88 research outputs found
Four-modulus "Swiss Cheese" chiral models
We study the 'Large Volume Scenario' on explicit, new, compact, four-modulus
Calabi-Yau manifolds. We pay special attention to the chirality problem pointed
out by Blumenhagen, Moster and Plauschinn. Namely, we thoroughly analyze the
possibility of generating neutral, non-perturbative superpotentials from
Euclidean D3-branes in the presence of chirally intersecting D7-branes. We find
that taking proper account of the Freed-Witten anomaly on non-spin cycles and
of the Kaehler cone conditions imposes severe constraints on the models.
Nevertheless, we are able to create setups where the constraints are solved,
and up to three moduli are stabilized.Comment: 40 pages, 10 figures, clarifying comments added, minor mistakes
correcte
Meta-Stable Brane Configurations of Triple Product Gauge Groups
From an N=1 supersymmetric electric gauge theory with the gauge group SU(N_c)
x SU(N_c') x SU(N_c'') with fundamentals for each gauge group and the
bifundamentals, we apply Seiberg dual to each gauge group and obtain the N=1
supersymmetric dual magnetic gauge theories with dual matters including the
additional gauge singlets. By analyzing the F-term equations of the dual
magnetic superpotentials, we describe the intersecting brane configurations of
type IIA string theory corresponding to the meta-stable nonsupersymmetric vacua
of this gauge theory. We apply also to the case for N=1 supersymmetric electric
gauge theory with the gauge group Sp(N_c) x SO(2N_c') x Sp(N_c'') with flavors
for each gauge group and the bifundamentals. Finally, we describe the
meta-stable brane configurations of multiple product gauge groups.Comment: 80pp, 10 figures; shorten the draft and to appear in IJMP
Meta-Stable Brane Configurations by Adding an Orientifold-Plane to Giveon-Kutasov
In hep-th/0703135, they have found the type IIA intersecting brane
configuration where there exist three NS5-branes, D4-branes and anti-D4-branes.
By analyzing the gravitational interaction for the D4-branes in the background
of the NS5-branes, the phase structures in different regions of the parameter
space were studied in the context of classical string theory. In this paper, by
adding the orientifold 4-plane and 6-plane to the above brane configuration, we
describe the intersecting brane configurations of type IIA string theory
corresponding to the meta-stable nonsupersymmetric vacua of these gauge
theories.Comment: 21 pp, 6 figures; reduced bytes of figures, DBI action analysis added
and to appear in JHE
D-brane instantons and the effective field theory of flux compactifications
We provide a description of the effects of fluxes on euclidean D-brane
instantons purely in terms of the 4d effective action. The effect corresponds
to the dressing of the effective non-perturbative 4d effective vertex with 4d
flux superpotential interactions, generated when the moduli fields made massive
by the flux are integrated out. The description in terms of effective field
theory allows a unified description of non-perturbative effects in all flux
compactifications of a given underlying fluxless model, globally in the moduli
space of the latter. It also allows us to describe explicitly the effects on
D-brane instantons of fluxes with no microscopic description, like
non-geometric fluxes. At the more formal level, the description has interesting
connections with the bulk-boundary map of open-closed two-dimensional
topological string theory, and with the \NN=1 special geometry.Comment: 33 page
Anomalies and O-plane charges in orientifolded brane tilings
We investigate orientifold of brane tilings. We clarify how the cancellations
of gauge anomaly and Witten's anomaly are guaranteed by the conservation of the
D5-brane charge. We also discuss the relation between brane tilings and the
dual Calabi-Yau cones realized as the moduli spaces of gauge theories. Two
types of flavor D5-branes in brane tilings and corresponding superpotentials of
fundamental quark fields are proposed, and it is shown that the massless loci
of these quarks in the moduli space correctly reproduce the worldvolume of
flavor D7-branes in the Calabi-Yau cone dual to the fivebrane system.Comment: 46 pages, 19 figure
Meta-Stable Supersymmetry Breaking in a Cooling Universe
We look at the recently proposed idea that susy breaking can be accomplished
in a meta-stable vacuum. In the context of one of the simplest models (the
Seiberg-dual of super-QCD), we address the following question: if we look at
this theory as it cools from high temperature, is it at all possible that we
can end up in a susy-breaking meta-stable vacuum? To get an idea about the
answer, we look at the free energy of the system at high temperature. We
conclude that the phase-structure of the free-energy as the temperature drops,
is indeed such that there is a second order phase transition in the direction
of the non-susy vacuum at a finite . On the other hand, the potential
barrier in the direction of the susy vacuum is there all the way till .Comment: writing full author name
No-scale supersymmetry breaking vacua and soft terms with torsion
We analyze the conditions to have no-scale supersymmetry breaking solutions
of type IIA and IIB supergravity compactified on manifolds of SU(3)-structure.
