AVOIDANCE OF COLLAPSE BY CIRCULAR CURRENT-CARRYING COSMIC-STRING LOOPS

Earlier attempts to calculate the nonlinear dynamical evolution of Wit ten-type superconducting vacuum vortex defects relied on the use of ap proximate conducting string models that were too simple to take proper account of the effect of current saturation. This effect is however a llowed for adequately in a newly developed class of rather more compli cated, though still conveniently analytic, conducting string models. T hese more realistic models have recently been employed by Larsen and A xenides for investigating the collapse of circular string loops in the case for which angular momentum is absent. The present work extends t his investigation to the generic case of circular string loops for whi ch angular momentum is present, so that there will be a centrifugal po tential barrier. This barrier will prevent collapse unless the initial conditions are such that the relevant current saturation limit is att ained, in which case the string description of the vortex defect will break down, so that its subsequent fate is hard to foresee. On the oth er hand if saturation is avoided one would expect that the loop will e ventually radiate away its excess energy and settle down into a vorton -type equilibrium state.