Limits on cosmic chiral vortons

We study chiral vorton production for Witten-type superconducting string models in the context of a recently developed analytic formalism. We delineate three distinct scenarios: First, a low energy regime (including the electroweak scale) where vortons can be a source of dark matter. Secondly, an intermediate energy regime where the vorton density is too high to be compatible with the standard cosmology (thereby excluding these models). Finally, a high energy regime (including the GUT scale) in which no vortons are expected to form. The vorton density is most sensitive to the order of the string-forming phase transition and relatively insensitive to the current-forming transition. For a second-order string transition, vorton production is cosmologically disastrous for the range 10(-28) less than or similar to G mu less than or similar to 10(-10) (10(5) GeV less than or similar to T-c less than or similar to 10(14) GeV), while for the first-order case we can only exclude 10(-20) less than or similar to G mu less than or similar to 10(-14) (10(9) GeV less than or similar to T-c less than or similar to 10(12) GeV). We provide a fitting formula which summarises our results. (C) 1998 Elsevier Science B.V. All rights reserved.