Exotic branes and non-geometric fluxes

TL;DR

This paper develops ten-dimensional effective actions for non-geometric fluxes with exotic branes as magnetic sources, revealing new solutions and dualities in string theory backgrounds.

Contribution

It introduces a U-dual version of $eta$-supergravity tailored for non-geometric backgrounds and identifies solutions corresponding to exotic branes and their dual instantons.

Findings

Exotic brane backgrounds are single-valued up to gauge transformations.

New solutions for exotic branes and their electric dual instantons are found.

Theories extend $eta$-supergravity to include non-geometric fluxes and exotic sources.

Abstract

We present and study ten-dimensional effective actions for various non-geometric fluxes of which exotic branes act as the magnetic sources. Each theory can be regarded as a U-dual version of the $\beta$-supergravity, a reformulation of the ten-dimensional supergravity which is suitable for describing non-geometric backgrounds with Q-flux. In each theory, we find a solution that corresponds to the background of an exotic brane and show that it is single-valued up to a gauge transformation, although the same background written in the standard background fields is not single-valued in a usual sense. Further, we also find a solution which corresponds to the background of an instanton that is the electric dual of the exotic brane and discuss its properties.