100 research outputs found
STRINGY EVIDENCE FOR D=11 STRUCTURE IN STRONGLY COUPLED TYPE II-A SUPERSTRING
Witten proposed that the low energy physics of strongly coupled D=10 type-IIA
superstring may be described by D=11 supergravity. To explore the stringy
aspects of the underlying theory we examine the stringy massive states. We
propose a systematic formula for identifying non-perturbative states in D=10
type-IIA superstring theory, such that, together with the elementary excited
string states, they form D=11 supersymmetric multiplets multiplets in SO(10)
representations. This provides hints for the construction of a weakly coupled
D=11 theory that is dual to the strongly coupled D=10 type IIA superstring.Comment: LaTeX, revtex, 2-column, 10 pages
Heterotic-type IIA duality with fluxes
In this paper we study a possible non-perturbative dual of the heterotic
string compactified on K3 x T^2 in the presence of background fluxes. We show
that type IIA string theory compactified on manifolds with SU(3) structure can
account for a subset of the possible heterotic fluxes. This extends our
previous analysis to a case of a non-perturbative duality with fluxes.Comment: 26 pages, minor corrections; version to appear in JHE
Twisting K3 x T^2 Orbifolds
We construct a class of geometric twists of Calabi-Yau manifolds of
Voisin-Borcea type (K3 x T^2)/Z_2 and study the superpotential in a type IIA
orientifold based on this geometry. The twists modify the direct product by
fibering the K3 over T^2 while preserving the Z_2 involution. As an important
application, the Voisin-Borcea class contains T^6/(Z_2 x Z_2), the usual
setting for intersecting D6 brane model building. Past work in this context
considered only those twists inherited from T^6, but our work extends these
twists to a subset of the blow-up modes. Our work naturally generalizes to
arbitrary K3 fibered Calabi-Yau manifolds and to nongeometric constructions.Comment: 57 pages, 4 figures; uses harvmac.tex, amssym.tex; v3: minor
corrections, references adde
Duality of Type II 7-branes and 8-branes
We present a version of ten-dimensional IIA supergravity containing a 9-form
potential for which the field equations are equivalent to those of the
standard, massless, IIA theory for vanishing 10-form field strength, ,
and to those of the `massive' IIA theory for non-vanishing . We present
a multi 8-brane solution of these equations that generalizes the 8-brane of
Polchinski and Witten. We show that this solution is T-dual to a new multi
7-brane solution of compactified IIB supergravity, and that the latter is
T-dual to the IIA 6-brane. When combined with the U-duality of the
type IIB superstring, the T-duality between type II 7-branes and 8-branes
implies a quantization of the cosmological constant of type IIA superstring
theory. These results are made possible by the construction of a new {\it
massive} N=2 D=9 supergravity theory. We also discuss the 11-dimensional
interpretation of these type II p-branes.Comment: Includes corrections to last section that will appear in the version
to be published in Nuclear Physics B. 36 pp. Phyzz
N=2 structures on solvable Lie algebras: the c=9 classification
Let G be a finite-dimensional Lie algebra (not necessarily semisimple). It is
known that if G is self-dual (that is, if it possesses an invariant metric)
then there is a canonical N=1 superconformal algebra associated to its N=1
affinization---that is, it admits an N=1 (affine) Sugawara construction. Under
certain additional hypotheses, this N=1 structure admits an N=2 extension. If
this is the case, G is said to possess an N=2 structure. It is also known that
an N=2 structure on a self-dual Lie algebra G is equivalent to a vector space
decomposition G = G_+ \oplus G_- where G_\pm are isotropic Lie subalgebras. In
other words, N=2 structures on G are in one-to-one correspondence with Manin
triples (G,G_+,G_-). In this paper we exploit this correspondence to obtain a
classification of the c=9 N=2 structures on self-dual solvable Lie algebras. In
the process we also give some simple proofs for a variety of Lie algebraic
results concerning self-dual Lie algebras admitting symplectic or K\"ahler
structures.Comment: 49 pages in 2 columns (=25 physical pages), (uufiles-gz-9)'d .dvi
file (uses AMSFonts 2.1+). Revision: Added 1 reference, corrected typos,
added some more materia
