On the unitarity of gauged non-compact WZNW strings

Understand

In this paper we investigate the unitarity of gauged non-compact WZNW strings i.e.

• string theories formulated as G/H' WZNW models, where G is a non-compact group.
• These models represent string theories on non-trivial curved space-times with one time-like component.
• We will prove that for the class of models connected to Hermitian symmetric spaces, and a natural set of discrete highest weight representations, the BRST formulation, in which the gauging is defined through a BRST condition, yields unitarity.