No-scale N=4 supergravity coupled to Yang-Mills: the scalar potential   and super-Higgs effect
  We derive the scalar potential of the effective theory of type   IIB orientifold with 3-form fluxes turned on in presence of non abelian brane coordinates. N=4 supergravity predicts a positive semidefinite potential with vanishing cosmological constant in the vacuum of commuting coordinates, with a classical moduli space given by three radial moduli and three RR scalars which complete three copies of the coset (U(1,1+n)/U(1)\otimes U(1+n)), together with 6n D3-branes coordinates, n being the rank of the gauge group G. Implications for the super Higgs mechanism are also discussed. 
Riccardo D'Auria, Sergio Ferrara, Maria Antonia Lled\'o and Silvia   Vaul\`a