜5 × 10-9 Hz. Finally, we discuss the implications of our analysis for the astrophysics of supermassive black hole binaries, and present 95 per cent upper limits on the string tension, Gμ/c2, characterizing a background produced by a cosmic string network for a set of possible scenarios, and for a stochastic relic GWB. For a Nambu-Goto field theory cosmic string network, we set a limit Gμ/c2 < 1.3 × 10-7, identical to that set by the Planck Collaboration, when combining Planck and high-ℓ cosmic microwave background data from other experiments. For a stochastic relic background, we set a limit of Ω ^relic_gw(f)h^2<1.2 × 10^{-9}, a factor of 9 improvement over the most stringent limits previously set by a pulsar timing array.
EDITORIAL: Lectures from the European RTN Winter School on Strings, Supergravity and Gauge Theories, CERN, 21 25 January 2008

NASA Astrophysics Data System (ADS)

Derendinger, J.-P.; Orlando, D.; Uranga, A.

2008-11-01

This special issue is devoted to the proceedings of the conference 'RTN Winter School on Strings, Supergravity and Gauge Theories', which took place at CERN, the European Centre for Nuclear Research, in Geneva, Switzerland, on the 21 25 January 2008. This event was organized in the framework of the European Mobility Research and Training Network entitled 'Constituents, Fundamental Forces and Symmetries of the Universe'. It is part of a yearly series of scientific schools, which represents what is by now a well established tradition. The previous ones have been held at SISSA, in Trieste, Italy, in February 2005 and at CERN in January 2006. The next one will again take place at CERN, in February 2009. The school was primarily meant for young doctoral students and postdoctoral researchers working in the area of string theory. It consisted of several general lectures of four hours each, whose notes are published in the present proceedings, and five working group discussion sessions, focused on specific topics of the network research program. It was attended by approximatively 250 participants. The topics of the lectures were chosen to provide an introduction to some of the areas of recent progress, and to the open problems, in string theory. One of the most active areas in string theory in recent years is the AdS/CFT or gauge/gravity correspondence, which proposes the complete equivalence of string theory on (asymptotically) anti-de Sitter spacetimes with gauge theories. The duality relates the weak coupling regime of one system to the strongly coupled regime of the other, and is therefore very non-trivial to test beyond the supersymmetry-protected BPS sector. One of the key ideas to quantitatively match several quantities on both sides is the use of integrability, both in the gauge theory and the string side. The lecture notes by Nick Dorey provide a pedagogical introduction to the fascinating topic of integrability in AdS/CFT. On the string theory side, progress has been limited by the difficulties of quantizing the worldsheet theory in the presence of RR backgrounds. There is increasing hope that these difficulties can be overcome, using the pure spinor formulation of string theory. The lectures by Yaron Oz overview the present status of this proposal. The gauge/gravity correspondence is already leading to important insights into questions of quantum gravity, like the entropy of black holes and its interpretation in terms of microstates. These questions can be addressed in string theory, for certain classes of supersymmetric black holes. The lectures by Vijay Balasubramanian, Jan de Boer, Sheer El-Showk and Ilies Messamah review recent progress in this direction. Throughout the years, formal developments in string theory have systematically led to improved understanding on how it may relate to nature. In this respect, the lectures by Henning Samtleben describe how the formal developments on gauged supergravities can be used to describe compactification vacua in string theory, and their implications for moduli stabilization and supersymmetry breaking. Indeed, softly broken supersymmetry is one of the leading proposals to describe particle physics at the TeV energy range, as described in the lectures by Gian Giudice (not covered in this issue). This connection with TeV scale physics is most appropriate and timely, given that this energy range will shortly become experimentally accessible in the LHC at CERN. The conference was financially supported by the European Commission under contract MRTN-CT-2004-005104 and by CERN. It was jointly organized by the Physics Institute of the University of Neuchâtel and the Theory Unit of the Physics Division of CERN. It is a great pleasure for us to warmly thank the Theory Unit of CERN for its very kind hospitality and for the high quality of the assistance and the infrastructure that it has provided. We also acknowledge helpful administrative assistance from the Physics Institute of the University of Neuchâtel. Special thanks also go to Denis Frank, for his very valuable help in preparing the conference web pages. Group photo
Black hole and cosmos with multiple horizons and multiple singularities in vector-tensor theories

NASA Astrophysics Data System (ADS)

Gao, Changjun; Lu, Youjun; Yu, Shuang; Shen, You-Gen

2018-05-01

A stationary and spherically symmetric black hole (e.g., Reissner-Nordström black hole or Kerr-Newman black hole) has, at most, one singularity and two horizons. One horizon is the outer event horizon and the other is the inner Cauchy horizon. Can we construct static and spherically symmetric black hole solutions with N horizons and M singularities? The de Sitter cosmos has only one apparent horizon. Can we construct cosmos solutions with N horizons? In this article, we present the static and spherically symmetric black hole and cosmos solutions with N horizons and M singularities in the vector-tensor theories. Following these motivations, we also construct the black hole solutions with a firewall. The deviation of these black hole solutions from the usual ones can be potentially tested by future measurements of gravitational waves or the black hole continuum spectrum.
A combinatorial approach to the design of vaccines.

PubMed

Martínez, Luis; Milanič, Martin; Legarreta, Leire; Medvedev, Paul; Malaina, Iker; de la Fuente, Ildefonso M

2015-05-01

We present two new problems of combinatorial optimization and discuss their applications to the computational design of vaccines. In the shortest λ-superstring problem, given a family S1,...,S(k) of strings over a finite alphabet, a set Τ of "target" strings over that alphabet, and an integer λ, the task is to find a string of minimum length containing, for each i, at least λ target strings as substrings of S(i). In the shortest λ-cover superstring problem, given a collection X1,...,X(n) of finite sets of strings over a finite alphabet and an integer λ, the task is to find a string of minimum length containing, for each i, at least λ elements of X(i) as substrings. The two problems are polynomially equivalent, and the shortest λ-cover superstring problem is a common generalization of two well known combinatorial optimization problems, the shortest common superstring problem and the set cover problem. We present two approaches to obtain exact or approximate solutions to the shortest λ-superstring and λ-cover superstring problems: one based on integer programming, and a hill-climbing algorithm. An application is given to the computational design of vaccines and the algorithms are applied to experimental data taken from patients infected by H5N1 and HIV-1.
Landau quantization in the spinning cosmic string spacetime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muniz, C.R., E-mail: celiomuniz@yahoo.com; Bezerra, V.B.; Cunha, M.S.

2014-11-15

We analyze the quantum phenomenon arising from the interaction of a spinless charged particle with a rotating cosmic string, under the action of a static and uniform magnetic field parallel to the string. We calculate the energy levels of the particle in the non-relativistic approach, showing how these energies depend on the parameters involved in the problem. In order to do this, we solve the time independent Schrödinger equation in the geometry of the spinning cosmic string, taking into account that the coupling between the rotation of the spacetime and the angular momentum of the particle is very weak, suchmore » that makes sense to apply the Schrödinger equation in a curved background whose metric has an off diagonal term which involves time and space. It is also assumed that the particle orbits sufficiently far from the boundary of the region of closed timelike curves which exist around this topological defect. Finally, we find the Landau levels of the particle in the presence of a spinning cosmic string endowed with internal structure, i.e., having a finite width and uniformly filled with both material and vacuum energies. - Highlights: • Solution of the wave equation characterizing the problem. • Energy levels of the particle in spacetime of the structureless string. • Expression for an analogous of the quadratic Zeeman effect. • Energy levels of the particle in spacetime of the string with internal structure. • Evidence of the string structure by the internal existence of the vacuum energy.« less
Description of the heterotic string solutions in U(N) supersymmetric QCD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bolokhov, P. A.; Theoretical Physics Department, St. Petersburg State University, Ulyanovskaya 1, Peterhof, St. Petersburg, 198504; Shifman, M.

2009-04-15

We continue the study of heterotic non-Abelian Bogomol'nyi-Prasad-Sommerfield-saturated flux tubes (strings). Previously, such solutions were obtained [M. Shifman and A. Yung, Phys. Rev. D 77, 125016 (2008).] in a particular U(2) gauge theory: N=2 supersymmetric QCD deformed by superpotential terms of a special type breaking N=2 supersymmetry down to N=1. Here we generalize the previous results to U(N) gauge theories. As was suggested by Edalati and Tong [M. Edalati and D. Tong, J. High Energy Phys. 05 (2007) 005.], the string world-sheet theory is a heterotic N=(0,2) sigma model, with the CP(N-1) target space for bosonic fields and an extramore » right-handed fermion which couples to the fermion fields of the N=(2,2) CP(N-1) model. We derive the heterotic N=(0,2) world-sheet model directly from the U(N) bulk theory. Parameters of the bulk theory are related to those of the world-sheet theory. Qualitatively this relation turns out to be the same as in the U(2) case.« less
Numerical solution of open string field theory in Schnabl gauge

NASA Astrophysics Data System (ADS)

Arroyo, E. Aldo; Fernandes-Silva, A.; Szitas, R.

2018-01-01

Using traditional Virasoro L 0 level-truncation computations, we evaluate the open bosonic string field theory action up to level (10 , 30). Extremizing this level-truncated potential, we construct a numerical solution for tachyon condensation in Schnabl gauge. We find that the energy associated to the numerical solution overshoots the expected value -1 at level L = 6. Extrapolating the level-truncation data for L ≤ 10 to estimate the vacuum energies for L > 10, we predict that the energy reaches a minimum value at L ˜ 12, and then turns back to approach -1 asymptotically as L → ∞. Furthermore, we analyze the tachyon vacuum expectation value (vev), for which by extrapolating its corresponding level-truncation data, we predict that the tachyon vev reaches a minimum value at L ˜ 26, and then turns back to approach the expected analytical result as L → ∞.
Quasinormal Modes of Charged Dilaton Black Holes and Their Entropy Spectra

NASA Astrophysics Data System (ADS)

Sakalli, I.

2013-08-01

In this study, we employ the scalar perturbations of the charged dilaton black hole (CDBH) found by Chan, Horne and Mann (CHM), and described with an action which emerges in the low-energy limit of the string theory. A CDBH is neither asymptotically flat (AF) nor non-asymptotically flat (NAF) spacetime. Depending on the value of its dilaton parameter a, it has both Schwarzschild and linear dilaton black hole (LDBH) limits. We compute the complex frequencies of the quasinormal modes (QNMs) of the CDBH by considering small perturbations around its horizon. By using the highly damped QNM in the process prescribed by Maggiore, we obtain the quantum entropy and area spectra of these black holes (BHs). Although the QNM frequencies are tuned by a, we show that the quantum spectra do not depend on a, and they are equally spaced. On the other hand, the obtained value of undetermined dimensionless constant ɛ is the double of Bekenstein's result. The possible reason of this discrepancy is also discussed.

Comments on real tachyon vacuum solution without square roots

NASA Astrophysics Data System (ADS)

Arroyo, E. Aldo

2018-01-01

We analyze the consistency of a recently proposed real tachyon vacuum solution without square roots in open bosonic string field theory. We show that the equation of motion contracted with the solution itself is satisfied. Additionally, by expanding the solution in the basis of the curly ℒ0 and the traditional L 0 eigenstates, we evaluate numerically the vacuum energy and obtain a result in agreement with Sen's conjecture.
Gravitational quasinormal modes of static Einstein-Gauss-Bonnet anti-de Sitter black holes

NASA Astrophysics Data System (ADS)

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)
DOE Office of Scientific and Technical Information (OSTI.GOV)

Degrand, Thomas

The Theoretical Advanced Study Institute was held at the University of Colorado, Boulder, during June 1 - 26, 2015. The topic was "New Frontiers in Fields and Strings." Topics included many discussions of entanglement entropy, the conformal bootstrap, AdS/CFT techniques and applications, cosmology, and the black hole information problem. The organizers were Professors Joseph Polchinski (KITP Santa Barbara) and Pedro Vieira (Perimeter Institute). Sixty-one students heard sixty-two lectures by sixteen lecturers. A Proceedings is in press.
Physical interpretation of antigravity

NASA Astrophysics Data System (ADS)

Bars, Itzhak; James, Albin

2016-02-01

Geodesic incompleteness is a problem in both general relativity and string theory. The Weyl-invariant Standard Model coupled to general relativity (SM +GR ), and a similar treatment of string theory, are improved theories that are geodesically complete. A notable prediction of this approach is that there must be antigravity regions of spacetime connected to gravity regions through gravitational singularities such as those that occur in black holes and cosmological bang/crunch. Antigravity regions introduce apparent problems of ghosts that raise several questions of physical interpretation. It was shown that unitarity is not violated, but there may be an instability associated with negative kinetic energies in the antigravity regions. In this paper we show that the apparent problems can be resolved with the interpretation of the theory from the perspective of observers strictly in the gravity region. Such observers cannot experience the negative kinetic energy in antigravity directly, but can only detect in and out signals that interact with the antigravity region. This is no different from a spacetime black box for which the information about its interior is encoded in scattering amplitudes for in/out states at its exterior. Through examples we show that negative kinetic energy in antigravity presents no problems of principles but is an interesting topic for physical investigations of fundamental significance.
Stringy horizons and generalized FZZ duality in perturbation theory

NASA Astrophysics Data System (ADS)

Giribet, Gaston

2017-02-01

We study scattering amplitudes in two-dimensional string theory on a black hole bakground. We start with a simple derivation of the Fateev-Zamolodchikov-Zamolodchikov (FZZ) duality, which associates correlation functions of the sine-Liouville integrable model on the Riemann sphere to tree-level string amplitudes on the Euclidean two-dimensional black hole. This derivation of FZZ duality is based on perturbation theory, and it relies on a trick originally due to Fateev, which involves duality relations between different Selberg type integrals. This enables us to rewrite the correlation functions of sine-Liouville theory in terms of a special set of correlators in the gauged Wess-Zumino-Witten (WZW) theory, and use this to perform further consistency checks of the recently conjectured Generalized FZZ (GFZZ) duality. In particular, we prove that n-point correlation functions in sine-Liouville theory involving n - 2 winding modes actually coincide with the correlation functions in the SL(2,R)/U(1) gauged WZW model that include n - 2 oscillator operators of the type described by Giveon, Itzhaki and Kutasov in reference [1]. This proves the GFZZ duality for the case of tree level maximally winding violating n-point amplitudes with arbitrary n. We also comment on the connection between GFZZ and other marginal deformations previously considered in the literature.
Black hole meiosis

NASA Astrophysics Data System (ADS)

van Herck, Walter; Wyder, Thomas

2010-04-01

The enumeration of BPS bound states in string theory needs refinement. Studying partition functions of particles made from D-branes wrapped on algebraic Calabi-Yau 3-folds, and classifying states using split attractor flow trees, we extend the method for computing a refined BPS index, [1]. For certain D-particles, a finite number of microstates, namely polar states, exclusively realized as bound states, determine an entire partition function (elliptic genus). This underlines their crucial importance: one might call them the ‘chromosomes’ of a D-particle or a black hole. As polar states also can be affected by our refinement, previous predictions on elliptic genera are modified. This can be metaphorically interpreted as ‘crossing-over in the meiosis of a D-particle’. Our results improve on [2], provide non-trivial evidence for a strong split attractor flow tree conjecture, and thus suggest that we indeed exhaust the BPS spectrum. In the D-brane description of a bound state, the necessity for refinement results from the fact that tachyonic strings split up constituent states into ‘generic’ and ‘special’ states. These are enumerated separately by topological invariants, which turn out to be partitions of Donaldson-Thomas invariants. As modular predictions provide a check on many of our results, we have compelling evidence that our computations are correct.
Hair-brane ideas on the horizon

DOE PAGES

Martinec, Emil J.; Niehoff, Ben E.

2015-11-27

We continue an examination of the microstate geometries program begun in arXiv:1409.6017, focussing on the role of branes that wrap the cycles which degenerate when a throat in the geometry deepens and a horizon forms. An associated quiver quantum mechanical model of minimally wrapped branes exhibits a non-negligible fraction of the gravitational entropy, which scales correctly as a function of the charges. The results suggest a picture of AdS3/CFT2 duality wherein the long string that accounts for BTZ black hole entropy in the CFT description, can also be seen to inhabit the horizon of BPS black holes on the gravitymore » side.« less
Anisotropic string cosmological model in Brans–Dicke theory of gravitation with time-dependent deceleration parameter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maurya, D. Ch., E-mail: dcmaurya563@gmail.com; Zia, R., E-mail: rashidzya@gmail.com; Pradhan, A., E-mail: pradhan.anirudh@gmail.com

We discuss a spatially homogeneous and anisotropic string cosmological models in the Brans–Dicke theory of gravitation. For a spatially homogeneous metric, it is assumed that the expansion scalar θ is proportional to the shear scalar σ. This condition leads to A = kB{sup m}, where k and m are constants. With these assumptions and also assuming a variable scale factor a = a(t), we find solutions of the Brans–Dicke field equations. Various phenomena like the Big Bang, expanding universe, and shift from anisotropy to isotropy are observed in the model. It can also be seen that in early stage ofmore » the evolution of the universe, strings dominate over particles, whereas the universe is dominated by massive strings at the late time. Some physical and geometrical behaviors of the models are also discussed and observed to be in good agreement with the recent observations of SNe la supernovae.« less
Wilson loops in warped resolved deformed conifolds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bennett, Stephen, E-mail: pystephen@swansea.ac.uk

We calculate quark-antiquark potentials using the relationship between the expectation value of the Wilson loop and the action of a probe string in the string dual. We review and categorise the possible forms of the dependence of the energy on the separation between the quarks. In particular, we examine the possibility of there being a minimum separation for probe strings which do not penetrate close to the origin of the bulk space, and derive a condition which determines whether this is the case. We then apply these considerations to the flavoured resolved deformed conifold background of Gaillard et al. (2010)more » . We suggest that the unusual behaviour that we observe in this solution is likely to be related to the IR singularity which is not present in the unflavoured case. - Highlights: > We calculate quark-antiquark potentials using the Wilson loop and the action of a probe string in the string dual. > We review and categorise the possible forms of the dependence of the energy on the separation between the quarks. > We look in particular at the flavoured resolved deformed conifold. > There appears to be unusual behaviour which seems likely to be related to the IR singularity introduced by flavours.« less
How could (should) we make contact between string/M-theory and our four-dimensional world, and associated LHC predictions?

NASA Astrophysics Data System (ADS)

Kane, Gordon

2015-12-01

String/M-theory is an exciting framework within which we try to understand our universe and its properties. Compactified string/M-theories address and offer solutions to almost every important question and issue in particle physics and particle cosmology. But earlier goals of finding a top-down “vacuum selection” principle and deriving the 4D theory have not yet been realized. Does that mean we should stop trying, as nearly all string theorists have? Or can we proceed in the historical way to make a few generic, robust assumptions not closely related to observables, and follow where they lead to testable predictions and explanations? Making only very generic assumptions is a significant issue. I discuss how to try to proceed with this approach, particularly in M-theory compactified on a 7D manifold of G2 holonomy. One goal is to understand our universe as a string/M-theory vacuum for its own sake, in the long tradition of trying to understand our world, and what that implies. In addition, understanding our vacuum may be a prelude to understanding its connection to the multiverse.
Automated Systematic Generation and Exploration of Flat Direction Phenomenology in Free Fermionic Heterotic String Theory

NASA Astrophysics Data System (ADS)

Greenwald, Jared

Any good physical theory must resolve current experimental data as well as offer predictions for potential searches in the future. The Standard Model of particle physics, Grand Unied Theories, Minimal Supersymmetric Models and Supergravity are all attempts to provide such a framework. However, they all lack the ability to predict many of the parameters that each of the theories utilize. String theory may yield a solution to this naturalness (or self-predictiveness) problem as well as offer a unifed theory of gravity. Studies in particle physics phenomenology based on perturbative low energy analysis of various string theories can help determine the candidacy of such models. After a review of principles and problems leading up to our current understanding of the universe, we will discuss some of the best particle physics model building techniques that have been developed using string theory. This will culminate in the introduction of a novel approach to a computational, systematic analysis of the various physical phenomena that arise from these string models. We focus on the necessary assumptions, complexity and open questions that arise while making a fully-automated at direction analysis program.
String Theory, the Crisis in Particle Physics and the Ascent of Metaphoric Arguments

NASA Astrophysics Data System (ADS)

Schroer, Bert

This essay presents a critical evaluation of the concepts of string theory and its impact on particle physics. The point of departure is a historical review of four decades of string theory within the broader context of six decades of failed attempts at an autonomous S matrix approach to particle theory. The central message, contained in Secs. 5 and 6, is that string theory is not what its name suggests, namely a theory of objects in space-time whose localization is string-instead of pointlike. Contrary to popular opinion, the oscillators corresponding to the Fourier models of a quantum-mechanical string do not become embedded in space-time and neither does the "range space" of a chiral conformal QFT acquire the interpretation of stringlike-localized quantum matter. Rather, string theory represents a solution to a problem which enjoyed some popularity in the 1960s: find a principle which, similar to the SO(4,2) group in the case of the hydrogen spectrum, determines an infinite component wave function with a (realistic) mass/spin spectrum. Instead of the group theory used in the old failed attempts, it creates this mass/spin spectrum by combining an internal oscillator quantum mechanics with a pointlike-localized quantum-field-theoretic object, i.e. the mass/spin tower "sits" over one point and does not arise from a wiggling string in space-time. The widespread acceptance of a theory whose interpretation has been based on metaphoric reasoning had a corroding influence on particle theory, a point which will be illustrated in the last section with some remarks of a more sociological nature. These remarks also lend additional support to observations on connections between the discourse in particle physics and the present Zeitgeist of the post-Cold War period that are made in the introduction.
Ineffective higher derivative black hole hair

NASA Astrophysics Data System (ADS)

Goldstein, Kevin; Mashiyane, James Junior

2018-01-01

Inspired by the possibility that the Schwarzschild black hole may not be the unique spherically symmetric vacuum solution to generalizations of general relativity, we consider black holes in pure fourth order higher derivative gravity treated as an effective theory. Such solutions may be of interest in addressing the issue of higher derivative hair or during the later stages of black hole evaporation. Non-Schwarzschild solutions have been studied but we have put earlier results on a firmer footing by finding a systematic asymptotic expansion for the black holes and matching them with known numerical solutions obtained by integrating out from the near-horizon region. These asymptotic expansions can be cast in the form of trans-series expansions which we conjecture will be a generic feature of non-Schwarzschild higher derivative black holes. Excitingly we find a new branch of solutions with lower free energy than the Schwarzschild solution, but as found in earlier work, solutions only seem to exist for black holes with large curvatures, meaning that one should not generically neglect even higher derivative corrections. This suggests that one effectively recovers the nonhair theorems in this context.
Wilsonian dark matter in string derived Z' model

NASA Astrophysics Data System (ADS)

Delle Rose, L.; Faraggi, A. E.; Marzo, C.; Rizos, J.

2017-09-01

The dark matter issue is among the most perplexing in contemporary physics. The problem is more enigmatic due to the wide range of possible solutions, ranging from the ultralight to the supermassive. String theory gives rise to plausible dark matter candidates due to the breaking of the non-Abelian grand unified theory (GUT) symmetries by Wilson lines. The physical spectrum then contains states that do not satisfy the quantization conditions of the unbroken GUT symmetry. Given that the Standard Model states are identified with broken GUT representations, and provided that any ensuing symmetry breakings are induced by components of GUT states, a remnant discrete symmetry remains that forbids the decay of the Wilsonian states. A class of such states are obtained in a heterotic-string-derived Z' model. The model exploits the spinor-vector duality symmetry, observed in the fermionic Z2×Z2 heterotic-string orbifolds, to generate a Z'∈E6 symmetry that may remain unbroken down to low energies. The E6 symmetry is broken at the string level with discrete Wilson lines. The Wilsonian dark matter candidates in the string-derived model are S O (10 ), and hence Standard Model, singlets and possess non-E6 U(1)Z' charges. Depending on the U(1)Z' breaking scale and the reheating temperature they give rise to different scenarios for the relic abundance, and are in accordance with the cosmological constraints.
String tensions in deformed Yang-Mills theory

NASA Astrophysics Data System (ADS)

Poppitz, Erich; Shalchian T., M. Erfan

2018-01-01

We study k-strings in deformed Yang-Mills (dYM) with SU(N) gauge group in the semiclassically calculable regime on R^3× S^1 . Their tensions Tk are computed in two ways: numerically, for 2 ≤ N ≤ 10, and via an analytic approach using a re-summed perturbative expansion. The latter serves both as a consistency check on the numerical results and as a tool to analytically study the large-N limit. We find that dYM k-string ratios Tk/T1 do not obey the well-known sine- or Casimir-scaling laws. Instead, we show that the ratios Tk/T1 are bound above by a square root of Casimir scaling, previously found to hold for stringlike solutions of the MIT Bag Model. The reason behind this similarity is that dYM dynamically realizes, in a theoretically controlled setting, the main model assumptions of the Bag Model. We also compare confining strings in dYM and in other four-dimensional theories with abelian confinement, notably Seiberg-Witten theory, and show that the unbroken Z_N center symmetry in dYM leads to different properties of k-strings in the two theories; for example, a "baryon vertex" exists in dYM but not in softly-broken Seiberg-Witten theory. Our results also indicate that, at large values of N, k-strings in dYM do not become free.
Black holes from large N singlet models

NASA Astrophysics Data System (ADS)

Amado, Irene; Sundborg, Bo; Thorlacius, Larus; Wintergerst, Nico

2018-03-01

The emergent nature of spacetime geometry and black holes can be directly probed in simple holographic duals of higher spin gravity and tensionless string theory. To this end, we study time dependent thermal correlation functions of gauge invariant observables in suitably chosen free large N gauge theories. At low temperature and on short time scales the correlation functions encode propagation through an approximate AdS spacetime while interesting departures emerge at high temperature and on longer time scales. This includes the existence of evanescent modes and the exponential decay of time dependent boundary correlations, both of which are well known indicators of bulk black holes in AdS/CFT. In addition, a new time scale emerges after which the correlation functions return to a bulk thermal AdS form up to an overall temperature dependent normalization. A corresponding length scale was seen in equal time correlation functions in the same models in our earlier work.
Boundary causality versus hyperbolicity for spherical black holes in Gauss-Bonnet gravity

NASA Astrophysics Data System (ADS)

Andrade, Tomás; Cáceres, Elena; Keeler, Cynthia

2017-07-01

We explore the constraints boundary causality places on the allowable Gauss-Bonnet gravitational couplings in asymptotically AdS spaces, specifically considering spherical black hole solutions. We additionally consider the hyperbolicity properties of these solutions, positing that hyperbolicity-violating solutions are sick solutions whose causality properties provide no information about the theory they reside in. For both signs of the Gauss-Bonnet coupling, spherical black holes violate boundary causality at smaller absolute values of the coupling than planar black holes do. For negative coupling, as we tune the Gauss-Bonnet coupling away from zero, both spherical and planar black holes violate hyperbolicity before they violate boundary causality. For positive coupling, the only hyperbolicity-respecting spherical black holes which violate boundary causality do not do so appreciably far from the planar bound. Consequently, eliminating hyperbolicity-violating solutions means the bound on Gauss-Bonnet couplings from the boundary causality of spherical black holes is no tighter than that from planar black holes.
Input-independent, Scalable and Fast String Matching on the Cray XMT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Villa, Oreste; Chavarría-Miranda, Daniel; Maschhoff, Kristyn J

2009-05-25

String searching is at the core of many security and network applications like search engines, intrusion detection systems, virus scanners and spam filters. The growing size of on-line content and the increasing wire speeds push the need for fast, and often real- time, string searching solutions. For these conditions, many software implementations (if not all) targeting conventional cache-based microprocessors do not perform well. They either exhibit overall low performance or exhibit highly variable performance depending on the types of inputs. For this reason, real-time state of the art solutions rely on the use of either custom hardware or Field-Programmable Gatemore » Arrays (FPGAs) at the expense of overall system flexibility and programmability. This paper presents a software based implementation of the Aho-Corasick string searching algorithm on the Cray XMT multithreaded shared memory machine. Our so- lution relies on the particular features of the XMT architecture and on several algorith- mic strategies: it is fast, scalable and its performance is virtually content-independent. On a 128-processor Cray XMT, it reaches a scanning speed of ≈ 28 Gbps with a performance variability below 10 %. In the 10 Gbps performance range, variability is below 2.5%. By comparison, an Intel dual-socket, 8-core system running at 2.66 GHz achieves a peak performance which varies from 500 Mbps to 10 Gbps depending on the type of input and dictionary size.« less
A black hole with torsion in 5D Lovelock gravity

NASA Astrophysics Data System (ADS)

Cvetković, B.; Simić, D.

2018-03-01

We analyze static spherically symmetric solutions of five dimensional (5D) Lovelock gravity in the first order formulation. In the Riemannian sector, when torsion vanishes, the Boulware–Deser black hole represents a unique static spherically symmetric black hole solution for the generic choice of the Lagrangian parameters. We show that a special choice of the Lagrangian parameters, different from the Lovelock Chern–Simons gravity, leads to the existence of a static black hole solution with torsion, the metric of which is asymptotically anti-de Sitter (AdS). We calculate the conserved charges and thermodynamical quantities of this black hole solution.
The sound of friction: Real-time models, playability and musical applications

NASA Astrophysics Data System (ADS)

Serafin, Stefania

Friction, the tangential force between objects in contact, in most engineering applications needs to be removed as a source of noise and instabilities. In musical applications, friction is a desirable component, being the sound production mechanism of different musical instruments such as bowed strings, musical saws, rubbed bowls and any other sonority produced by interactions between rubbed dry surfaces. The goal of the dissertation is to simulate different instrument whose main excitation mechanism is friction. An efficient yet accurate model of a bowed string instrument, which combines the latest results in violin acoustics with the efficient digital waveguide approach, is provided. In particular, the bowed string physical model proposed uses a thermodynamic friction model in which the finite width of the bow is taken into account; this solution is compared to the recently developed elasto-plastic friction models used in haptics and robotics. Different solutions are also proposed to model the body of the instrument. Other less common instruments driven by friction are also proposed, and the elasto-plastic model is used to provide audio-visual simulations of everyday friction sounds such as squeaking doors and rubbed wine glasses. Finally, playability evaluations and musical applications in which the models have been used are discussed.

