309 research outputs found
On the Topology of the Inflaton Field in Minimal Supergravity Models
We consider global issues in minimal supergravity models where a single field
inflaton potential emerges. In a particular case we reproduce the Starobinsky
model and its description dual to a certain formulation of R+R^2 supergravity.
For definiteness we confine our analysis to spaces at constant curvature,
either vanishing or negative. Five distinct models arise, two flat models with
respectively a quadratic and a quartic potential and three based on the
SU(1,1)/U(1) space where its distinct isometries, elliptic, hyperbolic and
parabolic are gauged. Fayet-Iliopoulos terms are introduced in a geometric way
and they turn out to be a crucial ingredient in order to describe the de Sitter
inflationary phase of the Starobinsky model.Comment: 31 pages, LaTex, 7 eps figures, 2 table
R-Symmetry and the Topological Twist of N=2 Effective Supergravities of Heterotic Strings
We discuss R-symmetries in locally supersymmetric N=2 gauge theories coupled
to hypermultiplets which can be thought of as effective theories of heterotic
superstring models. In this type of supergravities a suitable R-symmetry exists
and can be used to topologically twist the theory: the vector multiplet
containing the dilaton-axion field has different R-charge assignments with
respect to the other vector multiplets. Correspondingly a system of coupled
instanton equations emerges, mixing gravitational and Yang--Mills instantons
with triholomorphic hyperinstantons and axion-instantons. For the tree-level
classical special manifolds R-symmetry with the specified properties is a continuous symmetry, but
for the quantum corrected manifolds a discrete R--group of
electric--magnetic duality rotations is sufficient and we argue that it exists.Comment: 40 pages, plain LaTeX. Final version to appear on IJMP
Integrable scalar cosmologies II. Can they fit into Gauged Extended Supergravity or be encoded in N=1 superpotentials?
Brane solutions and integrability: a status report
We review the status of the integrability and solvability of the geodesics
equations of motion on symmetric coset spaces that appear as sigma models of
supergravity theories when reduced over respectively the timelike and spacelike
direction. Such geodesic curves describe respectively timelike and spacelike
brane solutions. We emphasize the applications to black holes.Comment: 4 pages, Proceedings of ERE 2010, Granada, 6-10 september 201
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