T-duality versus Gauge Symmetry

TL;DR

This paper reviews double field theory, which incorporates T-duality as a symmetry by introducing dual coordinates, and explores its relation to gauge symmetries in string theory.

Contribution

It presents a covariant formulation of string effective actions that unifies T-duality and gauge symmetries through double field theory.

Findings

T-duality is realized as a global symmetry in double field theory.

The theory introduces dual coordinates for winding modes.

It clarifies the relationship between duality symmetries and gauge invariance.

Abstract

We review the recently constructed `double field theory' which introduces in addition to the conventional coordinates associated to momentum modes coordinates associated to winding modes. Thereby, T-duality becomes a global symmetry of the theory, which can be viewed as an `O(D,D) covariantization' of the low-energy effective space-time action of closed string theory. We discuss its symmetries with a special emphasis on the relation between global duality symmetries and local gauge symmetries.