Non-Abelian Yang-Mills-Higgs vortices
In this Letter we present new, genuinely non-Abelian vortex solutions in SU(2) Yang-Mills--Higgs theory with only one {\it isovector} scalar field. These non-Abelian solutions branch off their Abelian counterparts (Abrikosov-Nielsen-Olesen vortices) for precise values of the Higgs potential coupling constant $λ$. For all values of $λ$, their energies lie below those of the Abelian energy profiles, the latter being logarithmically divergent as $λ\to\infty$. The non-Abelian branches plateau in the limit $λ\to\infty$ and their number increases with $λ$, this number becoming infinite. For each vorticity, the gaps between the plateauing energy levels become constant. In this limit the non-Abelian vortices are non-interacting and are described by the {\it self-dual} vortices of the O(3) sigma model. In the absence of a topological lower bound, we expect these non-Abelian vortices to be {\it sphalerons}.