Five-brane actions in double field theory

TL;DR

This paper develops a covariant action for NSNS 5-branes within double field theory, enabling a unified description of T-duality orbits and non-geometric five-branes through coordinate doubling and a gauged sigma model approach.

Contribution

It introduces a novel covariant worldvolume action for NSNS 5-branes that incorporates T-duality and non-geometric branes using doubled coordinates and a gauged sigma model framework.

Findings

Successfully constructs a T-duality covariant 5-brane action.

Unifies descriptions of IIB NS5, IIA KKM, and exotic branes.

Provides a framework for understanding non-geometric five-branes.

Abstract

We construct an action for NSNS 5-branes which is manifestly covariant under O(d,d). This is done by doubling $d$ of the spacetime coordinates which appear in the worldvolume action. By formulating the DBI part of the action in a manner similar to a "gauged sigma model", only half the doubled coordinates genuinely appear. Our approach allows one to describe the full T-duality orbit of the IIB NS5 brane, the IIA KKM and their exotic relations in one formalism. Furthermore, by using ideas from double field theory, our action can be said to describe various aspects of non-geometric five-branes.