329 research outputs found
The homogeneity theorem for supergravity backgrounds
We prove the strong homogeneity conjecture for eleven- and ten-dimensional
(Poincar\'e) supergravity backgrounds. In other words, we show that any
backgrounds of 11-dimensional, type I/heterotic or type II supergravity
theories preserving a fraction greater than one half of the supersymmetry of
the underlying theory are necessarily locally homogeneous. Moreover we show
that the homogeneity is due precisely to the supersymmetry, so that at every
point of the spacetime one can find a frame for the tangent space made out of
Killing vectors constructed out of the Killing spinors.Comment: 8 page
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
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
Pluecker-type relations for orthogonal planes
We explore a Pluecker-type relation which occurs naturally in the study of
maximally supersymmetric solutions of certain supergravity theories. This
relation generalises at the same time the classical Pluecker relation and the
Jacobi identity for a metric Lie algebra and coincides with the Jacobi identity
of a metric n-Lie algebra. In low dimension we present evidence for a geometric
characterisation of the relation in terms of middle-dimensional orthogonal
planes in euclidean or lorentzian inner product spaces.Comment: 39 pages (v2: substantial revision, 33% more material, link with
n-Lie algebras
Classification of IIB backgrounds with 28 supersymmetries
We show that all IIB backgrounds with strictly 28 supersymmetries are locally
isometric to the plane wave solution of arXiv:hep-th/0206195. Moreover, we
demonstrate that all solutions with more than 26 supersymmetries and only
5-form flux are maximally supersymmetric. The N=28 plane wave solution is a
superposition of the maximally supersymmetric IIB plane wave with a heterotic
string solution. We investigate the propagation of strings in this background,
find the spectrum and give the string light-cone Hamiltonian.Comment: 30 pages, typos correcte
Three-Algebras and N=6 Chern-Simons Gauge Theories
We derive the general form for a three-dimensional scale-invariant field
theory with N=6 supersymmetry, SU(4) R-symmetry and a U(1) global symmetry. The
results can be written in terms of a 3-algebra in which the triple product is
not antisymmetric. For a specific choice of 3-algebra we obtain the N=6
theories that have been recently proposed as models for M2-branes in an R^8/Z_k
orbifold background.Comment: 19 pages. Typos correcte
On the structure of symmetric self-dual Lie algebras
A finite-dimensional Lie algebra is called (symmetric) self-dual, if it
possesses an invariant nondegenerate (symmetric) bilinear form. Symmetric
self-dual Lie algebras have been studied by Medina and Revoy, who have proven a
very useful theorem about their structure. In this paper we prove a refinement
of their theorem which has wide applicability in Conformal Field Theory, where
symmetric self-dual Lie algebras start to play an important role due to the
fact that they are precisely the Lie algebras which admit a Sugawara
construction. We also prove a few corollaries which are important in Conformal
Field Theory. (This paper provides mathematical details of results used, but
only sketched, in the companion paper hep-th/9506151.)Comment: 19 pages, .dvi.uu (needs AMSFonts 2.1+
Strategy for the introduction of information technologies and communications
Las TecnologĂas de la InformaciĂłn y las Comunicaciones (TIC) son un medio para transmitir y gestionar datos, informaciĂłn y conocimiento; pero las profundas transformaciones sociales que han provocado, muestran lo importante y necesario que resulta en la actualidad que los procesos formativos universitarios las empleen en su perfeccionamiento y de este modo contribuir a la formaciĂłn de los profesionales que la sociedad necesita. El objetivo de este artĂculo es mostrar los principales elementos de una estrategia elaborada por un grupo de profesores para desarrollar un proceso de introducciĂłn de las TIC que permita transformar los planes de estudio y el proceso de enseñanza aprendizaje, acorde con los principios de la Nueva Universidad Cubana, en el Instituto Superior Minero MetalĂșrgico âAntonio NĂșñez JimĂ©nezâ (ISMMM).The Information and the Communications Technologies (ICT) are a
midway to transmit and manage data, information and knowledge; But the deep
social transformations that they have provoked, evidence the important and
necessary that work out at the present time that formative university processes use
them in his perfecting and in this way contributing to the formation of the
professionals that the society needs. The objective of this article is to show the
principal elements of strategy elaborated by a group of professors to develop a
process of introduction of the TIC that it permits transforming the curriculums and
the tuitional process learning, chord with the principles of the Nueva Universidad
Cubana at the Institute Superior Minero MetalĂșrgico Antonio NĂșñez JimĂ©nez,
(ISMMM)
Scaling limit of N=6 superconformal Chern-Simons theories and Lorentzian Bagger-Lambert theories
We show that the N=8 superconformal Bagger-Lambert theory based on the
Lorentzian 3-algebra can be derived by taking a certain scaling limit of the
recently proposed N=6 superconformal U(N)xU(N) Chern-Simons-matter theories at
level (k, -k). The scaling limit (and Inonu-Wigner contraction) is to scale the
trace part of the bifundamental fields as X_0 -> \lambda^{-1} X_0 and an axial
combination of the two gauge fields as B_{\mu} -> \lambda B_\mu. Simultaneously
we scale the level as k -> \lambda^{-1} k and then take \lambda -> 0 limit.
Interestingly the same constraint equation \partial^2 X_0=0 is derived by
imposing finiteness of the action. In this scaling limit, M2-branes are located
far from the origin of C^4/Z_k compared to their fluctuations and Z_k
identification becomes a circle identification. Hence the scaled theory
describes N=8 supersymmetric theory of 2-branes with dynamical coupling. The
coupling constant is promoted to a space-time dependent SO(8) vector X_0^I and
we show that the scaled theory has a generalized conformal symmetry as well as
manifest SO(8) with the transformation of the background fields X_0^I.Comment: 21 pages; v2 a subsection added to discuss Generalized Conformal
Invariance; v3 discussions on gravity dual added; v4 published version in PR
M2-branes, Einstein manifolds and triple systems
This is the written version of a talk given on 1 July 2009 at the XXV Max
Born Symposium: the Planck Scale, held in Wroclaw, Poland. I review the
possible transverse geometries to supersymmetric M2-brane configurations and
discuss the representation-theoretic description of their conjectured dual
superconformal Chern-Simons theories.Comment: 12 pages; V2: reference(s) adde
- âŠ