Maurer-Cartan forms and equations for two-dimensional superdiffeomorphisms

We present explicit expressions for the Maurer-Cartan forms of the superdiffeomorphism group associated to a super Riemann surface. As an application to superconformal field theory, we use these forms to evaluate the effective action for the factorized superdiffeomorphism anomaly.Comment: (LATEX, 8 pages), MPI-Ph/92-4

About Symmetries in Physics

The goal of this introduction to symmetries is to present some general ideas, to outline the fundamental concepts and results of the subject and to situate a bit the following lectures of this school. [These notes represent the write-up of a lecture presented at the fifth ``Seminaire Rhodanien de Physique: Sur les Symetries en Physique" held at Dolomieu (France), 17-21 March 1997. Up to the appendix and the graphics, it is to be published in "Symmetries in Physics", F.Gieres, M.Kibler,C.Lucchesi and O.Piguet, eds. (Editions Frontieres, 1998).]Comment: Latex, 42 pages, 4 figure

Conformal covariance in 2d conformal and integrable models, in W-algebras and in their supersymmetric extensions

Conformal symmetry underlies the mathematical description of various two-dimensional integrable models (e.g. for their Lax representation, Poisson algebra, zero curvature representation,...) or of conformal models (for the anomalous Ward identities, operator product expansion, Krichever-Novikov algebra,...) and of W-algebras. Here, we review the construction of conformally covariant differential operators which allow to render the conformal covariance manifest. The N=1 and N=2 supersymmetric generalizations of these results are also indicated and it is shown that they involve nonstandard matrix formats of Lie superalgebras.Comment: Proceedings of the workshop "Supersymmetries and Quantum Symmetries" (SQS'99, Dubna, July 1999

d=2, N=2 Superconformally Covariant Operators and Super W-Algebras

We construct and classify superconformally covariant differential operators defined on N=2 super Riemann surfaces. By contrast to the N=1 theory, these operators give rise to partial rather than ordinary differential equations which leads to novel features for their matrix representation. The latter is applied to the derivation of N=2 super W-algebras in terms of N=2 superfields.Comment: 29 pages, LaTe

Superconformally covariant operators and super W algebras

We study superdifferential operators of order $2n+1$ which are covariant with respect to superconformal changes of coordinates on a compact super Riemann surface. We show that all such operators arise from super M\"obius covariant ones. A canonical matrix representation is presented and applications to classical super W algebras are discussed.Comment: 23 pages, LATEX, MPI-Ph/92-66 and KA-THEP-7/9

Classical N=1N=1 and N=2N=2 super W-algebras from a zero-curvature condition

Starting from superdifferential operators in an $N=1$ superfield formulation, we present a systematic prescription for the derivation of classical $N=1$ and $N=2$ super W-algebras by imposing a zero-curvature condition on the connection of the corresponding first order system. We illustrate the procedure on the first non-trivial example (beyond the $N=1$ superconformal algebra) and also comment on the relation with the Gelfand-Dickey construction of $W$-algebras.Comment: 18 pages, tex, LMU-TPW 93-0

Relating Weyl and diffeomorphism anomalies on super Riemann surfaces

Starting from the Wess-Zumino action associated to the super Weyl anomaly, we determine the local counterterm which allows to pass from this anomaly to the chirally split superdiffeomorphism anomaly (as defined on a compact super Riemann surface without boundary). The counterterm involves the graded extension of the Verlinde functional and the results can be applied to the study of holomorphic factorization of partition functions in superconformal field theory.Comment: (LATEX, 18 pages), MPI-Ph/92-38, LPTB 92-

Formalisme de Dirac et surprises mathematiques en mecanique quantique

Differents formalismes sont utilises en mecanique quantique pour la description des etats et des observables : la mecanique ondulatoire, la mecanique matricielle et le formalisme invariant. Nous discutons les problemes et inconvenients du formalisme invariant ainsi que ceux de la notation des bras et kets introduite par Dirac dans ce contexte. Nous indiquons comment tous les problemes peuvent etre resolus ou du moins evites. Une serie d'exemples illustre les points souleves et montre comment l'insouciance mathematique peut aisement conduire a des contradictions mathematiques surprenantes.Comment: 40 pages, French version of the preprint LYCEN 9960

Vector supersymmetry in topological field theories

We present a simple derivation of vector supersymmetry transformations for topological field theories of Schwarz- and Witten-type. Our method is similar to the derivation of BRST-transformations from the so-called horizontality conditions or Russian formulae. We show that this procedure reproduces in a concise way the known vector supersymmetry transformations of various topological models and we use it to obtain some new transformations of this type for 4d topological YM-theories in different gauges.Comment: 19 page