Detuned branes and supersymmetry breaking

We consider the spontaneous breaking of supersymmetry in five dimensionalsupergravity with boundaries where the supersymmetry breaking mechanism isprovided by the even part of the bulk prepotential. The supersymmetric actioncomprises boundary brane terms with detuned tensions. The two branes haveopposite tensions. We analyse the possible vacua with spontaneously brokensupersymmetry. A class of solutions corresponds to rotated branes in an $AdS_5$bulk. In particular parallel branes which are rotated with respect to the bulkpreserve 1/4 of supersymmetry. We analyse more general vacua using the lowenergy effective action for gravity coupled to the radion field. Supersymmetrybreaking implies that the radion field acquires a potential which is negativeand unbounded from below. This potential is modified when coupling the boundarybranes to a bulk four--form field. For a brane charge larger than the deficitof brane tension, the radion potential is bounded from below while remainingflat when the charge equals the deficit of brane tension.Comment: 25 pages, new section on static solutions, minor changes, final versio