325 research outputs found
The Runaway Quiver
We point out that some recently proposed string theory realizations of
dynamical supersymmetry breaking actually do not break supersymmetry in the
usual desired sense. Instead, there is a runaway potential, which slides down
to a supersymmetric vacuum at infinite expectation values for some fields. The
runaway direction is not on a separated branch; rather, it shows up as
a"tadpole" everywhere on the moduli space of field expectation values.Comment: 12 pages, no figures. v2: reference chang
The Universal Kaehler Modulus in Warped Compactifications
We construct the effective theory of the universal Kaehler modulus in warped
compactifications using the Hamiltonian formulation of general relativity. The
spacetime dependent 10d solution is constructed at the linear level for both
the volume modulus and its axionic partner, and nontrivial cancellations of
warping effects are found in the dimensional reduction. Our main result is that
the Kaehler potential is not corrected by warping, up to an overall shift in
the background value of the volume modulus. We extend the analysis beyond the
linearized approximation by computing the fully backreacted 10d metric
corresponding to a finite volume modulus fluctuation. Also, we discuss the
behavior of the modulus in strongly warped regions and show that there are no
mixings with light Kaluza-Klein modes. These results are important for the
phenomenology and cosmology of flux compactifications.Comment: 28 pages, 1 figure; v2. corrected typos, added refs & minor
clarification
Inflation on Fractional Branes: D--Brane Inflation as D--Term Inflation
We describe a D--brane inflation model which consists of two fractional D3
branes separated on a transverse . Inflation arises due to the
resolved orbifold singularity of which corresponds to an anomalous D--term
on the brane. We show that D--brane inflation in the bulk corresponds to
D--term inflation on the brane. The inflaton and the trigger field parametrize
the interbrane distances on an respectively. After inflation the
branes reach a supersymmetric configuration in which they are at the origin of
but separated along the directions.Comment: 15 pages in phyzzx.tex; minor corrections including all factors of
2\pi; v3: more minor correction
Quantum symmetries and exceptional collections
We study the interplay between discrete quantum symmetries at certain points
in the moduli space of Calabi-Yau compactifications, and the associated
identities that the geometric realization of D-brane monodromies must satisfy.
We show that in a wide class of examples, both local and compact, the monodromy
identities in question always follow from a single mathematical statement. One
of the simplest examples is the Z_5 symmetry at the Gepner point of the
quintic, and the associated D-brane monodromy identity
On D3-brane Potentials in Compactifications with Fluxes and Wrapped D-branes
We study the potential governing D3-brane motion in a warped throat region of
a string compactification with internal fluxes and wrapped D-branes. If the
Kahler moduli of the compact space are stabilized by nonperturbative effects, a
D3-brane experiences a force due to its interaction with D-branes wrapping
certain four-cycles. We compute this interaction, as a correction to the warped
four-cycle volume, using explicit throat backgrounds in supergravity. This
amounts to a closed-string channel computation of the loop corrections to the
nonperturbative superpotential that stabilizes the volume. We demonstrate for
warped conical spaces that the superpotential correction is given by the
embedding equation specifying the wrapped four-cycle, in agreement with the
general form proposed by Ganor. Our approach automatically provides a solution
to the problem of defining a holomorphic gauge coupling on wrapped D7-branes in
a background with D3-branes. Finally, our results have applications to
cosmological inflation models in which the inflaton is modeled by a D3-brane
moving in a warped throat.Comment: 45 pages, 1 figure; v2: added reference, clarified notatio
A New Infinite Class of Quiver Gauge Theories
We construct a new infinite family of N=1 quiver gauge theories which can be
Higgsed to the Y^{p,q} quiver gauge theories. The dual geometries are toric
Calabi-Yau cones for which we give the toric data. We also discuss the action
of Seiberg duality on these quivers, and explore the different Seiberg dual
theories. We describe the relationship of these theories to five dimensional
gauge theories on (p,q) 5-branes. Using the toric data, we specify some of the
properties of the corresponding dual Sasaki-Einstein manifolds. These theories
generically have algebraic R-charges which are not quadratic irrational
numbers. The metrics for these manifolds still remain unknown.Comment: 29 pages, JHE
Brane Tilings and Exceptional Collections
Both brane tilings and exceptional collections are useful tools for
describing the low energy gauge theory on a stack of D3-branes probing a
Calabi-Yau singularity. We provide a dictionary that translates between these
two heretofore unconnected languages. Given a brane tiling, we compute an
exceptional collection of line bundles associated to the base of the
non-compact Calabi-Yau threefold. Given an exceptional collection, we derive
the periodic quiver of the gauge theory which is the graph theoretic dual of
the brane tiling. Our results give new insight to the construction of quiver
theories and their relation to geometry.Comment: 46 pages, 37 figures, JHEP3; v2: reference added, figure 13 correcte
Cosmic D--term Strings as Wrapped D3 Branes
We describe cosmic D--term strings as D3 branes wrapped on a resolved
conifold. The matter content that gives rise to D--term strings is shown to
describe the world--volume theory of a space--filling D3 brane transverse to
the conifold which itself is a wrapped D5 brane. We show that, in this brane
theory, the tension of the wrapped D3 brane mathces that of the D--term string.
We argue that there is a new type of cosmic string which arises from fractional
D1 branes on the world--volume of a fractional D3 brane.Comment: 13 pages in phyzzx.tex; eq. (17) corrected, other minor corrections;
v3: more minor correction
Seiberg Duality is an Exceptional Mutation
The low energy gauge theory living on D-branes probing a del Pezzo
singularity of a non-compact Calabi-Yau manifold is not unique. In fact there
is a large equivalence class of such gauge theories related by Seiberg duality.
As a step toward characterizing this class, we show that Seiberg duality can be
defined consistently as an admissible mutation of a strongly exceptional
collection of coherent sheaves.Comment: 32 pages, 4 figures; v2 refs added, "orbifold point" discussion
refined; v3 version to appear in JHEP, discussion of torsion sheaves improve
Dynamical Fine Tuning in Brane Inflation
We investigate a novel mechanism of dynamical tuning of a flat potential in
the open string landscape within the context of warped brane-antibrane
inflation in type IIB string theory. Because of competing effects between
interactions with the moduli stabilizing D7-branes in the warped throat and
anti-D3-branes at the tip, a stack of branes gives rise to a local minimum of
the potential, holding the branes high up in the throat. As branes successively
tunnel out of the local minimum to the bottom of the throat the potential
barrier becomes lower and is eventually replaced by a flat inflection point,
around which the remaining branes easily inflate. This dynamical flattening of
the inflaton potential reduces the need to fine tune the potential by hand, and
also leads to successful inflation for a larger range of inflaton initial
conditions, due to trapping in the local minimum.Comment: 23 pages, 9 figures. v2: Updated D3-dependence in potential, small
changes to numerical result
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