Bubble collisions in SU(2)×U(1) gauge theory and the production of nontopological strings

We extend work done previously concerning the formation of vortices in a U(1){r_arrow}1 gauge theory at a first order phase transition to the symmetry-breaking SU(2){sub T}{times}U(1){sub Y}{r_arrow}U(1){sub Q}. It is shown that the collision of bubbles, appearing at the phase transition, allows the possibility for forming nontopological strings associated with the gauge group. The method used also shows clearly how these vortices are related to the Nielsen-Olesen vortices. {copyright} {ital 1997} {ital The American Physical Society}