STABILITY OF Z-STRINGS IN STRONG MAGNETIC FIELDS

Abstract

We show that the Z-strings of the standard electroweak theory can be stabilized by strong external magnetic fields, provided that ${\beta }^{1/2}\equiv M_H/M_Z\le 1$, where $M_H$ and $M_Z$ are the Higgs and Z masses. The magnetic fields needed are larger than ${\beta }^{1/2}{B}_c$ and smaller than $B_c$, where $B_c\equiv M_W^2/e$ is the critical magnetic field which causes W-condensation in the usual broken phase vacuum. If such magnetic fields were present after the electroweak transition, they would stabilize strings for a period comparable to the inverse Hubble rate at that time. Pair creation of monopoles and antimonopoles linked by segments of string is briefly considered.

Comments: 12 pages, 3 uuencoded figs ,LaTeX (RevTeX). A postcript version can be obtained via anonymous ftp at ftp://ftp.ifae.es/preprint.ft