Higgsless Gauge Symmetry Breaking with a Large Mass Hierarchy

We propose a mechanism of Higgsless gauge symmetry breaking with a large mass hierarchy. We consider a 5D gauge theory on an orbifold $S^1/Z_2$. The gauge symmetry is broken by orbifolding and also nontrivial boundary conditions at fixed points. All 4D modes which survive at low energies are found to be localized around fixed points. Supersymmetry plays an important role in our mechanism. The tree-level unitarity in our model is briefly discussed.