New D=4 gauged supergravities from N=4 orientifolds with fluxes
C. Angelantonj, S. Ferrara, M. Trigiante
TL;DR
The paper analyzes four-dimensional ${ Scr N}=4$ orientifolds with fluxes, showing that different $T_6$ orientifold projections yield distinct duality embeddings and massless spectra. It identifies nilpotent axion algebras $N_p subseteq so(6,6)$ arising from RR and NS-NS axions, which determine the possible gaugings when fluxes are introduced. By embedding these theories into the ${ Scr N}=8$ framework with ${E}_{7(7)}$ duality, the authors derive the structure of the vector sector, scalar manifold, and the gauging mechanism via local Peccei–Quinn symmetries. The results provide a systematic route to generate new $D=4$ gauged ${ Scr N}=4$ supergravities with six bulk vector multiplets and a brane Yang–Mills sector, with implications for moduli stabilization and future extensions to ${ Scr N}=2,1$ models.
Abstract
We consider classes of T_6 orientifolds, where the orientifold projection contains an inversion I_{9-p} on 9-p coordinates, transverse to a Dp-brane. In absence of fluxes, the massless sector of these models corresponds to diverse forms of N=4 supergravity, with six bulk vector multiplets coupled to N=4 Yang--Mills theory on the branes. They all differ in the choice of the duality symmetry corresponding to different embeddings of SU(1,1)\times SO(6,6+n) in Sp(24+2n,R), the latter being the full group of duality rotations. Hence, these Lagrangians are not related by local field redefinitions. When fluxes are turned on one can construct new gaugings of N=4 supergravity, where the twelve bulk vectors gauge some nilpotent algebra which, in turn, depends on the choice of fluxes.
