RUNAWAY COLLAPSE OF WITTEN VORTEX LOOPS

We consider general properties of charged circular cosmic strings in a general family of worldsheet string models. We then specialize to a m odel recently proposed by Carter and Peter. This model was shown to gi ve a good description of the features of the superconducting cosmic st rings, originally discovered by Witten in a U(1)xU((1) over bar) field theory. We derive an explicit expression for the potential determinin g the dynamics of the string and we present explicit expressions for t he string tension and energy density, as a function of string-loop rad ius, in the locally preferred rest frame. We also obtain explicit expr essions for the wiggle and woggle speeds (speeds of transverse and lon gitudinal perturbations, respectively). We show that the contraction o f the uniformly charged string is essentially governed by the string t ension (for large loop radius) and a finite Coulomb barrier (for small loop radius). We argue for the unobstructed contraction of a uniforml y charged loop over the Coulombic barrier and its eventual collapse to a charged point. Finally, the implication of such an effect on the po ssible formation of naked singularities, in violation of the cosmic ce nsorship hypothesis, is discussed.