Quantum stabilization of a closed Nielsen-Olesen string

We revisit the classical instability of closed strings in the Abelian Higgs model. The instability is expressed by a vanishing energy as the torus-like configuration shrinks to zero size. We treat the radius of the torus as a collective coordinate and demonstrate that a quantum-mechanical treatment of this coordinate leads to a stabilization of the closed string at small radii. DOI: 10.1103/PhysRevD.87.085013