Fermions Destabilize Electroweak Strings

Abstract

Z-strings in the Weinberg-Salam model including fermions are unstable for all values of the parameters. The cause of this instability is the fermion vacuum energy in the Z-string background. Z-strings with non-zero fermion densities, however, may still be stable.

Comments: 11 pages; an additional paragraph describes the destabilization of a finite length string