Femtosecond laser fabricating black silicon in alkaline solution

NASA Astrophysics Data System (ADS)

Meng, Jiao; Song, Haiying; Li, Xiaoli; Liu, Shibing

2015-03-01

An efficient approach for enhancing the surface antireflection is proposed, in which a black silicon is fabricated by a femtosecond laser in alkaline solution. In the experiment, 2 wt% NaOH solution is formulated at room temperature (22 ± 1 °C). Then, a polished silicon is scanned via femtosecond laser irradiation in 2 wt% NaOH solution. Jungle-like microstructures on the black silicon surface are characterized using an atomic force microscopy. The reflectance of the black silicon is measured at the wavelengths ranging from 400 to 750 nm. Compared to the polished silicon, the black silicon can significantly suppress the optical reflection throughout the visible region (<5 %). Meanwhile, we also investigated the factors of the black silicon, including the femtosecond laser pulse energy and the scanning speed. This method is simple and effective to acquire the black silicon, which probably has a large advantage in fast and cost-effective black silicon fabrication.
Numerical exploration of the string theory landscape

NASA Astrophysics Data System (ADS)

Metallinos, Konstantinos

String theory is the best candidate to provide a consistent quantum theory of gravity. Its ten dimensional formulation forces us to perform a compactification of the six unobserved dimensions in a very special compact manifold known as Calabi-Yau. The standard way to address this issue is through the flux compactification scenarios. One of the major implications of these scenarios is that the string theory cannot provide a single and unique vacuum as a solution. Rather one can find an extremely large set of solutions, each with its own physical properties. This is the string theory Landscape. In the first part we present the formal description of the flux compactification theory. From the four dimensional point of view this is a supersymmetric theory, fully described only by two functions, the superpotential and the Kahler potential. Their expressions are crucially depend on the geometrical properties of the compact manifold. By writing these functions for the specific Calabi-Yau manifold P41,1,1,6,9 we are looking firstly for supersymmetric and then after breaking the supersymmetry, for non-supersymmetric numerical solutions. These solutions describe the possible vacua and our goal is using statistical analysis to categorize them based on their cosmological properties and to check their stability. Finally we present the existence of stable dS vacua with and without adding an uplifting term on the potential. In the case where there is not an uplifting term the breaking of supersymmetry is done by incorporating alpha' corrections to the Kahler potential. In the second part we construct a KKLT like inflation model, within string theory flux compactifications and, in particular a model of accidental inflation. We investigate the possibility that the apparent fine-tuning of the low energy parameters of the theory needed to have inflation can be generically obtained by scanning the values of the fluxes over the landscape. Furthermore, we find that the existence of a landscape of eternal inflation in this model provides us with a natural theory of initial conditions for the inflationary period in our vacuum. We demonstrate how these two effects work in a small corner of the landscape associated with the complex structure of the Calabi-Yau manifold P41,1,1,6,9 by numerically investigating the flux vacua of a reduced moduli space. This allows us to obtain the distribution of observable parameters for inflation in this mini-landscape directly from the fluxes.
Radiating black hole solutions in Einstein-Gauss-Bonnet gravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dominguez, Alfredo E.; Instituto Universitario Aeronautico, Avenida Fuerza Aerea km 6.5.; Gallo, Emanuel

2006-03-15

In this paper, we find some new exact solutions to the Einstein-Gauss-Bonnet equations. First, we prove a theorem which allows us to find a large family of solutions to the Einstein-Gauss-Bonnet gravity in n-dimensions. This family of solutions represents dynamic black holes and contains, as particular cases, not only the recently found Vaidya-Einstein-Gauss-Bonnet black hole, but also other physical solutions that we think are new, such as the Gauss-Bonnet versions of the Bonnor-Vaidya (de Sitter/anti-de Sitter) solution, a global monopole, and the Husain black holes. We also present a more general version of this theorem in which less restrictive conditionsmore » on the energy-momentum tensor are imposed. As an application of this theorem, we present the exact solution describing a black hole radiating a charged null fluid in a Born-Infeld nonlinear electrodynamics.« less
Black holes in a cubic Galileon universe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Babichev, E.; Charmousis, C.; Lehébel, A.

2016-09-01

We find and study the properties of black hole solutions for a subclass of Horndeski theory including the cubic Galileon term. The theory under study has shift symmetry but not reflection symmetry for the scalar field. The Galileon is assumed to have linear time dependence characterized by a velocity parameter. We give analytic 3-dimensional solutions that are akin to the BTZ solutions but with a non-trivial scalar field that modifies the effective cosmological constant. We then study the 4-dimensional asymptotically flat and de Sitter solutions. The latter present three different branches according to their effective cosmological constant. For two ofmore » these branches, we find families of black hole solutions, parametrized by the velocity of the scalar field. These spherically symmetric solutions, obtained numerically, are different from GR solutions close to the black hole event horizon, while they have the same de-Sitter asymptotic behavior. The velocity parameter represents black hole primary hair.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)

Pawellek, Michael

Using anti-de Sitter-space/conformal-field-theory correspondence we derive from the folded spinning string ordinary differential equations for the anomalous dimension of the dual N=4 super Yang-Mills theory twist-two operators at strong coupling. We show that for large spin the asymptotic solutions have the Gribov-Lipatov reciprocity property. To obtain this result we use a hidden modular invariance of the energy-spin relation of the folded spinning string. Furthermore, we identify the Moch-Vermaseren-Vogt relations, which were first recognized in plain QCD calculations, as the recurrence relations of the asymptotic series ansatz.
Relativistic Bessel cylinders

NASA Astrophysics Data System (ADS)

Krisch, J. P.; Glass, E. N.

2014-10-01

A set of cylindrical solutions to Einstein's field equations for power law densities is described. The solutions have a Bessel function contribution to the metric. For matter cylinders regular on axis, the first two solutions are the constant density Gott-Hiscock string and a cylinder with a metric Airy function. All members of this family have the Vilenkin limit to their mass per length. Some examples of Bessel shells and Bessel motion are given.
Rotating black hole solutions in relativistic analogue gravity

NASA Astrophysics Data System (ADS)

Giacomelli, Luca; Liberati, Stefano

2017-09-01

Simulation and experimental realization of acoustic black holes in analogue gravity systems have lead to a novel understanding of relevant phenomena such as Hawking radiation or superradiance. We explore here the possibility of using relativistic systems for simulating rotating black hole solutions and possibly get an acoustic analogue of a Kerr black hole. In doing so, we demonstrate a precise relation between nonrelativistic and relativistic solutions and provide a new class of vortex solutions for relativistic systems. Such solutions might be used in the future as a test bed in numerical simulations as well as concrete experiments.
Regarding `Information Preservation and Weather Forecasting for Black Holes' by S. W. Hawking

NASA Astrophysics Data System (ADS)

Winterberg, Friedwardt

2014-06-01

It is proposed that the `apparent horizons' assumed by Hawking to resolve the black hole information paradox, are in reality the regions where in Lorentzian relativity the absolute velocity against a preferred reference system at rest with the zero point vacuum energy reaches the velocity of light, and where an elliptical differential equation holding matter in a stable equilibrium goes over a transluminal Euler-Tricomi equation into a hyperbolic differential equation where such an equilibrium is not more possible, with matter in approaching this region disintegrating into radiation. Hawking's proposal depends on the anti-de Sitter/conformal field theory (AdS/CFT) conjecture which in turn depends on string/M theory which in the absence of super-symmetry will not work.
Scalar hair around charged black holes in Einstein-Gauss-Bonnet gravity

NASA Astrophysics Data System (ADS)

Grandi, Nicolás; Landea, Ignacio Salazar

2018-02-01

We explore charged black hole solutions in Einstein-Gauss-Bonnet gravity in five dimensions, with a charged scalar hair. We interpret such hairy black holes as the final state of the superradiant instability previously reported for this system. We explore the relation of the hairy black hole solutions with the nonbackreacting quasibound states and scalar clouds, as well as with the boson star solutions.
Black holes and stars in Horndeski theory

NASA Astrophysics Data System (ADS)

Babichev, Eugeny; Charmousis, Christos; Lehébel, Antoine

2016-08-01

We review black hole and star solutions for Horndeski theory. For non-shift symmetric theories, black holes involve a Kaluza-Klein reduction of higher dimensional Lovelock solutions. On the other hand, for shift symmetric theories of Horndeski and beyond Horndeski, black holes involve two classes of solutions: those that include, at the level of the action, a linear coupling to the Gauss-Bonnet term and those that involve time dependence in the galileon field. We analyze the latter class in detail for a specific subclass of Horndeski theory, discussing the general solution of a static and spherically symmetric spacetime. We then discuss stability issues, slowly rotating solutions as well as black holes coupled to matter. The latter case involves a conformally coupled scalar field as well as an electromagnetic field and the (primary) hair black holes thus obtained. We review and discuss the recent results on neutron stars in Horndeski theories.
Optimization for Guitar Fingering on Single Notes

NASA Astrophysics Data System (ADS)

Itoh, Masaru; Hayashida, Takumi

This paper presents an optimization method for guitar fingering. The fingering is to determine a unique combination of string, fret and finger corresponding to the note. The method aims to generate the best fingering pattern for guitar robots rather than beginners. Furthermore, it can be applied to any musical score on single notes. A fingering action can be decomposed into three motions, that is, a motion of press string, release string and move fretting hand. The cost for moving the hand is estimated on the basis of Manhattan distance which is the sum of distances along fret and string directions. The objective is to minimize the total fingering costs, subject to fret, string and finger constraints. As a sequence of notes on the score forms a line on time series, the optimization for guitar fingering can be resolved into a multistage decision problem. Dynamic programming is exceedingly effective to solve such a problem. A level concept is introduced into rendering states so as to make multiple DP solutions lead a unique one among the DP backward processes. For example, if two fingerings have the same value of cost at different states on a stage, then the low position would be taken precedence over the high position, and the index finger would be over the middle finger.
The formation of topological defects in phase transitions

NASA Technical Reports Server (NTRS)

Hodges, Hardy M.

1989-01-01

It was argued, and fought through numerical work that the results of non-dynamical Monte Carlo computer simulations cannot be applied to describe the formation of topological defects when the correlation length at the Ginzburg temperature is significantly smaller than the horizon size. To test the current hypothesis that infinite strings at formation are essentially described by Brownian walks of size the correlation length at the Ginzburg temperature, fields at the Ginzburg temperature were equilibrated. Infinite structure do not exist in equilibrium for reasonable definitions of the Ginzburg temperature, and horizons must be included in a proper treatment. A phase transition, from small-scale to large-scale string or domain wall structure, is found to occur very close to the Ginzburg temperature, in agreement with recent work. The formation process of domain walls and global strings were investigated through the breaking of initially ordered states. To mimic conditions in the early Universe, cooling times are chosen so that horizons exist in the sample volume when topological structure formation occurs. The classical fields are evolved in real-time by the numerical solution of Langevin equations of motion on a three dimensional spatial lattice. The results indicate that it is possible for most of the string energy to be in small loops, rather than in long strings, at formation.
SAGE: String-overlap Assembly of GEnomes.

PubMed

Ilie, Lucian; Haider, Bahlul; Molnar, Michael; Solis-Oba, Roberto

2014-09-15

De novo genome assembly of next-generation sequencing data is one of the most important current problems in bioinformatics, essential in many biological applications. In spite of significant amount of work in this area, better solutions are still very much needed. We present a new program, SAGE, for de novo genome assembly. As opposed to most assemblers, which are de Bruijn graph based, SAGE uses the string-overlap graph. SAGE builds upon great existing work on string-overlap graph and maximum likelihood assembly, bringing an important number of new ideas, such as the efficient computation of the transitive reduction of the string overlap graph, the use of (generalized) edge multiplicity statistics for more accurate estimation of read copy counts, and the improved use of mate pairs and min-cost flow for supporting edge merging. The assemblies produced by SAGE for several short and medium-size genomes compared favourably with those of existing leading assemblers. SAGE benefits from innovations in almost every aspect of the assembly process: error correction of input reads, string-overlap graph construction, read copy counts estimation, overlap graph analysis and reduction, contig extraction, and scaffolding. We hope that these new ideas will help advance the current state-of-the-art in an essential area of research in genomics.
Regular black holes: Electrically charged solutions, Reissner-Nordstroem outside a de Sitter core

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lemos, Jose P. S.; Zanchin, Vilson T.; Centro de Ciencias Naturais e Humanas, Universidade Federal do ABC, Rua Santa Adelia, 166, 09210-170, Santo Andre, Sao Paulo

2011-06-15

To have the correct picture of a black hole as a whole, it is of crucial importance to understand its interior. The singularities that lurk inside the horizon of the usual Kerr-Newman family of black hole solutions signal an endpoint to the physical laws and, as such, should be substituted in one way or another. A proposal that has been around for sometime is to replace the singular region of the spacetime by a region containing some form of matter or false vacuum configuration that can also cohabit with the black hole interior. Black holes without singularities are called regularmore » 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 types of solutions: regular nonextremal black holes with a null matter boundary, regular nonextremal black holes with a timelike matter boundary, regular extremal black holes with a timelike matter boundary, and regular overcharged stars with a timelike matter boundary. The main physical and geometrical properties of such charged regular solutions are analyzed.« less
Second quantization in bit-string physics

NASA Technical Reports Server (NTRS)

Noyes, H. Pierre

1993-01-01

Using a new fundamental theory based on bit-strings, a finite and discrete version of the solutions of the free one particle Dirac equation as segmented trajectories with steps of length h/mc along the forward and backward light cones executed at velocity +/- c are derived. Interpreting the statistical fluctuations which cause the bends in these segmented trajectories as emission and absorption of radiation, these solutions are analogous to a fermion propagator in a second quantized theory. This allows us to interpret the mass parameter in the step length as the physical mass of the free particle. The radiation in interaction with it has the usual harmonic oscillator structure of a second quantized theory. How these free particle masses can be generated gravitationally using the combinatorial hierarchy sequence (3,10,137,2(sup 127) + 136), and some of the predictive consequences are sketched.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Ko, Sung Moon; Park, Jeong-Hyuck; Suh, Minwoo, E-mail: sinsmk2003@sogang.ac.kr, E-mail: park@sogang.ac.kr, E-mail: minsuh@usc.edu

Double Field Theory suggests to view the whole massless sector of closed strings as the gravitational unity. The fundamental symmetries therein, including the O( D , D ) covariance, can determine unambiguously how the Standard Model as well as a relativistic point particle should couple to the closed string massless sector. The theory also refines the notion of singularity. We consider the most general, spherically symmetric, asymptotically flat, static vacuum solution to D =4 Double Field Theory, which contains three free parameters and consequently generalizes the Schwarzschild geometry. Analyzing the circular geodesic of a point particle in string frame, wemore » obtain the orbital velocity as a function of R /( M {sub ∞} G ) which is the dimensionless radial variable normalized by mass. The rotation curve generically features a maximum and thus non-Keplerian over a finite range, while becoming asymptotically Keplerian at infinity, R /( M {sub ∞} G )→ ∞. The adoption of the string frame rather than Einstein frame is the consequence of the fundamental symmetry principle. Our result opens up a new scheme to solve the dark matter/energy problems by modifying General Relativity at 'short' range of R /( M {sub ∞} G ).« less
Charge modulation as fingerprints of phase-string triggered interference

NASA Astrophysics Data System (ADS)

Zhu, Zheng; Tian, Chushun; Jiang, Hong-Chen; Qi, Yang; Weng, Zheng-Yu; Zaanen, Jan

2015-07-01

Charge order appears to be an ubiquitous phenomenon in doped Mott insulators, which is currently under intense experimental and theoretical investigations particularly in the high Tc cuprates. This phenomenon is conventionally understood in terms of Hartree-Fock-type mean-field theory. Here we demonstrate a mechanism for charge modulation which is rooted in the many-particle quantum physics arising in the strong coupling limit. Specifically, we consider the problem of a single hole in a bipartite t -J ladder. As a remnant of the fermion signs, the hopping hole picks up subtle phases pending the fluctuating spins, the so-called phase-string effect. We demonstrate the presence of charge modulations in the density matrix renormalization group solutions which disappear when the phase strings are switched off. This form of charge modulation can be understood analytically in a path-integral language with a mean-field-like approximation adopted, showing that the phase strings give rise to constructive interferences leading to self-localization. When the latter occurs, left- and right-moving propagating modes emerge inside the localization volume and their interference is responsible for the real space charge modulation.
Search for black holes and other new phenomena in high-multiplicity final states in proton-proton collisions at √{ s} = 13TeV

NASA Astrophysics Data System (ADS)

Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Brondolin, E.; Dragicevic, M.; Erö, J.; Flechl, M.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hartl, C.; Hörmann, N.; Hrubec, J.; Jeitler, M.; König, A.; Krätschmer, I.; Liko, D.; Matsushita, T.; Mikulec, I.; Rabady, D.; Rad, N.; Rahbaran, B.; Rohringer, H.; Schieck, J.; Strauss, J.; Waltenberger, W.; Wulz, C.-E.; Dvornikov, O.; Makarenko, V.; Mossolov, V.; Suarez Gonzalez, J.; Zykunov, V.; Shumeiko, N.; Alderweireldt, S.; De Wolf, E. A.; Janssen, X.; Lauwers, J.; Van De Klundert, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Abu Zeid, S.; Blekman, F.; D'Hondt, J.; Daci, N.; De Bruyn, I.; Deroover, K.; Lowette, S.; Moortgat, S.; Moreels, L.; Olbrechts, A.; Python, Q.; Skovpen, K.; Tavernier, S.; Van Doninck, W.; Van Mulders, P.; Van Parijs, I.; Brun, H.; Clerbaux, B.; De Lentdecker, G.; Delannoy, H.; Fasanella, G.; Favart, L.; Goldouzian, R.; Grebenyuk, A.; Karapostoli, G.; Lenzi, T.; Léonard, A.; Luetic, J.; Maerschalk, T.; Marinov, A.; Randle-conde, A.; Seva, T.; Vander Velde, C.; Vanlaer, P.; Vannerom, D.; Yonamine, R.; Zenoni, F.; Zhang, F.; Cimmino, A.; Cornelis, T.; Dobur, D.; Fagot, A.; Gul, M.; Khvastunov, I.; Poyraz, D.; Salva, S.; Schöfbeck, R.; Tytgat, M.; Van Driessche, W.; Yazgan, E.; Zaganidis, N.; Bakhshiansohi, H.; Beluffi, C.; Bondu, O.; Brochet, S.; Bruno, G.; Caudron, A.; De Visscher, S.; Delaere, C.; Delcourt, M.; Francois, B.; Giammanco, A.; Jafari, A.; Komm, M.; Krintiras, G.; Lemaitre, V.; Magitteri, A.; Mertens, A.; Musich, M.; Piotrzkowski, K.; Quertenmont, L.; Selvaggi, M.; Vidal Marono, M.; Wertz, S.; Beliy, N.; Aldá Júnior, W. L.; Alves, F. L.; Alves, G. A.; Brito, L.; Hensel, C.; Moraes, A.; Pol, M. E.; Rebello Teles, P.; Belchior Batista Das Chagas, E.; Carvalho, W.; Chinellato, J.; Custódio, A.; Da Costa, E. M.; Da Silveira, G. G.; De Jesus Damiao, D.; De Oliveira Martins, C.; Fonseca De Souza, S.; Huertas Guativa, L. M.; Malbouisson, H.; Matos Figueiredo, D.; Mora Herrera, C.; Mundim, L.; Nogima, H.; Prado Da Silva, W. L.; Santoro, A.; Sznajder, A.; Tonelli Manganote, E. J.; Torres Da Silva De Araujo, F.; Vilela Pereira, A.; Ahuja, S.; Bernardes, C. A.; Dogra, S.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Mercadante, P. G.; Moon, C. S.; Novaes, S. F.; Padula, Sandra S.; Romero Abad, D.; Ruiz Vargas, J. C.; Aleksandrov, A.; Hadjiiska, R.; Iaydjiev, P.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Vutova, M.; Dimitrov, A.; Glushkov, I.; Litov, L.; Pavlov, B.; Petkov, P.; Fang, W.; Ahmad, M.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Chen, M.; Chen, Y.; Cheng, T.; Jiang, C. H.; Leggat, D.; Liu, Z.; Romeo, F.; Ruan, M.; Shaheen, S. M.; Spiezia, A.; Tao, J.; Wang, C.; Wang, Z.; Zhang, H.; Zhao, J.; Ban, Y.; Chen, G.; Li, Q.; Liu, S.; Mao, Y.; Qian, S. J.; Wang, D.; Xu, Z.; Avila, C.; Cabrera, A.; Chaparro Sierra, L. F.; Florez, C.; Gomez, J. P.; González Hernández, C. F.; Ruiz Alvarez, J. D.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Puljak, I.; Ribeiro Cipriano, P. M.; Sculac, T.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Ferencek, D.; Kadija, K.; Mesic, B.; Susa, T.; Attikis, A.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Rykaczewski, H.; Tsiakkouri, D.; Finger, M.; Finger, M.; Carrera Jarrin, E.; Assran, Y.; Elkafrawy, T.; Mahrous, A.; Kadastik, M.; Perrini, L.; Raidal, M.; Tiko, A.; Veelken, C.; Eerola, P.; Pekkanen, J.; Voutilainen, M.; Härkönen, J.; Järvinen, T.; Karimäki, V.; Kinnunen, R.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Tuominiemi, J.; Tuovinen, E.; Wendland, L.; Talvitie, J.; Tuuva, T.; Besancon, M.; Couderc, F.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Favaro, C.; Ferri, F.; Ganjour, S.; Ghosh, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Kucher, I.; Locci, E.; Machet, M.; Malcles, J.; Rander, J.; Rosowsky, A.; Titov, M.; Abdulsalam, A.; Antropov, I.; Baffioni, S.; Beaudette, F.; Busson, P.; Cadamuro, L.; Chapon, E.; Charlot, C.; Davignon, O.; Granier de Cassagnac, R.; Jo, M.; Lisniak, S.; Miné, P.; Nguyen, M.; Ochando, C.; Ortona, G.; Paganini, P.; Pigard, P.; Regnard, S.; Salerno, R.; Sirois, Y.; Stahl Leiton, A. G.; Strebler, T.; Yilmaz, Y.; Zabi, A.; Zghiche, A.; Agram, J.-L.; Andrea, J.; Aubin, A.; Bloch, D.; Brom, J.-M.; Buttignol, M.; Chabert, E. C.; Chanon, N.; Collard, C.; Conte, E.; Coubez, X.; Fontaine, J.-C.; Gelé, D.; Goerlach, U.; Le Bihan, A.-C.; Van Hove, P.; Gadrat, S.; Beauceron, S.; Bernet, C.; Boudoul, G.; Carrillo Montoya, C. A.; Chierici, R.; Contardo, D.; Courbon, B.; Depasse, P.; El Mamouni, H.; Fay, J.; Gascon, S.; Gouzevitch, M.; Grenier, G.; Ille, B.; Lagarde, F.; Laktineh, I. B.; Lethuillier, M.; Mirabito, L.; Pequegnot, A. L.; Perries, S.; Popov, A.; Sabes, D.; Sordini, V.; Vander Donckt, M.; Verdier, P.; Viret, S.; Toriashvili, T.; Tsamalaidze, Z.; Autermann, C.; Beranek, S.; Feld, L.; Kiesel, M. K.; Klein, K.; Lipinski, M.; Preuten, M.; Schomakers, C.; Schulz, J.; Verlage, T.; Albert, A.; Brodski, M.; Dietz-Laursonn, E.; Duchardt, D.; Endres, M.; Erdmann, M.; Erdweg, S.; Esch, T.; Fischer, R.; Güth, A.; Hamer, M.; Hebbeker, T.; Heidemann, C.; Hoepfner, K.; Knutzen, S.; Merschmeyer, M.; Meyer, A.; Millet, P.; Mukherjee, S.; Olschewski, M.; Padeken, K.; Pook, T.; Radziej, M.; Reithler, H.; Rieger, M.; Scheuch, F.; Sonnenschein, L.; Teyssier, D.; Thüer, S.; Cherepanov, V.; Flügge, G.; Kargoll, B.; Kress, T.; Künsken, A.; Lingemann, J.; Müller, T.; Nehrkorn, A.; Nowack, A.; Pistone, C.; Pooth, O.; Stahl, A.; Aldaya Martin, M.; Arndt, T.; Asawatangtrakuldee, C.; Beernaert, K.; Behnke, O.; Behrens, U.; Bin Anuar, A. A.; Borras, K.; Campbell, A.; Connor, P.; Contreras-Campana, C.; Costanza, F.; Diez Pardos, C.; Dolinska, G.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Eren, E.; Gallo, E.; Garay Garcia, J.; Geiser, A.; Gizhko, A.; Grados Luyando, J. M.; Grohsjean, A.; Gunnellini, P.; Harb, A.; Hauk, J.; Hempel, M.; Jung, H.; Kalogeropoulos, A.; Karacheban, O.; Kasemann, M.; Keaveney, J.; Kleinwort, C.; Korol, I.; Krücker, D.; Lange, W.; Lelek, A.; Lenz, T.; Leonard, J.; Lipka, K.; Lobanov, A.; Lohmann, W.; Mankel, R.; Melzer-Pellmann, I.-A.; Meyer, A. B.; Mittag, G.; Mnich, J.; Mussgiller, A.; Pitzl, D.; Placakyte, R.; Raspereza, A.; Roland, B.; Sahin, M. Ö.; Saxena, P.; Schoerner-Sadenius, T.; Spannagel, S.; Stefaniuk, N.; Van Onsem, G. P.; Walsh, R.; Wissing, C.; Blobel, V.; Centis Vignali, M.; Draeger, A. R.; Dreyer, T.; Garutti, E.; Gonzalez, D.; Haller, J.; Hoffmann, M.; Junkes, A.; Klanner, R.; Kogler, R.; Kovalchuk, N.; Lapsien, T.; Marchesini, I.; Marconi, D.; Meyer, M.; Niedziela, M.; Nowatschin, D.; Pantaleo, F.; Peiffer, T.; Perieanu, A.; Scharf, C.; Schleper, P.; Schmidt, A.; Schumann, S.; Schwandt, J.; Stadie, H.; Steinbrück, G.; Stober, F. M.; Stöver, M.; Tholen, H.; Troendle, D.; Usai, E.; Vanelderen, L.; Vanhoefer, A.; Vormwald, B.; Akbiyik, M.; Barth, C.; Baur, S.; Baus, C.; Berger, J.; Butz, E.; Caspart, R.; Chwalek, T.; Colombo, F.; De Boer, W.; Dierlamm, A.; Fink, S.; Freund, B.; Friese, R.; Giffels, M.; Gilbert, A.; Goldenzweig, P.; Haitz, D.; Hartmann, F.; Heindl, S. M.; Husemann, U.; Katkov, I.; Kudella, S.; Mildner, H.; Mozer, M. U.; Müller, Th.; Plagge, M.; Quast, G.; Rabbertz, K.; Röcker, S.; Roscher, F.; Schröder, M.; Shvetsov, I.; Sieber, G.; Simonis, H. J.; Ulrich, R.; Wayand, S.; Weber, M.; Weiler, T.; Williamson, S.; Wöhrmann, C.; Wolf, R.; Anagnostou, G.; Daskalakis, G.; Geralis, T.; Giakoumopoulou, V. A.; Kyriakis, A.; Loukas, D.; Topsis-Giotis, I.; Kesisoglou, S.; Panagiotou, A.; Saoulidou, N.; Tziaferi, E.; Evangelou, I.; Flouris, G.; Foudas, C.; Kokkas, P.; Loukas, N.; Manthos, N.; Papadopoulos, I.; Paradas, E.; Filipovic, N.; Pasztor, G.; Bencze, G.; Hajdu, C.; Horvath, D.; Sikler, F.; Veszpremi, V.; Vesztergombi, G.; Zsigmond, A. J.; Beni, N.; Czellar, S.; Karancsi, J.; Makovec, A.; Molnar, J.; Szillasi, Z.; Bartók, M.; Raics, P.; Trocsanyi, Z. L.; Ujvari, B.; Komaragiri, J. R.; Bahinipati, S.; Bhowmik, S.; Choudhury, S.; Mal, P.; Mandal, K.; Nayak, A.; Sahoo, D. K.; Sahoo, N.; Swain, S. K.; Bansal, S.; Beri, S. B.; Bhatnagar, V.; Chawla, R.; Bhawandeep, U.; Kalsi, A. K.; Kaur, A.; Kaur, M.; Kumar, R.; Kumari, P.; Mehta, A.; Mittal, M.; Singh, J. B.; Walia, G.; Kumar, Ashok; Bhardwaj, A.; Choudhary, B. C.; Garg, R. B.; Keshri, S.; Malhotra, S.; Naimuddin, M.; Ranjan, K.; Sharma, R.; Sharma, V.; Bhattacharya, R.; Bhattacharya, S.; Chatterjee, K.; Dey, S.; Dutt, S.; Dutta, S.; Ghosh, S.; Majumdar, N.; Modak, A.; Mondal, K.; Mukhopadhyay, S.; Nandan, S.; Purohit, A.; Roy, A.; Roy, D.; Roy Chowdhury, S.; Sarkar, S.; Sharan, M.; Thakur, S.; Behera, P. K.; Chudasama, R.; Dutta, D.; Jha, V.; Kumar, V.; Mohanty, A. K.; Netrakanti, P. K.; Pant, L. M.; Shukla, P.; Topkar, A.; Aziz, T.; Dugad, S.; Kole, G.; Mahakud, B.; Mitra, S.; Mohanty, G. B.; Parida, B.; Sur, N.; Sutar, B.; Banerjee, S.; Dewanjee, R. K.; Ganguly, S.; Guchait, M.; Jain, Sa.; Kumar, S.; Maity, M.; Majumder, G.; Mazumdar, K.; Sarkar, T.; Wickramage, N.; Chauhan, S.; Dube, S.; Hegde, V.; Kapoor, A.; Kothekar, K.; Pandey, S.; Rane, A.; Sharma, S.; Chenarani, S.; Eskandari Tadavani, E.; Etesami, S. M.; Khakzad, M.; Mohammadi Najafabadi, M.; Naseri, M.; Paktinat Mehdiabadi, S.; Rezaei Hosseinabadi, F.; Safarzadeh, B.; Zeinali, M.; Felcini, M.; Grunewald, M.; Abbrescia, M.; Calabria, C.; Caputo, C.; Colaleo, A.; Creanza, D.; Cristella, L.; De Filippis, N.; De Palma, M.; Fiore, L.; Iaselli, G.; Maggi, G.; Maggi, M.; Miniello, G.; My, S.; Nuzzo, S.; Pompili, A.; Pugliese, G.; Radogna, R.; Ranieri, A.; Selvaggi, G.; Sharma, A.; Silvestris, L.; Venditti, R.; Verwilligen, P.; Abbiendi, G.; Battilana, C.; Bonacorsi, D.; Braibant-Giacomelli, S.; Brigliadori, L.; Campanini, R.; Capiluppi, P.; Castro, A.; Cavallo, F. R.; Chhibra, S. S.; Codispoti, G.; Cuffiani, M.; Dallavalle, G. M.; Fabbri, F.; Fanfani, A.; Fasanella, D.; Giacomelli, P.; Grandi, C.; Guiducci, L.; Marcellini, S.; Masetti, G.; Montanari, A.; Navarria, F. L.; Perrotta, A.; Rossi, A. M.; Rovelli, T.; Siroli, G. P.; Tosi, N.; Albergo, S.; Costa, S.; Di Mattia, A.; Giordano, F.; Potenza, R.; Tricomi, A.; Tuve, C.; Barbagli, G.; Ciulli, V.; Civinini, C.; D'Alessandro, R.; Focardi, E.; Lenzi, P.; Meschini, M.; Paoletti, S.; Russo, L.; Sguazzoni, G.; Strom, D.; Viliani, L.; Benussi, L.; Bianco, S.; Fabbri, F.; Piccolo, D.; Primavera, F.; Calvelli, V.; Ferro, F.; Monge, M. R.; Robutti, E.; Tosi, S.; Brianza, L.; Brivio, F.; Ciriolo, V.; Dinardo, M. E.; Fiorendi, S.; Gennai, S.; Ghezzi, A.; Govoni, P.; Malberti, M.; Malvezzi, S.; Manzoni, R. A.; Menasce, D.; Moroni, L.; Paganoni, M.; Pedrini, D.; Pigazzini, S.; Ragazzi, S.; Tabarelli de Fatis, T.; Buontempo, S.; Cavallo, N.; De Nardo, G.; Di Guida, S.; Fabozzi, F.; Fienga, F.; Iorio, A. O. M.; Lista, L.; Meola, S.; Paolucci, P.; Sciacca, C.; Thyssen, F.; Azzi, P.; Bacchetta, N.; Benato, L.; Bisello, D.; Boletti, A.; Carlin, R.; Carvalho Antunes De Oliveira, A.; Checchia, P.; Dall'Osso, M.; De Castro Manzano, P.; Dorigo, T.; Dosselli, U.; Gasparini, F.; Gasparini, U.; Gozzelino, A.; Lacaprara, S.; Margoni, M.; Meneguzzo, A. T.; Pazzini, J.; Pozzobon, N.; Ronchese, P.; Simonetto, F.; Torassa, E.; Zanetti, M.; Zotto, P.; Zumerle, G.; Braghieri, A.; Fallavollita, F.; Magnani, A.; Montagna, P.; Ratti, S. P.; Re, V.; Riccardi, C.; Salvini, P.; Vai, I.; Vitulo, P.; Alunni Solestizi, L.; Bilei, G. M.; Ciangottini, D.; Fanò, L.; Lariccia, P.; Leonardi, R.; Mantovani, G.; Menichelli, M.; Saha, A.; Santocchia, A.; Androsov, K.; Azzurri, P.; Bagliesi, G.; Bernardini, J.; Boccali, T.; Castaldi, R.; Ciocci, M. A.; Dell'Orso, R.; Donato, S.; Fedi, G.; Giassi, A.; Grippo, M. T.; Ligabue, F.; Lomtadze, T.; Martini, L.; Messineo, A.; Palla, F.; Rizzi, A.; Savoy-Navarro, A.; Spagnolo, P.; Tenchini, R.; Tonelli, G.; Venturi, A.; Verdini, P. G.; Barone, L.; Cavallari, F.; Cipriani, M.; Del Re, D.; Diemoz, M.; Gelli, S.; Longo, E.; Margaroli, F.; Marzocchi, B.; Meridiani, P.; Organtini, G.; Paramatti, R.; Preiato, F.; Rahatlou, S.; Rovelli, C.; Santanastasio, F.; Amapane, N.; Arcidiacono, R.; Argiro, S.; Arneodo, M.; Bartosik, N.; Bellan, R.; Biino, C.; Cartiglia, N.; Cenna, F.; Costa, M.; Covarelli, R.; Degano, A.; Demaria, N.; Finco, L.; Kiani, B.; Mariotti, C.; Maselli, S.; Migliore, E.; Monaco, V.; Monteil, E.; Monteno, M.; Obertino, M. M.; Pacher, L.; Pastrone, N.; Pelliccioni, M.; Pinna Angioni, G. L.; Ravera, F.; Romero, A.; Ruspa, M.; Sacchi, R.; Shchelina, K.; Sola, V.; Solano, A.; Staiano, A.; Traczyk, P.; Belforte, S.; Casarsa, M.; Cossutti, F.; Della Ricca, G.; Zanetti, A.; Kim, D. H.; Kim, G. N.; Kim, M. S.; Lee, S.; Lee, S. W.; Oh, Y. D.; Sekmen, S.; Son, D. C.; Yang, Y. C.; Lee, A.; Kim, H.; Brochero Cifuentes, J. A.; Kim, T. J.; Cho, S.; Choi, S.; Go, Y.; Gyun, D.; Ha, S.; Hong, B.; Jo, Y.; Kim, Y.; Lee, K.; Lee, K. S.; Lee, S.; Lim, J.; Park, S. K.; Roh, Y.; Almond, J.; Kim, J.; Lee, H.; Oh, S. B.; Radburn-Smith, B. C.; Seo, S. h.; Yang, U. K.; Yoo, H. D.; Yu, G. B.; Choi, M.; Kim, H.; Kim, J. H.; Lee, J. S. H.; Park, I. C.; Ryu, G.; Ryu, M. S.; Choi, Y.; Goh, J.; Hwang, C.; Lee, J.; Yu, I.; Dudenas, V.; Juodagalvis, A.; Vaitkus, J.; Ahmed, I.; Ibrahim, Z. A.; Md Ali, M. A. B.; Mohamad Idris, F.; Wan Abdullah, W. A. T.; Yusli, M. N.; Zolkapli, Z.; Castilla-Valdez, H.; De La Cruz-Burelo, E.; Heredia-De La Cruz, I.; Hernandez-Almada, A.; Lopez-Fernandez, R.; Magaña Villalba, R.; Mejia Guisao, J.; Sanchez-Hernandez, A.; Carrillo Moreno, S.; Oropeza Barrera, C.; Vazquez Valencia, F.; Carpinteyro, S.; Pedraza, I.; Salazar Ibarguen, H. A.; Uribe Estrada, C.; Morelos Pineda, A.; Krofcheck, D.; Butler, P. H.; Ahmad, A.; Ahmad, M.; Hassan, Q.; Hoorani, H. R.; Khan, W. A.; Saddique, A.; Shah, M. A.; Shoaib, M.; Waqas, M.; Bialkowska, H.; Bluj, M.; Boimska, B.; Frueboes, T.; Górski, M.; Kazana, M.; Nawrocki, K.; Romanowska-Rybinska, K.; Szleper, M.; Zalewski, P.; Bunkowski, K.; Byszuk, A.; Doroba, K.; Kalinowski, A.; Konecki, M.; Krolikowski, J.; Misiura, M.; Olszewski, M.; Walczak, M.; Bargassa, P.; Beirão Da Cruz E Silva, C.; Calpas, B.; Di Francesco, A.; Faccioli, P.; Ferreira Parracho, P. G.; Gallinaro, M.; Hollar, J.; Leonardo, N.; Lloret Iglesias, L.; Nemallapudi, M. V.; Rodrigues Antunes, J.; Seixas, J.; Toldaiev, O.; Vadruccio, D.; Varela, J.; Alexakhin, V.; Belotelov, I.; Bunin, P.; Gavrilenko, M.; Golutvin, I.; Gorbunov, I.; Karjavin, V.; Lanev, A.; Malakhov, A.; Matveev, V.; Palichik, V.; Perelygin, V.; Savina, M.; Shmatov, S.; Shulha, S.; Skatchkov, N.; Smirnov, V.; Zarubin, A.; Chtchipounov, L.; Golovtsov, V.; Ivanov, Y.; Kim, V.; Kuznetsova, E.; Murzin, V.; Oreshkin, V.; Sulimov, V.; Vorobyev, A.; Andreev, Yu.; Dermenev, A.; Gninenko, S.; Golubev, N.; Karneyeu, A.; Kirsanov, M.; Krasnikov, N.; Pashenkov, A.; Tlisov, D.; Toropin, A.; Epshteyn, V.; Gavrilov, V.; Lychkovskaya, N.; Popov, V.; Pozdnyakov, I.; Safronov, G.; Spiridonov, A.; Toms, M.; Vlasov, E.; Zhokin, A.; Aushev, T.; Bylinkin, A.; Chadeeva, M.; Markin, O.; Tarkovskii, E.; Andreev, V.; Azarkin, M.; Dremin, I.; Kirakosyan, M.; Leonidov, A.; Terkulov, A.; Baskakov, A.; Belyaev, A.; Boos, E.; Bunichev, V.; Dubinin, M.; Dudko, L.; Ershov, A.; Gribushin, A.; Klyukhin, V.; Kodolova, O.; Lokhtin, I.; Miagkov, I.; Obraztsov, S.; Petrushanko, S.; Savrin, V.; Blinov, V.; Skovpen, Y.; Shtol, D.; Azhgirey, I.; Bayshev, I.; Bitioukov, S.; Elumakhov, D.; Kachanov, V.; Kalinin, A.; Konstantinov, D.; Krychkine, V.; Petrov, V.; Ryutin, R.; Sobol, A.; Troshin, S.; Tyurin, N.; Uzunian, A.; Volkov, A.; Adzic, P.; Cirkovic, P.; Devetak, D.; Dordevic, M.; Milosevic, J.; Rekovic, V.; Alcaraz Maestre, J.; Barrio Luna, M.; Calvo, E.; Cerrada, M.; Chamizo Llatas, M.; Colino, N.; De La Cruz, B.; Delgado Peris, A.; Escalante Del Valle, A.; Fernandez Bedoya, C.; Fernández Ramos, J. P.; Flix, J.; Fouz, M. C.; Garcia-Abia, P.; Gonzalez Lopez, O.; Goy Lopez, S.; Hernandez, J. M.; Josa, M. I.; Navarro De Martino, E.; Pérez-Calero Yzquierdo, A.; Puerta Pelayo, J.; Quintario Olmeda, A.; Redondo, I.; Romero, L.; Soares, M. S.; de Trocóniz, J. F.; Missiroli, M.; Moran, D.; Cuevas, J.; Fernandez Menendez, J.; Gonzalez Caballero, I.; González Fernández, J. R.; Palencia Cortezon, E.; Sanchez Cruz, S.; Suárez Andrés, I.; Vischia, P.; Vizan Garcia, J. M.; Cabrillo, I. J.; Calderon, A.; Curras, E.; Fernandez, M.; Garcia-Ferrero, J.; Gomez, G.; Lopez Virto, A.; Marco, J.; Martinez Rivero, C.; Matorras, F.; Piedra Gomez, J.; Rodrigo, T.; Ruiz-Jimeno, A.; Scodellaro, L.; Trevisani, N.; Vila, I.; Vilar Cortabitarte, R.; Abbaneo, D.; Auffray, E.; Auzinger, G.; Baillon, P.; Ball, A. H.; Barney, D.; Bloch, P.; Bocci, A.; Botta, C.; Camporesi, T.; Castello, R.; Cepeda, M.; Cerminara, G.; Chen, Y.; d'Enterria, D.; Dabrowski, A.; Daponte, V.; David, A.; De Gruttola, M.; De Roeck, A.; Di Marco, E.; Dobson, M.; Dorney, B.; du Pree, T.; Duggan, D.; Dünser, M.; Dupont, N.; Elliott-Peisert, A.; Everaerts, P.; Fartoukh, S.; Franzoni, G.; Fulcher, J.; Funk, W.; Gigi, D.; Gill, K.; Girone, M.; Glege, F.; Gulhan, D.; Gundacker, S.; Guthoff, M.; Harris, P.; Hegeman, J.; Innocente, V.; Janot, P.; Kieseler, J.; Kirschenmann, H.; Knünz, V.; Kornmayer, A.; Kortelainen, M. J.; Kousouris, K.; Krammer, M.; Lange, C.; Lecoq, P.; Lourenço, C.; Lucchini, M. T.; Malgeri, L.; Mannelli, M.; Martelli, A.; Meijers, F.; Merlin, J. A.; Mersi, S.; Meschi, E.; Milenovic, P.; Moortgat, F.; Morovic, S.; Mulders, M.; Neugebauer, H.; Orfanelli, S.; Orsini, L.; Pape, L.; Perez, E.; Peruzzi, M.; Petrilli, A.; Petrucciani, G.; Pfeiffer, A.; Pierini, M.; Racz, A.; Reis, T.; Rolandi, G.; Rovere, M.; Sakulin, H.; Sauvan, J. B.; Schäfer, C.; Schwick, C.; Seidel, M.; Sharma, A.; Silva, P.; Sphicas, P.; Steggemann, J.; Stoye, M.; Takahashi, Y.; Tosi, M.; Treille, D.; Triossi, A.; Tsirou, A.; Veckalns, V.; Veres, G. I.; Verweij, M.; Wardle, N.; Wöhri, H. K.; Zagozdzinska, A.; Zeuner, W. D.; Bertl, W.; Deiters, K.; Erdmann, W.; Horisberger, R.; Ingram, Q.; Kaestli, H. C.; Kotlinski, D.; Langenegger, U.; Rohe, T.; Wiederkehr, S. A.; Bachmair, F.; Bäni, L.; Bianchini, L.; Casal, B.; Dissertori, G.; Dittmar, M.; Donegà, M.; Grab, C.; Heidegger, C.; Hits, D.; Hoss, J.; Kasieczka, G.; Lustermann, W.; Mangano, B.; Marionneau, M.; Martinez Ruiz del Arbol, P.; Masciovecchio, M.; Meinhard, M. T.; Meister, D.; Micheli, F.; Musella, P.; Nessi-Tedaldi, F.; Pandolfi, F.; Pata, J.; Pauss, F.; Perrin, G.; Perrozzi, L.; Quittnat, M.; Rossini, M.; Schönenberger, M.; Starodumov, A.; Tavolaro, V. R.; Theofilatos, K.; Wallny, R.; Aarrestad, T. K.; Amsler, C.; Caminada, L.; Canelli, M. F.; De Cosa, A.; Galloni, C.; Hinzmann, A.; Hreus, T.; Kilminster, B.; Ngadiuba, J.; Pinna, D.; Rauco, G.; Robmann, P.; Salerno, D.; Seitz, C.; Yang, Y.; Zucchetta, A.; Candelise, V.; Doan, T. H.; Jain, Sh.; Khurana, R.; Konyushikhin, M.; Kuo, C. M.; Lin, W.; Pozdnyakov, A.; Yu, S. S.; Kumar, Arun; Chang, P.; Chang, Y. H.; Chao, Y.; Chen, K. F.; Chen, P. H.; Fiori, F.; Hou, W.-S.; Hsiung, Y.; Liu, Y. F.; Lu, R.-S.; Miñano Moya, M.; Paganis, E.; Psallidas, A.; Tsai, J. f.; Asavapibhop, B.; Singh, G.; Srimanobhas, N.; Suwonjandee, N.; Adiguzel, A.; Cerci, S.; Damarseckin, S.; Demiroglu, Z. S.; Dozen, C.; Dumanoglu, I.; Girgis, S.; Gokbulut, G.; Guler, Y.; Hos, I.; Kangal, E. E.; Kara, O.; Kayis Topaksu, A.; Kiminsu, U.; Oglakci, M.; Onengut, G.; Ozdemir, K.; Sunar Cerci, D.; Topakli, H.; Turkcapar, S.; Zorbakir, I. S.; Zorbilmez, C.; Bilin, B.; Bilmis, S.; Isildak, B.; Karapinar, G.; Yalvac, M.; Zeyrek, M.; Gülmez, E.; Kaya, M.; Kaya, O.; Yetkin, E. A.; Yetkin, T.; Cakir, A.; Cankocak, K.; Sen, S.; Grynyov, B.; Levchuk, L.; Sorokin, P.; Aggleton, R.; Ball, F.; Beck, L.; Brooke, J. J.; Burns, D.; Clement, E.; Cussans, D.; Flacher, H.; Goldstein, J.; Grimes, M.; Heath, G. P.; Heath, H. F.; Jacob, J.; Kreczko, L.; Lucas, C.; Newbold, D. M.; Paramesvaran, S.; Poll, A.; Sakuma, T.; Seif El Nasr-storey, S.; Smith, D.; Smith, V. J.; Bell, K. W.; Belyaev, A.; Brew, C.; Brown, R. M.; Calligaris, L.; Cieri, D.; Cockerill, D. J. A.; Coughlan, J. A.; Harder, K.; Harper, S.; Olaiya, E.; Petyt, D.; Shepherd-Themistocleous, C. H.; Thea, A.; Tomalin, I. R.; Williams, T.; Baber, M.; Bainbridge, R.; Buchmuller, O.; Bundock, A.; Burton, D.; Casasso, S.; Citron, M.; Colling, D.; Corpe, L.; Dauncey, P.; Davies, G.; De Wit, A.; Della Negra, M.; Di Maria, R.; Dunne, P.; Elwood, A.; Futyan, D.; Haddad, Y.; Hall, G.; Iles, G.; James, T.; Lane, R.; Laner, C.; Lucas, R.; Lyons, L.; Magnan, A.-M.; Malik, S.; Mastrolorenzo, L.; Nash, J.; Nikitenko, A.; Pela, J.; Penning, B.; Pesaresi, M.; Raymond, D. M.; Richards, A.; Rose, A.; Scott, E.; Seez, C.; Summers, S.; Tapper, A.; Uchida, K.; Vazquez Acosta, M.; Virdee, T.; Wright, J.; Zenz, S. C.; Cole, J. E.; Hobson, P. R.; Khan, A.; Kyberd, P.; Reid, I. D.; Symonds, P.; Teodorescu, L.; Turner, M.; Borzou, A.; Call, K.; Dittmann, J.; Hatakeyama, K.; Liu, H.; Pastika, N.; Bartek, R.; Dominguez, A.; Buccilli, A.; Cooper, S. I.; Henderson, C.; Rumerio, P.; West, C.; Arcaro, D.; Avetisyan, A.; Bose, T.; Gastler, D.; Rankin, D.; Richardson, C.; Rohlf, J.; Sulak, L.; Zou, D.; Benelli, G.; Cutts, D.; Garabedian, A.; Hakala, J.; Heintz, U.; Hogan, J. M.; Jesus, O.; Kwok, K. H. M.; Laird, E.; Landsberg, G.; Mao, Z.; Narain, M.; Piperov, S.; Sagir, S.; Spencer, E.; Syarif, R.; Breedon, R.; Burns, D.; Calderon De La Barca Sanchez, M.; Chauhan, S.; Chertok, M.; Conway, J.; Conway, R.; Cox, P. T.; Erbacher, R.; Flores, C.; Funk, G.; Gardner, M.; Ko, W.; Lander, R.; Mclean, C.; Mulhearn, M.; Pellett, D.; Pilot, J.; Shalhout, S.; Shi, M.; Smith, J.; Squires, M.; Stolp, D.; Tos, K.; Tripathi, M.; Bachtis, M.; Bravo, C.; Cousins, R.; Dasgupta, A.; Florent, A.; Hauser, J.; Ignatenko, M.; Mccoll, N.; Saltzberg, D.; Schnaible, C.; Valuev, V.; Weber, M.; Bouvier, E.; Burt, K.; Clare, R.; Ellison, J.; Gary, J. W.; Ghiasi Shirazi, S. M. A.; Hanson, G.; Heilman, J.; Jandir, P.; Kennedy, E.; Lacroix, F.; Long, O. R.; Olmedo Negrete, M.; Paneva, M. I.; Shrinivas, A.; Si, W.; Wei, H.; Wimpenny, S.; Yates, B. R.; Branson, J. G.; Cerati, G. B.; Cittolin, S.; Derdzinski, M.; Gerosa, R.; Holzner, A.; Klein, D.; Krutelyov, V.; Letts, J.; Macneill, I.; Olivito, D.; Padhi, S.; Pieri, M.; Sani, M.; Sharma, V.; Simon, S.; Tadel, M.; Vartak, A.; Wasserbaech, S.; Welke, C.; Wood, J.; Würthwein, F.; Yagil, A.; Zevi Della Porta, G.; Amin, N.; Bhandari, R.; Bradmiller-Feld, J.; Campagnari, C.; Dishaw, A.; Dutta, V.; Franco Sevilla, M.; George, C.; Golf, F.; Gouskos, L.; Gran, J.; Heller, R.; Incandela, J.; Mullin, S. D.; Ovcharova, A.; Qu, H.; Richman, J.; Stuart, D.; Suarez, I.; Yoo, J.; Anderson, D.; Bendavid, J.; Bornheim, A.; Bunn, J.; Duarte, J.; Lawhorn, J. M.; Mott, A.; Newman, H. B.; Pena, C.; Spiropulu, M.; Vlimant, J. R.; Xie, S.; Zhu, R. Y.; Andrews, M. B.; Ferguson, T.; Paulini, M.; Russ, J.; Sun, M.; Vogel, H.; Vorobiev, I.; Weinberg, M.; Cumalat, J. P.; Ford, W. T.; Jensen, F.; Johnson, A.; Krohn, M.; Leontsinis, S.; Mulholland, T.; Stenson, K.; Wagner, S. R.; Alexander, J.; Chaves, J.; Chu, J.; Dittmer, S.; Mcdermott, K.; Mirman, N.; Nicolas Kaufman, G.; Patterson, J. R.; Rinkevicius, A.; Ryd, A.; Skinnari, L.; Soffi, L.; Tan, S. M.; Tao, Z.; Thom, J.; Tucker, J.; Wittich, P.; Zientek, M.; Winn, D.; Abdullin, S.; Albrow, M.; Apollinari, G.; Apresyan, A.; Banerjee, S.; Bauerdick, L. A. T.; Beretvas, A.; Berryhill, J.; Bhat, P. C.; Bolla, G.; Burkett, K.; Butler, J. N.; Cheung, H. W. K.; Chlebana, F.; Cihangir, S.; Cremonesi, M.; Elvira, V. D.; Fisk, I.; Freeman, J.; Gottschalk, E.; Gray, L.; Green, D.; Grünendahl, S.; Gutsche, O.; Hare, D.; Harris, R. M.; Hasegawa, S.; Hirschauer, J.; Hu, Z.; Jayatilaka, B.; Jindariani, S.; Johnson, M.; Joshi, U.; Klima, B.; Kreis, B.; Lammel, S.; Linacre, J.; Lincoln, D.; Lipton, R.; Liu, M.; Liu, T.; Lopes De Sá, R.; Lykken, J.; Maeshima, K.; Magini, N.; Marraffino, J. M.; Maruyama, S.; Mason, D.; McBride, P.; Merkel, P.; Mrenna, S.; Nahn, S.; O'Dell, V.; Pedro, K.; Prokofyev, O.; Rakness, G.; Ristori, L.; Sexton-Kennedy, E.; Soha, A.; Spalding, W. J.; Spiegel, L.; Stoynev, S.; Strait, J.; Strobbe, N.; Taylor, L.; Tkaczyk, S.; Tran, N. V.; Uplegger, L.; Vaandering, E. W.; Vernieri, C.; Verzocchi, M.; Vidal, R.; Wang, M.; Weber, H. A.; Whitbeck, A.; Wu, Y.; Acosta, D.; Avery, P.; Bortignon, P.; Bourilkov, D.; Brinkerhoff, A.; Carnes, A.; Carver, M.; Curry, D.; Das, S.; Field, R. D.; Furic, I. K.; Konigsberg, J.; Korytov, A.; Low, J. F.; Ma, P.; Matchev, K.; Mei, H.; Mitselmakher, G.; Rank, D.; Shchutska, L.; Sperka, D.; Thomas, L.; Wang, J.; Wang, S.; Yelton, J.; Linn, S.; Markowitz, P.; Martinez, G.; Rodriguez, J. L.; Ackert, A.; Adams, T.; Askew, A.; Bein, S.; Hagopian, S.; Hagopian, V.; Johnson, K. F.; Kolberg, T.; Prosper, H.; Santra, A.; Yohay, R.; Baarmand, M. M.; Bhopatkar, V.; Colafranceschi, S.; Hohlmann, M.; Noonan, D.; Roy, T.; Yumiceva, F.; Adams, M. R.; Apanasevich, L.; Berry, D.; Betts, R. R.; Bucinskaite, I.; Cavanaugh, R.; Evdokimov, O.; Gauthier, L.; Gerber, C. E.; Hofman, D. J.; Jung, K.; Sandoval Gonzalez, I. D.; Varelas, N.; Wang, H.; Wu, Z.; Zakaria, M.; Zhang, J.; Bilki, B.; Clarida, W.; Dilsiz, K.; Durgut, S.; Gandrajula, R. P.; Haytmyradov, M.; Khristenko, V.; Merlo, J.-P.; Mermerkaya, H.; Mestvirishvili, A.; Moeller, A.; Nachtman, J.; Ogul, H.; Onel, Y.; Ozok, F.; Penzo, A.; Snyder, C.; Tiras, E.; Wetzel, J.; Yi, K.; Blumenfeld, B.; Cocoros, A.; Eminizer, N.; Fehling, D.; Feng, L.; Gritsan, A. V.; Maksimovic, P.; Roskes, J.; Sarica, U.; Swartz, M.; Xiao, M.; You, C.; Al-bataineh, A.; Baringer, P.; Bean, A.; Boren, S.; Bowen, J.; Castle, J.; Forthomme, L.; Kenny, R. P., III; Khalil, S.; Kropivnitskaya, A.; Majumder, D.; Mcbrayer, W.; Murray, M.; Sanders, S.; Stringer, R.; Tapia Takaki, J. D.; Wang, Q.; Ivanov, A.; Kaadze, K.; Maravin, Y.; Mohammadi, A.; Saini, L. K.; Skhirtladze, N.; Toda, S.; Rebassoo, F.; Wright, D.; Anelli, C.; Baden, A.; Baron, O.; Belloni, A.; Calvert, B.; Eno, S. C.; Ferraioli, C.; Gomez, J. A.; Hadley, N. J.; Jabeen, S.; Jeng, G. Y.; Kellogg, R. G.; Kunkle, J.; Mignerey, A. C.; Ricci-Tam, F.; Shin, Y. H.; Skuja, A.; Tonjes, M. B.; Tonwar, S. C.; Abercrombie, D.; Allen, B.; Apyan, A.; Azzolini, V.; Barbieri, R.; Baty, A.; Bi, R.; Bierwagen, K.; Brandt, S.; Busza, W.; Cali, I. A.; D'Alfonso, M.; Demiragli, Z.; Gomez Ceballos, G.; Goncharov, M.; Hsu, D.; Iiyama, Y.; Innocenti, G. M.; Klute, M.; Kovalskyi, D.; Krajczar, K.; Lai, Y. S.; Lee, Y.-J.; Levin, A.; Luckey, P. D.; Maier, B.; Marini, A. C.; Mcginn, C.; Mironov, C.; Narayanan, S.; Niu, X.; Paus, C.; Roland, C.; Roland, G.; Salfeld-Nebgen, J.; Stephans, G. S. F.; Tatar, K.; Velicanu, D.; Wang, J.; Wang, T. W.; Wyslouch, B.; Benvenuti, A. C.; Chatterjee, R. M.; Evans, A.; Hansen, P.; Kalafut, S.; Kao, S. C.; Kubota, Y.; Lesko, Z.; Mans, J.; Nourbakhsh, S.; Ruckstuhl, N.; Rusack, R.; Tambe, N.; Turkewitz, J.; Acosta, J. G.; Oliveros, S.; Avdeeva, E.; Bloom, K.; Claes, D. R.; Fangmeier, C.; Gonzalez Suarez, R.; Kamalieddin, R.; Kravchenko, I.; Malta Rodrigues, A.; Monroy, J.; Siado, J. E.; Snow, G. R.; Stieger, B.; Alyari, M.; Dolen, J.; Godshalk, A.; Harrington, C.; Iashvili, I.; Kaisen, J.; Nguyen, D.; Parker, A.; Rappoccio, S.; Roozbahani, B.; Alverson, G.; Barberis, E.; Hortiangtham, A.; Massironi, A.; Morse, D. M.; Nash, D.; Orimoto, T.; Teixeira De Lima, R.; Trocino, D.; Wang, R.-J.; Wood, D.; Bhattacharya, S.; Charaf, O.; Hahn, K. A.; Kumar, A.; Mucia, N.; Odell, N.; Pollack, B.; Schmitt, M. H.; Sung, K.; Trovato, M.; Velasco, M.; Dev, N.; Hildreth, M.; Hurtado Anampa, K.; Jessop, C.; Karmgard, D. J.; Kellams, N.; Lannon, K.; Marinelli, N.; Meng, F.; Mueller, C.; Musienko, Y.; Planer, M.; Reinsvold, A.; Ruchti, R.; Rupprecht, N.; Smith, G.; Taroni, S.; Wayne, M.; Wolf, M.; Woodard, A.; Alimena, J.; Antonelli, L.; Bylsma, B.; Durkin, L. S.; Flowers, S.; Francis, B.; Hart, A.; Hill, C.; Hughes, R.; Ji, W.; Liu, B.; Luo, W.; Puigh, D.; Winer, B. L.; Wulsin, H. W.; Cooperstein, S.; Driga, O.; Elmer, P.; Hardenbrook, J.; Hebda, P.; Lange, D.; Luo, J.; Marlow, D.; Medvedeva, T.; Mei, K.; Ojalvo, I.; Olsen, J.; Palmer, C.; Piroué, P.; Stickland, D.; Svyatkovskiy, A.; Tully, C.; Malik, S.; Barker, A.; Barnes, V. E.; Folgueras, S.; Gutay, L.; Jha, M. K.; Jones, M.; Jung, A. W.; Khatiwada, A.; Miller, D. H.; Neumeister, N.; Schulte, J. F.; Shi, X.; Sun, J.; Wang, F.; Xie, W.; Parashar, N.; Stupak, J.; Adair, A.; Akgun, B.; Chen, Z.; Ecklund, K. M.; Geurts, F. J. M.; Guilbaud, M.; Li, W.; Michlin, B.; Northup, M.; Padley, B. P.; Roberts, J.; Rorie, J.; Tu, Z.; Zabel, J.; Betchart, B.; Bodek, A.; de Barbaro, P.; Demina, R.; Duh, Y. t.; Ferbel, T.; Galanti, M.; Garcia-Bellido, A.; Han, J.; Hindrichs, O.; Khukhunaishvili, A.; Lo, K. H.; Tan, P.; Verzetti, M.; Agapitos, A.; Chou, J. P.; Gershtein, Y.; Gómez Espinosa, T. A.; Halkiadakis, E.; Heindl, M.; Hughes, E.; Kaplan, S.; Kunnawalkam Elayavalli, R.; Kyriacou, S.; Lath, A.; Nash, K.; Osherson, M.; Saka, H.; Salur, S.; Schnetzer, S.; Sheffield, D.; Somalwar, S.; Stone, R.; Thomas, S.; Thomassen, P.; Walker, M.; Delannoy, A. G.; Foerster, M.; Heideman, J.; Riley, G.; Rose, K.; Spanier, S.; Thapa, K.; Bouhali, O.; Celik, A.; Dalchenko, M.; De Mattia, M.; Delgado, A.; Dildick, S.; Eusebi, R.; Gilmore, J.; Huang, T.; Juska, E.; Kamon, T.; Mueller, R.; Pakhotin, Y.; Patel, R.; Perloff, A.; Perniè, L.; Rathjens, D.; Safonov, A.; Tatarinov, A.; Ulmer, K. A.; Akchurin, N.; Cowden, C.; Damgov, J.; De Guio, F.; Dragoiu, C.; Dudero, P. R.; Faulkner, J.; Gurpinar, E.; Kunori, S.; Lamichhane, K.; Lee, S. W.; Libeiro, T.; Peltola, T.; Undleeb, S.; Volobouev, I.; Wang, Z.; Greene, S.; Gurrola, A.; Janjam, R.; Johns, W.; Maguire, C.; Melo, A.; Ni, H.; Sheldon, P.; Tuo, S.; Velkovska, J.; Xu, Q.; Arenton, M. W.; Barria, P.; Cox, B.; Goodell, J.; Hirosky, R.; Ledovskoy, A.; Li, H.; Neu, C.; Sinthuprasith, T.; Sun, X.; Wang, Y.; Wolfe, E.; Xia, F.; Clarke, C.; Harr, R.; Karchin, P. E.; Sturdy, J.; Belknap, D. A.; Buchanan, J.; Caillol, C.; Dasu, S.; Dodd, L.; Duric, S.; Gomber, B.; Grothe, M.; Herndon, M.; Hervé, A.; Klabbers, P.; Lanaro, A.; Levine, A.; Long, K.; Loveless, R.; Perry, T.; Pierro, G. A.; Polese, G.; Ruggles, T.; Savin, A.; Smith, N.; Smith, W. H.; Taylor, D.; Woods, N.; CMS Collaboration

