7,179 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
Supersymmetry and homogeneity of M-theory backgrounds
We describe the construction of a Lie superalgebra associated to an arbitrary
supersymmetric M-theory background, and discuss some examples. We prove that
for backgrounds with more than 24 supercharges, the bosonic subalgebra acts
locally transitively. In particular, we prove that backgrounds with more than
24 supersymmetries are necessarily (locally) homogeneous.Comment: 19 pages (Erroneous Section 6.3 removed from the paper.
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
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
The return of the four- and five-dimensional preons
We prove the existence of 3/4-BPS preons in four- and five-dimensional gauged
supergravities by explicitly constructing them as smooth quotients of the AdS_4
and AdS_5 maximally supersymmetric backgrounds, respectively. This result
illustrates how the spacetime topology resurrects a fraction of supersymmetry
previously ruled out by the local analysis of the Killing spinor equations.Comment: 10 pages (a minor imprecision has been corrected
Supersymmetry and gauge theory on Calabi-Yau 3-folds
We consider the dimensional reduction of supersymmetric Yang-Mills on a
Calabi-Yau 3-fold. We show by construction how the resulting cohomological
theory is related to the balanced field theory of the Kaehler Yang-Mills
equations introduced by Donaldson and Uhlenbeck-Yau.Comment: 11 page
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