Vacuum defects without a vacuum

Topological defects can arise in symmetry breaking models where the scalar field potential $V\left(\phi \right)$ has no minima and is a monotonically decreasing function of |φ|. The properties of such vacuumless defects are quite different from those of the “usual” strings and monopoles. In some models such defects can serve as seeds for structure formation, or produce an appreciable density of mini-black holes.