7 research outputs found
A Kaluza-Klein inspired action for chiral p-forms and their anomalies
The dynamics of chiral p-forms can be captured by a lower-dimensional
parity-violating action motivated by a Kaluza-Klein reduction on a circle. The
massless modes are (p-1)-forms with standard kinetic terms and Chern-Simons
couplings to the Kaluza-Klein vector of the background metric. The massive
modes are p-forms charged under the Kaluza-Klein vector and admit parity-odd
first-order kinetic terms. Gauge invariance is implemented by a
Stueckelberg-like mechanism using (p-1)-forms. A Chern-Simons term for the
Kaluza-Klein vector is generated at one loop by massive p-form modes. These
findings are shown to be consistent with anomalies and supersymmetry for
six-dimensional supergravity theories with chiral tensor multiplets.Comment: 4 pages, 1 figur
Defect Branes
We discuss some general properties of "defect branes", i.e. branes of
co-dimension two, in (toroidally compactified) IIA/IIB string theory. In
particular, we give a full classification of the supersymmetric defect branes
in dimensions 2 < D < 11 as well as their higher-dimensionalstring and M-theory
origin as branes and a set of "generalized" Kaluza-Klein monopoles. We point
out a relation between the generalized Kaluza-Klein monopole solutions and a
particular type of mixed-symmetry tensors. These mixed-symmetry tensors can be
defined at the linearized level as duals of the supergravity potentials that
describe propagating degrees of freedom. It is noted that the number of
supersymmetric defect branes is always twice the number of corresponding
central charges in the supersymmetry algebra.Comment: Latex2e paper, 28 pages, no figures. Footnote adde
H-FGK formalism for black-hole solutions of N=2, d=4 and d=5 supergravity
We rewrite the Ferrara-Gibbons-Kallosh (FGK) black-hole effective action of
N=2, d=4,5 supergravities coupled to vector multiplets, replacing the metric
warp factor and the physical scalars with real variables that transform in the
same way as the charges under duality transformations, which simplifies the
equations of motion. For a given model, the form of the solution in these
variables is the same for all spherically symmetric black holes, regardless of
supersymmetry or extremality.Comment: 10 pages; v2: references added, some editing of the text, results
unchanged; v3: references added as in the published versio
Fluxed M5-instantons in F-theory
We analyse the non-perturbative superpotential due to M5-brane instantons in
F-theory compactifications on Calabi-Yau fourfolds. The M5 partition function
is obtained via holomorphic factorisation by explicitly performing the sum over
chiral 3-form fluxes. Comparison with the partition function of fluxed
Euclidean D3-brane instantons in Type IIB orientifolds allows us to fix the
spin structure on the intermediate Jacobian of the M5-instanton. We furthermore
analyse the contribution of the M5-instanton to the superpotential in the
presence of G4 gauge flux, where the superpotential is dressed with matter
fields. We explicitly evaluate the pullback of G4 onto the M5-brane as a
measure for the presence of charged instanton zero modes. This accounts for the
M5 charge both under massless U(1)s, if present, and under what corresponds in
Type II language to geometrically massive U(1)s.Comment: 47 pages. v3: refs. added, matches version published in Nuclear
Physics
Consistent reductions from D=11 beyond Sasaki-Einstein
The most general class of warped AdS5 x M6 supersymmetric solutions in D=11
supergravity permit a consistent truncation to D=5 N=2 minimal gauged
supergravity. Here we extend this truncation, for a particular subclass of M6
manifolds, to D=5 N=4 gauged supergravity coupled to two vector multiplets. We
obtain the reduction ansatz by T-duality of a recently discussed type IIB
truncation on a generic Sasaki-Einstein five-fold, which becomes non-trivial in
D=11 and displays non-standard features due to the G-structure of the internal
M6. Using this truncation, we construct two new classes of warped and unwarped
non-supersymmetric AdS5 M-theory backgrounds. We also comment on possible
extensions of the reduction ansatz to the general class of M6 geometries.Comment: Seven double column pages; v2: Acknowledgement added, version to be
published in Phys. Lett.
On Type IIB moduli stabilization and N = 4, 8 supergravities
We analyze D = 4 compactifications of Type IIB theory with generic, geometric
and non-geometric, dual fluxes turned on. In particular, we study N = 1
toroidal orbifold compactifications that admit an embedding of the untwisted
sector into gauged N = 4, 8 supergravities. Truncations, spontaneous breaking
of supersymmetry and the inclusion of sources are discussed. The algebraic
identities satisfied by the supergravity gaugings are used to implement the
full set of consistency constraints on the background fluxes. This allows to
perform a generic study of N = 1 vacua and identify large regions of the
parameter space that do not admit complete moduli stabilization. Illustrative
examples of AdS and Minkowski vacua are presented.Comment: 48 pages, 1 figure. References added. Published in NP B 849 (2011)
pp. 80-11