Strings from $N=2$ Gauged Wess-Zumino-Witten Models

TL;DR

This paper develops an algebraic framework for string theory using $sl(2|1)$ embeddings in super Lie algebras, leading to a classification of extended $N=2$ superconformal algebras and associated string models.

Contribution

It provides a comprehensive classification of $sl(2|1)$ embeddings in Lie superalgebras and their role in constructing extended $N=2$ superconformal algebras and string theories.

Findings

Classified all embeddings of $sl(2|1)$ into Lie superalgebras.

Characterized the resulting extended $N=2$ superconformal algebras.

Connected embeddings to string theory BRST structures.

Abstract

We present an algebraic approach to string theory. An embedding of $sl(2|1)$ in a super Lie algebra together with a grading on the Lie algebra determines a nilpotent subalgebra of the super Lie algebra. Chirally gauging this subalgebra in the corresponding Wess-Zumino-Witten model, breaks the affine symmetry of the Wess-Zumino-Witten model to some extension of the $N=2$ superconformal algebra. The extension is completely determined by the $sl(2|1)$ embedding. The realization of the superconformal algebra is determined by the grading. For a particular choice of grading, one obtains in this way, after twisting, the BRST structure of a string theory. We classify all embeddings of $sl(2|1)$ into Lie super algebras and give a detailed account of the branching of the adjoint representation. This provides an exhaustive classification and characterization of both all extended $N=2$ superconformal algebras and all string theories which can be obtained in this way.