Non-unimodular reductions and N = 4 gauged supergravities

TL;DR

This paper explores a class of four-dimensional N=4 supergravities derived from higher-dimensional theories using non-unimodular reductions, expanding the understanding of fluxes and gaugings in string theory.

Contribution

It introduces a method to obtain N=4 supergravities via non-unimodular Scherk--Schwarz reductions, linking heterotic fluxes to gauged supergravities with axionic symmetries.

Findings

Demonstrates how to evade unimodularity constraints in reductions.

Establishes a correspondence between heterotic fluxes and gauged supergravities.

Provides a framework for deriving N=4 supergravities from higher dimensions.

Abstract

We analyze the class of four-dimensional N = 4 supergravities obtained by gauging the axionic shift and axionic rescaling symmetries. These theories are formulated with the machinery of embedding tensors and shown to be deducible from higher dimensions using a Scherk--Schwarz reduction with a twist by a non-compact symmetry. This allows to evade the usual unimodularity requirement and completes the dictionary between heterotic gaugings and fluxes, at least for the "geometric sector".