Supersymmetric brane-worlds

We present warped metrics which solve Einstein equations with arbitrary cos mological constants in both in upper and lower dimensions. When the lower-d imensional metric is the maximally symmetric one compatible with the chosen value of the cosmological constant, the upper-dimensional metric is also t he maximally symmetric one and there is maximal unbroken supersymmetry as w ell. We then introduce brane sources and find solutions with analogous propertie s, except for supersymmetry, which is generically broken in the orbifolding procedure (one half is preserved in two special cases), and analyze metric perturbations in these backgrounds. In analogy with the D8-brane we propose an effective ((d) over cap - 2)-bra ne action which acts as a source for the RS solution. The action consists o f a Nambu-Goto piece and a Wess-Zumino term containing a ((d) over cap - 1) -form field. It has the standard form of the action for a BPS extended obje ct, in correspondence with the supersymmetry preserved by the solution. (C) 2000 Elsevier Science B.V. All rights reserved.