1,480 research outputs found
Fractional D1-Branes at Finite Temperature
The supergravity dual of regular and fractional D1-branes on the cone
over the Einstein manifold has a naked singularity in the infrared.
The supergravity dual of regular and fractional D3-branes on the
conifold also has such a singularity. Buchel suggested and Gubser et al. have
shown that in the D3-brane case, the naked singularity is cloaked by a horizon
at a sufficiently high temperature. In this paper we derive the system of
second-order differential equations necessary to find such a solution for
. We also find solutions to this system in perturbation theory that
is valid when the Hawking temperature of the horizon is very high.Comment: 22 pages, v2: minor change
More Anomalies from Fractional Branes
In this note we show how the anomalies of both pure and matter coupled N=1,2
supersymmetric gauge theories describing the low energy dynamics of fractional
branes on orbifolds can be derived from supergravity.Comment: 11 pages, latex; v2: minor typos fixe
N=1 gauge superpotentials from supergravity
We review the supergravity derivation of some non-perturbatively generated
effective superpotentials for N=1 gauge theories. Specifically, we derive the
Veneziano-Yankielowicz superpotential for pure N=1 Super Yang-Mills theory from
the warped deformed conifold solution, and the Affleck-Dine-Seiberg
superpotential for N=1 SQCD from a solution describing fractional D3-branes on
a C^3 / Z_2 x Z_2 orbifold.Comment: LaTeX, iopart class, 8 pages, 3 figures. Contribution to the
proceedings of the workshop of the RTN Network "The quantum structure of
space-time and the geometric nature of fundamental interactions", Copenhagen,
September 2003; v2: published version with minor clarification
Fuzzy spaces and new random matrix ensembles
We analyze the expectation value of observables in a scalar theory on the
fuzzy two sphere, represented as a generalized hermitian matrix model. We
calculate explicitly the form of the expectation values in the large-N limit
and demonstrate that, for any single kind of field (matrix), the distribution
of its eigenvalues is still a Wigner semicircle but with a renormalized radius.
For observables involving more than one type of matrix we obtain a new
distribution corresponding to correlated Wigner semicircles.Comment: 12 pages, 1 figure; version to appear in Phys. Rev.
Absorption by Threebranes and the AdS/CFT Correspondence
In the first part of this talk I discuss two somewhat different supergravity
approaches to calculating correlation functions in strongly coupled Yang-Mills
theory. The older approach relates two-point functions to cross-sections for
absorption of certain incident quanta by threebranes. In this approach the
normalization of operators corresponding to the incident particles is fixed
unambiguously by the D3-brane DBI action. By calculating absorption
cross-sections of all partial waves of the dilaton we find corresponding
two-point functions at strong `t Hooft coupling and show that they are
identical to the weak coupling results. The newer approach to correlation
functions relates them to boundary conditions in AdS space. Using this method
we show that for a certain range of negative mass-squared there are two
possible operator dimensions corresponding to a given scalar field in AdS, and
indicate how to calculate correlation functions for either of these choices. In
the second part of the talk I discuss an example of AdS/CFT duality which
arises in the context of type 0 string theory. The CFT on N coincident electric
and magnetic D3-branes is argued to be stable for sufficiently weak `t Hooft
coupling. It is suggested that its transition to instability at a critical
coupling is related to singularity of planar diagrams.Comment: 14 pages, LaTeX; Talk at Strings '99, Potsdam, German
On the Moduli Space of the Cascading SU(M+p)xSU(p) Gauge Theory
We carry out a thorough analysis of the moduli space of the cascading gauge
theory found on p D3-branes and M wrapped D5-branes at the tip of the conifold.
We find various mesonic branches of the moduli space whose string duals involve
the warped deformed conifold with different numbers of mobile D3-branes. The
branes that are not mobile form a BPS bound state at threshold. In the special
case where p is divisible by M there also exists a one-dimensional baryonic
branch whose family of supergravity duals, the resolved warped deformed
conifolds, was constructed recently. The warped deformed conifold is a special
case of these backgrounds where the resolution parameter vanishes and a Z_2
symmetry is restored. We study various brane probes on the resolved warped
deformed conifolds, and successfully match the results with the gauge theory.
In particular, we show that the radial potential for a D3-brane on this space
varies slowly, suggesting a new model of D-brane inflation.Comment: 55 pages, 8 figures; v2: minor corrections; v3: added comments in
section 1
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