New D = 4 gauged supergravities from N = 4 orientifolds with fluxes

We consider classes of T6–orientifolds, where the orientifold projection contains an inversion I9−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)×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.