12 research outputs found
Rotational Graviton Modes in the Brane World
For a brane world embedded in various ten or eleven-dimensional geometries,
we calculate the corrections to the four-dimensional gravitational potential
due to graviton modes propagating in the extra dimensions, including those
rotating around compact directions. Due to additional "warp" factors, these
rotation modes may have as significant an effect as the s-wave modes which
propagate in the large or infinite extra dimension.Comment: 9 pages, LaTe
Gravitational Lorentz Violations from M-Theory
In an attempt to bridge the gap between M-theory and braneworld
phenomenology, we present various gravitational Lorentz-violating braneworlds
which arise from p-brane systems. Lorentz invariance is still preserved locally
on the braneworld. For certain p-brane intersections, the massless graviton is
quasi-localized. This also results from an M5-brane in a C-field. In the case
of a p-brane perturbed from extremality, the quasi-localized graviton is
massive. For a braneworld arising from global AdS_5, gravitons travel faster
when further in the bulk, thereby apparently traversing distances faster than
light.Comment: 13 pages, 1 figure, LaTeX, references added, minor corrections and
addition
Four-dimensional Einstein Yang–Mills de Sitter gravity from eleven dimensions
We obtain D=4 de Sitter gravity coupled to SU(2) Yang-Mills gauge fields from
an explicit and consistent truncation of D=11 supergravity via Kaluza-Klein
dimensional reduction on a non-compact space. The ``internal'' space is a
smooth hyperbolic 7-space (H^7) written as a foliation of two 3-spheres, on
which the SU(2) Yang-Mills fields reside. The positive cosmological constant is
completely fixed by the SU(2) gauge coupling constant. The explicit reduction
ansatz enables us to lift any of the D=4 solutions to D=11. In particular, we
obtain dS_2 in M-theory, where the nine-dimensional transverse space is an H^7
bundle over S^2. We also obtain a new smooth embedding of dS_3 in D=6
supergravity.Comment: Latex, 10 pages, references adde
A Supersymmetric and Smooth Compactification of M-theory to AdS(5)
We obtain smooth M-theory solutions whose geometry is a warped product of
AdS_5 and a compact internal space that can be viewed as an S^4 bundle over
S^2. The bundle can be trivial or twisted, depending on the even or odd values
of the two diagonal monopole charges. The solution preserves N=2 supersymmetry
and is dual to an N=1 D=4 superconformal field theory, providing a concrete
framework to study the AdS_5/CFT_4 correspondence in M-theory. We construct
analogous embeddings of AdS_4, AdS_3 and AdS_2 in massive type IIA, type IIB
and M-theory, respectively. The internal spaces have generalized holonomy and
can be viewed as S^n bundles over S^2 for n=4, 5 and 7. Surprisingly, the
dimensions of spaces with generalized holonomy includes D=9. We also obtain a
large class of solutions of AdS\times H^2.Comment: Latex, 12 pages, references added, incorrect statement remove
Massive-Scalar Absorption by Extremal p-branes
We study the absorption probability of minimally-coupled massive scalars by
extremal p-branes. In particular, we find that the massive scalar wave equation
under the self-dual string background has the same form as the massless scalar
wave equation under the dyonic string background. Thus it can be cast into the
form of a modified Mathieu equation and solved exactly. Another example that we
can solve exactly is that of the D=4 two-charge black hole with equal charges,
for which we obtain the closed-form absorption probability. We also obtain the
leading-order absorption probabilities for D3-, M2- and M5-branes.Comment: Latex, 11 pages, reference adde
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
Resolution of Overlapping Branes
We obtain singularity resolutions for various overlapping brane
configurations, including those of two heterotic 5-branes, type II 5-branes or
D4-branes. In these solutions, the ``harmonic'' function H for each brane
component depends only on the associated four-dimensional relative transverse
space. The resolution is achieved by replacing these transverse spaces with
Eguchi-Hanson or Taub-NUT spaces, both of which admit a normalisable self-dual
(or anti-self-dual) harmonic 2-form. Due to the manner in which the interaction
terms for the form fields modify their Bianchi identities or equations of
motion, these normalisable harmonic 2-forms provide regular sources for the
branes. We also obtain resolved 5-branes and D4-branes wrapped on S^1, which is
fibred over the transverse Eguchi-Hanson or Taub-NUT spaces. The T-duality
invariance of the NS-NS 5-brane is retained after the resolution. The resolved
5-branes and D4-branes provide regular supergravity duals of certain
supersymmetric Yang-Mills theories in five and four dimensions.Comment: Latex, 13 pages, typo corrected, references added, resolved D4-brane
wrapped on S^1 adde
Interpolating from AdS_(D-2) X S^2 to AdS_D
We investigate a large class of supersymmetric magnetic brane solutions
supported by U(1) gauge fields in AdS gauged supergravities. We obtain
first-order equations in terms of a superpotential. In particular, we find
systems which interpolate between AdS_{D-2}\times \Omega^2 (where \Omega^2=S^2
or H^2) in the horizon and AdS_D-type geometry in the asymptotic region, for
4\le D\le 7. The boundary geometry of the AdS_D-type metric is
Minkowski_{D-3}\times \Omega^2. This provides smooth supergravity solutions for
which the boundary of the AdS spacetime compactifies spontaneously. These
solutions indicate the existence of a large class of superconformal field
theories in diverse dimensions whose renormalization group flow runs from the
UV to the IR fixed point. We show that the same set of first-order equations
also admits solutions which are asymptotically AdS_{D-2}\times \Omega^2 but
singular at small distance. This implies that the stationary AdS_{D-2}\times
\Omega^2 solutions typically lie on the inflection points of the modulus space.Comment: Latex three times, 49 pages, 9 figure
From AdS Black Holes to Supersymmetric Flux-branes
We show that AdS black hole solutions admit an analytical continuation to
become magnetic flux-branes. Although a BPS AdS black hole generally has a
naked singularity, the BPS flux-brane can be regular everywhere with an
appropriate choice of U(1)-charges. This flux-brane interpolates from AdS_{D-2}
\times H^2 at small distance to an asymptotic AdS_D-type metric with an
AdS_{D-2}\times S^1 boundary. We also obtain a smooth cosmological solution of
de Sitter Einstein-Maxwell gravity which flows from dS_2\times S^{D-2} in the
infinite past to a dS_D-type metric, with an S^{D-2}\times S^1 boundary, in the
infinite future.Comment: Plain latex, 25 pages, references adde
Spacelike strings and jet quenching from a Wilson loop
We investigate stationary string solutions with spacelike worldsheet in a
five-dimensional AdS black hole background, and find that there are many
branches of such solutions. Using a non-perturbative definition of the jet
quenching parameter proposed by Liu et. al., hep-ph/0605178, we take the
lightlike limit of these solutions to evaluate the jet quenching parameter in
an N=4 super Yang-Mills thermal bath. We show that this proposed definition
gives zero jet quenching parameter, independent of how the lightlike limit is
taken. In particular, the minimum-action solution giving the dominant
contribution to the Wilson loop has a leading behavior that is linear, rather
than quadratic, in the quark separation.Comment: 38 pages, 6 figures, statements correcte