Unusual gauged supergravities from type IIA and type IIB orientifolds

TL;DR

This paper investigates how fluxes in type IIA and IIB orientifold compactifications lead to novel N=4 supergravities with non-semisimple gauge algebras, revealing new mechanisms of gauge symmetry breaking and non-abelian structures.

Contribution

It identifies the specific gauge algebras arising from flux compactifications and describes their structure and implications for supergravity theories.

Findings

Fluxes induce non-semisimple gauge algebras in supergravity.

Non-metric axions have Stueckelberg couplings causing symmetry breaking.

Four cases exhibit non-abelian gauge structures due to fluxes.

Abstract

We analyse different N=4 supergravities coupled to six vector multiplets corresponding to low-energy descriptions of the bulk sector of T6/Z2 orientifolds with p-brane in IIB (p odd) and in IIA (p even) superstrings. When fluxes are turned on, a gauging emerges corresponding to some non-semisimple Lie algebra related to nilpotent algebras N_p inside so(6,6), with dimension 15 + (p-3)(9-p). The non-metric axions have Stueckelberg couplings that induce a spontaneous breaking of gauge symmetries. In four cases the gauge algebra is non-abelian with a non-commutative structure of the compactification torus, due to fluxes of NS-NS and R-R forms.