157 research outputs found
Phases of Braneworlds, Spinning D3-branes and Strongly-Coupled Gauge Theories
A spinning nonextremal D3-brane undergoes a phase transition to a naked
singularity which, from the braneworld point of view, corresponds to the
apparent graviton speed passing from subluminal to superluminal. We investigate
this phase transition from the dual perspectives of braneworld scenarios and
holography. We discuss the relevance of the thermodynamic stability domains of
a spinning D3-brane to the physics of braneworld scenarios. We also describe
various gravitational Lorentz violations which arise from static D3-branes.Comment: 18 pages, 6 figures, LaTeX, additional comment and reference
No-Drag String Configurations for Steadily Moving Quark-Antiquark Pairs in a Thermal Bath
We investigate the behavior of stationary string configurations on a
five-dimensional AdS black hole background which correspond to quark-antiquark
pairs steadily moving in an N=4 super Yang-Mills thermal bath. There are many
branches of solutions, depending on the quark velocity and separation as well
as on whether Euclidean or Lorentzian configurations are examined.Comment: references added; statements corrected; eliminated computation of jet
quenching parameter from Wilson loop of [Liu, Rajagopal, Wiedemann,
hep-th/0605178] using Euclidean string configurations since those authors
advocate [hep-th/0607062, footnote 14] the use of spacelike Lorentzian string
configurations instea
Supergravity brane worlds and tachyon potentials
We study massless and massive graviton modes that bind on thick branes which
are supergravity domain walls solutions in -dimensional supergravity
theories where only the supergravity multiplet and the scalar supermultiplet
are turned on. The domain walls are bulk solutions provided by tachyon
potentials. Such domain walls are regarded as BPS branes of one lower dimension
that are formed due to tachyon potentials on a non-BPS D-brane.Comment: RevTex4, 6 pages; version to appear in Phys. Rev.
Bubbling AdS Black Holes
We explore the non-BPS analog of `AdS bubbles', which are regular spherically
symmetric 1/2 BPS geometries in type IIB supergravity. They have regular
horizons and can be thought of as bubbling generalizations of non-extremal AdS
black hole solutions in five-dimensional gauged supergravity. Due to the
appearance of the Heun equation even at the linearized level, various
approximation and numerical methods are needed in order to extract information
about this system. We study how the vacuum expectation value and mass of a
particular dimension two chiral primary operator depend on the temperature and
chemical potential of the thermal Yang-Mills theory. In addition, the mass of
the bubbling AdS black holes is computed. As is shown numerically, there are
also non-BPS solitonic bubbles which are completely regular and arise from
continuous deformations of BPS AdS bubbles.Comment: 37 pages, 2 figure
Resolving the M2-brane
We construct deformed, T^2 wrapped, rotating M2-branes on a resolved cone
over Q^{1,1,1} and Q^{1,1,1}/Z_2, as well as on a product of two Eguchi-Hanson
instantons. All worldvolume directions of these supersymmetric and regular
solutions are fibred over the transverse space. These constitute gravity duals
of D=3, N=2 gauge theories. In particular, the deformed M2-brane on a resolved
cone over Q^{1,1,1} and the S^1 wrapped M2-brane on a resolved cone over
Q^{1,1,1}/Z_2 provide explicit realizations of holographic renormalization
group flows in M-theory for which both conformal and Lorentz symmetries are
broken in the IR region and restored in the UV limit. These solutions can be
dualized to supersymmetric type IIB pp-waves, which are rendered non-singular
either by additional flux or a twisted time-like direction.Comment: Latex, 23 pages, references adde
From Marginal Deformations to Confinement
We consider type IIB supergravity backgrounds which describe marginal
deformations of the Coulomb branch of N=4 super Yang-Mills theory with SO(4) x
SO(2) global symmetry. Wilson loop calculations indicate that certain
deformations enhance the Coulombic attraction between quarks and anti-quarks at
the UV conformal fixed-point. In the IR region, these deformations can induce a
transition to linear confinement.Comment: 14 pages, 4 figures, minor corrections, comments and references adde
Systematics of M-theory spinorial geometry
We reduce the classification of all supersymmetric backgrounds in eleven
dimensions to the evaluation of the supercovariant derivative and of an
integrability condition, which contains the field equations, on six types of
spinors. We determine the expression of the supercovariant derivative on all
six types of spinors and give in each case the field equations that do not
arise as the integrability conditions of Killing spinor equations. The Killing
spinor equations of a background become a linear system for the fluxes,
geometry and spacetime derivatives of the functions that determine the spinors.
The solution of the linear system expresses the fluxes in terms of the geometry
and specifies the restrictions on the geometry of spacetime for all
supersymmetric backgrounds. We also show that the minimum number of field
equations that is needed for a supersymmetric configuration to be a solution of
eleven-dimensional supergravity can be found by solving a linear system. The
linear systems of the Killing spinor equations and their integrability
conditions are given in both a timelike and a null spinor basis. We illustrate
the construction with examples.Comment: 46 pages. v2: systematics of a null spinor basis is included in
section
Deformations of flows from type IIB supergravity
We consider supersymmetric SL(3,R) deformations of various type IIB
supergravity backgrounds which exhibit flows away from an asymptotically
locally AdS_5 x S^5 fixed point. This includes the gravity dual of the Coulomb
branch of N=1 super Yang Mills theory, for which the deformed superpotential is
known. We also consider the gravity duals of field theories which live on
various curved backgrounds, such as Minkowski_2 x H^2, AdS_3 x S^1 and R x S^3.
Some of the deformed theories flow from a four-dimensional N=1 superconformal
UV fixed point to a two-dimensional (2,2) superconformal IR fixed point. We
study nonsupersymmetric generalizations of the deformations of the above
Coulomb branch flows.Comment: 29 pages, additional references and comment
From de Sitter to de Sitter
We obtain D=6, N=(1,1) de Sitter supergravity from a hyperbolic reduction of
the massive type IIA* theory. We construct a smooth cosmological solution in
which the co-moving time runs from an infinite past, which is dS_4\times S^2,
to an infinite future, which is a dS_6-type spacetime with the boundary
R^3\times S^2. This provides an effective four-dimensional cosmological model
with two compact extra dimensions forming an S^2. Interestingly enough,
although the solution is time-dependent, it arises from a first-order system
via a superpotential construction. We lift the solutions back to D=10, and in
particular obtain two smooth embeddings of dS_4 in massive type IIA*, with the
internal space being either H^4\times S^2 or an H^4 bundle over S^2. We also
obtain the analogous D=5 and D=4 solutions. We show that there exist
cosmological solutions that describe an expanding universe with the expansion
rate significantly larger in the past than in the future.Comment: Latex three times, 22 pages, references adde
New supersymmetric solutions of N=2, D=5 gauged supergravity with hyperscalars
We construct new supersymmetric solutions, including AdS bubbles, in an N=2
truncation of five-dimensional N=8 gauged supergravity. This particular
truncation is given by N=2 gauged supergravity coupled to two vector multiples
and three incomplete hypermultiplets, and was originally investigated in the
context of obtaining regular AdS bubble geometries with multiple active
R-charges. We focus on cohomogeneity-one solutions corresponding to objects
with two equal angular momenta and up to three independent R-charges.
Curiously, we find a new set of zero and negative mass solitons asymptotic to
AdS_5/Z_k, for k \ge 3, which are everywhere regular without closed timelike
curves.Comment: Latex 3 times, 42 page
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