7 research outputs found
Maximally supersymmetric solutions of D=4 N=2 gauged supergravity
We determine and analyze maximally supersymmetric configurations in
four-dimensional gauged N=2 supergravity, preserving eight supercharges. These
models include arbitrary electric gaugings in the vector- and hypermultiplet
sectors. We present several examples of such solutions and connect some of them
to vacuum solutions of flux compactifications in string theory.Comment: 29 pages, no figures; v2 typos corrected and references added; v3
notes added in sections 2.3, 2.4 and app.B to simplify the vacuum conditions
for zero-curvature vacua; v4 minor change
On NS5-brane instantons and volume stabilization
We study general aspects of NS5-brane instantons in relation to the
stabilization of the volume modulus in Calabi-Yau compactifications of type II
strings with fluxes, and their orientifold versions. These instantons correct
the Kahler potential and generically yield significant contributions to the
scalar potential at intermediate values of string coupling constant and volume.
Under suitable conditions they yield uplifting terms that allow for
meta--stable de Sitter vacua.Comment: 29 pages, 3 figures; statements about fields G^a made more precise,
added some clarifications, typos correcte
BPS black holes in N=2 D=4 gauged supergravities
We construct and analyze BPS black hole solutions in gauged N=2, D=4
supergravity with charged hypermultiplets. A class of solutions can be found
through spontaneous symmetry breaking in vacua that preserve maximal
supersymmetry. The resulting black holes do not carry any hair for the scalars.
We demonstrate this with explicit examples of both asymptotically flat and
anti-de Sitter black holes. Next, we analyze the BPS conditions for
asymptotically flat black holes with scalar hair and spherical or axial
symmetry. We find solutions only in cases when the metric contains ripples and
the vector multiplet scalars become ghost-like. We give explicit examples that
can be analyzed numerically. Finally, we comment on a way to circumvent the
ghost-problem by introducing also fermionic hair.Comment: 40 pages, 2 figures; v2 references added; v3 minor changes, published
versio