198 research outputs found
Intersecting M-branes as Four-Dimensional Black Holes
We present two 1/8 supersymmetric intersecting p-brane solutions of
11-dimensional supergravity which upon compactification to four dimensions
reduce to extremal dyonic black holes with finite area of horizon. The first
solution is a configuration of three intersecting 5-branes with an extra
momentum flow along the common string. The second describes a system of two
2-branes and two 5-branes. Related (by compactification and T-duality) solution
of type IIB theory corresponds to a completely symmetric configuration of four
intersecting 3-branes. We suggest methods for counting the BPS degeneracy of
three intersecting 5-branes which, in the macroscopic limit, reproduce the
Bekenstein-Hawking entropy.Comment: 15 pages, harvmac; a reference added (the version to appear in
Nulcear Physics B
String Tensions and Three Dimensional Confining Gauge Theories
In the context of gauge/gravity duality, we try to understand better the
proposed duality between the fractional D2-brane supergravity solutions of
(Nucl. Phys. B 606 (2001) 18, hep-th/0101096) and a confining 2+1 dimensional
gauge theory. Based on the similarities between this fractional D2-brane
solution and D3-brane supergravity solutions with more firmly established gauge
theory duals, we conjecture that a confining q-string in the 2+1 dimensional
gauge theory is dual to a wrapped D4-brane. In particular, the D4-brane looks
like a string in the gauge theory directions but wraps a S**3 in S**4 in the
transverse geometry. For one of the supergravity solutions, we find a near
quadratic scaling law for the tension: . Based on the tension,
we conjecture that the gauge theory dual is SU(N) far in the infrared. We also
conjecture that a quadratic or near quadratic scaling is a generic feature of
confining 2+1 dimensional SU(N) gauge theories.Comment: 23 pages, 2 figure
Non-Singularity of the Exact Two-Dimensional String Black Hole
We study the global structure of the exact two-dimensional space-time which
emerges from string theory. Previous work has shown that in the semi-classical
limit, this is a black hole similar to the Schwarzschild solution. However, we
find that in the exact case, a new Euclidean region appears "between" the
singularity and black hole interior. However the boundary between the
Lorentzian and Euclidean regions is a coordinate singularity, which turns out
to be a surface of time reflection symmetry in an extended space-time. Thus
strings having fallen through the black hole horizon would eventually emerge
through another one into a new asymptotically flat region. The maximally
extended space-time consists of an infinite number of universes connected by
wormholes. There are no singularities present in this geometry. We also
calculate the mass and temperature associated with the space-time.Comment: 9 pages, latex, DAMTP R93/
Black Hole Graybody Factor and Black Hole Entropy
We have proposed the entropy formula of the black hole which is constructed
by the intersecting D1-brane and D5-brane with no momentum, whose
compactification radii are constrained by the surface gravities in
ten-dimensions. We interpret the entropy of the black hole as the statistical
entropy of the effective string living on the D5-brane. We further study the
behavior of the absorption cross-section of the black hole using our entropy
formula.Comment: 15 pages, RevTex, version to appear in PR
Moduli Instability in Warped Compactifications of the Type IIB Supergravity
We show that the conifold and deformed-conifold warped compactifications of
the ten-dimensional type IIB supergravity, including the Klebanov-Strassler
solution, are dynamically unstable in the moduli sector representing the scale
of a Calabi-Yau space, although it can be practically stable for a quite long
time in a region with a large warp factor. This instability is associated with
complete supersymmetry breaking except for a special case and produces
significant time-dependence in the structure of the four-dimensional base
spacetime as well as of the internal space.Comment: 24 pages, no figure. Typos corrected, and some arguments in section 5
are adde
Absorption of Fixed scalars and the D-brane Approach to Black Holes
We calculate the emission and absorption rates of fixed scalars by the
near-extremal five-dimensional black holes that have recently been modeled
using intersecting D-branes. We find agreement between the semi-classical and
D-brane computations. At low energies the fixed scalar absorption cross-section
is smaller than for ordinary scalars and depends on other properties of the
black hole than just the horizon area. In the D-brane description, fixed scalar
absorption is suppressed because these scalars must split into at least four,
rather than two, open strings running along the D-brane. Consequently, this
comparison provides a more sensitive test of the effective string picture of
the D-brane bound state than does the cross-section for ordinary scalars. In
particular, it allows us to read off the value of the effective string tension.
