New Model of N=8 Superconformal Mechanics

10 pagesUsing an N =4, d=1 superfield approach, we construct an N =8 supersymmetric action of the self-interacting off-shell N =8 multiplet (1, 8, 7). This action is found to be invariant under the exceptional N =8, d=1 superconformal group F (4) with the R-symmetry subgroup SO(7). The general N =8 supersymmetric (1,8, 7) action is a sum of the super- conformal action and the previously known free bilinear action. We show that the general action is also superconformal, but with respect to redefined superfield transformation laws. The scalar potential can be generated by two Fayet-Iliopoulos N =4 superfield terms which preserve N =8 supersymmetry but break the superconformal and S O(7) symmetries

Supersymmetric Black Holes from Toda Theories

On the example of nonabelian Toda type theory associated with the Lie superalgebra $osp(2|4)$ we show that this integrable dynamical system is relevant to a black hole background metric in the corresponding target space. In the even sector the model under consideration reduces to the exactly solvable conformal theory (nonabelian $B_2$ Toda system) in the presence of a black hole recently proposed in the article "Black holes from non-abelian Toda theories" by the last two authors (hep-th 9203039).Comment: 4 pages, Late

d=2, N=2 Superconformal Symmetries and Models

We discuss the following aspects of two-dimensional N=2 supersymmetric theories defined on compact super Riemann surfaces: parametrization of (2,0) and (2,2) superconformal structures in terms of Beltrami coefficients and formulation of superconformal models on such surfaces (invariant actions, anomalies and compensating actions, Ward identities).Comment: 43 pages, late

Observables in Topological Theories: A Superspace Formulation

Observables of topological Yang-Mills theory were defined by Witten as the classes of an equivariant cohomology. We propose to define them alternatively as the BRST cohomology classes of a superspace version of the theory, where BRST invariance is associated to super Yang-Mills invariance. We provide and discuss the general solution of this cohomology.Comment: Prepared for International Conference on Renormalization Group and Anomalies in Gravity and Cosmology (IRGA 2003), Ouro Preto, MG, Brazil, 17-23 Mar 200

Observables in Topological Yang-Mills Theories

Using topological Yang-Mills theory as example, we discuss the definition and determination of observables in topological field theories (of Witten-type) within the superspace formulation proposed by Horne. This approach to the equivariant cohomology leads to a set of bi-descent equations involving the BRST and supersymmetry operators as well as the exterior derivative. This allows us to determine superspace expressions for all observables, and thereby to recover the Donaldson-Witten polynomials when choosing a Wess-Zumino-type gauge.Comment: 39 pages, Late

Note on Constrained Cohomology

The cohomology of the BRS operator corresponding to a group of rigid symmetries is studied in a space of local field functionals subjected to a condition of gauge invariance. We propose a procedure based on a filtration operator counting the degree in the infinitesimal parameters of the rigid symmetry transformations. An application to Witten's topological Yang-Mills theory is given.Comment: appendix and refs adde

Light-like integrability in loop superspace, Kac-Moody central charges and Chern-Simons terms

We apply the idea of light-like integrability in loop superspace to give a complete derivation of all the constraints of on-shell ten-dimensional supergravity coupled to Yang-Mills. The Yang-Mills Chern-Simons coupling terms are obtained by adding a central extension to the Kac-Moody algebra of the Yang-Mills generators. The form of the loop-superspace covariant derivatives, including the central charge modifications, can also be derived by means of canonical quantization from a Green-Schwarz superstring coupled to a supergravity and super-Yang-Mills background. There the Yang-Mills sector is represented by bosonic group coordinates, which are chiral and describe a gauged Wess-Zumino-Witten model.