2017-11-01

A search for new physics in energetic, high-multiplicity final states has been performed using proton-proton collision data collected with the CMS detector at a center-of-mass energy of 13TeV and corresponding to an integrated luminosity of 2.3fb-1. The standard model background, dominated by multijet production, is determined exclusively from control regions in data. No statistically significant excess of events is observed. Model-independent limits on the product of the cross section and the acceptance of a new physics signal in these final states are set and further interpreted in terms of limits on the production of black holes. Semiclassical black holes and string balls with masses as high as 9.5TeV, and quantum black holes with masses as high as 9.0TeV are excluded by this search in the context of models with extra dimensions, thus significantly extending limits set at a center-of-mass energy of 8TeV with the LHC Run 1 data.
Motion and collision of particles in a rotating linear dilaton black hole

NASA Astrophysics Data System (ADS)

González, P. A.; Olivares, Marco; Papantonopoulos, Eleftherios; Vásquez, Yerko

2018-03-01

We study the motion of particles in the background of a four-dimensional linear dilaton black hole. We solve analytically the equations of motion of the test particles, and we describe their motion. We show that the dilaton black hole acts as a particle accelerator by analyzing the energy in the center of mass frame of two colliding particles in the vicinity of its horizon. In particular, we find that there is a critical value of the angular momentum, which depends on the string coupling, and a particle with this critical angular momentum can reach the inner horizon with an arbitrarily high c.m. energy. This is known as the Bañados, Silk, and West process. We also show that the motion and collisions of particles have behavior similar to the three-dimensional Bañados-Teitelboim-Zanelli black hole. In fact, the photons can plunge into the horizon or escape to infinity, and they cannot be deflected, while for massive particles there are no confined orbits of the first kind, like planetary or circular orbits.
Functional determinants, index theorems, and exact quantum black hole entropy

NASA Astrophysics Data System (ADS)

Murthy, Sameer; Reys, Valentin

2015-12-01

The exact quantum entropy of BPS black holes can be evaluated using localization in supergravity. An important ingredient in this program, that has been lacking so far, is the one-loop effect arising from the quadratic fluctuations of the exact deformation (the QV operator). We compute the fluctuation determinant for vector multiplets and hyper multiplets around Q-invariant off-shell configurations in four-dimensional N=2 supergravity with AdS 2 × S 2 boundary conditions, using the Atiyah-Bott fixed-point index theorem and a subsequent zeta function regularization. Our results extend the large-charge on-shell entropy computations in the literature to a regime of finite charges. Based on our results, we present an exact formula for the quantum entropy of BPS black holes in N=2 supergravity. We explain cancellations concerning 1/8 -BPS black holes in N=8 supergravity that were observed in arXiv:1111.1161. We also make comments about the interpretation of a logarithmic term in the topological string partition function in the low energy supergravity theory.

Generalized uncertainty principle: implications for black hole complementarity

NASA Astrophysics Data System (ADS)

Chen, Pisin; Ong, Yen Chin; Yeom, Dong-han

2014-12-01

At the heart of the black hole information loss paradox and the firewall controversy lies the conflict between quantum mechanics and general relativity. Much has been said about quantum corrections to general relativity, but much less in the opposite direction. It is therefore crucial to examine possible corrections to quantum mechanics due to gravity. Indeed, the Heisenberg Uncertainty Principle is one profound feature of quantum mechanics, which nevertheless may receive correction when gravitational effects become important. Such generalized uncertainty principle [GUP] has been motivated from not only quite general considerations of quantum mechanics and gravity, but also string theoretic arguments. We examine the role of GUP in the context of black hole complementarity. We find that while complementarity can be violated by large N rescaling if one assumes only the Heisenberg's Uncertainty Principle, the application of GUP may save complementarity, but only if certain N -dependence is also assumed. This raises two important questions beyond the scope of this work, i.e., whether GUP really has the proposed form of N -dependence, and whether black hole complementarity is indeed correct.
Search for black holes and other new phenomena in high-multiplicity final states in proton–proton collisions at s = 13 TeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sirunyan, A. M.; Tumasyan, A.; Adam, W.

A search for new physics in energetic, high-multiplicity final states has been performed using proton-proton collision data collected with the CMS detector at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 2.3 inverse femtobarns. The standard model background, dominated by multijet production, is determined exclusively from control regions in data. No statistically significant excess of events is observed. Model-independent limits on the product of the cross section and the acceptance of a new physics signal in these final states are set and further interpreted in terms of limits on the production of black holes. Semiclassicalmore » black holes and string balls with masses as high as 9.5 TeV, and quantum black holes with masses as high as 9.0 TeV are excluded by this search in the context of models with extra dimensions, thus significantly extending limits set at a center-of-mass energy of 8 TeV with the LHC Run 1 data.« less
Holographic entanglement entropy and entanglement thermodynamics of 'black' non-susy D3 brane

NASA Astrophysics Data System (ADS)

Bhattacharya, Aranya; Roy, Shibaji

2018-06-01

Like BPS D3 brane, the non-supersymmetric (non-susy) D3 brane of type IIB string theory is also known to have a decoupling limit and leads to a non-supersymmetric AdS/CFT correspondence. The throat geometry in this case represents a QFT which is neither conformal nor supersymmetric. The 'black' version of the non-susy D3 brane in the decoupling limit describes a QFT at finite temperature. Here we first compute the entanglement entropy for small subsystem of such QFT from the decoupled geometry of 'black' non-susy D3 brane using holographic technique. Then we study the entanglement thermodynamics for the weakly excited states of this QFT from the asymptotically AdS geometry of the decoupled 'black' non-susy D3 brane. We observe that for small subsystem this background indeed satisfies a first law like relation with a universal (entanglement) temperature inversely proportional to the size of the subsystem and an (entanglement) pressure normal to the entangling surface. Finally we show how the entanglement entropy makes a cross-over to the thermal entropy at high temperature.
Search for black holes and other new phenomena in high-multiplicity final states in proton–proton collisions at s = 13 TeV

DOE PAGES

Sirunyan, A. M.; Tumasyan, A.; Adam, W.; ...

2017-09-22

A search for new physics in energetic, high-multiplicity final states has been performed using proton-proton collision data collected with the CMS detector at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 2.3 inverse femtobarns. The standard model background, dominated by multijet production, is determined exclusively from control regions in data. No statistically significant excess of events is observed. Model-independent limits on the product of the cross section and the acceptance of a new physics signal in these final states are set and further interpreted in terms of limits on the production of black holes. Semiclassicalmore » black holes and string balls with masses as high as 9.5 TeV, and quantum black holes with masses as high as 9.0 TeV are excluded by this search in the context of models with extra dimensions, thus significantly extending limits set at a center-of-mass energy of 8 TeV with the LHC Run 1 data.« less
The Future of Theoretical Physics and Cosmology

NASA Astrophysics Data System (ADS)

Gibbons, G. W.; Shellard, E. P. S.; Rankin, S. J.

2003-11-01

Based on lectures given in honor of Stephen Hawking's 60th birthday, this book comprises contributions from the world's leading theoretical physicists. Popular lectures progress to a critical evaluation of more advanced subjects in modern cosmology and theoretical physics. Topics covered include the origin of the universe, warped spacetime, cosmological singularities, quantum gravity, black holes, string theory, quantum cosmology and inflation. The volume provides a fascinating overview of the variety of subjects to which Stephen Hawking has contributed.
Applications of holography to condensed matter physics

NASA Astrophysics Data System (ADS)

Ross, Simon F.

2012-10-01

Holography is one of the key insights to emerge from string theory. It connects quantum gravity to field theory, and thereby provides a non-perturbative formulation of string theory. This has enabled progress on a range of theoretical issues, from the quantum description of spacetime to the calculation of scattering amplitudes in supersymmetric field theories. There have been important insights into both the field theories and the spacetime picture. More recently, applied holography has been the subject of intense and rapid development. The idea here is to use the spacetime description to address questions about strongly coupled field theory relevant to application areas such as finite-temperature QCD and condensed matter physics; the focus in this special issue is on the latter. This involves the study of field theory at finite temperature and with chemical potentials for appropriate charges, described in spacetime by charged black hole solutions. The use of holography to study these systems requires a significant extrapolation, from the field theories where classical gravitational calculations in the bulk are a useful approximation to the experimentally relevant theories. Nonetheless, the approach has had some striking qualitative successes, including the construction of holographic versions of superconducting or superfluid phase transitions, the identification of Fermi liquids with a variety of thermal behaviours, and the construction of a map between a class of gravity solutions and the hydrodynamic regime in the field theory. The use of holography provides a qualitatively new perspective on these aspects of strong coupling dynamics. In addition to insight into the behaviour of the strongly coupled field theories, this work has led to new insights into the bulk dynamics and a deeper understanding of holography. The purpose of this focus issue is to strengthen the connections between this direction and other gravitational research and to make the gravity community more aware of these developments. The issue is made up of original research contributions at the forefront of this area, giving a sense of the range of activity and presenting significant new contributions. Simon F RossGuest Editor
Black hole solution in the framework of arctan-electrodynamics

NASA Astrophysics Data System (ADS)

Kruglov, S. I.

An arctan-electrodynamics coupled with the gravitational field is investigated. We obtain the regular black hole solution that at r →∞ gives corrections to the Reissner-Nordström solution. The corrections to Coulomb’s law at r →∞ are found. We evaluate the mass of the black hole that is a function of the dimensional parameter β introduced in the model. The magnetically charged black hole was investigated and we have obtained the magnetic mass of the black hole and the metric function at r →∞. The regular black hole solution is obtained at r → 0 with the de Sitter core. We show that there is no singularity of the Ricci scalar for electrically and magnetically charged black holes. Restrictions on the electric and magnetic fields are found that follow from the requirement of the absence of superluminal sound speed and the requirement of a classical stability.
Excitations in the Yang–Gaudin Bose gas

DOE PAGES

Robinson, Neil J.; Konik, Robert M.

2017-06-01

Here, we study the excitation spectrum of two-component delta-function interacting bosons confined to a single spatial dimension, the Yang–Gaudin Bose gas. We show that there are pronounced finite-size effects in the dispersion relations of excitations, perhaps best illustrated by the spinon single particle dispersion which exhibits a gap at 2k F and a finite-momentum roton-like minimum. Such features occur at energies far above the finite volume excitation gap, vanish slowly as 1/L for fixed spinon number, and can persist to the thermodynamic limit at fixed spinon density. Features such as the 2k F gap also persist to multi-particle excitation continua. Our results show that excitations in the finite system can behave in a qualitatively different manner to analogous excitations in the thermodynamic limit. The Yang–Gaudin Bose gas is also host to multi-spinon bound states, known asmore » $$\\Lambda$$ -strings. We study these excitations both in the thermodynamic limit under the string hypothesis and in finite size systems where string deviations are taken into account. In the zero-temperature limit we present a simple relation between the length n $$\\Lambda$$-string dressed energies $$\\epsilon_n(\\lambda)$$ and the dressed energy $$\\epsilon(k)$$. We solve the Yang–Yang–Takahashi equations numerically and compare to the analytical solution obtained under the strong couple expansion, revealing that the length n $$\\Lambda$$ -string dressed energy is Lorentzian over a wide range of real string centers λ in the vicinity of $$\\lambda = 0$$ . We then examine the finite size effects present in the dispersion of the two-spinon bound states by numerically solving the Bethe ansatz equations with string deviations.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)

Robinson, Neil J.; Konik, Robert M.

Here, we study the excitation spectrum of two-component delta-function interacting bosons confined to a single spatial dimension, the Yang–Gaudin Bose gas. We show that there are pronounced finite-size effects in the dispersion relations of excitations, perhaps best illustrated by the spinon single particle dispersion which exhibits a gap at 2k F and a finite-momentum roton-like minimum. Such features occur at energies far above the finite volume excitation gap, vanish slowly as 1/L for fixed spinon number, and can persist to the thermodynamic limit at fixed spinon density. Features such as the 2k F gap also persist to multi-particle excitation continua. Our results show that excitations in the finite system can behave in a qualitatively different manner to analogous excitations in the thermodynamic limit. The Yang–Gaudin Bose gas is also host to multi-spinon bound states, known asmore » $$\\Lambda$$ -strings. We study these excitations both in the thermodynamic limit under the string hypothesis and in finite size systems where string deviations are taken into account. In the zero-temperature limit we present a simple relation between the length n $$\\Lambda$$-string dressed energies $$\\epsilon_n(\\lambda)$$ and the dressed energy $$\\epsilon(k)$$. We solve the Yang–Yang–Takahashi equations numerically and compare to the analytical solution obtained under the strong couple expansion, revealing that the length n $$\\Lambda$$ -string dressed energy is Lorentzian over a wide range of real string centers λ in the vicinity of $$\\lambda = 0$$ . We then examine the finite size effects present in the dispersion of the two-spinon bound states by numerically solving the Bethe ansatz equations with string deviations.« less
Evolution of the mean jet shape and dijet asymmetry distribution of an ensemble of holographic jets in strongly coupled plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brewer, Jasmine; Rajagopal, Krishna; Sadofyev, Andrey

Some of the most important experimentally accessible probes of the quark- gluon plasma (QGP) produced in heavy ion collisions come from the analysis of how the shape and energy of sprays of energetic particles produced within a cone with a specified opening angle (jets) in a hard scattering are modified by their passage through the strongly coupled, liquid, QGP. We model an ensemble of back-to-back dijets for the purpose of gaining a qualitative understanding of how the shapes of the individual jets and the asymmetry in the energy of the pairs of jets in the ensemble are modified by theirmore » passage through an expanding cooling droplet of strongly coupled plasma, in the model in a holographic gauge theory that is dual to a 4+1-dimensional black-hole spacetime that is asymptotically anti-de Sitter (AdS). We build our model by constructing an ensemble of strings in the dual gravitational description of the gauge theory. We model QCD jets in vacuum using strings whose endpoints are moving “downward” into the gravitational bulk spacetime with some fixed small angle, an angle that represents the opening angle (ratio of jet mass to jet energy) that the QCD jet would have in vacuum. Such strings must be moving through the gravitational bulk at (close to) the speed of light; they must be (close to) null. This condition does not specify the energy distribution along the string, meaning that it does not specify the shape of the jet being modeled. We study the dynamics of strings that are initially not null and show that strings with a wide range of initial conditions rapidly accelerate and become null and, as they do, develop a similar distribution of their energy density. We use this distribution of the energy density along the string, choose an ensemble of strings whose opening angles and energies are distributed as in perturbative QCD, and show that we can then fix one of the two model parameters such that the mean jet shape for the jets in the ensemble that we have built matches that measured in proton-proton collisions reasonably well. This is a novel way for hybridizing relevant inputs from perturbative QCD and a strongly coupled holographic gauge theory in the service of modeling jets in QGP. We send our ensemble of strings through an expanding cooling droplet of strongly coupled plasma, choosing the second model parameter so as to get a reasonable value for R AA jet , the suppression in the number of jets, and study how the mean jet shape and the dijet asymmetry are modified, comparing both to measurements from heavy ion collisions at the LHC.« less
Evolution of the mean jet shape and dijet asymmetry distribution of an ensemble of holographic jets in strongly coupled plasma

DOE PAGES

Brewer, Jasmine; Rajagopal, Krishna; Sadofyev, Andrey; ...

2018-02-02

Some of the most important experimentally accessible probes of the quark- gluon plasma (QGP) produced in heavy ion collisions come from the analysis of how the shape and energy of sprays of energetic particles produced within a cone with a specified opening angle (jets) in a hard scattering are modified by their passage through the strongly coupled, liquid, QGP. We model an ensemble of back-to-back dijets for the purpose of gaining a qualitative understanding of how the shapes of the individual jets and the asymmetry in the energy of the pairs of jets in the ensemble are modified by theirmore » passage through an expanding cooling droplet of strongly coupled plasma, in the model in a holographic gauge theory that is dual to a 4+1-dimensional black-hole spacetime that is asymptotically anti-de Sitter (AdS). We build our model by constructing an ensemble of strings in the dual gravitational description of the gauge theory. We model QCD jets in vacuum using strings whose endpoints are moving “downward” into the gravitational bulk spacetime with some fixed small angle, an angle that represents the opening angle (ratio of jet mass to jet energy) that the QCD jet would have in vacuum. Such strings must be moving through the gravitational bulk at (close to) the speed of light; they must be (close to) null. This condition does not specify the energy distribution along the string, meaning that it does not specify the shape of the jet being modeled. We study the dynamics of strings that are initially not null and show that strings with a wide range of initial conditions rapidly accelerate and become null and, as they do, develop a similar distribution of their energy density. We use this distribution of the energy density along the string, choose an ensemble of strings whose opening angles and energies are distributed as in perturbative QCD, and show that we can then fix one of the two model parameters such that the mean jet shape for the jets in the ensemble that we have built matches that measured in proton-proton collisions reasonably well. This is a novel way for hybridizing relevant inputs from perturbative QCD and a strongly coupled holographic gauge theory in the service of modeling jets in QGP. We send our ensemble of strings through an expanding cooling droplet of strongly coupled plasma, choosing the second model parameter so as to get a reasonable value for R AA jet , the suppression in the number of jets, and study how the mean jet shape and the dijet asymmetry are modified, comparing both to measurements from heavy ion collisions at the LHC.« less
Evolution of the mean jet shape and dijet asymmetry distribution of an ensemble of holographic jets in strongly coupled plasma

NASA Astrophysics Data System (ADS)

Brewer, Jasmine; Rajagopal, Krishna; Sadofyev, Andrey; van der Schee, Wilke

2018-02-01

Some of the most important experimentally accessible probes of the quark- gluon plasma (QGP) produced in heavy ion collisions come from the analysis of how the shape and energy of sprays of energetic particles produced within a cone with a specified opening angle (jets) in a hard scattering are modified by their passage through the strongly coupled, liquid, QGP. We model an ensemble of back-to-back dijets for the purpose of gaining a qualitative understanding of how the shapes of the individual jets and the asymmetry in the energy of the pairs of jets in the ensemble are modified by their passage through an expanding cooling droplet of strongly coupled plasma, in the model in a holographic gauge theory that is dual to a 4+1-dimensional black-hole spacetime that is asymptotically anti-de Sitter (AdS). We build our model by constructing an ensemble of strings in the dual gravitational description of the gauge theory. We model QCD jets in vacuum using strings whose endpoints are moving "downward" into the gravitational bulk spacetime with some fixed small angle, an angle that represents the opening angle (ratio of jet mass to jet energy) that the QCD jet would have in vacuum. Such strings must be moving through the gravitational bulk at (close to) the speed of light; they must be (close to) null. This condition does not specify the energy distribution along the string, meaning that it does not specify the shape of the jet being modeled. We study the dynamics of strings that are initially not null and show that strings with a wide range of initial conditions rapidly accelerate and become null and, as they do, develop a similar distribution of their energy density. We use this distribution of the energy density along the string, choose an ensemble of strings whose opening angles and energies are distributed as in perturbative QCD, and show that we can then fix one of the two model parameters such that the mean jet shape for the jets in the ensemble that we have built matches that measured in proton-proton collisions reasonably well. This is a novel way for hybridizing relevant inputs from perturbative QCD and a strongly coupled holographic gauge theory in the service of modeling jets in QGP. We send our ensemble of strings through an expanding cooling droplet of strongly coupled plasma, choosing the second model parameter so as to get a reasonable value for R AA jet , the suppression in the number of jets, and study how the mean jet shape and the dijet asymmetry are modified, comparing both to measurements from heavy ion collisions at the LHC.
Thermodynamics of new black hole solutions in the Einstein-Maxwell-dilaton gravity

NASA Astrophysics Data System (ADS)

Dehghani, M.

In the present work, thermodynamics of the new black hole solutions to the four-dimensional Einstein-Maxwell-dilaton gravity theory have been studied. The dilaton potential, as the solution to the scalar field equations, has been constructed out by a linear combination of three Liouville-type potentials. Three new classes of charged dilatonic black hole solutions, as the exact solutions to the coupled equations of gravitational, electromagnetic and scalar fields, have been introduced. The conserved charge and mass of the new black holes have been calculated by utilizing Gauss's electric law and Abbott-Deser mass proposal, respectively. Also, the temperature, entropy and the electric potential of these new classes of charged dilatonic black holes have been calculated, making use of the geometrical approaches. Through a Smarr-type mass formula, the intensive parameters of the black holes have been calculated and validity of the first law of black hole thermodynamics has been confirmed. A thermal stability or phase transition analysis has been performed, making use of the canonical ensemble method. The heat capacity of the new black holes has been calculated and the points of type one- and type two-phase transitions as well as the ranges at which the new charged dilatonic black holes are locally stable have been determined, precisely.
Smooth Horizonless Geometries Deep Inside the Black-Hole Regime.

PubMed

Bena, Iosif; Giusto, Stefano; Martinec, Emil J; Russo, Rodolfo; Shigemori, Masaki; Turton, David; Warner, Nicholas P

2016-11-11

We construct the first family of horizonless supergravity solutions that have the same mass, charges, and angular momenta as general supersymmetric rotating D1-D5-P black holes in five dimensions. This family includes solutions with arbitrarily small angular momenta, deep within the regime of quantum numbers and couplings for which a large classical black hole exists. These geometries are well approximated by the black-hole solution, and in particular exhibit the same near-horizon throat. Deep in this throat, the black-hole singularity is resolved into a smooth cap. We also identify the holographically dual states in the N=(4,4) D1-D5 orbifold conformal field theory (CFT). Our solutions are among the states counted by the CFT elliptic genus, and provide examples of smooth microstate geometries within the ensemble of supersymmetric black-hole microstates.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Bena, Iosif; Kraus, Per; Warner, Nicholas P.

We construct the most generic three-charge, three-dipole-charge, BPS black-ring solutions in a Taub-NUT background. These solutions depend on seven charges and six moduli, and interpolate between a four-dimensional black hole and a five-dimensional black ring. They are also instrumental in determining the correct microscopic description of the five-dimensional BPS black rings.
Do semiclassical zero temperature black holes exist?

PubMed

Anderson, P R; Hiscock, W A; Taylor, B E

2000-09-18

The semiclassical Einstein equations are solved to first order in epsilon = Planck's over 2pi/M2 for the case of a Reissner-Nordström black hole perturbed by the vacuum stress energy of quantized free fields. Massless and massive fields of spin 0, 1/2, and 1 are considered. We show that in all physically realistic cases, macroscopic zero temperature black hole solutions do not exist. Any static zero temperature semiclassical black hole solutions must then be microscopic and isolated in the space of solutions; they do not join smoothly onto the classical extreme Reissner-Nordström solution as epsilon-->0.
Safety Performance of Small Lithium-Ion Cells in High Voltage Batteries

NASA Technical Reports Server (NTRS)

Cowles, Philip R.; Darcy, Eric C.; Davies, Frank J.; Jeevarajan, Judith A.; Spurrett, Robert P.

2003-01-01

Topics covered include: Small-cell EAPU work done by NASA-JSC & COM DEV; Looking at safety features (short circuit protection - PTCs); Early tests showed that long strings do not withstand short circuit; a) Some PTCs experience large negative voltages; b) Destructive results. Solution: group cells into shorter substrings, with bypass diodes Work included: a) Tests with single cells shorted; b) Tests with single cells with imposed-negative voltages; c) 6s, 7s and 8s string shorts; and d) Tests with protection scheme in place, on 12s and 41s x 5p.
Dynamics and stability of light-like tachyon condensation

NASA Astrophysics Data System (ADS)

Barnaby, Neil; Mulryne, David J.; Nunes, Nelson J.; Robinson, Patrick

2009-03-01

Recently, Hellerman and Schnabl considered the dynamics of unstable D-branes in the background of a linear dilaton. Remarkably, they were able to construct light-like tachyon solutions which interpolate smoothly between the perturbative and nonperturbative vacua, without undergoing the wild oscillations that plague time-like solutions. In their analysis, however, the full structure of the initial value problem for the nonlocal dynamical equations was not considered. In this paper, therefore, we reexamine the nonlinear dynamics of light-like tachyon condensation using a combination of numerical and analytical techniques. We find that for the p-adic string the monotonic behaviour obtained previously relied on a special choice of initial conditions near the unstable maximum. For generic initial conditions the wild oscillations come back to haunt us. Interestingly, we find an ``island of stability'' in initial condition space that leads to sensible evolution at late times. For the string field theory case, on the other hand, we find that the evolution is completely stable for generic choices of initial data. This provides an explicit example of a string theoretic system that admits infinitely many initial data but is nevertheless nonperturbatively stable. Qualitatively similar dynamics are obtained in nonlocal cosmologies where the Hubble damping plays a role very analogous to the dilaton gradient.
A Hybrid Parallel Strategy Based on String Graph Theory to Improve De Novo DNA Assembly on the TianHe-2 Supercomputer.

