741 research outputs found
Flux-induced Soft Supersymmetry Breaking in Chiral Type IIB Orientifolds with D3/D7-Branes
We discuss supersymmetry breaking via 3-form fluxes in chiral supersymmetric
type IIB orientifold vacua with D3- and D7-branes. After a general discussion
of possible choices of fluxes allowing for stabilizing of a part of the moduli,
we determine the resulting effective action including all soft supersymmetry
breaking terms. We also extend the computation of our previous work concerning
the matter field metrics arising from various open string sectors, in
particular focusing on the 1/2 BPS D3/D7-brane configuration. Afterwards, the
F-theory lift of our constructions is investigated.Comment: 55 pages, harvma
A Large Class of New Gravitational and Axionic Backgrounds for Four-Dimensional Superstrings
A large class of new 4-D superstring vacua with non-trivial/singular
geometries, spacetime supersymmetry and other background fields (axion,
dilaton) are found. Killing symmetries are generic and are associated with
non-trivial dilaton and antisymmetric tensor fields. Duality symmetries
preserving N=2 superconformal invariance are employed to generate a large class
of explicit metrics for non-compact 4-D Calabi-Yau manifolds with Killing
symmetries.Comment: LateX file, 34pp., (v5) Some misprints corrected in sections 3.1, 3.2
as pointed out in the paper of Hori and Kapustin (hep-th/0203147). Some
comsetic changes also made in the same section
The Neveu-Schwarz Five-Brane and its Dual Geometries
In this paper we discuss two aspects of duality transformations on the
Neveu-Schwarz (NS) 5-brane solutions in type II and heterotic string theories.
First we demonstrate that the non-extremal NS 5-brane background is U-dual to
its CGHS limit, a two-dimensional black hole times ; an
intermediate step is provided by the near horizon geometry which is given by
the three-dimensional black hole (being closely related to )
times . In the second part of the paper we discuss the T-duality
between NS 5-branes and the Taub-NUT spaces respectively ALE spaces, which
are related to the resolution of the singularities of the non-compact
orbifold . In particular in the framework of N=1
supersymmetric gauge theories related to brane box constructions we give the
metric dual to two sets of intersecting NS 5-branes. In this way we get a
picture of a dual orbifold background which is fibered
together out of two N=2 models (). Finally
we also discuss the intersection of NS 5-branes with D branes, which can serve
as probes of the dual background spaces.Comment: 18pp, added reference
Duality Symmetries and Supersymmetry Breaking in String Compactifications
We discuss the spontaneous supersymetry breaking within the low-energy
effective supergravity action of four-dimensional superstrings. In particular,
we emphasize the non-universality of the soft supersymmetry breaking
parameters, the -problem and the duality symmetries.Comment: (invited talk to the 27th ICHEP, Glasgow, July 1994), 11 page
Heterotic String Theory on non-Kaehler Manifolds with H-Flux and Gaugino Condensate
We discuss compactifications of heterotic string theory to four dimensions in
the presence of H-fluxes, which deform the geometry of the internal manifold,
and a gaugino condensate which breaks supersymmetry. We focus on the
compensation of the two effects in order to obtain vacua with zero cosmological
constant and we comment on the effective superpotential describing these vacua.Comment: 6 page
BPS Action and Superpotential for Heterotic String Compactifications with Fluxes
We consider N =1 compactifications to four dimensions of heterotic string
theory in the presence of fluxes. We show that up to order O(\alpha'^2) the
associated action can be written as a sum of squares of BPS-like quantities. In
this way we prove that the equations of motion are solved by backgrounds which
fulfill the supersymmetry conditions and the Bianchi identities. We also argue
for the expression of the related superpotential and discuss the radial modulus
stabilization for a class of examples.Comment: LaTeX, 28 pages. Minor changes, one more reference added. Final
version to appear on JHE
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