Vorton construction and dynamics
  Vortons are closed loops of superconducting cosmic strings carrying current and charge. In this paper we present the first numerical construction of vortons in the global version of Witten's U(1)xU(1) theory. An energy minimization procedure is used to compute stationary vortons for a range of charges and currents, and the associated vorton radius is calculated. It is found that the standard analysis based on infinite straight cosmic strings does not provide a good description of the vorton cross-section. The computed solutions are used as initial conditions in an axially symmetric time evolution code, which verifies that the solutions are indeed stationary, and are stable to axially symmetric perturbations. Perturbations which preserve the axial symmetry excite oscillatory modes and produce an evolution which eventually returns to a stationary vorton. Finally, the constructed vorton solutions are used as initial conditions in a full (3+1)-dimensional simulation and an instability to non-axial perturbations is found. The instability produces a pinching and bending of the vorton which results in its destruction. 
Richard Battye and Paul Sutcliffe