Spontaneous Scherk-Schwarz Supersymmetry Breaking and Radion Stabilization

In this talk I review the issues of supersymmetry breaking and radion stabilization in a five dimensional theory compactified on the Z₂ orbifold. Supersymmetry breaking by Scherk-Schwarz boundary conditions is interpreted as spontaneous breaking of local supersymmetry by the Hosotani mechanism. The auxiliary field responsible for spontaneous supersymmetry breaking is inside the five-dimensional off-shell minimal supergravity multiplet. Different ways of fixing the supersymmetry breaking order parameter are analyzed. In the presence of supersymmetry breaking the one-loop effective potential for the radion has a minimum that fixes its vacuum expectation value. The radion is stabilized in a metastable Minkowski₄ minimum (versus the AdS₄ vacuum) with a mass in the meV range making it interesting for future deviations from the gravitational inverse-square law.