Vacuum defects without a vacuum

Abstract

Topological defects can arise in symmetry breaking models where the scalar field potential $V(\varphi )$ has no minima and is a monotonically decreasing function of $|\varphi |$. 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.

Comments: 11 pages, REVTeX, 1 Postscript figure. Minor changes. Final version, to appear in Phys. Rev. D