Gauging of Flat Groups in Four Dimensional Supergravity

TL;DR

This paper demonstrates that certain N=8 supergravity theories, obtained via Scherk-Schwarz reduction, can be understood through gauging specific electric subgroups of the U-duality group, revealing new inequivalent gaugings.

Contribution

It shows that Scherk-Schwarz gaugings are distinct from previously classified N=8 supergravities by analyzing electric subgroup gaugings of E_{7,7}.

Findings

Different electric subgroups lead to inequivalent supergravity theories.

Scherk-Schwarz gaugings are not included in previous classifications.

Gauging flat groups relates to string compactifications with brane fluxes.

Abstract

We show that N=8 spontaneously broken supergravity in four dimensions obtained by Scherk-Schwarz generalized dimensional reduction can be obtained from a pure four dimensional perspective by gauging a suitable electric subgroup of E_{7,7}. Owing to the fact that there are non isomorphic choices of maximal electric subgroups of the U-duality group their gaugings give rise to inequivalent theories. This in particular shows that the Scherk-Schwarz gaugings do not fall in previous classifications of possible gauged N=8 supergravities. Gauging of flat groups appear in many examples of string compactifications in presence of brane fluxes.