NewD= 4 gauged supergravities from Script N = 4 orientifolds with fluxes

We consider classes of T_6 orientifolds, where the orientifold projectioncontains an inversion I_{9-p} on 9-p coordinates, transverse to a Dp-brane. Inabsence of fluxes, the massless sector of these models corresponds to diverseforms of N=4 supergravity, with six bulk vector multiplets coupled to N=4Yang--Mills theory on the branes. They all differ in the choice of the dualitysymmetry corresponding to different embeddings of SU(1,1)\times SO(6,6+n) inSp(24+2n,R), the latter being the full group of duality rotations. Hence, theseLagrangians are not related by local field redefinitions. When fluxes areturned on one can construct new gaugings of N=4 supergravity, where the twelvebulk vectors gauge some nilpotent algebra which, in turn, depends on the choiceof fluxes.Comment: 51 pages, 1 figure. Latex. Reference added. Typos corrected. Discussion on gaugings expande