8,712 research outputs found
Perturbative and non-perturbative monodromies in N=2 heterotic string vacua
In this talk we summarise our recent results on perturbative and
non-perturbative monodromies in four-dimensional heterotic strings with
space-time supersymmetry, and we compare our results with the rigid
Yang-Mills monodromies.Comment: 6 pages, latex using espcrc2. Based on Talks given at the 29th
International Symposium on the Theory of Elementary Particles, Buckow, August
1995 and at the 5th Hellenic School and Workshop on Elementary Particle
Physics, Corfu, September 199
Hessian geometry and the holomorphic anomaly
We present a geometrical framework which incorporates higher derivative
corrections to the action of N = 2 vector multiplets in terms of an enlarged
scalar manifold which includes a complex deformation parameter. This enlarged
space carries a deformed version of special Kahler geometry which we
characterise. The holomorphic anomaly equation arises in this framework from
the integrability condition for the existence of a Hesse potential.Comment: 43 pages. Revised version: minimal changes. Final version, accepted
for publication by JHE
Natural Supergravity Inflation
We show that a single uncharged chiral superfield, canonically coupled to
\mbox{} supergravity with vanishing superpotential, naturally drives
inflation in the early universe for a class of simple Kahler potentials.
Inflation occurs due to the one-loop generation of a Kahler anomaly
proportional to . The coefficient of this term is of the correct
magnitude to describe all aspects of an inflationary cosmology, including
sufficient amplitude perturbations and reheating. Higher order terms
proportional to for are naturally suppressed relative to the
term and, hence, do not destabilize the theory.Comment: 13 pages, CERN-TH.6685/92, UPR-0526
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
Curved BPS domain wall solutions in five-dimensional gauged supergravity
We analyze the possibility of constructing supersymmetric curved domain wall
solutions in five-dimensional gauged supergravity, which are
supported by non-constant scalar fields belonging either to vector multiplets
only or to vector and hypermultiplets. We show that the BPS equations for the
warp factor and for the vector scalars are modified by the presence of a
four-dimensional cosmological constant on the domain wall, in agreement with
earlier results by DeWolfe, Freedman, Gubser and Karch. We also show that the
cosmological constant on the domain wall is anti-de Sitter like and that it
constitutes an independent quantity, not related to any of the objects
appearing in the context of very special geometry.Comment: 13 pages, latex, error corrected plus substantial revision (title
changed
Indefinite theta functions for counting attractor backgrounds
In this note, we employ indefinite theta functions to regularize canonical
partition functions for single-center dyonic BPS black holes. These partition
functions count dyonic degeneracies in the Hilbert space of four-dimensional
toroidally compactified heterotic string theory, graded by electric and
magnetic charges. The regularization is achieved by viewing the weighted sums
of degeneracies as sums over charge excitations in the near-horizon attractor
geometry of an arbitrarily chosen black hole background, and eliminating the
unstable modes. This enables us to rewrite these sums in terms of indefinite
theta functions. Background independence is then implemented by using the
transformation property of indefinite theta functions under elliptic
transformations, while modular transformations are used to make contact with
semi-classical results in supergravity.Comment: 24 pages, LaTe
Supersymmetric Solutions in Three-Dimensional Heterotic String Theory
We consider the low-energy effective field theory of heterotic string theory
compactified on a seven-torus, and we construct electrically charged as well as
more general solitonic solutions. These solutions preserve 1/2, 1/4 and 1/8 of
N=8, D=3 supersymmetry and have Killing spinors which exist due to cancellation
of holonomies. The associated space-time line elements do not exhibit the
conical structure that often arises in 2+1 dimensional gravity theories.Comment: 40 pages, LaTeX, minor correction
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