PubMed

Zhang, Feng; Liao, Xiangke; Peng, Shaoliang; Cui, Yingbo; Wang, Bingqiang; Zhu, Xiaoqian; Liu, Jie

2016-06-01

' The de novo assembly of DNA sequences is increasingly important for biological researches in the genomic era. After more than one decade since the Human Genome Project, some challenges still exist and new solutions are being explored to improve de novo assembly of genomes. String graph assembler (SGA), based on the string graph theory, is a new method/tool developed to address the challenges. In this paper, based on an in-depth analysis of SGA we prove that the SGA-based sequence de novo assembly is an NP-complete problem. According to our analysis, SGA outperforms other similar methods/tools in memory consumption, but costs much more time, of which 60-70 % is spent on the index construction. Upon this analysis, we introduce a hybrid parallel optimization algorithm and implement this algorithm in the TianHe-2's parallel framework. Simulations are performed with different datasets. For data of small size the optimized solution is 3.06 times faster than before, and for data of middle size it's 1.60 times. The results demonstrate an evident performance improvement, with the linear scalability for parallel FM-index construction. This results thus contribute significantly to improving the efficiency of de novo assembly of DNA sequences.
Models for small-scale structure on cosmic strings. II. Scaling and its stability

NASA Astrophysics Data System (ADS)

Vieira, J. P. P.; Martins, C. J. A. P.; Shellard, E. P. S.

2016-11-01

We make use of the formalism described in a previous paper [Martins et al., Phys. Rev. D 90, 043518 (2014)] to address general features of wiggly cosmic string evolution. In particular, we highlight the important role played by poorly understood energy loss mechanisms and propose a simple Ansatz which tackles this problem in the context of an extended velocity-dependent one-scale model. We find a general procedure to determine all the scaling solutions admitted by a specific string model and study their stability, enabling a detailed comparison with future numerical simulations. A simpler comparison with previous Goto-Nambu simulations supports earlier evidence that scaling is easier to achieve in the matter era than in the radiation era. In addition, we also find that the requirement that a scaling regime be stable seems to notably constrain the allowed range of energy loss parameters.

On pp wave limit for η deformed superstrings

NASA Astrophysics Data System (ADS)

Roychowdhury, Dibakar

2018-05-01

In this paper, based on the notion of plane wave string/gauge theory duality, we explore the pp wave limit associated with the bosonic sector of η deformed superstrings propagating in ( AdS 5 × S 5) η . Our analysis reveals that in the presence of NS-NS and RR fluxes, the pp wave limit associated to full ABF background satisfies type IIB equations in its standard form. However, the beta functions as well as the string Hamiltonian start receiving non trivial curvature corrections as one starts probing beyond pp wave limit which thereby takes solutions away from the standard type IIB form. Furthermore, using uniform gauge, we also explore the BMN dynamics associated with short strings and compute the corresponding Hamiltonian density. Finally, we explore the Penrose limit associated with the HT background and compute the corresponding stringy spectrum for the bosonic sector.
Quantization of parameters and the string landscape problem

NASA Astrophysics Data System (ADS)

Bouhmadi-López, Mariam; Vargas Moniz, Paulo

2007-05-01

We broaden the domain of application of Brustein and de Alwis's recent paper, where they introduce a (dynamical) selection principle on the landscape of string solutions using FRW quantum cosmology. More precisely, we (i) explain how their analysis is based in choosing a restrictive range of parameters, thereby affecting the validity of the predictions extracted and (ii) subsequently provide a wider and cohesive description, regarding the probability distribution induced by quantum cosmological transition amplitudes. In addition, employing DeWitt's argument for an initial condition on the wavefunction of the Universe, we found that the string and gravitational parameters become related through interesting expressions involving an integer n, suggesting a quantization relation for some of the involved parameters. This research work was supported by the grants POCI/FP/63916/2005, FEDER-POCI/P/FIS/57547/2004 and Acções Integradas (CRUP-CSIC) Luso-Espanholas E-138/04.
Quantum no-scale regimes in string theory

NASA Astrophysics Data System (ADS)

Coudarchet, Thibaut; Fleming, Claude; Partouche, Hervé

2018-05-01

We show that in generic no-scale models in string theory, the flat, expanding cosmological evolutions found at the quantum level can be attracted to a "quantum no-scale regime", where the no-scale structure is restored asymptotically. In this regime, the quantum effective potential is dominated by the classical kinetic energies of the no-scale modulus and dilaton. We find that this natural preservation of the classical no-scale structure at the quantum level occurs when the initial conditions of the evolutions sit in a subcritical region of their space. On the contrary, supercritical initial conditions yield solutions that have no analogue at the classical level. The associated intrinsically quantum universes are sentenced to collapse and their histories last finite cosmic times. Our analysis is done at 1-loop, in perturbative heterotic string compactified on tori, with spontaneous supersymmetry breaking implemented by a stringy version of the Scherk-Schwarz mechanism.
Nonlinear stress waves in a perfectly flexible string. [for aerodynamic decelerating system

NASA Technical Reports Server (NTRS)

Fan, D.-N.; Mcgarvey, J. F.

1977-01-01

This paper discusses nonlinear stress-wave propagation in a perfectly flexible string obeying a quasilinear (rate-dependent) constitutive equation. Wave speeds and compatibility relations valid along various families of characteristics were determined. It was shown that the compatibility relations associated with the transverse as well as the longitudinal waves readily yield a physical interpretation when they are expressed in suitable variables and in vector form. Coding based on the present information was completed for the machine solution of a class of mixed initial- and boundary-value problems of practical interest. Computer simulation of the stress-wave interaction in the 40-foot lanyard in the Arcas 'Rocoz' system during deployment was carried out using a stress-strain relation for nylon at the strain rate of 30/second. A method for estimating the maximum tension and strain in a string during the initial loading phase is proposed.
Thermodynamical properties of hairy black holes in n spacetime dimensions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nadalini, Mario; Vanzo, Luciano; Zerbini, Sergio

The issue concerning the existence of exact black hole solutions in the presence of a nonvanishing cosmological constant and scalar fields is reconsidered. With regard to this, in investigating no-hair theorem violations, exact solutions of gravity having as a source an interacting and conformally coupled scalar field are revisited in arbitrary dimensional nonasymptotically flat space-times. New and known hairy black hole solutions are discussed. The thermodynamical properties associated with these solutions are investigated and the invariance of the black hole entropy with respect to different conformal frames is proved. The issue of the positivity of the entropy is discussed andmore » resolved for the case of black holes immersed in de Sitter space.« less
Chaos in the gauge/gravity correspondence

NASA Astrophysics Data System (ADS)

Pando Zayas, Leopoldo A.; Terrero-Escalante, César A.

2010-09-01

We study the motion of a string in the background of the Schwarzschild black hole in AdS 5 by applying the standard arsenal of dynamical systems. Our description of the phase space includes: the power spectrum, the largest Lyapunov exponent, Poincare sections and basins of attractions. We find convincing evidence that the motion is chaotic. We discuss the implications of some of the quantities associated with chaotic systems for aspects of the gauge/gravity correspondence. In particular, we suggest some potential relevance for the information loss paradox.
Remnants, fuzzballs or wormholes?

NASA Astrophysics Data System (ADS)

Mathur, Samir D.

2014-11-01

The black hole information paradox has caused enormous confusion over four decades. But in recent years, the theorem of quantum strong-subadditivity has sorted out the possible resolutions into three sharp categories: (i) No new physics at r ≫ lp; this necessarily implies remnants/information loss. A realization of remnants is given by a baby universe attached near r 0. (ii) Violation of the "no-hair" theorem by nontrivial effects at the horizon r M. This possibility is realized by fuzzballs in string theory, and gives unitary evaporation. (iii) Having the vacuum at the horizon, but requiring that Hawking quanta at r M3 be somehow identified with degrees of freedom inside the black hole. A model for this "extreme nonlocality" is realized by conjecturing that wormholes connect the radiation quanta to the hole.
Perspectives on Geometrodynamics: The Nonlinear Dynamics of Curved Spacetime

NASA Astrophysics Data System (ADS)

Thorne, Kip S.

2012-03-01

In the 1950s John Archibald Wheeler exhorted his students and colleagues to explore ``Geometrodynamics,'' i.e. the dynamical behavior of curved spacetime, as predicted by Einstein's general relativity theory. Unfortunately, the research tools of that era were inadequate for the task. This has changed over the past ten years and will change further in the coming decade, thanks to two new sets of tools - numerical relativity, and gravitational wave observations, coupled to theory. In this lecture, I will review the progress and prospects for geometrodynamics, focusing especially on: 1. Geometrodynamics near singularities, 2. Geometrodynamics triggered by colliding black holes, 3. Geometrodynamics triggered by black-string instabilities in four space dimensions, and 4. Preparations for observing the dynamics of curved spacetime with interferometric gravitational wave detectors: LIGO and its international partners.
Large Black Holes in the Randall-Sundrum II Model

NASA Astrophysics Data System (ADS)

Yaghoobpour Tari, Shima

The Einstein equation with a negative cosmological constant ! in the five dimensions for the Randall-Sundrum II model, which includes a black hole, has been solved numerically. We have constructed an AdS5-CFT 4 solution numerically, using a spectral method to minimize the integral of the square of the error of the Einstein equation, with 210 parameters to be determined by optimization. This metric is conformal to the Schwarzschild metric at an AdS5 boundary with an infinite scale factor. So, we consider this solution as an infinite-mass black hole solution. We have rewritten the infinite-mass black hole in the Fefferman-Graham form and obtained the numerical components of the CFT energy-momentum tensor. Using them, we have perturbed the metric to relocate the brane from infinity and obtained a large static black hole solution for the Randall- Sundrum II model. The changes of mass, entropy, temperature and area of the large black hole from the Schwarzschild metric are studied up to the first order for the perturbation parameter 1/(-Λ5M 2). The Hawking temperature and entropy for our large black hole have the same values as the Schwarzschild metric with the same mass, but the horizon area is increased by about 4.7/(-Λ5). Figueras, Lucietti, and Wiseman found an AdS5-CFT4 solution using an independent and different method from us, called the Ricci-DeTurck-flow method. Then, Figueras and Wiseman perturbed this solution in a same way as we have done and obtained the solution for the large black hole in the Randall-Sundrum II model. These two numerical solutions are the first mathematical proofs for having a large black hole in the Randall-Sundrum II. We have compared their results with ours for the CFT energy-momentum tensor components and the perturbed metric. We have shown that the results are closely in agreement, which can be considered as evidence that the solution for the large black hole in the Randall-Sundrum II model exists.
Bianchi Type-II String Cosmological Model with Magnetic Field in f ( R, T) Gravity

NASA Astrophysics Data System (ADS)

Sharma, N. K.; Singh, J. K.

2014-09-01

The spatially homogeneous and totally anisotropic Bianchi type-II cosmological solutions of massive strings have been investigated in the presence of the magnetic field in the framework of f( R, T) gravity proposed by Harko et al. (Phys Rev D 84:024020, 2011). With the help of special law of variation for Hubble's parameter proposed by Berman (Nuovo Cimento B 74:182, 1983) cosmological model is obtained in this theory. We consider f( R, T) model and investigate the modification R+ f( T) in Bianchi type-II cosmology with an appropriate choice of a function f( T)= μ T. We use the power law relation between average Hubble parameter H and average scale factor R to find the solution. The assumption of constant deceleration parameter leads to two models of universe, i.e. power law model and exponential model. Some physical and kinematical properties of the model are also discussed.
Spin(7) compactifications and 1/4-BPS vacua in heterotic supergravity

NASA Astrophysics Data System (ADS)

Angus, Stephen; Matti, Cyril; Svanes, Eirik E.

2016-03-01

We continue the investigation into non-maximally symmetric compactifications of the heterotic string. In particular, we consider compactifications where the internal space is allowed to depend on two or more external directions. For preservation of supersymmetry, this implies that the internal space must in general be that of a Spin(7) manifold, which leads to a 1/4-BPS four-dimensional supersymmetric perturbative vacuum breaking all but one supercharge. We find that these solutions allow for internal geometries previously excluded by the domain-wall-type solutions, and hence the resulting four-dimensional superpotential is more generic. In particular, we find an interesting resemblance to the superpotentials that appear in non-geometric flux compactifications of type II string theory. If the vacua are to be used for phenomenological applications, they must be lifted to maximal symmetry by some non-perturbative or higher-order effect.
D2-brane as the wormhole and the number of the universes

NASA Astrophysics Data System (ADS)

Gusin, Paweł

2016-02-01

We construct wormhole-like solutions in type IIA string theory. These solutions represent wormholes in four dimensions and are given by the D2-branes within appropriated backgrounds fields. We present the conditions on these fields which lead to the four-dimensional wormholes. In the special case, we show how the particular solution in type IIA theory leads to the dynamic wormhole. We also speculate about the number of universes and the cosmological constant.
Non-existence of time-periodic solutions of the Dirac equation in a Reissner-Nordström black hole background

NASA Astrophysics Data System (ADS)

Finster, Felix; Smoller, Joel; Yau, Shing-Tung

2000-04-01

It is shown analytically that the Dirac equation has no normalizable, time-periodic solutions in a Reissner-Nordström black hole background; in particular, there are no static solutions of the Dirac equation in such a background metric. The physical interpretation is that Dirac particles can either disappear into the black hole or escape to infinity, but they cannot stay on a periodic orbit around the black hole.
Chameleonic dilaton, nonequivalent frames, and the cosmological constant problem in quantum string theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zanzi, Andrea

2010-08-15

The chameleonic behavior of the string theory dilaton is suggested. Some of the possible consequences of the chameleonic string dilaton are analyzed in detail. In particular, (1) we suggest a new stringy solution to the cosmological constant problem and (2) we point out the nonequivalence of different conformal frames at the quantum level. In order to obtain these results, we start taking into account the (strong coupling) string loop expansion in the string frame (S-frame), therefore the so-called form factors are present in the effective action. The correct dark energy scale is recovered in the Einstein frame (E-frame) without unnaturalmore » fine-tunings and this result is robust against all quantum corrections, granted that we assume a proper structure of the S-frame form factors in the strong coupling regime. At this stage, the possibility still exists that a certain amount of fine-tuning may be required to satisfy some phenomenological constraints. Moreover in the E-frame, in our proposal, all the interactions are switched off on cosmological length scales (i.e., the theory is IR-free), while higher derivative gravitational terms might be present locally (on short distances) and it remains to be seen whether these facts clash with phenomenology. A detailed phenomenological analysis is definitely necessary to clarify these points.« less
Charged rotating black holes in Einstein-Maxwell-Chern-Simons theory with a negative cosmological constant

NASA Astrophysics Data System (ADS)

Blázquez-Salcedo, Jose Luis; Kunz, Jutta; Navarro-Lérida, Francisco; Radu, Eugen

2017-03-01

We consider rotating black hole solutions in five-dimensional Einstein-Maxwell-Chern-Simons theory with a negative cosmological constant and a generic value of the Chern-Simons coupling constant λ . Using both analytical and numerical techniques, we focus on cohomogeneity-1 configurations, with two equal-magnitude angular momenta, which approach at infinity a globally anti-de Sitter background. We find that the generic solutions share a number of basic properties with the known Cvetič, Lü, and Pope black holes which have λ =1 . New features occur as well; for example, when the Chern-Simons coupling constant exceeds a critical value, the solutions are no longer uniquely determined by their global charges. Moreover, the black holes possess radial excitations which can be labelled by the node number of the magnetic gauge potential function. Solutions with small values of λ possess other distinct features. For instance, the extremal black holes there form two disconnected branches, while not all near-horizon solutions are associated with global solutions.
Trivial solutions of generalized supergravity vs non-abelian T-duality anomaly

NASA Astrophysics Data System (ADS)

Wulff, Linus

2018-06-01

The equations that follow from kappa symmetry of the type II Green-Schwarz string are a certain deformation, by a Killing vector field K, of the type II supergravity equations. We analyze under what conditions solutions of these 'generalized' supergravity equations are trivial in the sense that they solve also the standard supergravity equations. We argue that for this to happen K must be null and satisfy dK =iK H with H = dB the NSNS three-form field strength. Non-trivial examples are provided by symmetric pp-wave solutions. We then analyze the consequences for non-abelian T-duality and the closely related homogenous Yang-Baxter sigma models. When one performs non-abelian T-duality of a string sigma model on a non-unimodular (sub)algebra one generates a non-vanishing K proportional to the trace of the structure constants. This is expected to lead to an anomaly but we show that when K satisfies the same conditions the anomaly in fact goes away leading to more possibilities for non-anomalous non-abelian T-duality.
Charged black holes in quartic quasi-topological gravity

NASA Astrophysics Data System (ADS)

Ghanaatian, M.; Naeimipour, F.; Bazrafshan, A.; Abkar, M.

2018-05-01

In this paper, we construct exact solutions of charged black holes in the presence of quartic quasi-topological gravity. We obtain thermodynamics and conserved quantities of the solutions and check the first law of thermodynamics. In studying the physical properties of the solutions, we consider anti-de Sitter, de Sitter, and flat solutions of charged black holes in quartic quasi-topological gravity and compare them with Einstein and third-order quasi-topological gravities. We also investigate the thermal stability of the solutions and show that thermal stability is just for anti-de Sitter solutions, not for de Sitter and flat ones.
Electromagnetic perturbations of black holes in general relativity coupled to nonlinear electrodynamics

NASA Astrophysics Data System (ADS)

Toshmatov, Bobir; Stuchlík, Zdeněk; Schee, Jan; Ahmedov, Bobomurat

2018-04-01

The electromagnetic (EM) perturbations of the black hole solutions in general relativity coupled to nonlinear electrodynamics (NED) are studied for both electrically and magnetically charged black holes, assuming that the EM perturbations do not alter the spacetime geometry. It is shown that the effective potentials of the electrically and magnetically charged black holes related to test perturbative NED EM fields are related to the effective metric governing the photon motion, contrary to the effective potential of the linear electrodynamic (Maxwell) field that is related to the spacetime metric. Consequently, corresponding quasinormal (QN) frequencies differ as well. As a special case, we study new family of the NED black hole solutions which tend in the weak field limit to the Maxwell field, giving the Reissner-Nordström (RN) black hole solution. We compare the NED Maxwellian black hole QN spectra with the RN black hole QN spectra.
Asymptotically flat black holes in Horndeski theory and beyond

DOE Office of Scientific and Technical Information (OSTI.GOV)

Babichev, E.; Charmousis, C.; Lehébel, A., E-mail: eugeny.babichev@th.u-psud.fr, E-mail: christos.charmousis@th.u-psud.fr, E-mail: antoine.lehebel@th.u-psud.fr

We find spherically symmetric and static black holes in shift-symmetric Horndeski and beyond Horndeski theories. They are asymptotically flat and sourced by a non trivial static scalar field. The first class of solutions is constructed in such a way that the Noether current associated with shift symmetry vanishes, while the scalar field cannot be trivial. This in certain cases leads to hairy black hole solutions (for the quartic Horndeski Lagrangian), and in others to singular solutions (for a Gauss-Bonnet term). Additionally, we find the general spherically symmetric and static solutions for a pure quartic Lagrangian, the metric of which ismore » Schwarzschild. We show that under two requirements on the theory in question, any vacuum GR solution is also solution to the quartic theory. As an example, we show that a Kerr black hole with a non-trivial scalar field is an exact solution to these theories.« less
Regular black holes in f(T) Gravity through a nonlinear electrodynamics source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Junior, Ednaldo L.B.; Rodrigues, Manuel E.; Houndjo, Mahouton J.S., E-mail: ednaldobarrosjr@gmail.com, E-mail: esialg@gmail.com, E-mail: sthoundjo@yahoo.fr

2015-10-01

We seek to obtain a new class of exact solutions of regular black holes in f(T) Gravity with non-linear electrodynamics material content, with spherical symmetry in 4D. The equations of motion provide the regaining of various solutions of General Relativity, as a particular case where the function f(T)=T. We developed a powerful method for finding exact solutions, where we get the first new class of regular black holes solutions in the f(T) Theory, where all the geometrics scalars disappear at the origin of the radial coordinate and are finite everywhere, as well as a new class of singular black holes.

Black hole thermalization, D0 brane dynamics, and emergent spacetime

NASA Astrophysics Data System (ADS)

Riggins, Paul; Sahakian, Vatche

2012-08-01

When matter falls past the horizon of a large black hole, the expectation from string theory is that the configuration thermalizes and the information in the probe is rather quickly scrambled away. The traditional view of a classical unique spacetime near a black hole horizon conflicts with this picture. The question then arises as to what spacetime does the probe actually see as it crosses a horizon, and how does the background geometry imprint its signature onto the thermal properties of the probe. In this work, we explore these questions through an extensive series of numerical simulations of D0 branes. We determine that the D0 branes quickly settle into an incompressible symmetric state—thermalized within a few oscillations through a process driven entirely by internal nonlinear dynamics. Surprisingly, thermal background fluctuations play no role in this mechanism. Signatures of the background fields in this thermal state arise either through fluxes, i.e. black hole hair; or if the probe expands to the size of the horizon—which we see evidence of. We determine simple scaling relations for the D0 branes’ equilibrium size, time to thermalize, lifetime, and temperature in terms of their number, initial energy, and the background fields. Our results are consistent with the conjecture that black holes are the fastest scramblers as seen by matrix theory.
(2+1)-Dimensional charged black holes with scalar hair in Einstein-Power-Maxwell Theory

NASA Astrophysics Data System (ADS)

Xu, Wei; Zou, De-Cheng

2017-06-01

In (2+1)-dimensional AdS spacetime, we obtain new exact black hole solutions, including two different models (power parameter k=1 and k≠1), in the Einstein-Power-Maxwell (EPM) theory with nonminimally coupled scalar field. For the charged hairy black hole with k≠1, we find that the solution contains a curvature singularity at the origin and is nonconformally flat. The horizon structures are identified, which indicates the physically acceptable lower bound of mass in according to the existence of black hole solutions. Later, the null geodesic equations for photon around this charged hairy black hole are also discussed in detail.
Supersymmetrizing the Gorsky-Shifman-Yung soliton

NASA Astrophysics Data System (ADS)

Ireson, E.; Shifman, M.; Yung, A.

2018-05-01

We supersymmetrize the Hopfion studied by Gorsky et al. [Phys. Rev. D 88, 045026 (2013)., 10.1103/PhysRevD.88.045026]. This soliton represents a closed semilocal vortex string in U(1) gauge theory. It carries nonzero Hopf number due to the additional winding of a phase modulus as one moves along the closed string. We study this solution in N =2 supersymmetric QED with two flavors. As a preliminary exercise, we compactify one space dimension and consider a straight vortex with periodic boundary conditions. It turns out to be 1 /2 -BPS saturated. An additional winding along the string can be introduced and it does not spoil the BPS nature of the object. Next, we consider a ringlike vortex in a non-compact space and show that the circumference of the ring L can be stabilized once the previously mentioned winding along the string is introduced. Of course, the ringlike vortex is not BPS but its energy becomes close to the BPS bound if L is large, which can be guaranteed in the case that we have a large value of the angular momentum J . Thus we arrive at the concept of asymptotically BPS-saturated solitons. BPS saturation is achieved in the limit J →∞ .
Exploring the String Landscape: The Dynamics, Statistics, and Cosmology of Parallel Worlds

NASA Astrophysics Data System (ADS)

Ahlqvist, Stein Pontus

This dissertation explores various facets of the low-energy solutions in string theory known as the string landscape. Three separate questions are addressed - the tunneling dynamics between these vacua, the statistics of their location in moduli space, and the potential realization of slow-roll inflation in the flux potentials generated in string theory. We find that the tunneling transitions that occur between a certain class of supersymmetric vacua related to each other via monodromies around the conifold point are sensitive to the details of warping in the near-conifold regime. We also study the impact of warping on the distribution of vacua near the conifold and determine that while previous work has concluded that the conifold point acts as an accumulation point for vacua, warping highly dilutes the distribution in precisely this regime. Finally we investigate a novel form of inflation dubbed spiral inflation to see if it can be realized near the conifold point. We conclude that for our particular models, spiral inflation seems to rely on a de Sitter-like vacuum energy. As a result, whenever spiral inflation is realized, the inflation is actually driven by a vacuum energy.
Rigged String Configurations, Bethe Ansatz Qubits, and Conservation of Parity

NASA Astrophysics Data System (ADS)

Lulek, T.

Bethe Ansatz solutions for the Heisenberg Hamiltonian of a one - dimensional magnetic ring of N nodes, each with the spin 1/2, within the XXX model, have been presented as some composite systems, in a spirit of quantum information theory. The constituents are single - node spin states, which organize into strings of various length, and "seas of holes". The former are responsible for dynamics, whereas the latter determine the range of riggings for strings. Another aim was to demonstrate a unification of Bethe Ansatz eigenstates by means of Galois symmetries of finite field extensions. The key observation is that the original eigenproblem is expressible in integers, and thus, for a finite fixed N, the splitting field of the characteristic polynom of the Heisenberg Hamiltonian is also finite. The Galois group of the latter field permutes, by definition, roots of this polynom, which implies permutation of eigenstates. General considerations are demonstrated on the example of heptagon (N = 7), which admits an implementation of a collection of arithmetic qubits, and also demonstrates a special case of degeneration of the spectrum of the Hamiltonian, resulting from conservation of parity, within the realm of rigged string configurations.
New solutions of exotic charged black holes and their stability

NASA Astrophysics Data System (ADS)

Farhangkhah, N.

2016-01-01

We find a class of charged black hole solutions in third-order Lovelock Gravity. To obtain this class of solutions, we are not confined to the usual assumption of maximal symmetry on the horizon and will consider the solution whose boundary is Einstein space with supplementary conditions on its Weyl tensor. The Weyl tensor of such exotic horizons exposes two chargelike parameter to the solution. These parameters in addition with the electric charge, cause different features in comparison with the charged solution with constant-curvature horizon. For this class of asymptotically (A)dS solutions, the electric charge dominates the behavior of the metric as r goes to zero, and thus the central singularity is always timelike. We also compute the thermodynamic quantities for these solutions and will show that the first law of thermodynamics is satisfied. We also show that the extreme black holes with nonconstant-curvature horizons whose Ricci scalar are zero or a positive constant could exist depending on the value of the electric charge and chargelike parameters. Finally, we investigate the stability of the black holes by analyzing the behavior of free energy and heat capacity specially in the limits of small and large horizon radius. We will show that in contrast with charged solution with constant-curvature horizon, a phase transition occurs between very small and small black holes from a stable phase to an unstable one, while the large black holes show stability to both perturbative and nonperturbative fluctuations.
Black holes thermodynamics in a new kind of noncommutative geometry

NASA Astrophysics Data System (ADS)

Faizal, Mir; Amorim, R. G. G.; Ulhoa, S. C.

Motivated by the energy-dependent metric in gravity’s rainbow, we will propose a new kind of energy-dependent noncommutative geometry. It will be demonstrated that like gravity’s rainbow, this new noncommutative geometry is described by an energy-dependent metric. We will analyze the effect of this noncommutative deformation on the Schwarzschild black holes and Kerr black holes. We will perform our analysis by relating the commutative and this new energy-dependent noncommutative metrics using an energy-dependent Moyal star product. We will also analyze the thermodynamics of these new noncommutative black hole solutions. We will explicitly derive expression for the corrected entropy and temperature for these black hole solutions. It will be demonstrated that, for these deformed solutions, black remnants cannot form. This is because these corrections increase rather than reduce the temperature of the black holes.
Improved passivation effect in multicrystalline black silicon by chemical solution pre-treatment

NASA Astrophysics Data System (ADS)

Jiang, Ye; Shen, Honglie; Pu, Tian; Zheng, Chaofan

2018-04-01

Though black silicon has excellent anti-reflectance property, its passivation is one of the main technical bottlenecks due to its large specific surface area. In this paper, multicrystalline black silicon is fabricated by metal assisted chemical etching, and is rebuilt in low concentration alkali solution. Different solution pre-treatment is followed to make surface modification on black silicon before Al2O3 passivation by atomic layer deposition. HNO3 and H2SO4 + H2O2 solution pre-treatment makes the silicon surface become hydrophilic, with contact angle decrease from 117.28° to about 30°. It is demonstrated that when the pre-treatment solution is nitric acid, formed ultrathin SiO x layer between Al2O3 layer and black silicon is found to increase effective carrier lifetime to 72.64 µs, which is obviously higher than that of the unpassivated black silicon. The passivation stacks of SiO x /Al2O3 are proved to be effective double layers for nanoscaled multicrystalline silicon surface.
Phase transitions in Yang-Mills theories and their gravity duals

NASA Astrophysics Data System (ADS)

Marsano, Joseph Daniel

This thesis is a study of the thermal phase structure of systems that admit dual gauge theory and string theory descriptions. In a pair of examples, we explore the connection between perturbative Yang-Mills and gravitational thermodynamics which arises from the fact that these descriptions probe different corners of a single phase diagram. The structure that emerges from a detailed study of these isolated regions generally suggests a natural conjecture how they may be connected to one another within the full phase diagram. This permits the identification of interesting phenomena in the gauge and gravity regimes under a continuous change in parameters. We begin by studying the AdS5/CFT 4 system which, when the supergravity description is valid, exhibits a first order Hawking-Page phase transition as a function of temperature from a thermal gas of gravitons to a large black hole. In the perturbative Yang-Mills regime, we find that the free theory exhibits a weakly first order deconfinement transition whose precise nature at small nonzero coupling depends on the result of a nontrivial perturbative computation. It is conjectured that this deconfinement transition is continuously connected in the full phase diagram to the Hawking-Page transition at strong coupling, with the confined phase identified with the graviton gas and the deconfined phase identified with the black hole. We then turn to the study of Gregory-Laflamme (GL) black hole/black string transitions in supergravity and their realization in a setup that admits a dual description via the maximally supersymmetric Yang-Mills theory on T2. The thermodynamics of Yang-Mills theories on low dimensional tori is studied in detail revealing an intricate structure of which the GL transition at strong coupling is a small piece. We are led to conjecture that GL physics is continuously connected to deconfinement in maximally supersymmetric 0 + 1-dimensional gauged matrix quantum mechanics. This identification will then permit us to probe GL transitions from the gauge theory point of view and comment on some puzzles regarding their precise nature.
Asymptotically flat, stable black hole solutions in Einstein-Yang-Mills-Chern-Simons theory.

