118 research outputs found
Wilson Loops, D-Branes, and Reparametrization Path-Integrals
We study path-integrals over reparametrizations of the world-sheet boundary.
Such integrals arise when string propagates between fixed space-time contours.
In gauge/string duality they are needed to describe gauge theory Wilson loops.
We show that (1) in AdS/CFT, the integral is well defined and gives a finite
1-loop correction to the Wilson loop; (2) in critical string theory, the
integral is UV divergent, and fixed contour amplitudes are off shell. In the
second case, we show that the divergences can be removed by renormalizing the
contour. We calculate the 2-loop contour beta-function and explain how it is
related to the D0-brane effective action. We also apply this method to compute
the first alpha' correction to the effective action of higher dimensional
branes.Comment: 36p
Baryon Spectra and AdS/CFT Correspondence
We provide a detailed map between wrapped D3-branes in Anti-de Sitter (AdS)
backgrounds and dibaryon operators in the corresponding conformal field theory
(CFT). The effective five dimensional action governing the dynamics of AdS
space contains a gauge field that mediates interactions between
objects possessing R-charge. We show that the charge of these wrapped
D3-branes as measured by the gauge field matches the R-charge of the dibaryons
expected from field theory considerations. We are able, through a careful probe
brane calculation in an background, to understand the
exact relation between the mass of the wrapped D3-brane and the dimension of
the corresponding dibaryon. We also make some steps toward matching the
counting of dibaryon operators in the CFT with the ground states of a
supersymmetric quantum mechanical system whose target space is the moduli space
of D-branes. Finally, we discuss BPS excitations of the D3-brane and compare
them with higher dimension operators in the CFT.Comment: 24 pages, typos correcte
Kappa-symmetric deformations of M5-brane dynamics
We calculate the first supersymmetric and kappa-symmetric derivative
deformation of the M5-brane worldvolume theory in a flat eleven-dimensional
background. By applying cohomological techniques we obtain a deformation of the
standard constraint of the superembedding formalism. The first possible
deformation of the constraint and hence the equations of motion arises at cubic
order in fields and fourth order in a fundamental length scale . The
deformation is unique up to this order. In particular this rules out any
induced Einstein-Hilbert terms on the worldvolume. We explicitly calculate
corrections to the equations of motion for the tensor gauge supermultiplet.Comment: 17 pages. Additional comments in section
Solitons and giants in matrix models
We present a method for solving BPS equations obtained in the
collective-field approach to matrix models. The method enables us to find BPS
solutions and quantum excitations around these solutions in the one-matrix
model, and in general for the Calogero model. These semiclassical solutions
correspond to giant gravitons described by matrix models obtained in the
framework of AdS/CFT correspondence. The two-field model, associated with two
types of giant gravitons, is investigated. In this duality-based matrix model
we find the finite form of the -soliton solution. The singular limit of this
solution is examined and a realization of open-closed string duality is
proposed.Comment: 17 pages, JHEP cls; v2: final version to appear in JHEP, 2 references
added, physical motivation and interpretation clarifie
Quantum geometry and gravitational entropy
Most quantum states have wavefunctions that are widely spread over the
accessible Hilbert space and hence do not have a good description in terms of a
single classical geometry. In order to understand when geometric descriptions
are possible, we exploit the AdS/CFT correspondence in the half-BPS sector of
asymptotically AdS_5 x S^5 universes. In this sector we devise a
"coarse-grained metric operator" whose eigenstates are well described by a
single spacetime topology and geometry. We show that such half-BPS universes
have a non-vanishing entropy if and only if the metric is singular, and that
the entropy arises from coarse-graining the geometry. Finally, we use our
entropy formula to find the most entropic spacetimes with fixed asymptotic
moments beyond the global charges.Comment: 29 pages, 2 figures; references adde
Strings in flat space and pp waves from Super Yang Mills
We explain how the string spectrum in flat space and pp-waves arises from the
large limit, at fixed , of U(N) super Yang Mills.
