Racetrack models in theories from extra dimensions

We have investigated moduli stabilization leading to hierarchical supersymmetry breakdown in racetrack models with two moduli fields simultaneously present in the effective racetrack superpotential. We have shown that stabilization of moduli occurs when a shift symmetry of the moduli space becomes gauged. This gauging results in a D-term contribution to the scalar potential that depends on moduli scalars. To break supersymmetry at a minimum created this way in the case where only a single combination of moduli is present in the superpotential one needs supergravity corrections. If the superpotential depends on two independent combinations of moduli, supersymmetry is broken by non-vanishing F-terms without supergravity terms. Some of the minima that we see correspond to a non-vanishing expectation value of the blowing-up modulus in the case of type-IIB orientifold models. We point out that the mass of the gauge boson associated with gauged shift symmetry becomes naturally light in warped compactifications. (author)