PubMed

Brihaye, Yves; Radu, Eugen; Tchrakian, D H

2011-02-18

We construct finite mass, asymptotically flat black hole solutions in d=5 Einstein-Yang-Mills-Chern-Simons theory. Our results indicate the existence of a second order phase transition between Reissner-Nordström solutions and the non-Abelian black holes which generically are thermodynamically preferred. Some of the non-Abelian configurations are also stable under linear, spherically symmetric perturbations.
Universal instability of hairy black holes in Lovelock-Galileon theories in D dimensions

NASA Astrophysics Data System (ADS)

Takahashi, Kazufumi; Suyama, Teruaki; Kobayashi, Tsutomu

2016-03-01

We analyze spherically symmetric black hole solutions with time-dependent scalar hair in a class of Lovelock-Galileon theories, which are the scalar-tensor theories with second-order field equations in arbitrary dimensions. We first show that known black hole solutions in five dimensions are always plagued by the ghost/gradient instability in the vicinity of the horizon. We then generalize such black hole solutions to higher dimensions and show that the same instability found in five dimensions appears universally in any number of dimensions.
Book Review:

NASA Astrophysics Data System (ADS)

Israel, W.

2006-07-01

The evaporation of a black hole formed by the collapse of matter is a nonunitary process involving loss of information. At least, this is how it appears in Hawking's semiclassical description, in which gravity is not quantized and the emergent radiation appears thermal. Since unitarity is one of the pillars of quantum mechanics there has been an understandable reluctance to accept this as an ironclad conclusion. Conformal field theories in flat space are manifestly unitary, and the AdS/CFT correspondence therefore suggests that the information trapped in the depths of the hole must find some way to escape—a conclusion almost universally accepted today, at least among particle theorists. Just how it could escape remains a mystery, however, since nothing can escape without violating causality until the black hole has shrunk too far to hold much information. Gerard 't Hooft and the senior author of this book, Leonard Susskind, have been vocal advocates of the view that the information paradox poses a real crisis for physics requiring significant paradigm shifts. They suggest that locality must be given up as an objective property of physical phenomena (even on large scales) and replaced by a new principle of 'black hole complementarity'. Specifically, there are two very different ways to view the process of collapse and evaporation. To a free-falling observer, nothing unusual happens at the horizon and matter and information fall deep into the hole. To a stationary observer hovering just outside the hole it appears instead that the matter and information are deposited on the horizon (which he experiences as very hot because of his large acceleration), to be eventually re-emitted from there as Hawking radiation. According to 't Hooft and Susskind, these must be viewed as equally valid, 'complementary' descriptions of the same process. Black hole complementarity is essentially the statement (supported by operational arguments) that their simultaneous validity cannot lead to inconsistencies. Students and non-specialists will welcome this book, which provides an entry into this fascinating realm at a level that can be enjoyed by an enterprising undergraduate. The first chapter introduces the Schwarzschild black hole and the various coordinate systems used for its description. In four brief chapters (29 pages) the authors then manage a clear presentation of the thermal properties of quantum fields in Rindler and Schwarzschild space that skirts the operator formalism of QFT. Two further chapters treat charged black holes and the stretched-horizon description of black hole electrodynamics. Chapter 8, 'The Laws of Nature', explains how information is quantified, the quantum xerox principle and the entanglement entropy of black holes, with a detailed account of how this evolves as the hole evaporates. This sets the stage for a discussion of the black hole information puzzle and the complementarity principle in chapter 9. The pace heats up in the second part of the book, which in 48 pages sketches a variety of topics: Bousso's entropy bound and holography, the AdS/CFT correspondence, a 13 page introduction to string theory and the ideas underlying the string-based derivations of the entropy area relation for higher-dimensional black holes. This well-planned, stimulating and sometimes provocative book can be enthusiastically recommended.
Thermodynamics of charged dilatonic BTZ black holes in rainbow gravity

NASA Astrophysics Data System (ADS)

Dehghani, M.

2018-02-01

In this paper, the charged three-dimensional Einstein's theory coupled to a dilatonic field has been considered in the rainbow gravity. The dilatonic potential has been written as the linear combination of two Liouville-type potentials. Four new classes of charged dilatonic rainbow black hole solutions, as the exact solution to the coupled field equations of the energy dependent space time, have been obtained. Two of them are correspond to the Coulomb's electric field and the others are consequences of a modified Coulomb's law. Total charge and mass as well as the entropy, temperature and electric potential of the new charged black holes have been calculated in the presence of rainbow functions. Although the thermodynamic quantities are affected by the rainbow functions, it has been found that the first law of black hole thermodynamics is still valid for all of the new black hole solutions. At the final stage, making use of the canonical ensemble method and regarding the black hole heat capacity, the thermal stability or phase transition of the new rainbow black hole solutions have been analyzed.
Comment on high resolution simulations of cosmic strings. 1: Network evoloution

NASA Technical Reports Server (NTRS)

Turok, Neil; Albrecht, Andreas

1990-01-01

Comments are made on recent claims (Albrecht and Turok, 1989) regarding simulations of cosmic string evolution. Specially, it was claimed that results were dominated by a numerical artifact which rounds out kinks on a scale of the order of the correlation length on the network. This claim was based on an approximate analysis of an interpolation equation which is solved herein. The typical rounding scale is actually less than one fifth of the correlation length, and comparable with other numerical cutoffs. Results confirm previous estimates of numerical uncertainties, and show that the approximations poorly represent the real solutions to the interpolation equation.
A premier analysis of supersymmetric closed string tachyon cosmology

NASA Astrophysics Data System (ADS)

Vázquez-Báez, V.; Ramírez, C.

2018-04-01

From a previously found worldline supersymmetric formulation for the effective action of the closed string tachyon in a FRW background, the Hamiltonian of the theory is constructed, by means of the Dirac procedure, and written in a quantum version. Using the supersymmetry algebra we are able to find solutions to the Wheeler-DeWitt equation via a more simple set of first order differential equations. Finally, for the k = 0 case, we compute the expectation value of the scale factor with a suitably potential also favored in the present literature. We give some interpretations of the results and state future work lines on this matter.
Three-dimensional gauge theories and gravitational instantons from string theory

NASA Astrophysics Data System (ADS)

Cherkis, Sergey Alexander

Various realizations of gauge theories in string theory allow an identification of their spaces of vacua with gravitational instantons. Also, they provide a correspondence of vacua of gauge theories with nonabelian monopole configurations and solutions of a system of integrable equations called Nahm equations. These identifications make it possible to apply powerful techniques of differential and algebraic geometry to solve the gauge theories in question. In other words, it becomes possible to find the exact metrics on their moduli spaces of vacua with all quantum corrections included. As another outcome we obtain for the first time the description of a series of all Dk-type gravitational instantons.
Spectral methods in general relativity and large Randall-Sundrum II black holes

NASA Astrophysics Data System (ADS)

Abdolrahimi, Shohreh; Cattoën, Céline; Page, Don N.; \\\\; Yaghoobpour-Tari, Shima

2013-06-01

Using a novel numerical spectral method, we have found solutions for large static Randall-Sundrum II (RSII) black holes by perturbing a numerical AdS5-CFT4 solution to the Einstein equation with a negative cosmological constant Λ that is asymptotically conformal to the Schwarzschild metric. We used a numerical spectral method independent of the Ricci-DeTurck-flow method used by Figueras, Lucietti, and Wiseman for a similar numerical solution. We have compared our black-hole solution to the one Figueras and Wiseman have derived by perturbing their numerical AdS5-CFT4 solution, showing that our solution agrees closely with theirs. We have obtained a closed-form approximation to the metric of the black hole on the brane. We have also deduced the new results that to first order in 1/(-ΛM2), the Hawking temperature and entropy of an RSII static black hole have the same values as the Schwarzschild metric with the same mass, but the horizon area is increased by about 4.7/(-Λ).
Non-Abelian semilocal strings in N=2 supersymmetric QCD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shifman, M.; Yung, A.; Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg 188300

2006-06-15

We consider a benchmark bulk theory in four dimensions: N=2 supersymmetric QCD with the gauge group U(N) and N{sub f} flavors of fundamental matter hypermultiplets (quarks). The nature of the Bogomol'nyi-Prasad-Sommerfield (BPS) strings in this benchmark theory crucially depends on N{sub f}. If N{sub f}{>=}N and all quark masses are equal, it supports non-Abelian BPS strings which have internal (orientational) moduli. If N{sub f}>N these strings become semilocal, developing additional moduli {rho} related to (unlimited) variations of their transverse size. Using the U(2) gauge group with N{sub f}=3, 4 as an example, we derive an effective low-energy theory on themore » (two-dimensional) string world sheet. Our derivation is field theoretic, direct and explicit: we first analyze the Bogomol'nyi equations for string-geometry solitons, suggest an ansatz, and solve it at large {rho}. Then we use this solution to obtain the world-sheet theory. In the semiclassical limit our result confirms the Hanany-Tong conjecture, which rests on brane-based arguments, that the world-sheet theory is an N=2 supersymmetric U(1) gauge theory with N positively and N{sub e}=N{sub f}-N negatively charged matter multiplets and the Fayet-Iliopoulos term determined by the four-dimensional coupling constant. We conclude that the Higgs branch of this model is not lifted by quantum effects. As a result, such strings cannot confine. Our analysis of infrared effects, not seen in the Hanany-Tong consideration, shows that, in fact, the derivative expansion can make sense only provided that the theory under consideration is regularized in the infrared, e.g. by the quark mass differences. The world-sheet action discussed in this paper becomes a bona fide low-energy effective action only if {delta}m{sub AB}{ne}0.« less
Aspects of noncommutative (1+1)-dimensional black holes

NASA Astrophysics Data System (ADS)

Mureika, Jonas R.; Nicolini, Piero

2011-08-01

We present a comprehensive analysis of the spacetime structure and thermodynamics of (1+1)-dimensional black holes in a noncommutative framework. It is shown that a wider variety of solutions are possible than the commutative case considered previously in the literature. As expected, the introduction of a minimal length θ cures singularity pathologies that plague the standard two-dimensional general relativistic case, where the latter solution is recovered at large length scales. Depending on the choice of input parameters (black hole mass M, cosmological constant Λ, etc.), black hole solutions with zero, up to six, horizons are possible. The associated thermodynamics allows for the either complete evaporation, or the production of black hole remnants.
Supergravity backgrounds for deformations of AdS n × S n supercoset string models

DOE PAGES

Lunin, O.; Roiban, R.; Tseytlin, A. A.

2014-12-11

We considermore » type IIB supergravity backgrounds corresponding to the deformed AdS n × S n × T 10 - 2 n supercoset string models of the type constructed in arXiv:1309.5850[2] which depend on one deformation parameter κ. In AdS 2 × S 2 case we find that the deformed metric can be extended to a full supergravity solution with non-trivial dilaton, RR scalar and RR 5-form strength. The solution depends on a free parameter a that should be chosen as a particular function of κ to correspond to the deformed supercoset model. In AdS 3 × S 3 case the full solution supported by the dilaton, RR scalar and RR 3-form strength exists only in the two special cases, a = 0 and a = 1 . We conjecture that there may be a more general one-parameter solution supported by several RR fields that for particular a = a ( κ ) corresponds to the supercoset model. In the most complicated deformed AdS 5 × S 5 case we were able to find only the expressions for the dilaton and the RR scalar. The full solution is likely to be supported by a combination of the 5-form and 3-form field strengths. We comment on the singularity structure of the resulting metric and exact dilaton field.« less

Supergravity backgrounds for deformations of AdS n × S n supercoset string models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lunin, O.; Roiban, R.; Tseytlin, A. A.

We considermore » type IIB supergravity backgrounds corresponding to the deformed AdS n × S n × T 10 - 2 n supercoset string models of the type constructed in arXiv:1309.5850[2] which depend on one deformation parameter κ. In AdS 2 × S 2 case we find that the deformed metric can be extended to a full supergravity solution with non-trivial dilaton, RR scalar and RR 5-form strength. The solution depends on a free parameter a that should be chosen as a particular function of κ to correspond to the deformed supercoset model. In AdS 3 × S 3 case the full solution supported by the dilaton, RR scalar and RR 3-form strength exists only in the two special cases, a = 0 and a = 1 . We conjecture that there may be a more general one-parameter solution supported by several RR fields that for particular a = a ( κ ) corresponds to the supercoset model. In the most complicated deformed AdS 5 × S 5 case we were able to find only the expressions for the dilaton and the RR scalar. The full solution is likely to be supported by a combination of the 5-form and 3-form field strengths. We comment on the singularity structure of the resulting metric and exact dilaton field.« less
Gravitational tension, spacetime pressure and black hole volume

NASA Astrophysics Data System (ADS)

Armas, Jay; Obers, Niels A.; Sanchioni, Marco

2016-09-01

We study the first law of black hole thermodynamics in the presence of surrounding gravitational fields and argue that variations of these fields are naturally incorporated in the first law by defining gravitational tension or gravitational binding energy. We demonstrate that this notion can also be applied in Anti-de Sitter spacetime, in which the surrounding gravitational field is sourced by a cosmological fluid, therefore showing that spacetime volume and gravitational tension encode the same physics as spacetime pressure and black hole volume. We furthermore show that it is possible to introduce a definition of spacetime pressure and black hole volume for any spacetime with characteristic length scales which does not necessarily require a cosmological constant sourcing Einstein equations. However, we show that black hole volume is non-universal in the flat spacetime limit, questioning its significance. We illustrate these ideas by studying the resulting black hole volume of Kaluza-Klein black holes and of a toy model for a black hole binary system in five spacetime dimensions (the black saturn solution) as well as of several novel perturbative black hole solutions. These include the higher-dimensional Kerr-Newman solution in Anti-de Sitter spacetime as well as other black holes in plane wave and Lifshitz spacetimes.
Strings on plane-waves and spin chains on orbifolds

NASA Astrophysics Data System (ADS)

Sadri, Darius

This thesis covers a number of topics in string theory focusing on various aspects of the AdS/CFT duality in various guises and regimes. In the first chapter we present a self-contained review of the Plane-wave/super-Yang-Mills duality. This duality is a specification of the usual AdS/CFT correspondence in the "Penrose limit". In chapter two we study the most general parallelizable pp-wave backgrounds which are non-dilatonic solutions in the NS-NS sector of type IIA and IIB string theories. We demonstrate that parallelizable pp-wave backgrounds are necessarily homogeneous plane-waves, and that a large class of homogeneous plane-waves are parallelizable, stating the necessary conditions. Quantization of string modes, their compactification and behaviour under T-duality are also studied, as are BPS Dp-branes on such backgrounds. In chapter three we consider giant gravitons on the maximally supersymmetric plane-wave background. We deduce the low energy effective light-cone Hamiltonian of the three-sphere giant graviton, and place sources in this effective gauge theory. Although non-vanishing net electric charge configurations are disallowed by Gauss' law, electric dipoles can be formed. From the string theory point of view these dipoles can be understood as open strings piercing the three-sphere, giving a two dimensional (worldsheet) description of giant gravitons. Chapter four presents some new ideas regarding the relation between super-conformal gauge theories and string theories with three-dimensional target spaces, possible relations of these systems to Hamiltonian lattice gauge theories, and integrable spin chains. We consider N = 1, D = 4 superconformal SU( N)px q Yang-Mills theories dual to AdS5 x S5/Zp x Zq orbifolds. We show that a specific sector of this dilatation operator can be thought of as the transfer matrix for a three-dimensional statistical mechanical system, which in turn is equivalent to a 2 + 1-dimensional string theory where the spatial slices are discretized on a triangular lattice, and comment on the integrability of this N = 1 gauge theory, its connection to three-dimensional lattice gauge theories, extensions to six-dimensional string theories, AdS/CFT type dualities and finally their construction via orbifolds and brane-box models. In the process we discover a new class of almost-BPS BMN type operators with large engineering dimensions but controllably small anomalous corrections.
Efficient Aho-Corasick String Matching on Emerging Multicore Architectures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tumeo, Antonino; Villa, Oreste; Secchi, Simone

String matching algorithms are critical to several scientific fields. Beside text processing and databases, emerging applications such as DNA protein sequence analysis, data mining, information security software, antivirus, ma- chine learning, all exploit string matching algorithms [3]. All these applica- tions usually process large quantity of textual data, require high performance and/or predictable execution times. Among all the string matching algorithms, one of the most studied, especially for text processing and security applica- tions, is the Aho-Corasick algorithm. 1 2 Book title goes here Aho-Corasick is an exact, multi-pattern string matching algorithm which performs the search in a time linearlymore » proportional to the length of the input text independently from pattern set size. However, depending on the imple- mentation, when the number of patterns increase, the memory occupation may raise drastically. In turn, this can lead to significant variability in the performance, due to the memory access times and the caching effects. This is a significant concern for many mission critical applications and modern high performance architectures. For example, security applications such as Network Intrusion Detection Systems (NIDS), must be able to scan network traffic against very large dictionaries in real time. Modern Ethernet links reach up to 10 Gbps, and malicious threats are already well over 1 million, and expo- nentially growing [28]. When performing the search, a NIDS should not slow down the network, or let network packets pass unchecked. Nevertheless, on the current state-of-the-art cache based processors, there may be a large per- formance variability when dealing with big dictionaries and inputs that have different frequencies of matching patterns. In particular, when few patterns are matched and they are all in the cache, the procedure is fast. Instead, when they are not in the cache, often because many patterns are matched and the caches are continuously thrashed, they should be retrieved from the system memory and the procedure is slowed down by the increased latency. Efficient implementations of string matching algorithms have been the fo- cus of several works, targeting Field Programmable Gate Arrays [4, 25, 15, 5], highly multi-threaded solutions like the Cray XMT [34], multicore proces- sors [19] or heterogeneous processors like the Cell Broadband Engine [35, 22]. Recently, several researchers have also started to investigate the use Graphic Processing Units (GPUs) for string matching algorithms in security applica- tions [20, 10, 32, 33]. Most of these approaches mainly focus on reaching high peak performance, or try to optimize the memory occupation, rather than looking at performance stability. However, hardware solutions supports only small dictionary sizes due to lack of memory and are difficult to customize, while platforms such as the Cell/B.E. are very complex to program.« less
Action growth for black holes in modified gravity

NASA Astrophysics Data System (ADS)

Sebastiani, Lorenzo; Vanzo, Luciano; Zerbini, Sergio

2018-02-01

The general form of the action growth for a large class of static black hole solutions in modified gravity which includes F (R ) -gravity models is computed. The cases of black hole solutions with nonconstant Ricci scalar are also considered, generalizing the results previously found and valid only for black holes with constant Ricci scalar. An argument is put forward to provide a physical interpretation of the results, which seem tightly connected with the generalized second law of black hole thermodynamics.
Quantum electron levels in the field of a charged black hole

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dokuchaev, V. I.; Eroshenko, Yu. N., E-mail: eroshenko@ms2.inr.ac.ru

2015-12-15

Stationary solutions of the Dirac equation in the metric of the charged Reissner–Nordstrom black hole are found. In the case of an extremal black hole, the normalization integral of the wave functions is finite, and the regular stationary solution is physically self-consistent. The presence of quantum electron levels under the Cauchy horizon can have an impact on the final stage of the Hawking evaporation of the black hole, as well as on the particle scattering in the field of the black hole.
Modular operads and the quantum open-closed homotopy algebra

NASA Astrophysics Data System (ADS)

Doubek, Martin; Jurčo, Branislav; Münster, Korbinian

2015-12-01

We verify that certain algebras appearing in string field theory are algebras over Feynman transform of modular operads which we describe explicitly. Equivalent description in terms of solutions of generalized BV master equations are explained from the operadic point of view.
Thermal fluctuations of dilaton black holes in gravity's rainbow

NASA Astrophysics Data System (ADS)

Dehghani, M.

2018-06-01

In this work, thermodynamics and phase transition of some new dilaton black hole solutions have been explored in the presence of the rainbow functions. By introducing an energy dependent space time, the dilaton potential has been obtained as the linear combination of two Liouville-type potentials and three new classes of black hole solutions have been constructed. The conserved and thermodynamic quantities of the new dilaton black holes have been calculated in the energy dependent space times. It has been shown that, even if some of the thermodynamic quantities are affected by the rainbow functions, the thermodynamical first law still remains valid. Also, the impacts of rainbow functions on the stability or phase transition of the new black hole solutions have been investigated. Finally, the quantum gravitational effects on the thermodynamics and phase transition of the solutions have been studied through consideration of the thermal fluctuations.
Evasion of No-Hair Theorems and Novel Black-Hole Solutions in Gauss-Bonnet Theories

NASA Astrophysics Data System (ADS)

Antoniou, G.; Bakopoulos, A.; Kanti, P.

2018-03-01

We consider a general Einstein-scalar-Gauss-Bonnet theory with a coupling function f (ϕ ) . We demonstrate that black-hole solutions appear as a generic feature of this theory since a regular horizon and an asymptotically flat solution may be easily constructed under mild assumptions for f (ϕ ). We show that the existing no-hair theorems are easily evaded, and a large number of regular black-hole solutions with scalar hair are then presented for a plethora of coupling functions f (ϕ ).
Evasion of No-Hair Theorems and Novel Black-Hole Solutions in Gauss-Bonnet Theories.

PubMed

Antoniou, G; Bakopoulos, A; Kanti, P

2018-03-30

We consider a general Einstein-scalar-Gauss-Bonnet theory with a coupling function f(ϕ). We demonstrate that black-hole solutions appear as a generic feature of this theory since a regular horizon and an asymptotically flat solution may be easily constructed under mild assumptions for f(ϕ). We show that the existing no-hair theorems are easily evaded, and a large number of regular black-hole solutions with scalar hair are then presented for a plethora of coupling functions f(ϕ).
Scattering of massless scalar waves by magnetically charged black holes in Einstein-Yang-Mills-Higgs theory

NASA Astrophysics Data System (ADS)

Gußmann, Alexander

2017-03-01

The existence of the classical black hole solutions of the Einstein-Yang-Mills-Higgs equations with non-Abelian Yang-Mills-Higgs hair implies that not all classical stationary magnetically charged black holes can be uniquely described by their asymptotic characteristics. In fact, in a certain domain of parameters, there exist different spherically-symmetric, non-rotating and asymptotically-flat classical black hole solutions of the Einstein-Yang-Mills-Higgs equations which have the same ADM mass and the same magnetic charge but significantly different geometries in the near-horizon regions. (These are black hole solutions which are described by a Reissner-Nordström metric on the one hand and the black hole solutions with non-Abelian Yang-Mills-Higgs hair which are described by a metric which is not of Reissner-Nordström form on the other hand). One can experimentally distinguish such black holes with the same asymptotic characteristics but different near-horizon geometries classically by probing the near-horizon regions of the black holes. We argue that one way to probe the near-horizon region of a black hole which allows one to distinguish magnetically charged black holes with the same asymptotic characteristics but different near-horizon geometries is by classical scattering of waves. Using the example of a minimally-coupled massless probe scalar field scattered by magnetically charged black holes which can be obtained as solutions of the Einstein-Yang-Mills-Higgs equations with a Higgs triplet and gauge group SU(2) in the limit of an infinite Higgs self-coupling constant we show how, in this case, the scattering cross sections differ for the magnetically charged black holes with different near-horizon geometries but the same asymptotic characteristics. We find in particular that the characteristic glory peaks in the cross sections are located at different scattering angles.
The role of meaning in grapheme-colour synaesthesia.

PubMed

Dixon, Mike J; Smilek, Daniel; Duffy, Patricia L; Zanna, Mark P; Merikle, Philip M

2006-02-01

When the synaesthete, J, is shown black graphemes, in addition to perceiving the black digits or letters she also experiences highly specific colours that overlay the graphemes (e.g., 5 is pink, S is green). We used ambiguous graphemes in a Stroop-type task to show that the exact same forms (e.g., 5) can elicit different synaesthetic colours depending on whether they are interpreted as digits or letters. J was shown strings of black digits (e.g., 3 4 5 6 7) or words (e.g., M U S I C for 1 sec. All but one of the graphemes then disappeared and the remaining grapheme changed to a colour that J had to name as quickly as possible. The key trials involved coloured graphemes that were ambiguous (e.g., the 5 in the strings above could be interpreted either as a digit or as a letter). On congruent trials, the colour of the ambiguous target grapheme was the same as J's photism for the digit or letter interpretations of the grapheme. On incongruent trials, the colours of the ambiguous target graphemes were different than the colours of J's photisms for the digit or letter interpretations of the graphemes. On digit-context incongruent trials, the ambiguous graphemes were presented in J's colour for the letter-interpretations of the graphemes, whereas on letter-context incongruent trials, the ambiguous graphemes were presented in J's colours for the digit-interpretations of the graphemes. Thus the same ambiguous grapheme (e.g., a pink 5) served as a congruent stimulus in one context and an incongruent stimulus in another context. J's response times showed that ambiguous graphemes elicited different photisms depending on whether they were interpreted as digits or letters. This finding suggests that it is not the form but the meaning of graphemes (whether they are interpreted as digits or letters) that determines the colours of synaesthetic photisms.
Three dimensional magnetic solutions in massive gravity with (non)linear field

NASA Astrophysics Data System (ADS)

Hendi, S. H.; Eslam Panah, B.; Panahiyan, S.; Momennia, M.

2017-12-01

The Noble Prize in physics 2016 motivates one to study different aspects of topological properties and topological defects as their related objects. Considering the significant role of the topological defects (especially magnetic strings) in cosmology, here, we will investigate three dimensional horizonless magnetic solutions in the presence of two generalizations: massive gravity and nonlinear electromagnetic field. The effects of these two generalizations on properties of the solutions and their geometrical structure are investigated. The differences between de Sitter and anti de Sitter solutions are highlighted and conditions regarding the existence of phase transition in geometrical structure of the solutions are studied.
BPS Jumping Loci are Automorphic

NASA Astrophysics Data System (ADS)

Kachru, Shamit; Tripathy, Arnav

2018-06-01

We show that BPS jumping loci-loci in the moduli space of string compactifications where the number of BPS states jumps in an upper semi-continuous manner—naturally appear as Fourier coefficients of (vector space-valued) automorphic forms. For the case of T 2 compactification, the jumping loci are governed by a modular form studied by Hirzebruch and Zagier, while the jumping loci in K3 compactification appear in a story developed by Oda and Kudla-Millson in arithmetic geometry. We also comment on some curious related automorphy in the physics of black hole attractors and flux vacua.
Mass, angular momentum, and charge inequalities for black holes in Einstein-Maxwell-axion-dilaton gravity

NASA Astrophysics Data System (ADS)

Rogatko, Marek

2014-02-01

Mass, angular momentum, and charge inequalities for axisymmetric maximal time-symmetric initial data invariant under an action of U(1) group, in Einstein-Maxwell-axion-dilaton gravity being the low-energy limit of the heterotic string theory, is established. We assume that a data set with two asymptotically flat regions is given on a smooth simply connected manifold. We also pay attention to the area momentum charge inequalities for a closed orientable two-dimensional spacelike surface embedded in the spacetime of the considered theory.
With string model to time series forecasting

NASA Astrophysics Data System (ADS)

Pinčák, Richard; Bartoš, Erik

2015-10-01

Overwhelming majority of econometric models applied on a long term basis in the financial forex market do not work sufficiently well. The reason is that transaction costs and arbitrage opportunity are not included, as this does not simulate the real financial markets. Analyses are not conducted on the non equidistant date but rather on the aggregate date, which is also not a real financial case. In this paper, we would like to show a new way how to analyze and, moreover, forecast financial market. We utilize the projections of the real exchange rate dynamics onto the string-like topology in the OANDA market. The latter approach allows us to build the stable prediction models in trading in the financial forex market. The real application of the multi-string structures is provided to demonstrate our ideas for the solution of the problem of the robust portfolio selection. The comparison with the trend following strategies was performed, the stability of the algorithm on the transaction costs for long trade periods was confirmed.
A covert authentication and security solution for GMOs.