That value is precisely what is needed to reproduce the near-extremal 5-brane
entropy.Comment: 33 pages, harvmac, version to appear in Nucl. Phys.
Entropy of Near-Extremal Black p-branes
We carry out a thorough survey of entropy for a large class of -branes in
various dimensions. We find that the Bekenstein-Hawking entropy may be given a
simple world volume interpretation only for the non-dilatonic -branes, those
with the dilaton constant throughout spacetime. The entropy of extremal
non-dilatonic -branes is non-vanishing only for the solutions preserving 1/8
of the original supersymmetries. Upon toroidal compactification these reduce to
dyonic black holes in 4 and 5 dimensions. For the self-dual string in 6
dimensions, which preserves 1/4 of the original supersymmetries, the
near-extremal entropy is found to agree with a world sheet calculation, in
support of the existing literature. The remaining 3 interesting cases preserve
1/2 of the original supersymmetries. These are the self-dual 3-brane in 10
dimensions, and the 2- and 5-branes in 11 dimensions. For all of them the
scaling of the near-extremal Bekenstein-Hawking entropy with the Hawking
temperature is in agreement with a statistical description in terms of free
massless fields on the world volume.Comment: 16 pages, harvmac; improved discussion of M-theory charge
quantization (version to appear in Nucl. Phys. B
Curvature Dependence of Running Gauge Coupling and Confinement in AdS/CFT Correspondence
We construct IIB supergravity (viewed as dilatonic gravity) background with
non-trivial dilaton and with curved four-dimensional space. Such a background
may describe another vacuum of maximally supersymmetric Yang-Mills theory or
strong coupling regime of (non)-supersymmetric gauge theory with (power-like)
running gauge coupling which depends on curvature. Curvature dependent
quark-antiquark potential is calculated where the geometry type of hyperbolic
(or de Sitter universe) shows (or not) the tendency of the confinement.
Generalization of IIB supergravity background with non-constant axion is
presented. Quark-antiquark potential being again curvature-dependent has a
possibility to produce the standard area law for large separations.Comment: LaTeX file, 24 pages, presentation is improve
Multi-Trace Operators and the Generalized AdS/CFT Prescription
We show that multi-trace interactions can be consistently incorporated into
an extended AdS/CFT prescription involving the inclusion of generalized
boundary conditions and a modified Legendre transform prescription. We find new
and consistent results by considering a self-contained formulation which
relates the quantization of the bulk theory to the AdS/CFT correspondence and
the perturbation at the boundary by double-trace interactions. We show that
there exist particular double-trace perturbations for which irregular modes are
allowed to propagate as well as the regular ones. We perform a detailed
analysis of many different possible situations, for both minimally and
non-minimally coupled cases. In all situations, we make use of a new constraint
which is found by requiring consistence. In the particular non-minimally
coupled case, the natural extension of the Gibbons-Hawking surface term is
generated.Comment: 27 pages, LaTeX, v.2:minor changes, v.3:comments added, v.4:several
new results, discussions, references and a section of Conclusions added.
Previous results unchanged, v.5: minor changes. Final version to be published
in Phys.Rev.
Winding Strings and Decay of D-Branes with Flux
We study the boundary state associated with the decay of an unstable D-brane
with uniform electric field, 1>e>0 in the string units. Compactifying the
D-brane along the direction of the electric field, we find that the decay
process is dominated by production of closed strings with some winding numbers;
closed strings produced are such that the winding mode carries precisely the
fraction of the individual string energy. This supports the conjecture that
the final state at tree level is composed of winding strings with heavy
oscillations turned on. As a corollary, we argue that the closed strings
disperse into spacetime at a much slower rate than the case without electric
field.Comment: 14 pages, harvmac, minor changes, clarified gauge choice, version to
appear in JHE
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