INFLUENCE OF THE ELECTRIC COUPLING STRENGTH IN CURRENT-CARRYING COSMIC STRINGS

The fully coupled Witten model for superconducting cosmic strings is analyzed in detail, with special emphasis on the effects due to a nonzero value of the electromagnetic coupling constant in order to check the accuracy of the neutral-limit treatment of the equation of state. Qualitative differences for the influence of the coupling constant between timelike and spacelike situations are examined in order to obtain a new understanding of the mechanical (as opposed to electromagnetic) properties of a cosmic string. Longitudinal- and transverse-perturbation velocities are estimated and related to stability criteria. It transpires that superconducting cosmic-string loops are generally not strictly stable against nonaxisymmetric perturbations.