10,492 research outputs found
Lorentzian Lie n-algebras
We classify Lie n-algebras possessing an invariant lorentzian inner product.Comment: 10 pages (V2: more details on Section 3 and a new lemma. V3: typos
corrected
Untwisting Topological Field Theories
A method is presented by which a hidden N=2 superconformal symmetry can be
exhibited in a string theory or indeed in a topological conformal field theory.
More precisely, we present strong evidence, based on calculations with string
theories, in favour of the conjecture that any topological conformal field
theory can be obtained by twisting an N=2 superconformal field theory. (Talk
given at the Workshop on Gauge Theories, Applied Supersymmetry and Quantum
Gravity held at Imperial College, London, 5-10 July 1996.)Comment: 9 pages, LaTeX 2e (amsfonts, euscript
New Supersymmetrizations of the Generalized KdV Hierarchies
Recently we investigated a new supersymmetrization procedure for the KdV
hierarchy inspired in some recent work on supersymmetric matrix models. We
extend this procedure here for the generalized KdV hierarchies. The resulting
supersymmetric hierarchies are generically nonlocal, except for the case of
Boussinesque which we treat in detail. The resulting supersymmetric hierarchy
is integrable and bihamiltonian and contains the Boussinesque hierarchy as a
subhierarchy. In a particular realization, we extend it by defining
supersymmetric odd flows. We end with some comments on a slight modification of
this supersymmetrization which yields local equations for any generalized KdV
hierarchy.Comment: 10 pages, uuencoded compressed tar'd .dvi file, Bonn-HE-93-1
A geometric construction of the exceptional Lie algebras F4 and E8
We present a geometric construction of the exceptional Lie algebras F4 and E8
starting from the round 8- and 15-spheres, respectively, inspired by the
construction of the Killing superalgebra of a supersymmetric supergravity
background. (There is no supergravity in the paper.)Comment: 12 page
D-brane charge, flux quantisation and relative (co)homology
We reconsider the problem of U(1) flux and D0-charge for D-branes in the WZW
model and investigate the relationship between the different definitions that
have been proposed recently. We identify the D0-charge as a particular
reduction of a class in the relative cohomology of the group modulo the
D-submanifold. We investigate under which conditions this class is equivalent
to the first Chern class of a line bundle on the D-submanifold and we find that
in general there is an obstruction given by the cohomology class of the NS
3-form. Therefore we conclude that for topologically nontrivial B-fields, there
is strictly speaking no U(1) gauge field on the D-submanifold. Nevertheless the
ambiguity in the flux is not detected by the D0-charge. This has a natural
interpretation in terms of gerbes.Comment: 16 pages, 3 figures (v2: cosmetic changes and definition of relative
de Rham complex
Supersymmetric Kaluza-Klein reductions of M-waves and MKK-monopoles
We investigate the Kaluza-Klein reductions to ten dimensions of the purely
gravitational half-BPS M-theory backgrounds: the M-wave and the Kaluza-Klein
monopole. We determine the moduli space of smooth (supersymmetric) Kaluza-Klein
reductions by classifying the freely-acting spacelike Killing vectors which
preserve some Killing spinor. As a consequence we find a wealth of new
supersymmetric IIA configurations involving composite and/or bound-state
configurations of waves, D0 and D6-branes, Kaluza-Klein monopoles in type IIA
and flux/nullbranes, and some other new configurations. Some new features
raised by the geometry of the Taub-NUT space are discussed, namely the
existence of reductions with no continuous moduli. We also propose an
interpretation of the flux 5-brane in terms of the local description (close to
the branes) of a bound state of D6-branes and ten-dimensional Kaluza-Klein
monopoles.Comment: 36 pages (v2: Reference added, "draft" mode disabled; v3: two
singular reductions discarded, appendix on spin structures added, references
updated
A new maximally supersymmetric background of IIB superstring theory
We present a maximally supersymmetric IIB string background. The geometry is
that of a conformally flat lorentzian symmetric space G/K with solvable G, with
a homogeneous five-form flux. We give the explicit supergravity solution,
compute the isometries, the 32 Killing spinors, and the symmetry superalgebra,
and then discuss T-duality and the relation to M-theory.Comment: 17 page
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