Twisted vortices, string solitons, and world sheet instantons

Twist modes of oscillation for Higgs vortices are discussed. In the pure gauge case these are described by a two-dimensional massive photon carrying a twist in the magnetic flux tube. These twists can decay by a two dimensional instanton. With fermions the twist mode has a vacuum current of the broken U(1) symmetry running along the zero of the Higgs field. The case of bosonic charge carriers, where the charge is also that of the broken U(1), is then presented. There are world sheet solitons acting as a source of twist, and for certain coupling the vortex has a non-cylindrically symmetric profile. These phenomena have relevance to cosmic string models and possibly other areas of physics. (orig.)