We reproduce the spectrum by summing a subset of the planar Feynman diagrams.
We give a heuristic argument for why we can neglect other diagrams. We also
discuss some other aspects of pp-waves and we present a matrix model associated
to the DLCQ description of the maximally supersymmetric eleven dimensional
pp-waves.Comment: 36 pages, 5 figures. v3: minor typos corrected, references adde
The Library of Babel: On the origin of gravitational thermodynamics
We show that heavy pure states of gravity can appear to be mixed states to
almost all probes. For AdS_5 Schwarzschild black holes, our arguments are made
using the field theory dual to string theory in such spacetimes. Our results
follow from applying information theoretic notions to field theory operators
capable of describing very heavy states in gravity. For half-BPS states of the
theory which are incipient black holes, our account is exact: typical
microstates are described in gravity by a spacetime ``foam'', the precise
details of which are almost invisible to almost all probes. We show that
universal low-energy effective description of a foam of given global charges is
via certain singular spacetime geometries. When one of the specified charges is
the number of D-branes, the effective singular geometry is the half-BPS
``superstar''. We propose this as the general mechanism by which the effective
thermodynamic character of gravity emerges.Comment: LaTeX, 6 eps figures, uses young.sty and wick.sty; Version 2: typos
corrected, minor rewordings and clarifications, references adde
An orientifold of adS_5xT^11 with D7-branes, the associated alpha'^2- corrections and their role in the dual N=1 Sp(2N+2M)xSp(2N) gauge theory
We study the N=1 Sp(2N+2M)xSp(2N) gauge theory on a stack of N physical and M
fractional D3-branes in the background of an orientifolded conifold. The
gravity dual is a type IIB orientifold of adS_5xT^11 (with certain background
fluxes turned on) containing an O7-plane and 8 D7-branes. In the conformal case
(M=0), we argue that the alpha'^2-corrections localized on the 8 D7-branes and
the O7-plane should give vanishing contributions to the supergravity equations
of motion for the bulk fields. In the cascading case (M not equal to 0), we
argue that the alpha'^2-terms give rise to corrections which in the dual
Sp(2N+2M)xSp(2N) gauge theory can be interpreted as corrections to the
anomalous dimensions of the matter fields.Comment: 28 pages, 3 figures, LaTeX; v2: references added; v3: minor change
On the Holographic RG-flow and the Low-energy, Strong Coupling, Large N Limit
From the AdS/CFT correspondence, we learn that the classical evolution of
supergravity in the bulk can be reduced to a RG-flow equation for the dual
low-energy, strongly coupled and large N gauge theory on the boundary. This
result has been used to obtain interesting relations between the various terms
in the gravitational part of the boundary effective action, in particular the
term that affect the cosmological constant. It is found that once the
cosmological constant is cancelled in the UV theory, the RG-flow symmetry of
the boundary effective action automatically implies the existence of zero
cosmological constant solutions that extend all the way into the IR. Given the
standard (and well founded) contradiction between the RG-flow idea and the
observational evidence of a small cosmological constant, this is considered to
be an important progress, albeit incomplete, towards the final solution.
Motivated by this success, it would be interesting to see whether this
RG-stability extends outside the scope of strong 't Hooft coupling and large N
regime that are implicitly assumed in the de Boer-Verlinde-Verlinde
Hamilton-Jacobi formulation of the holographic RG-flow equations of the
boundary theory. In this paper, we address this question. Taking into account
the leading order corrections in the 1/N and parameters, we
derive new bulk/boundary relations, from which one can read all the local terms
in the boundary effective action. Next, we use the resulting constraints, to
examine whether the RG-stability of the cosmological constant extends to the
new coupling regime. It would be also interesting to use these constraints to
study the Randall-Sundrum scenario in this case.Comment: 27 pages, LateX, no figures, minor changes, typos corrected and added
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