Supersymmetry breakdown at a hidden wall

We consider hidden sector supersymmetry breakdown in the strongly coupled heterotic Es x Es theory of Horava and Witten. Using effective field theory methods in four dimensions, we can show hat gravitational interactions induce soft breaking terms in the observable sector that are of order of the gravitino mass. We apply these methods to the mechanism of gaugino condensation at the hidden wall. Although the situation is very similar to the weakly coupled case, there is a decisive difference concerning the observable sector gaugino mass; with desirable phenomenological as well as cosmological consequences. (C) 1998 Elsevier Science B.V.