149 research outputs found
A landscape of non-supersymmetric AdS vacua on coset manifolds
We construct new families of non-supersymmetric sourceless type IIA AdS4
vacua on those coset manifolds that also admit supersymmetric solutions. We
investigate the spectrum of left-invariant modes and find that most, but not
all, of the vacua are stable under these fluctuations. Generically, there are
also no massless moduli.Comment: 20 pages, 11 figures, v2: added some clarifications, references, v3:
corrections addressing comments refere
Solvable Lie algebras are not that hypo
We study a type of left-invariant structure on Lie groups, or equivalently on
Lie algebras. We introduce obstructions to the existence of a hypo structure,
namely the 5-dimensional geometry of hypersurfaces in manifolds with holonomy
SU(3). The choice of a splitting g^*=V_1 + V_2, and the vanishing of certain
associated cohomology groups, determine a first obstruction. We also construct
necessary conditions for the existence of a hypo structure with a fixed
almost-contact form. For non-unimodular Lie algebras, we derive an obstruction
to the existence of a hypo structure, with no choice involved. We apply these
methods to classify solvable Lie algebras that admit a hypo structure.Comment: 21 pages; v2: presentation improved, typos corrected, notational
conflicts eliminated. To appear in Transformation Group
Supersymmetric AdS(4) compactifications of IIA supergravity
We derive necessary and sufficient conditions for N=1 compactifications of
(massive) IIA supergravity to AdS(4) in the language of SU(3) structures. We
find new solutions characterized by constant dilaton and nonzero fluxes for all
form fields. All fluxes are given in terms of the geometrical data of the
internal compact space. The latter is constrained to belong to a special class
of half-flat manifolds.Comment: 24 pages, references adde
A model realisation of the Jaffe-Wilczek correlation for pentaquarks
We discuss a realisation of the pentaquark structure proposed by Jaffe and
Wilczek within a simple quark model with colour-spin contact interactions and
coloured harmonic confinement, which accurately describes the
splitting. In this model spatially compact diquarks are formed in the
pentaquark but no such compact object exists in the nucleon. The colour-spin
attraction brings the Jaffe-Wilczek-like state down to a low mass, compatible
with the experimental observation and below that of the naive ground state with
all -waves. We find, however, that although these trends are maintained, the
extreme effects observed do not survive the required ``smearing'' of the delta
function contact interaction. We also demonstrate the weakness of the
``schematic'' approximation when applied to a system containing a -wave. An
estimate of the anti-charmed pentaquark mass is made which is in line with the
Jaffe-Wilczek prediction and significantly less than the value reported by the
H1 collaboration.Comment: 10 pages, uses psfra
AdS Strings with Torsion: Non-complex Heterotic Compactifications
Combining the effects of fluxes and gaugino condensation in heterotic
supergravity, we use a ten-dimensional approach to find a new class of
four-dimensional supersymmetric AdS compactifications on almost-Hermitian
manifolds of SU(3) structure. Computation of the torsion allows a
classification of the internal geometry, which for a particular combination of
fluxes and condensate, is nearly Kahler. We argue that all moduli are fixed,
and we show that the Kahler potential and superpotential proposed in the
literature yield the correct AdS radius. In the nearly Kahler case, we are able
to solve the H Bianchi using a nonstandard embedding. Finally, we point out
subtleties in deriving the effective superpotential and understanding the
heterotic supergravity in the presence of a gaugino condensate.Comment: 42 pages; v2. added refs, revised discussion of Bianchi for N
Gauging the Heisenberg algebra of special quaternionic manifolds
We show that in N=2 supergravity, with a special quaternionic manifold of
(quaternionic) dimension h_1+1 and in the presence of h_2 vector multiplets, a
h_2+1 dimensional abelian algebra, intersecting the 2h_1+3 dimensional
Heisenberg algebra of quaternionic isometries, can be gauged provided the h_2+1
symplectic charge--vectors V_I, have vanishing symplectic invariant scalar
product V_I X V_J=0. For compactifications on Calabi--Yau three--folds with
Hodge numbers (h_1,h_2) such condition generalizes the half--flatness condition
as used in the recent literature. We also discuss non--abelian extensions of
the above gaugings and their consistency conditions.Comment: 9 pages, LaTe
Non-Kaehler attracting manifolds
We observe that the new attractor mechanism describing IIB flux vacua for
Calabi-Yau compactifications has a possible extension to the landscape of
non-Kaehler vacua that emerge in heterotic compactifications with fluxes. We
focus on the effective theories coming from compactifications on generalized
half-flat manifolds, showing that the Minkowski "attractor points'' for 3-form
fluxes are special-hermitian manifolds.Comment: 18 pages. v2: Minor polishing, reference added. v3: More cleanup,
final version for JHE
Complete Calabi-Yau metrics from Kahler metrics in D=4
In the present work the local form of certain Calabi-Yau metrics possessing a
local Hamiltonian Killing vector is described in terms of a single non linear
equation. The main assumptions are that the complex -form is of the form
, where is preserved by the Killing
vector, and that the space of the orbits of the Killing vector is, for fixed
value of the momentum map coordinate, a complex 4-manifold, in such a way that
the complex structure of the 4-manifold is part of the complex structure of the
complex 3-fold. The link with the solution generating techniques of [26]-[28]
is made explicit and in particular an example with holonomy exactly SU(3) is
found by use of the linearization of [26], which was found in the context of D6
branes wrapping a holomorphic 1-fold in a hyperkahler manifold. But the main
improvement of the present method, unlike the ones presented in [26]-[28], does
not rely in an initial hyperkahler structure. Additionally the complications
when dealing with non linear operators over the curved hyperkahler space are
avoided by use of this method.Comment: Version accepted for publication in Phys.Rev.
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