48 research outputs found
Domain walls inside localised orientifolds
The equations of motion of toroidal orientifold compactifications with fluxes
are in one-to-one correspondence with gauged supergravity if the orientifold
(and D-brane) sources are smeared over the compact space. This smeared limit is
identical to the approximation that ignores warping. It is therefore relevant
to compare quantities obtained from the gauged supergravity with the true 10d
solution with localised sources. In this paper we find the correspondence
between BPS domain walls in gauged SUGRA and 10D SUGRA with localised sources.
Our model is the simplest orientifold with fluxes we are aware of: an O6/D6
compactification on T^3/Z_2 in massive IIA with H_3-flux. The BPS domain walls
correspond to a O6/D6/NS5/D8 bound state. Our analysis reveals that the domain
wall energy computed in gauged SUGRA is unaffected by the localisation of the
O6/D6 sources.Comment: 26 pages, 1 figur
Antibranes don't go black
When D-branes are inserted in flux backgrounds of opposite charge, the
resulting solution has a certain singularity in the fluxes. Recently it has
been argued, using numerical solutions, that for anti-D3 branes in the
Klebanov-Strassler background these singularities cannot be cloaked by a
horizon, which strongly suggests they are not physical. In this note we provide
an analytic proof that the singularity of all codimension-three antibrane
solutions (such as anti-D6 branes in massive type IIA supergravity or anti-D3
branes smeared on the T^3 of R^3xT^3 with fluxes) cannot be hidden behind a
horizon, and that the charge of black branes with smooth event horizons must
have the same sign as the charge of the flux background. Our result indicates
that infinitesimally blackening the antibranes immediately triggers brane-flux
annihilation, and strengthens the intuition that antibranes placed in flux with
positive charge immediately annihilate against it.Comment: 9 pages, 1 figur
Universal dS vacua in STU-models
Stable de Sitter solutions in minimal F-term supergravity are known to lie
close to Minkowski critical points. We consider a class of STU-models arising
from type IIB compactifications with generalised fluxes. There, we apply an
analytical method for solving the equations of motion for the moduli fields
based on the idea of treating derivatives of the superpotential of different
orders up to third as independent objects. In particular, supersymmetric and
no-scale Minkowski solutions are singled out by physical reasons. Focusing on
the study of dS vacua close to supersymmetric Minkowski points, we are able to
elaborate a complete analytical treatment of the mass matrix based on the
sGoldstino bound. This leads to a class of interesting universal dS vacua. We
finally explore a similar possibility around no-scale Minkowski points and
discuss some examples.Comment: 31 pages, 4 figures and 7 table
Localised anti-branes in non-compact throats at zero and finite T
We investigate the 3-form singularities that are typical to anti-brane
solutions in supergravity and check whether they can be cloaked by a finite
temperature horizon. For anti-D3-branes in the Klebanov-Strassler background,
this was already shown numerically to be impossible when the branes are
partially smeared. In this paper, we present analytic arguments that also
localised branes remain with singular 3-form fluxes at both zero and finite
temperature. These results may have important, possibly fatal, consequences for
constructions of meta-stable de Sitter vacua through uplifting.Comment: 18 + 9 page
(Anti-)Brane backreaction beyond perturbation theory
We improve on the understanding of the backreaction of anti-D6-branes in a
flux background that is mutually BPS with D6-branes. This setup is analogous to
the study of the backreaction of anti-D3-branes inserted in the KS throat, but
does not require us to smear the anti-branes or do a perturbative analysis
around the BPS background. We solve the full equations of motion near the
anti-D6-branes and show that only two boundary conditions are consistent with
the equations of motion. Upon invoking a topological argument we eliminate the
boundary condition with regular H flux since it cannot lead to a solution that
approaches the right kind of flux away from the anti-D6-brane. This leaves us
with a boundary condition which has singular, but integrable, H flux energy
density.Comment: 12 pages + appendices, 1 figure; v2: minor changes, version published
in JHE
The problematic backreaction of SUSY-breaking branes
In this paper we investigate the localisation of SUSY-breaking branes which,
in the smeared approximation, support specific non-BPS vacua. We show, for a
wide class of boundary conditions, that there is no flux vacuum when the branes
are described by a genuine delta-function. Even more, we find that the smeared
solution is the unique solution with a regular brane profile. Our setup
consists of a non-BPS AdS_7 solution in massive IIA supergravity with smeared
anti-D6-branes and fluxes T-dual to ISD fluxes in IIB supergravity.Comment: 27 pages, Latex2e, 5 figure
Fractional branes, warped compactifications and backreacted orientifold planes
The standard extremal p-brane solutions in supergravity are known to allow
for a generalisation which consists of adding a linear dependence on the
world-volume coordinates to the usual harmonic function. In this note we
demonstrate that remarkably this generalisation goes through in exactly the
same way for p-branes with fluxes added to it that correspond to fractional
p-branes. We relate this to warped orientifold compactifications by trading the
Dp-branes for Op-planes that solve the RR tadpole condition. This allows us to
interpret the worldvolume dependence as due to lower-dimensional scalars that
flow along the massless directions in the no-scale potential. Depending on the
details of the fluxes these flows can be supersymmetric domain wall flows. Our
solutions provide explicit examples of backreacted orientifold planes in
compactifications with non-constant moduli.Comment: 20 pages, incl. references. v2: small changes required for JHEP
publication. v3: few equation typos correcte
Smeared versus localised sources in flux compactifications
We investigate whether vacuum solutions in flux compactifications that are
obtained with smeared sources (orientifolds or D-branes) still survive when the
sources are localised. This seems to rely on whether the solutions are BPS or
not. First we consider two sets of BPS solutions that both relate to the GKP
solution through T-dualities: (p+1)-dimensional solutions from
spacetime-filling Op-planes with a conformally Ricci-flat internal space, and
p-dimensional solutions with Op-planes that wrap a 1-cycle inside an everywhere
negatively curved twisted torus. The relation between the solution with smeared
orientifolds and the localised version is worked out in detail. We then
demonstrate that a class of non-BPS AdS_4 solutions that exist for IASD fluxes
and with smeared D3-branes (or analogously for ISD fluxes with anti-D3-branes)
does not survive the localisation of the (anti) D3-branes. This casts doubts on
the stringy consistency of non-BPS solutions that are obtained in the limit of
smeared sources.Comment: 23 pages; v2: minor corrections, added references, version published
in JHE