Towards a world-sheet description of doubled geometry in string theory

TL;DR

This paper develops a formalism to reduce doubled target-space dimensions in string theory models via gauging, illustrating T-duality and conformality preservation with examples like the SU(2) WZW model.

Contribution

It introduces a gauging procedure to obtain lower-dimensional string backgrounds from doubled geometries, demonstrating T-duality and conformality in the process.

Findings

Reduction of target-space dimensions by half through gauging.

Identification of T-dual backgrounds as reduced conformal theories.

Explicit example with SU(2) WZW model leading to cigar and trumpet CFTs.

Abstract

Starting from a sigma-model for a doubled target-space geometry, we show that the number of target-space dimensions can be reduced by half through a gauging procedure. We apply this formalism to a class of backgrounds relevant for double field theory, and illustrate how choosing different gaugings leads to string-theory configurations T-dual to each other. We furthermore discuss that given a conformal doubled theory, the reduced theories are conformal as well. As an example we consider the three-dimensional SU(2) WZW model and show that the only possible reduced backgrounds are the cigar and trumpet CFTs in two dimensions, which are indeed T-dual to each other.