Generalized metric formulation of double field theory

TL;DR

This paper presents a new formulation of double field theory using a generalized metric that makes T-duality symmetry manifest, providing a clearer geometric understanding of the massless sector of closed strings.

Contribution

It introduces a simple, T-duality covariant formulation of double field theory based on a generalized metric and a generalized Lie derivative, extending the Courant bracket.

Findings

Manifest T-duality in double field theory

Unified geometric framework for metric and B-field

Extension of Courant bracket algebra

Abstract

The generalized metric is a T-duality covariant symmetric matrix constructed from the metric and two-form gauge field and arises in generalized geometry. We view it here as a metric on the doubled spacetime and use it to give a simple formulation with manifest T-duality of the double field theory that describes the massless sector of closed strings. The gauge transformations are written in terms of a generalized Lie derivative whose commutator algebra is defined by a double field theory extension of the Courant bracket.