PubMed

Mueller, Siguna; Jafari, Farhad; Roth, Don

2016-09-21

Proliferation and expansion of security risks necessitates new measures to ensure authenticity and validation of GMOs. Watermarking and other cryptographic methods are available which conceal and recover the original signature, but in the process reveal the authentication information. In many scenarios watermarking and standard cryptographic methods are necessary but not sufficient and new, more advanced, cryptographic protocols are necessary. Herein, we present a new crypto protocol, that is applicable in broader settings, and embeds the authentication string indistinguishably from a random element in the signature space and the string is verified or denied without disclosing the actual signature. Results show that in a nucleotide string of 1000, the algorithm gives a correlation of 0.98 or higher between the distribution of the codon and that of E. coli, making the signature virtually invisible. This algorithm may be used to securely authenticate and validate GMOs without disclosing the actual signature. While this protocol uses watermarking, its novelty is in use of more complex cryptographic techniques based on zero knowledge proofs to encode information.
Entertaining Chemistry--Two Colorful Reactions.

ERIC Educational Resources Information Center

Elsworth, John F.

2000-01-01

Describes two related color-change reactions that are relatively easy and safe to demonstrate. In the "Sunday School Reaction", a black and a white solution are mixed to form a white solution. In the "South Africa Reaction", a series of black, brown, red, and white solutions are mixed to form a clear, colorless solution. (WRM)
Five dimensional microstate geometries

NASA Astrophysics Data System (ADS)

Wang, Chih-Wei

In this thesis, we discuss the possibility of exploring the statistical mechanics description of a black hole from the point view of supergravity. Specifically, we study five dimensional microstate geometries of a black hole or black ring. At first, we review the method to find the general three-charge BPS supergravity solutions proposed by Bena and Warner. By applying this method, we show the classical merger of a black ring and black hole on [Special characters omitted.] base space in general are irreversible. On the other hand, we review the solutions on ambi-polar Gibbons-Hawking (GH) base which are bubbled geometries. There are many possible microstate geometries among the bubbled geometries. Particularly, we show that a generic blob of GH points that satisfy certain conditions can be either microstate geometry of a black hole or black ring without horizon. Furthermore, using the result of the entropy analysis in classical merger as a guide, we show that one can have a merger of a black-hole blob and a black-ring blob or two black-ring blobs that corresponds to a classical irreversible merger. From the irreversible mergers, we find the scaling solutions and deep microstates which are microstate geometries of a black hole/ring with macroscopic horizon. These solutions have the same AdS throats as classical black holes/rings but instead of having infinite throats, the throat is smoothly capped off at a very large depth with some local structure at the bottom. For solutions that produced from U (1) × U (1) invariant merger, the depth of the throat is limited by flux quantization. The mass gap is related with the depth of this throat and we show the mass gap of these solutions roughly match with the mass gap of the typical conformal-field-theory (CFT) states. Therefore, based on AdS/CFT correspondence, they can be dual geometries of the typical CFT states that contribute to the entropy of a black hole/ring. On the other hand, we show that for the solutions produced from more general merger (without U (1) × U (1) invariance), the throat can be arbitrarily deep. This presents a puzzle from the point view of AdS/CFT correspondence. We propose that this puzzle may be solved by some quantization of the angle or promoting the flux vectors to quantum spins. Finally, we suggest some future directions of further study including the puzzle of arbitrary long AdS throat and a general coarse-graining picture of microstate geometries.
On the solubility of certain classes of non-linear integral equations in p-adic string theory

NASA Astrophysics Data System (ADS)

Khachatryan, Kh. A.

2018-04-01

We study classes of non-linear integral equations that have immediate application to p-adic mathematical physics and to cosmology. We prove existence and uniqueness theorems for non-trivial solutions in the space of bounded functions.

On Closed Timelike Curves and Warped Brane World Models

NASA Astrophysics Data System (ADS)

Slagter, Reinoud Jan

2013-09-01

At first glance, it seems possible to construct in general relativity theory causality violating solutions. The most striking one is the Gott spacetime. Two cosmic strings, approaching each other with high velocity, could produce closed timelike curves. It was quickly recognized that this solution violates physical boundary conditions. The effective one particle generator becomes hyperbolic, so the center of mass is tachyonic. On a 5-dimensional warped spacetime, it seems possible to get an elliptic generator, so no obstruction is encountered and the velocity of the center of mass of the effective particle has an overlap with the Gott region. So a CTC could, in principle, be constructed. However, from the effective 4D field equations on the brane, which are influenced by the projection of the bulk Weyl tensor on the brane, it follows that no asymptotic conical space time is found, so no angle deficit as in the 4D counterpart model. This could also explain why we do not observe cosmic strings.
Evolutionary algorithms for the optimization of advective control of contaminated aquifer zones

NASA Astrophysics Data System (ADS)

Bayer, Peter; Finkel, Michael

2004-06-01

Simple genetic algorithms (SGAs) and derandomized evolution strategies (DESs) are employed to adapt well capture zones for the hydraulic optimization of pump-and-treat systems. A hypothetical contaminant site in a heterogeneous aquifer serves as an application template. On the basis of the results from numerical flow modeling, particle tracking is applied to delineate the pathways of the contaminants. The objective is to find the minimum pumping rate of up to eight recharge wells within a downgradient well placement area. Both the well coordinates and the pumping rates are subject to optimization, leading to a mixed discrete-continuous problem. This article discusses the ideal formulation of the objective function for which the number of particles and the total pumping rate are used as decision criteria. Boundary updating is introduced, which enables the reorganization of the decision space limits by the incorporation of experience from previous optimization runs. Throughout the study the algorithms' capabilities are evaluated in terms of the number of model runs which are needed to identify optimal and suboptimal solutions. Despite the complexity of the problem both evolutionary algorithm variants prove to be suitable for finding suboptimal solutions. The DES with weighted recombination reveals to be the ideal algorithm to find optimal solutions. Though it works with real-coded decision parameters, it proves to be suitable for adjusting discrete well positions. Principally, the representation of well positions as binary strings in the SGA is ideal. However, even if the SGA takes advantage of bookkeeping, the vital high discretization of pumping rates results in long binary strings, which escalates the model runs that are needed to find an optimal solution. Since the SGA string lengths increase with the number of wells, the DES gains superiority, particularly for an increasing number of wells. As the DES is a self-adaptive algorithm, it proves to be the more robust optimization method for the selected advective control problem than the SGA variants of this study, exhibiting a less stochastic search which is reflected in the minor variability of the found solutions.
Skyrmions, Skyrme stars and black holes with Skyrme hair in five spacetime dimension

NASA Astrophysics Data System (ADS)

Brihaye, Yves; Herdeiro, Carlos; Radu, Eugen; Tchrakian, D. H.

2017-11-01

We consider a class of generalizations of the Skyrme model to five spacetime dimensions ( d = 5), which is defined in terms of an O(5) sigma model. A special ansatz for the Skyrme field allows angular momentum to be present and equations of motion with a radial dependence only. Using it, we obtain: 1) everywhere regular solutions describing localised energy lumps ( Skyrmions); 2) Self-gravitating, asymptotically flat, everywhere non-singular solitonic solutions ( Skyrme stars), upon minimally coupling the model to Einstein's gravity; 3) both static and spinning black holes with Skyrme hair, the latter with rotation in two orthogonal planes, with both angular momenta of equal magnitude. In the absence of gravity we present an analytic solution that satisfies a BPS-type bound and explore numerically some of the non-BPS solutions. In the presence of gravity, we contrast the solutions to this model with solutions to a complex scalar field model, namely boson stars and black holes with synchronised hair. Remarkably, even though the two models present key differences, and in particular the Skyrme model allows static hairy black holes, when introducing rotation, the synchronisation condition becomes mandatory, providing further evidence for its generality in obtaining rotating hairy black holes.
A Non-Critical String (Liouville) Approach to Brain Microtubules:. State Vector Reduction, Memory Coding and Capacity

NASA Astrophysics Data System (ADS)

Mavromatos, N. E.; Nanopoulos, D. V.

Microtubule (MT) networks, subneural paracrystalline cytoskeletal structures, seem to play a fundamental role in the neurons. We cast here the complicated MT dynamics in the form of a (1+1)-dimensional noncritical string theory, thus enabling us to provide a consistent quantum treatment of MTs, including enviromental friction effects. We suggest, thus, that the MTs are the microsites, in the brain, for the emergence of stable, macroscopic quantum coherent states, identifiable with the preconscious states. Quantum space-time effects, as described by noncritical string theory, trigger then an organized collapse of the coherent states down to a specific or conscious state. The whole process we estimate to take { O}(1 sec), in excellent agreement with a plethora of experimental/observational findings. The microscopic arrow of time, endemic in noncritical string theory, and apparent here in the self-collapse process, provides a satisfactory and simple resolution to the age-old problem of how the, central to our feelings of awareness, sensation of the progression of time is generated. In addition, the complete integrability of the stringy model for MT we advocate in this work proves sufficient in providing a satisfactory solution to memory coding and capacity. Such features might turn out to be important for a model of the brain as a quantum computer.
On the stability of dyons and dyonic black holes in Einstein-Yang-Mills theory

NASA Astrophysics Data System (ADS)

Nolan, Brien C.; Winstanley, Elizabeth

2016-02-01

We investigate the stability of four-dimensional dyonic soliton and black hole solutions of {su}(2) Einstein-Yang-Mills theory in anti-de Sitter space. We prove that, in a neighbourhood of the embedded trivial (Schwarzschild-)anti-de Sitter solution, there exist non-trivial dyonic soliton and black hole solutions of the field equations which are stable under linear, spherically symmetric, perturbations of the metric and non-Abelian gauge field.
Wet-chemical systems and methods for producing black silicon substrates

DOEpatents

Yost, Vernon; Yuan, Hao-Chih; Page, Matthew

2015-05-19

A wet-chemical method of producing a black silicon substrate. The method comprising soaking single crystalline silicon wafers in a predetermined volume of a diluted inorganic compound solution. The substrate is combined with an etchant solution that forms a uniform noble metal nanoparticle induced Black Etch of the silicon wafer, resulting in a nanoparticle that is kinetically stabilized. The method comprising combining with an etchant solution having equal volumes acetonitrile/acetic acid:hydrofluoric acid:hydrogen peroxide.
Bopp-Podolsky black holes and the no-hair theorem

NASA Astrophysics Data System (ADS)

Cuzinatto, R. R.; de Melo, C. A. M.; Medeiros, L. G.; Pimentel, B. M.; Pompeia, P. J.

2018-01-01

Bopp-Podolsky electrodynamics is generalized to curved space-times. The equations of motion are written for the case of static spherically symmetric black holes and their exterior solutions are analyzed using Bekenstein's method. It is shown that the solutions split up into two parts, namely a non-homogeneous (asymptotically massless) regime and a homogeneous (asymptotically massive) sector which is null outside the event horizon. In addition, in the simplest approach to Bopp-Podolsky black holes, the non-homogeneous solutions are found to be Maxwell's solutions leading to a Reissner-Nordström black hole. It is also demonstrated that the only exterior solution consistent with the weak and null energy conditions is the Maxwell one. Thus, in the light of the energy conditions, it is concluded that only Maxwell modes propagate outside the horizon and, therefore, the no-hair theorem is satisfied in the case of Bopp-Podolsky fields in spherically symmetric space-times.
Spinning BTZ black hole versus Kerr black hole: A closer look

NASA Astrophysics Data System (ADS)

Kim, Hongsu

1999-03-01

By applying Newman's algorithm, the AdS3 rotating black hole solution is ``derived'' from the nonrotating black hole solution of Bañados, Teitelboim, and Zanelli (BTZ). The rotating BTZ solution derived in this fashion is given in ``Boyer-Lindquist-type'' coordinates whereas the form of the solution originally given by BTZ is given in kind of ``unfamiliar'' coordinates which are related to each other by a transformation of time coordinate alone. The relative physical meaning between these two time coordinates is carefully studied. Since the Kerr-type and Boyer-Lindquist-type coordinates for rotating BTZ solution are newly found via Newman's algorithm, the transformation to Kerr-Schild-type coordinates is looked for. Indeed, such a transformation is found to exist. In these Kerr-Schild-type coordinates, a truly maximal extension of its global structure by analytically continuing to an ``antigravity universe'' region is carried out.
Solutions of the Bethe ansatz equations for XXX antiferromagnet of arbitrary spin in the case of a finite number of sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Avdeev, L.V.; Doerfel, B.D.

1987-11-01

The exactly integrable isotropic Heisenberg chain of N spins s is studied, and numerical solutions to the Bethe ansatz equations corresponding to the antiferromagnetic vacuum (for sN less than or equal to 128) and the simplest excitations have been obtained. For s = 1, a complete set of states for N = 6 is given, and the vacuum solution for finite N is estimated analytically. The deviations from the string picture at large N are discussed.
Confined phase in the real time formalism and the fate of the world behind the horizon

NASA Astrophysics Data System (ADS)

Furuuchi, Kazuyuki

2006-02-01

In the real time formulation of finite temperature field theories, one introduces an additional set of fields (type-2 fields) associated to each field in the original theory (type-1 field). In [J. M. Maldacena, J. High Energy Phys., JHEPFG, 1029-8479 04 (2003) 021., 10.1088/1126-6708/2003/04/021], in the context of the anti-de Sitter (AdS)-conformal field theories (CFT) correspondence, Maldacena interpreted type-2 fields as living on a boundary behind the black hole horizon. However, below the Hawking-Page transition temperature, the thermodynamically preferred configuration is the thermal AdS without a black hole, and hence there are no horizon and boundary behind it. This means that when the dual gauge theory is in confined phase, the type-2 fields cannot be associated with the degrees of freedom behind the black hole horizon. I argue that in this case the role of the type-2 fields is to make up bulk type-2 fields of classical closed string field theory on AdS at finite temperature in the real time formalism.
Thermodynamics of charged black holes with a nonlinear electrodynamics source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gonzalez, Hernan A.; Hassaiene, Mokhtar; Martinez, Cristian

2009-11-15

We study the thermodynamical properties of electrically charged black hole solutions of a nonlinear electrodynamics theory defined by a power p of the Maxwell invariant, which is coupled to Einstein gravity in four and higher spacetime dimensions. Depending on the range of the parameter p, these solutions present different asymptotic behaviors. We compute the Euclidean action with the appropriate boundary term in the grand canonical ensemble. The thermodynamical quantities are identified and, in particular, the mass and the charge are shown to be finite for all classes of solutions. Interestingly, a generalized Smarr formula is derived and it is shownmore » that this latter encodes perfectly the different asymptotic behaviors of the black hole solutions. The local stability is analyzed by computing the heat capacity and the electrical permittivity and we find that a set of small black holes is locally stable. In contrast to the standard Reissner-Nordstroem solution, there is a first-order phase transition between a class of these nonlinear charged black holes and the Minkowski spacetime.« less
Exact solutions in 3D gravity with torsion

NASA Astrophysics Data System (ADS)

González, P. A.; Vásquez, Yerko

2011-08-01

We study the three-dimensional gravity with torsion given by the Mielke-Baekler (MB) model coupled to gravitational Chern-Simons term, and that possess electric charge described by Maxwell-Chern-Simons electrodynamics. We find and discuss this theory's charged black holes solutions and uncharged solutions. We find that for vanishing torsion our solutions by means of a coordinate transformation can be written as three-dimensional Chern-Simons black holes. We also discuss a special case of this theory, Topologically Massive Gravity (TMG) at chiral point, and we show that the logarithmic solution of TMG is also a solution of the MB model at a fixed point in the space of parameters. Furthermore, we show that our solutions generalize Gödel type solutions in a particular case. Also, we recover BTZ black hole in Riemann-Cartan spacetime for vanishing charge.
An exact solution for a rotating black hole in modified gravity

NASA Astrophysics Data System (ADS)

Filippini, Francesco; Tasinato, Gianmassimo

2018-01-01

Exact solutions describing rotating black holes can offer important tests for alternative theories of gravity, motivated by the dark energy and dark matter problems. We present an analytic rotating black hole solution for a class of vector-tensor theories of modified gravity, valid for arbitrary values of the rotation parameter. The new configuration is characterised by parametrically large deviations from the Kerr-Newman geometry, controlled by non-minimal couplings between vectors and gravity. It has an oblate horizon in Boyer-Lindquist coordinates, and it can rotate more rapidly and have a larger ergosphere than black holes in General Relativity (GR) with the same asymptotic properties. We analytically investigate the features of the innermost stable circular orbits for massive objects on the equatorial plane, and show that stable orbits lie further away from the black hole horizon with respect to rotating black holes in GR. We also comment on possible applications of our findings for the extraction of rotational energy from the black hole.
Stable black phosphorus quantum dots for alkali PH sensor

NASA Astrophysics Data System (ADS)

Guo, Weilan; Song, Haizeng; Yan, Shancheng

2018-01-01

Black phosphorus, as a new two-dimensional material has been widely used in sensors, photovoltaic devices, etc. However, thin layered black phosphorus chemically degrades rapidly under ambient and aqueous conditions, which hinders the application of it in the chemical sensors. In this work, stable black phosphorus quantum dots (BPQDs) in solution are successfully synthesized by functionalization with 4-nitrobenzene-diazonium (4-NBD). The stable BPQDs are investigated by TEM, AFM, Raman, and UV-absorption. As a potential application, the stable BPQDs are used as sensors in alkali solution, which exhibit outstanding performance. Our work paves the way towards a new application with BPQDs in solution.
Yang-Baxter σ -models, conformal twists, and noncommutative Yang-Mills theory

NASA Astrophysics Data System (ADS)

Araujo, T.; Bakhmatov, I.; Colgáin, E. Ó.; Sakamoto, J.; Sheikh-Jabbari, M. M.; Yoshida, K.

2017-05-01

The Yang-Baxter σ -model is a systematic way to generate integrable deformations of AdS5×S5 . We recast the deformations as seen by open strings, where the metric is undeformed AdS5×S5 with constant string coupling, and all information about the deformation is encoded in the noncommutative (NC) parameter Θ . We identify the deformations of AdS5 as twists of the conformal algebra, thus explaining the noncommutativity. We show that the unimodularity condition on r -matrices for supergravity solutions translates into Θ being divergence-free. Integrability of the σ -model for unimodular r -matrices implies the existence and planar integrability of the dual NC gauge theory.
Tachyon driven quantum cosmology in string theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia-Compean, H.; Garcia-Jimenez, G.; Obregon, O.

2005-03-15

Recently an effective action of the SDp-brane decaying process in string theory has been proposed. This effective description involves the Tachyon driven matter coupled to bosonic ten-dimensional Type II supergravity. Here the Hamiltonian formulation of this system is given. Exact solutions for the corresponding quantum theory by solving the Wheeler-deWitt equation in the late-time limit of the rolling tachyon are found. The energy spectrum and the probability densities for several values of p are shown and their possible interpretation is discussed. In the process the effects of electromagnetic fields are also incorporated and it is shown that in this casemore » the interpretation of tachyon regarded as 'matter clock' is modified.« less
Integrability in conformally coupled gravity: Taub-NUT spacetimes and rotating black holes

NASA Astrophysics Data System (ADS)

Bardoux, Yannis; Caldarelli, Marco M.; Charmousis, Christos

2014-05-01

We consider four dimensional stationary and axially symmetric spacetimes for conformally coupled scalar-tensor theories. We show that, in analogy to the Lewis-Papapetrou problem in General Relativity (GR), the theory at hand can be recast in an analogous integrable form. We give the relevant rod formalism, introduced by Weyl for vacuum GR, explicitly giving the rod structure of the black hole of Bocharova et al. and Bekenstein (BBMB), in complete analogy to the Schwarzschild solution. The additional scalar field is shown to play the role of an extra Weyl potential. We then employ the Ernst method as a concrete solution generating example to obtain the Taub-NUT version of the BBMB hairy black hole. The solution is easily extended to include a cosmological constant. We show that the anti-de Sitter hyperbolic version of this solution is free of closed timelike curves that plague usual Taub-NUT metrics, and thus consists of a rotating, asymptotically locally anti-de Sitter black hole. This stationary solution has no curvature singularities whatsoever in the conformal frame, and the NUT charge is shown here to regularize the central curvature singularity of the corresponding static black hole. Given our findings we discuss the anti-de Sitter hyperbolic version of Taub-NUT in four dimensions, and show that the curvature singularity of the NUT-less solution is now replaced by a neighbouring chronological singularity screened by horizons. We argue that the properties of this rotating black hole are very similar to those of the rotating BTZ black hole in three dimensions.
Unruh thermal hadronization and the cosmological constant

NASA Astrophysics Data System (ADS)

Frassino, Antonia M.; Bleicher, Marcus; Mann, Robert B.

2018-05-01

We use black holes with a negative cosmological constant to investigate aspects of the freeze-out temperature for hadron production in high energy heavy-ion collisions. The two black hole solutions present in the anti-de Sitter geometry have different mass and are compared to the data showing that the small black hole solution is in good agreement. This is a new feature in the literature since the small black hole in general relativity has different thermodynamic behavior from that of the large black hole solution. We find that the inclusion of the cosmological constant (which can be interpreted as the plasma pressure) leads to a lowering of the temperature of the freeze-out curve as a function of the baryochemical potential, improving the description previously suggested by Castorina, Kharzeev, and Satz.
Deforming regular black holes

NASA Astrophysics Data System (ADS)

Neves, J. C. S.

2017-06-01

In this work, we have deformed regular black holes which possess a general mass term described by a function which generalizes the Bardeen and Hayward mass functions. By using linear constraints in the energy-momentum tensor to generate metrics, the solutions presented in this work are either regular or singular. That is, within this approach, it is possible to generate regular or singular black holes from regular or singular black holes. Moreover, contrary to the Bardeen and Hayward regular solutions, the deformed regular black holes may violate the weak energy condition despite the presence of the spherical symmetry. Some comments on accretion of deformed black holes in cosmological scenarios are made.
Constraining the braneworld with gravitational wave observations.

PubMed

McWilliams, Sean T

2010-04-09

Some braneworld models may have observable consequences that, if detected, would validate a requisite element of string theory. In the infinite Randall-Sundrum model (RS2), the AdS radius of curvature, l, of the extra dimension supports a single bound state of the massless graviton on the brane, thereby reproducing Newtonian gravity in the weak-field limit. However, using the AdS/CFT correspondence, it has been suggested that one possible consequence of RS2 is an enormous increase in Hawking radiation emitted by black holes. We utilize this possibility to derive two novel methods for constraining l via gravitational wave measurements. We show that the EMRI event rate detected by LISA can constrain l at the approximately 1 microm level for optimal cases, while the observation of a single galactic black hole binary with LISA results in an optimal constraint of l < or = 5 microm.

Constraining the Braneworld with Gravitational Wave Observations

NASA Technical Reports Server (NTRS)

McWilliams, Sean T.

2011-01-01

Some braneworld models may have observable consequences that, if detected, would validate a requisite element of string theory. In the infinite Randall-Sundrum model (RS2), the AdS radius of curvature, L, of the extra dimension supports a single bound state of the massless graviton on the brane, thereby reproducing Newtonian gravity in the weak-field limit. However, using the AdS/CFT correspondence, it has been suggested that one possible consequence of RS2 is an enormous increase in Hawking radiation emitted by black holes. We utilize this possibility to derive two novel methods for constraining L via gravitational wave measurements. We show that the EMRI event rate detected by LISA can constrain L at the approximately 1 micron level for optimal cases, while the observation of a single galactic black hole binary with LISA results in an optimal constraint of L less than or equal to 5 microns.
Charged black lens in de Sitter space

NASA Astrophysics Data System (ADS)

Tomizawa, Shinya

2018-02-01

We obtain a charged black lens solution in the five-dimensional Einstein-Maxwell-Chern-Simons theory with a positive cosmological constant. It is shown that the solution obtained here describes the formation of a black hole with the spatial cross section of a sphere from that of the lens space of L (n ,1 ) in five-dimensional de Sitter space.
Social Groups Prioritize Selective Attention to Faces: How Social Identity Shapes Distractor Interference

PubMed Central

Hill, LaBarron K.; Williams, DeWayne P.; Thayer, Julian F.

2016-01-01

Human faces automatically attract visual attention and this process appears to be guided by social group memberships. In two experiments, we examined how social groups guide selective attention toward in-group and out-group faces. Black and White participants detected a target letter among letter strings superimposed on faces (Experiment 1). White participants were less accurate on trials with racial out-group (Black) compared to in-group (White) distractor faces. Likewise, Black participants were less accurate on trials with racial out-group (White) compared to in-group (Black) distractor faces. However, this pattern of out-group bias was only evident under high perceptual load—when the task was visually difficult. To examine the malleability of this pattern of racial bias, a separate sample of participants were assigned to mixed-race minimal groups (Experiment 2). Participants assigned to groups were less accurate on trials with their minimal in-group members compared to minimal out-group distractor faces, regardless of race. Again, this pattern of out-group bias was only evident under high perceptual load. Taken together, these results suggest that social identity guides selective attention toward motivationally relevant social groups—shifting from out-group bias in the domain of race to in-group bias in the domain of minimal groups—when perceptual resources are scarce. PMID:27556646
Double-black-hole solutions of the Einstein-Maxwell-dilaton theory in five dimensions

NASA Astrophysics Data System (ADS)

Stelea, Cristian

2018-01-01

We describe a solution-generating technique that maps a static charged solution of the Einstein-Maxwell theory in four (or five) dimensions to a five-dimensional solution of the Einstein-Maxwell-Dilaton theory. As examples of this technique first we show how to construct the dilatonic version of the Reissner-Nordström solution in five dimensions and then we consider the more general case of the double black hole solutions and describe some of their properties. We found that in the general case the value of the conical singularities in between the black holes is affected by the dilaton's coupling constant to the gauge field and only in the particular case when all charges are proportional to the masses this dependence cancels out.
Brane-world black hole solutions via a confining potential

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heydari-Fard, M.; Sepangi, H. R.; Razmi, H.

2007-09-15

Using a confining potential, we consider spherically symmetric vacuum (static black hole) solutions in a brane-world scenario. Working with a constant curvature bulk, two interesting cases/solutions are studied. A Schwarzschild-de Sitter black hole solution similar to the standard solution in the presence of a cosmological constant is obtained which confirms the idea that an extra term in the field equations on the brane can play the role of a positive cosmological constant and may be used to account for the accelerated expansion of the universe. The other solution is one in which we can have a proper potential to explainmore » the galaxy rotation curves without assuming the existence of dark matter and without working with new modified theories (modified Newtonian dynamics)« less
Abundant stable gauge field hair for black holes in anti-de Sitter space.

PubMed

Baxter, J E; Helbling, Marc; Winstanley, Elizabeth

2008-01-11

We present new hairy black hole solutions of SU(N) Einstein-Yang-Mills (EYM) theory in asymptotically anti-de Sitter (AdS) space. These black holes are described by N+1 independent parameters and have N-1 independent gauge field degrees of freedom. Solutions in which all gauge field functions have no zeros exist for all N, and for a sufficiently large (and negative) cosmological constant. At least some of these solutions are shown to be stable under classical, linear, spherically symmetric perturbations. Therefore there is no upper bound on the amount of stable gauge field hair with which a black hole in AdS can be endowed.
BIonic system: Extraction of Lovelock gravity from a Born-Infeld-type theory

NASA Astrophysics Data System (ADS)

Naimi, Yaghoob; Sepehri, Alireza; Ghaffary, Tooraj; Ghaforyan, Hossein; Ebrahimzadeh, Majid

It was shown that both Lovelock gravity and Born-Infeld (BI) electrodynamics can be obtained from low effective limit of string theory. Motivated by the mentioned unique origin of the gauge-gravity theories, we are going to find a close relation between them. In this research, we start from the Lagrangian of a BI-type nonlinear electrodynamics with an exponential form to extract the action of Lovelock gravity. We investigate the origin of Lovelock gravity in a system of branes which are connected with each other by different wormholes through a BIonic system. These wormholes are produced as due to the nonlinear electrodynamics which are emerged on the interacting branes. By approaching branes, wormholes dissolve into branes and Lovelock gravity is generated. Also, throats of some wormholes become smaller than their horizons and they transit to black holes. Generalizing calculations to M-theory, it is found that by compacting Mp-branes, Lovelock gravity changes to nonlinear electrodynamics and thus both of them have the same origin. This result is consistent with the prediction of BIonic model in string theory.
Scalar hairy black holes and scalarons in the isolated horizons formalism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corichi, Alejandro; Instituto de Matematicas, Universidad Nacional Autonoma de Mexico, A. Postal 61-3, Morelia, Michoacan, 58090; Nucamendi, Ulises

The Isolated Horizons (IH) formalism, together with a simple phenomenological model for colored black holes has been used to predict nontrivial formulas that relate the ADM mass of the solitons and hairy Black Holes of Gravity-Matter system on the one hand, and several horizon properties of the black holes in the other. In this article, the IH formalism is tested numerically for spherically symmetric solutions to an Einstein-Higgs system where hairy black holes were recently found to exist. It is shown that the mass formulas still hold and that, by appropriately extending the current model, one can account for themore » behavior of the horizon properties of these new solutions. An empirical formula that approximates the ADM mass of hairy solutions is put forward, and some of its properties are analyzed.« less
Fuzzy spaces topology change as a possible solution to the black hole information loss paradox

NASA Astrophysics Data System (ADS)

Silva, C. A. S.

