Semitopological solitons

A class of three-dimensional solitons, only partially stabilized by topology, is discussed. These are circular configurations of matter, hoops of generalized Nielsen-Olesen vortex lines. They are stabilized against collapse by conserved charges on the vortex world sheet. Such charges come from conserved two-dimensional currents, which arise from interactions of a simple vortex with either fermions or bosons in the underlying four-dimensional field theory. This article treats classical and quantum stability of the system in the special case that the currents are neutral with respect to any background fields. Some implications are discussed in the conclusion.