Massive IIA flux compactifications and U-dualities
We attempt to find a rigorous formulation for the massive type IIA
orientifold compactifications of string theory introduced in hep-th/0505160. An
approximate double T-duality converts this background into IIA string theory on
a twisted torus, but various arguments indicate that the back reaction of the
orientifold on this geometry is large. In particular, an AdS calculation of the
entropy suggests a scaling appropriate for N M2-branes, in a certain limit of
the compactification, though not the one studied in hep-th/0505160. The
M-theory lift of this specific regime is not 4 dimensional. We suggest that the
generic limit of the background corresponds to a situation analogous to
F-theory, where the string coupling is small in some regions of a compact
geometry, and large in others, so that neither a long wavelength 11D SUGRA
expansion, nor a world sheet expansion exists for these compactifications. We
end with a speculation on the nature of the generic compactification.Comment: JHEP3 LaTeX - 34 pages - 3 figures; v2: Added references; v3: mistake
in entropy scaling corrected, major changes in conclusions; v4: changed
claims about original DeWolfe et al. setup, JHEP versio
Introduction to M Theory and AdS/CFT Duality
An introductory survey of some of the developments that have taken place in
superstring theory in the past few years is presented. The main focus is on
three particular dualities. The first one is the appearance of an 11th
dimension in the strong coupling limit of the type IIA theory, which give rise
to M theory. The second one is the duality between the type IIB theory
compactified on a circle and M theory on a two-torus. The final topic is an
introduction to the recently proposed duality between superstring theory or M
theory on certain anti de Sitter space backgrounds and conformally invariant
quantum field theories.Comment: 26 pages; To be published in the Proceedings of a conference held in
Corfu, Greece in September 1998. v2: reference adde
Heterotic String Compactifications on Half-flat Manifolds II
In this paper, we continue the analysis of heterotic string compactifications
on half-flat mirror manifolds by including the 10-dimensional gauge fields. It
is argued, that the heterotic Bianchi identity is solved by a variant of the
standard embedding. Then, the resulting gauge group in four dimensions is still
E6 despite the fact that the Levi-Civita connection has SO(6) holonomy. We
derive the associated four-dimensional effective theories including matter
field terms for such compactifications. The results are also extended to more
general manifolds with SU(3) structure.Comment: 31 page
Pure type I supergravity and DE(10)
We establish a dynamical equivalence between the bosonic part of pure type I
supergravity in D=10 and a D=1 non-linear sigma-model on the Kac-Moody coset
space DE(10)/K(DE(10)) if both theories are suitably truncated. To this end we
make use of a decomposition of DE(10) under its regular SO(9,9) subgroup. Our
analysis also deals partly with the fermionic fields of the supergravity theory
and we define corresponding representations of the generalized spatial Lorentz
group K(DE(10)).Comment: 28 page
Nongeometric Flux Compactifications
We investigate a simple class of type II string compactifications which
incorporate nongeometric "fluxes" in addition to "geometric flux" and the usual
H-field and R-R fluxes. These compactifications are nongeometric analogues of
the twisted torus. We develop T-duality rules for NS-NS geometric and
nongeometric fluxes, which we use to construct a superpotential for the
dimensionally reduced four-dimensional theory. The resulting structure is
invariant under T-duality, so that the distribution of vacua in the IIA and IIB
theories is identical when nongeometric fluxes are included. This gives a
concrete framework in which to investigate the possibility that generic string
compactifications may be nongeometric in any duality frame. The framework
developed in this paper also provides some concrete hints for how mirror
symmetry can be generalized to compactifications with arbitrary H-flux, whose
mirrors are generically nongeometric.Comment: 26 pages, JHEP3. v3: references, minor corrections, and
clarifications added. v4: sign correcte
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