2009-06-01

The black hole information loss paradox is one of the most intricate problems in modern theoretical physics. A proposal to solve this is one related with topology change. However it has found some obstacles related to unitarity and cluster decomposition (locality). In this Letter we argue that modelling the black hole's event horizon as a noncommutative manifold - the fuzzy sphere - we can solve the problems with topology change, getting a possible solution to the black hole information loss paradox.
Charged Galileon black holes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Babichev, Eugeny; Charmousis, Christos; Hassaine, Mokhtar, E-mail: eugeny.babichev@th.u-psud.fr, E-mail: christos.charmousis@th.u-psud.fr, E-mail: hassaine@inst-mat.utalca.cl

We consider an Abelian gauge field coupled to a particular truncation of Horndeski theory. The Galileon field has translation symmetry and couples non minimally both to the metric and the gauge field. When the gauge-scalar coupling is zero the gauge field reduces to a standard Maxwell field. By taking into account the symmetries of the action, we construct charged black hole solutions. Allowing the scalar field to softly break symmetries of spacetime we construct black holes where the scalar field is regular on the black hole event horizon. Some of these solutions can be interpreted as the equivalent of Reissner-Nordstrommore » black holes of scalar tensor theories with a non trivial scalar field. A self tuning black hole solution found previously is extended to the presence of dyonic charge without affecting whatsoever the self tuning of a large positive cosmological constant. Finally, for a general shift invariant scalar tensor theory we demonstrate that the scalar field Ansatz and method we employ are mathematically compatible with the field equations. This opens up the possibility for novel searches of hairy black holes in a far more general setting of Horndeski theory.« less
Meteorological Sensor Array (MSA)-Phase I. Volume 2 (Data Management Tool: Proof of Concept)

DTIC Science & Technology

2014-10-01

directory of next hourly file to read *** utcString = CStr (CInt(utcString) + 1) utcString = String(2 - Len(utcString), Ŕ...hourly file to read *** utcString = CStr (CInt(utcString) + 1) utcString = String(2 - Len(utcString), Ŕ") & utcString
BOOK REVIEW: Black Holes, Cosmology and Extra Dimensions Black Holes, Cosmology and Extra Dimensions

NASA Astrophysics Data System (ADS)

Frolov, Valeri P.

2013-10-01

The book Black holes, Cosmology and Extra Dimensions written by Kirill A Bronnikov and Sergey G Rubin has been published recently by World Scientific Publishing Company. The authors are well known experts in gravity and cosmology. The book is a monograph, a considerable part of which is based on the original work of the authors. Their original point of view on some of the problems makes the book quite interesting, covering a variety of important topics of the modern theory of gravity, astrophysics and cosmology. It consists of 11 chapters which are organized in three parts. The book starts with an introduction, where the authors briefly discuss the main ideas of General Relativity, giving some historical remarks on its development and application to cosmology, and mentioning some more recent subjects such as brane worlds, f(R)-theories and gravity in higher dimensions. Part I of the book is called 'Gravity'. Chapters two and three are devoted to the Einstein equations and their spherical symmetric black hole solutions. This material is quite standard and can be found in practically any book on General Relativity. A brief summary of the Kerr metric and black hole thermodynamics are given in chapter four. The main part of this chapter is devoted to spherically symmetric black holes in non-Einstein gravity (with scalar and phantom fields), black holes with regular interior, and black holes in brane worlds. Chapters five and six are mainly dedicated to wormholes and the problem of their stability. Part II (Cosmology) starts with discussion of the Friedmann-Robertson-Walker and de Sitter solutions of the Einstein equations and their properties. It follows by describing a `big picture' of the modern cosmology (inflation, post-inflationary reheating, the radiation-dominated and matter-dominated states, and modern stage of the (secondary) inflation). The authors explain how the inflation models allow one to solve many of the long-standing problems of cosmology, such as flatness of the Universe, the horizon problem and isotropy of cosmological microwave background. All this material is covered in chapter seven. Chapter eight contains brief discussion of several popular inflation models. Chapter nine is devoted to the problem of the large-scale structure formation from initial quantum vacuum fluctuation during the inflation and the spectrum of the density fluctuations. It also contains remarks on the baryonic asymmetry of the Universe, baryogenesis and primordial black holes. Part III covers the material on extra dimensions. It describes how Einstein gravity is modified in the presence of one or more additional spatial dimensions and how these extra dimensions are compactified in the Kaluza-Klein scheme. The authors also discuss how extra dimensions may affect low energy physics. They present examples of higher-dimensional generalizations of the gravity with higher-in-curvature corrections and discuss a possible mechanism of self-stabilization of an extra space. A considerable part of the chapter 10 is devoted to cosmological models with extra dimensions. In particular, the authors discuss how extra dimensions can modify 'standard' inflation models. At the end of this chapter they make several remarks on a possible relation of the value of fundamental constants in our universe with the existence of extra dimensions. Finally, in chapter 11 they demonstrate that several observable properties of the Universe are closely related with the special value of the fundamental physical constants and their fine tuning. They give interesting examples of such fine tuning and summarize many other cases. The book ends with discussion of a so-called 'cascade birth of universes in multidimensional spaces' model, proposed by one of the authors. As is evident from this brief summary of topics presented in the book, many interesting areas of modern gravity and cosmology are covered. However, since the subject is so wide, this inevitably implies that the selection of the topics and level of their presentation in many cases reflects the authors' own preferences. As a result, several important subjects on black holes, cosmology and extra dimensions, widely discussed in the modern literature, are not covered by the book. For example, a reader will not find discussion of non-spherically symmetric higher dimensional black holes which are either non-trivial generalization of the Kerr black holes, or even have a non-spherical topology of the horizon (black rings, black strings and so on). The book does not contain any information on supersymmetric black holes, black branes solutions and their properties. This list can easily be continued (black hole perturbations, gravitational radiation from binary black hole coalescence, cosmology in massive gravity and Hořava-Lifshitz models, etc). However the number of publications connected with the title of the book is so huge now, that it is practically impossible to cover all of them in a single book. Some selection of topics is inevitable. To summarize, I think that the authors did a great job and the book will find its readers. It might be interesting for researchers working in theoretical physics, astrophysics and cosmology. I do not think that it would be very helpful as a textbook for students, although it contains a lot of interesting material which can be used by students for additional reading connected with the basic university courses on gravity and cosmology. It might be also useful to students for their term paper projects and presentations.
Black holes in vector-tensor theories and their thermodynamics

NASA Astrophysics Data System (ADS)

Fan, Zhong-Ying

2018-01-01

In this paper, we study Einstein gravity either minimally or non-minimally coupled to a vector field which breaks the gauge symmetry explicitly in general dimensions. We first consider a minimal theory which is simply the Einstein-Proca theory extended with a quartic self-interaction term for the vector field. We obtain its general static maximally symmetric black hole solution and study the thermodynamics using Wald formalism. The aspects of the solution are much like a Reissner-Nordstrøm black hole in spite of that a global charge cannot be defined for the vector. For non-minimal theories, we obtain a lot of exact black hole solutions, depending on the parameters of the theories. In particular, many of the solutions are general static and have maximal symmetry. However, there are some subtleties and ambiguities in the derivation of the first laws because the existence of an algebraic degree of freedom of the vector in general invalids the Wald entropy formula. The thermodynamics of these solutions deserves further studies.
Planckian charged black holes in ultraviolet self-complete quantum gravity

NASA Astrophysics Data System (ADS)

Nicolini, Piero

2018-03-01

We present an analysis of the role of the charge within the self-complete quantum gravity paradigm. By studying the classicalization of generic ultraviolet improved charged black hole solutions around the Planck scale, we showed that the charge introduces important differences with respect to the neutral case. First, there exists a family of black hole parameters fulfilling the particle-black hole condition. Second, there is no extremal particle-black hole solution but quasi extremal charged particle-black holes at the best. We showed that the Hawking emission disrupts the condition of particle-black hole. By analyzing the Schwinger pair production mechanism, the charge is quickly shed and the particle-black hole condition can ultimately be restored in a cooling down phase towards a zero temperature configuration, provided non-classical effects are taken into account.
A new mechanism for selective adsorption of rubber on carbon black surface caused by nano-confinement in SBR/NBR solution

NASA Astrophysics Data System (ADS)

Kawazoe, Masayuki

A novel mechanism of selective adsorption of rubber molecules onto carbon black surface in a binary immiscible rubber blend solution has been proposed in this dissertation. The phenomenon leads to uneven distribution of carbon black to the specific polymer in the blend and the obtained electrically conductive composite showed drastic reduction of percolation threshold concentration (PTC). The mechanism and the feature of conductive network formation have much potential concerning both fundamental understanding and industrial application to improve conductive polymer composites. In chapter I, carbon black filled conductive polymer composites are briefly reviewed. Then, in chapter II, a mechanism of rubber molecular confinement into carbon black aggregate structure is introduced to explain the selective adsorption of a specific rubber onto carbon black surface in an immiscible rubber solution blend (styrene butadiene rubber (SBR) and acrylonitrile butadiene rubber (NBR) with toluene or chloroform). Next, in chapters III and IV, polymers with various radius of gyration (Rg) and carbon blacks with various aggregate structure are examined to verify the selective adsorption mechanism. Finally, in chapter V, the novel mechanism was applied to create unique meso-/micro-unit conductive network in carbon black dispersed SBR/NBR composites.
Geometry of deformed black holes. I. Majumdar-Papapetrou binary

NASA Astrophysics Data System (ADS)

Semerák, O.; Basovník, M.

2016-08-01

Although black holes are eminent manifestations of very strong gravity, the geometry of space-time around and even inside them can be significantly affected by additional bodies present in their surroundings. We study such an influence within static and axially symmetric (electro)vacuum space-times described by exact solutions of Einstein's equations, considering astrophysically motivated configurations (such as black holes surrounded by rings) as well as those of pure academic interest (such as specifically "tuned" systems of multiple black holes). The geometry is represented by the simplest invariants determined by the metric (the lapse function) and its gradient (gravitational acceleration), with special emphasis given to curvature (the Kretschmann and Ricci-square scalars). These quantities are analyzed and their level surfaces plotted both above and below the black-hole horizons, in particular near the central singularities. Estimating that the black hole could be most strongly affected by the other black hole, we focus, in this first paper, on the Majumdar-Papapetrou solution for a binary black hole and compare the deformation caused by "the other" hole (and the electrostatic field) with that induced by rotational dragging in the well-known Kerr and Kerr-Newman solutions.
Euclidean black hole vortices

NASA Technical Reports Server (NTRS)

Dowker, Fay; Gregory, Ruth; Traschen, Jennie

1991-01-01

We argue the existence of solutions of the Euclidean Einstein equations that correspond to a vortex sitting at the horizon of a black hole. We find the asymptotic behaviors, at the horizon and at infinity, of vortex solutions for the gauge and scalar fields in an abelian Higgs model on a Euclidean Schwarzschild background and interpolate between them by integrating the equations numerically. Calculating the backreaction shows that the effect of the vortex is to cut a slice out of the Schwarzschild geometry. Consequences of these solutions for black hole thermodynamics are discussed.
Problem of gas accretion on a gravitational center

NASA Technical Reports Server (NTRS)

Ladygin, V. A.

1980-01-01

A method of the approximated solution of the problem of accretion on a rapidly moving gravitational center is developed. This solution is obtained in the vicinity of the axis of symmetry in the region of the potential flow. The solution of the problem of stationary gas accretion on a moving gravitational center simulates the movement of a substance in interstellar space in the vicinity of a black hole. A detailed picture of gas accretion on a black hole is of interest in connection with the problem of observation of black holes.
Energy-dependent topological anti-de Sitter black holes in Gauss-Bonnet Born-Infeld gravity

NASA Astrophysics Data System (ADS)

Hendi, S. H.; Behnamifard, H.; Bahrami-Asl, B.

2018-03-01

Employing higher-curvature corrections to Einstein-Maxwell gravity has garnered a great deal of attention motivated by the high-energy regime in the quantum nature of black hole physics. In addition, one may employ gravity's rainbow to encode quantum gravity effects into black hole solutions. In this paper, we regard an energy-dependent static spacetime with various topologies and study its black hole solutions in the context of Gauss-Bonnet Born-Infeld (GB-BI) gravity. We study the thermodynamic properties and examine the first law of thermodynamics. Using a suitable local transformation, we endow the Ricci-flat black hole solutions with a global rotation and study the effects of rotation on thermodynamic quantities. We also investigate thermal stability in a canonical ensemble by calculating the heat capacity. We obtain the effects of various parameters on the horizon radius of stable black holes. Finally, we discuss a second-order phase transition in the extended phase space thermodynamics and investigate the critical behavior.
Quadratic curvature terms and deformed Schwarzschild-de Sitter black hole analogues in the laboratory

NASA Astrophysics Data System (ADS)

da Rocha, R.; Sobreiro, R. F.; Tomaz, A. A.

2017-12-01

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 Schwarzschild-de 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.

Binary black hole in a double magnetic monopole field

NASA Astrophysics Data System (ADS)

Rodriguez, Maria J.

2018-01-01

Ambient magnetic fields are thought to play a critical role in black hole jet formation. Furthermore, dual electromagnetic signals could be produced during the inspiral and merger of binary black hole systems. In this paper, we derive the exact solution for the electromagnetic field occurring when a static, axisymmetric binary black hole system is placed in the field of two magnetic or electric monopoles. As a by-product of this derivation, we also find the exact solution of the binary black hole configuration in a magnetic or electric dipole field. The presence of conical singularities in the static black hole binaries represent the gravitational attraction between the black holes that also drag the external two monopole field. We show that these off-balance configurations generate no energy outflows.
String inspired brane world cosmology.

PubMed

Germani, Cristiano; Sopuerta, Carlos F

2002-06-10

We consider brane world scenarios including the leading correction to the Einstein-Hilbert action suggested by superstring theory, the Gauss-Bonnet term. We obtain and study the complete set of equations governing the cosmological dynamics. We find they have the same form as those in Randall-Sundrum scenarios but with time-varying four-dimensional gravitational and cosmological constants. By studying the bulk geometry we show that this variation is produced by bulk curvature terms parametrized by the mass of a black hole. Finally, we show there is a coupling between these curvature terms and matter that can be relevant for early universe cosmology.
What Exactly is the Information Paradox?

NASA Astrophysics Data System (ADS)

Mathur, S. D.

The black hole information paradox tells us something important about the way quantum mechanics and gravity fit together. In these lectures I try to give a pedagogical review of the essential physics leading to the paradox, using mostly pictures. Hawking's argument is recast as a "theorem": if quantum gravity effects are confined to within a given length scale and the vacuum is assumed to be unique, then there will be information loss. We conclude with a brief summary of how quantum effects in string theory violate the first condition and make the interior of the hole a "fuzzball".
The evolution of structure in the universe from axions

NASA Technical Reports Server (NTRS)

Stecker, F. W.; Shafi, Q.

1982-01-01

A scenario where axions provide the dark matter in the universe is considered. Fluctuations in the axion field density produced by domain walls and strings cause the appearance of axion clumps of masses of order 10 to the 6th power solar mass which most likely collapse to black holes by or at the time that the universe becomes axion dominated at T is approximately 10 eV. These objects form the building blocks for a clustering hierarchy theory of galaxy and supercluster formation on scales up to approximately 10 Mpc and approximately 10 to the 15th power solar mass.
The Exploration of Hot Nuclear Matter

NASA Astrophysics Data System (ADS)

Jacak, Barbara V.; Müller, Berndt

2012-07-01

When nuclear matter is heated beyond 2 trillion degrees, it becomes a strongly coupled plasma of quarks and gluons. Experiments using highly energetic collisions between heavy nuclei have revealed that this new state of matter is a nearly ideal, highly opaque liquid. A description based on string theory and black holes in five dimensions has made the quark-gluon plasma an archetypical strongly coupled quantum system. Open questions about the structure and theory of the quark-gluon plasma are under active investigation. Many of the insights are also relevant to ultracold fermionic atoms and strongly correlated condensed matter.
Almost Classical Creation of a Universe

NASA Astrophysics Data System (ADS)

Guendelman, E. I.; Portnoy, J.

We study the problem of a 1+1 cord with a dynamical massless scalar field living in it, which separates a false vacuum and a conical region in a 2+1 space. A stable ``particle-like'' configuration can be found. Also, oscillating solutions exist which can tunnel to an expanding type solution. The most outstanding feature for these oscillating solution is that we do not need a singularity to create an infinite universe from them, and that an arbitrarily small tunneling is needed to achieve this. Possible consequences for similar processes, involving cosmic strings in 3+1 dimensions are discussed.
Bianchi type string cosmological models in f(R,T) gravity

NASA Astrophysics Data System (ADS)

Sahoo, P. K.; Mishra, B.; Sahoo, Parbati; Pacif, S. K. J.

2016-09-01

In this work we have studied Bianchi-III and - VI 0 cosmological models with string fluid source in f( R, T) gravity (T. Harko et al., Phys. Rev. D 84, 024020 (2011)), where R is the Ricci scalar and T the trace of the stress energy-momentum tensor in the context of late time accelerating expansion of the universe as suggested by the present observations. The exact solutions of the field equations are obtained by using a time-varying deceleration parameter. The universe is anisotropic and free from initial singularity. Our model initially shows acceleration for a certain period of time and then decelerates consequently. Several dynamical and physical behaviors of the model are also discussed in detail.
Axions, inflation and the anthropic principle

NASA Astrophysics Data System (ADS)

Mack, Katherine J.

2011-07-01

The QCD axion is the leading solution to the strong-CP problem, a dark matter candidate, and a possible result of string theory compactifications. However, for axions produced before inflation, symmetry-breaking scales of fagtrsim1012 GeV (which are favored in string-theoretic axion models) are ruled out by cosmological constraints unless both the axion misalignment angle θ0 and the inflationary Hubble scale HI are extremely fine-tuned. We show that attempting to accommodate a high-fa axion in inflationary cosmology leads to a fine-tuning problem that is worse than the strong-CP problem the axion was originally invented to solve. We also show that this problem remains unresolved by anthropic selection arguments commonly applied to the high-fa axion scenario.
Pre-inflationary clues from String Theory?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kitazawa, N.; Sagnotti, A., E-mail: kitazawa@phys.se.tmu.ac.jp, E-mail: sagnotti@sns.it

2014-04-01

''Brane supersymmetry breaking'' occurs in String Theory when the only available combinations of D-branes and orientifolds are not mutually BPS and yet do not introduce tree-level tachyon instabilities. It is characterized by the emergence of a steep exponential potential, and thus by the absence of maximally symmetric vacua. The corresponding low-energy supergravity admits intriguing spatially-flat cosmological solutions where a scalar field is forced to climb up toward the steep potential after an initial singularity, and additional milder terms can inject an inflationary phase during the ensuing descent. We show that, in the resulting power spectra of scalar perturbations, an infraredmore » suppression is typically followed by a pre-inflationary peak that reflects the end of the climbing phase and can lie well apart from the approximately scale invariant profile. A first look at WMAP9 raw data shows that, while the χ{sup 2} fits for the low-ℓ CMB angular power spectrum are clearly compatible with an almost scale invariant behavior, they display nonetheless an eye-catching preference for this type of setting within a perturbative string regime.« less
Families of FPGA-Based Accelerators for Approximate String Matching1

PubMed Central

Van Court, Tom; Herbordt, Martin C.

2011-01-01

Dynamic programming for approximate string matching is a large family of different algorithms, which vary significantly in purpose, complexity, and hardware utilization. Many implementations have reported impressive speed-ups, but have typically been point solutions – highly specialized and addressing only one or a few of the many possible options. The problem to be solved is creating a hardware description that implements a broad range of behavioral options without losing efficiency due to feature bloat. We report a set of three component types that address different parts of the approximate string matching problem. This allows each application to choose the feature set required, then make maximum use of the FPGA fabric according to that application’s specific resource requirements. Multiple, interchangeable implementations are available for each component type. We show that these methods allow the efficient generation of a large, if not complete, family of accelerators for this application. This flexibility was obtained while retaining high performance: We have evaluated a sample against serial reference codes and found speed-ups of from 150× to 400× over a high-end PC. PMID:21603598
Worldsheet instantons and the amplitude for string pair production in an external field as a WKB exact functional integral

NASA Astrophysics Data System (ADS)

Gordon, James; Semenoff, Gordon W.

2018-05-01

We revisit the problem of charged string pair creation in a constant external electric field. The string states are massive and creation of pairs from the vacuum is a tunnelling process, analogous to the Schwinger process where charged particle-anti-particle pairs are created by an electric field. We find the instantons in the worldsheet sigma model which are responsible for the tunnelling events. We evaluate the sigma model partition function in the multi-instanton sector in the WKB approximation which keeps the classical action and integrates the quadratic fluctuations about the solution. We find that the summation of the result over all multi-instanton sectors reproduces the known amplitude. This suggests that corrections to the WKB limit must cancel. To show that they indeed cancel, we identify a fermionic symmetry of the sigma model which occurs in the instanton sectors and which is associated with collective coordinates. We demonstrate that the action is symmetric and that the interaction action is an exact form. These conditions are sufficient for localization of the worldsheet functional integral onto its WKB limit.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Zheng; Tian, Chushun; Jiang, Hong-Chen

Charge order appears to be an ubiquitous phenomenon in doped Mott insulators, which is currently under intense experimental and theoretical investigations particularly in the high T c cuprates. This phenomenon is conventionally understood in terms of Hartree-Fock-type mean-field theory. Here we demonstrate a mechanism for charge modulation which is rooted in the many-particle quantum physics arising in the strong coupling limit. Specifically, we consider the problem of a single hole in a bipartite t - J ladder. As a remnant of the fermion signs, the hopping hole picks up subtle phases pending the fluctuating spins, the so-called phase-string effect. Wemore » demonstrate the presence of charge modulations in the density matrix renormalization group solutions which disappear when the phase strings are switched off. This form of charge modulation can be understood analytically in a path-integral language with a mean-field-like approximation adopted, showing that the phase strings give rise to constructive interferences leading to self-localization. When the latter occurs, left- and right-moving propagating modes emerge inside the localization volume and their interference is responsible for the real space charge modulation.« less
The geometry of singularities and the black hole information paradox

NASA Astrophysics Data System (ADS)

Stoica, O. C.

2015-07-01

The information loss occurs in an evaporating black hole only if the time evolution ends at the singularity. But as we shall see, the black hole solutions admit analytical extensions beyond the singularities, to globally hyperbolic solutions. The method used is similar to that for the apparent singularity at the event horizon, but at the singularity, the resulting metric is degenerate. When the metric is degenerate, the covariant derivative, the curvature, and the Einstein equation become singular. However, recent advances in the geometry of spacetimes with singular metric show that there are ways to extend analytically the Einstein equation and other field equations beyond such singularities. This means that the information can get out of the singularity. In the case of charged black holes, the obtained solutions have nonsingular electromagnetic field. As a bonus, if particles are such black holes, spacetime undergoes dimensional reduction effects like those required by some approaches to perturbative Quantum Gravity.
Lifshitz black branes and DC transport coefficients in massive Einstein-Maxwell-dilaton gravity

NASA Astrophysics Data System (ADS)

Kuang, Xiao-Mei; Papantonopoulos, Eleftherios; Wu, Jian-Pin; Zhou, Zhenhua

2018-03-01

We construct analytical Lifshitz massive black brane solutions in massive Einstein-Maxwell-dilaton gravity theory. We also study the thermodynamics of these black brane solutions and obtain the thermodynamical stability conditions. On the dual nonrelativistic boundary field theory with Lifshitz symmetry, we analytically compute the DC transport coefficients, including the electric conductivity, thermoelectric conductivity, and thermal conductivity. The novel property of our model is that the massive term supports the Lifshitz black brane solutions with z ≠1 in such a way that the DC transport coefficients in the dual field theory are finite. We also find that the Wiedemann-Franz law in this dual boundary field theory is violated, which indicates that it may involve strong interactions.
G-structures and domain walls in heterotic theories

NASA Astrophysics Data System (ADS)

Lukas, Andre; Matti, Cyril

2011-01-01

We consider heterotic string solutions based on a warped product of a four-dimensional domain wall and a six-dimensional internal manifold, preserving two supercharges. The constraints on the internal manifolds with SU(3) structure are derived. They are found to be generalized half-flat manifolds with a particular pattern of torsion classes and they include half-flat manifolds and Strominger's complex non-Kahler manifolds as special cases. We also verify that previous heterotic compactifications on half-flat mirror manifolds are based on this class of solutions.
STEADY GENERAL RELATIVISTIC MAGNETOHYDRODYNAMIC INFLOW/OUTFLOW SOLUTION ALONG LARGE-SCALE MAGNETIC FIELDS THAT THREAD A ROTATING BLACK HOLE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pu, Hung-Yi; Nakamura, Masanori; Hirotani, Kouichi

2015-03-01

General relativistic magnetohydrodynamic (GRMHD) flows along magnetic fields threading a black hole can be divided into inflow and outflow parts, according to the result of the competition between the black hole gravity and magneto-centrifugal forces along the field line. Here we present the first self-consistent, semi-analytical solution for a cold, Poynting flux–dominated (PFD) GRMHD flow, which passes all four critical (inner and outer, Alfvén, and fast magnetosonic) points along a parabolic streamline. By assuming that the dominating (electromagnetic) component of the energy flux per flux tube is conserved at the surface where the inflow and outflow are separated, the outflowmore » part of the solution can be constrained by the inflow part. The semi-analytical method can provide fiducial and complementary solutions for GRMHD simulations around the rotating black hole, given that the black hole spin, global streamline, and magnetizaion (i.e., a mass loading at the inflow/outflow separation) are prescribed. For reference, we demonstrate a self-consistent result with the work by McKinney in a quantitative level.« less
Static Einstein-Maxwell Black Holes with No Spatial Isometries in AdS Space.

PubMed

Herdeiro, Carlos A R; Radu, Eugen

2016-11-25

We explicitly construct static black hole solutions to the fully nonlinear, D=4, Einstein-Maxwell-anti-de Sitter (AdS) equations that have no continuous spatial symmetries. These black holes have a smooth, topologically spherical horizon (section), but without isometries, and approach, asymptotically, global AdS spacetime. They are interpreted as bound states of a horizon with the Einstein-Maxwell-AdS solitons recently discovered, for appropriate boundary data. In sharp contrast to the uniqueness results for a Minkowski electrovacuum, the existence of these black holes shows that single, equilibrium, black hole solutions in an AdS electrovacuum admit an arbitrary multipole structure.
Two kissing bolts

NASA Astrophysics Data System (ADS)

Bossard, Guillaume; Katmadas, Stefanos; Turton, David

2018-02-01

The study of non-supersymmetric black hole microstates offers the potential to resolve the black hole information paradox. A system of equations was recently obtained that enables the systematic construction of non-supersymmetric smooth horizonless supergravity solutions, that are candidates to describe microstates of non-extremal black holes. Within this system we construct a family of six-dimensional supergravity solutions that feature two topologically-nontrivial three-cycles known as bolts. The two bolts touch at a single point and are supported by fluxes. We find that the fluxes on the two three-cycles can be either aligned or anti-aligned, and exhibit examples of both. We present several examples of smooth solutions, including near-extremal solutions that have an approximate AdS3 region, and far-from extremal solutions that have arbitrarily small charge compared to their mass.
Warped AdS3 black holes

NASA Astrophysics Data System (ADS)

Song, Wei; Anninos, Dionysios; Li, Wei; Padi, Megha; Strominger, Andrew

2009-03-01

Three dimensional topologically massive gravity (TMG) with a negative cosmological constant -ell-2 and positive Newton constant G admits an AdS3 vacuum solution for any value of the graviton mass μ. These are all known to be perturbatively unstable except at the recently explored chiral point μell = 1. However we show herein that for every value of μell ≠ 3 there are two other (potentially stable) vacuum solutions given by SL(2,Bbb R) × U(1)-invariant warped AdS3 geometries, with a timelike or spacelike U(1) isometry. Critical behavior occurs at μell = 3, where the warping transitions from a stretching to a squashing, and there are a pair of warped solutions with a null U(1) isometry. For μell > 3, there are known warped black hole solutions which are asymptotic to warped AdS3. We show that these black holes are discrete quotients of warped AdS3 just as BTZ black holes are discrete quotients of ordinary AdS3. Moreover new solutions of this type, relevant to any theory with warped AdS3 solutions, are exhibited. Finally we note that the black hole thermodynamics is consistent with the hypothesis that, for μell > 3, the warped AdS3 ground state of TMG is holographically dual to a 2D boundary CFT with central charges c_R-formula and c_L-formula.
Warped AdS3 black holes

NASA Astrophysics Data System (ADS)

Anninos, Dionysios; Li, Wei; Padi, Megha; Song, Wei; Strominger, Andrew

2009-03-01

Three dimensional topologically massive gravity (TMG) with a negative cosmological constant -l-2 and positive Newton constant G admits an AdS3 vacuum solution for any value of the graviton mass μ. These are all known to be perturbatively unstable except at the recently explored chiral point μl = 1. However we show herein that for every value of μl ≠ 3 there are two other (potentially stable) vacuum solutions given by SL(2,Bbb R) × U(1)-invariant warped AdS3 geometries, with a timelike or spacelike U(1) isometry. Critical behavior occurs at μl = 3, where the warping transitions from a stretching to a squashing, and there are a pair of warped solutions with a null U(1) isometry. For μl > 3, there are known warped black hole solutions which are asymptotic to warped AdS3. We show that these black holes are discrete quotients of warped AdS3 just as BTZ black holes are discrete quotients of ordinary AdS3. Moreover new solutions of this type, relevant to any theory with warped AdS3 solutions, are exhibited. Finally we note that the black hole thermodynamics is consistent with the hypothesis that, for μl > 3, the warped AdS3 ground state of TMG is holographically dual to a 2D boundary CFT with central charges c_R-formula and c_L-formula.

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