The supersymmetry is spontaneously broken by the intrinsic torsion of the
internal space. For type IIB orientifolds with O9 and O5-planes the mass of the
gravitino is governed by the torsion class W_1, and the breaking is mediated
through F-terms associated to descendants of the original N=2 hypermultiplets.
For type IIA orientifolds with O6-planes we find two families of solutions,
depending on whether the breaking is mediated exclusively by hypermultiplets or
by a mixture of hypermultiplets and vector multiplets, the latter case
corresponding to a class of Scherk-Schwarz compactifications not dual to any
geometric IIB setup. We compute the geometrically induced mu-terms for D5, D6
and D9-branes on twisted tori, and discuss the patterns of soft-terms which
arise for pure moduli mediation in each type of breaking. As for D3 and
D7-branes in presence of 3-form fluxes, the effective scalar potential turns
out to possess interesting phenomenological properties.Comment: 44 pages; several minor corrections and added reference
SU(5) D-brane realizations, Yukawa couplings and proton stability
We discuss SU(5) Grand Unified Theories in the context of orientifold
compactifications. Specifically, we investigate two and three D-brane stack
realizations of the Georgi-Glashow and the flipped SU(5) model and analyze them
with respect to their Yukawa couplings. As pointed out in arXiv:0909.0271 the
most economical Georgi-Glashow realization based on two stacks generically
suffers from a disastrous large proton decay rate. We show that allowing for an
additional U(1) D-brane stack this as well as other phenomenological problems
can be resolved. We exemplify with globally consistent Georgi-Glashow models
based on RCFT that these D-brane quivers can be indeed embedded in a global
setting. These globally consistent realizations admit rigid O(1) instantons
inducing the perturbatively missing coupling 10105^H. Finally we show that
flipped SU(5) D-brane realizations even with multiple U(1) D-brane stacks are
plagued by severe phenomenological drawbacks which generically cannot be
overcome.Comment: 34 pages v2 minor correction
Meta-Stable Brane Configurations with Seven NS5-Branes
We present the intersecting brane configurations consisting of NS-branes,
D4-branes(and anti D4-branes) and O6-plane, of type IIA string theory
corresponding to the meta-stable nonsupersymmetric vacua in four dimensional
N=1 supersymmetric SU(N_c) x SU(N_c') x SU(N_c'') gauge theory with a symmetric
tensor field, a conjugate symmetric tensor field and bifundamental fields. We
also describe the intersecting brane configurations of type IIA string theory
corresponding to the nonsupersymmetric meta-stable vacua in the above gauge
theory with an antisymmetric tensor field, a conjugate symmetric tensor field,
eight fundamental flavors and bifundamentals. These brane configurations
consist of NS-branes, D4-branes(and anti D4-branes), D6-branes and O6-planes.Comment: 34pp, 9 figures; Improved the draft and added some footnotes; Figure
1, footnote 7 and captions of Figures 7,8,9 added or improved and to appear
in CQ
Two Loop R-Symmetry Breaking
We analyze two loop quantum corrections for pseudomoduli in O'Raifeartaigh
like models. We argue that R-symmetry can be spontaneously broken at two loop
in non supersymmetric vacua. We provide a basic example with this property. We
discuss on phenomenological applications.Comment: 13 pages, 5 figures, JHEP3.cls, reference adde
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