Background independent action for double field theory

TL;DR

This paper develops a background-independent, T-duality invariant action for double field theory, unifying gravity, antisymmetric tensor, and dilaton fields with dual fields and gauge invariance.

Contribution

It constructs the first nonlinear background-independent action for double field theory that realizes the Courant gauge algebra and maintains T-duality invariance.

Findings

The action unifies standard and dual fields with gauge invariance.

It demonstrates T-duality invariance of the nonlinear action.

The formulation includes a mixed term ensuring gauge invariance.

Abstract

Double field theory describes a massless subsector of closed string theory with both momentum and winding excitations. The gauge algebra is governed by the Courant bracket in certain subsectors of this double field theory. We construct the associated nonlinear background-independent action that is T-duality invariant and realizes the Courant gauge algebra. The action is the sum of a standard action for gravity, antisymmetric tensor, and dilaton fields written with ordinary derivatives, a similar action for dual fields with dual derivatives, and a mixed term that is needed for gauge invariance.