New solutions for non-Abelian cosmic strings
  We study the properties of classical vortex solutions in a non-Abelian gauge
theory. A system of two adjoint Higgs fields breaks the SU(2) gauge symmetry to
$Z_2$, producing 't Hooft-Polyakov monopoles trapped on cosmic strings, termed
beads; there are two charges of monopole and two degenerate string solutions.
The strings break an accidental discrete $Z_2$ symmetry of the theory,
explaining the degeneracy of the ground state. Further symmetries of the model,
not previously appreciated, emerge when the masses of the two adjoint Higgs
fields are degenerate. The breaking of the enlarged discrete symmetry gives
rise to additional string solutions and splits the monopoles into four types of
`semipole': kink solutions that interpolate between the string solutions,
classified by a complex gauge invariant magnetic flux and a $Z_4$ charge. At
special values of the Higgs self-couplings, the accidental symmetry broken by
the string is continuous, giving rise to supercurrents on the strings. The
SU(2) theory can be embedded in a wide class of Grand Unified Theories,
including SO(10). We argue that semipoles and supercurrents are generic on GUT
strings.
