Embedded Topological Defects in Electroweak Theory: From Percolating   Networks to Sphalerons
  New defects (Z-vortices and Nambu monopoles) are found to become thermodynamically relevant for the broken phase near to the (weakly first order) electroweak phase transition, and below the crossover for higher Higgs mass. The symmetric phase is characterized by vortex condensation (percolation). The percolation transition persists in the crossover region. The quasiclassical nature of the vortices is supported by correlations with Higgs field and gauge field energy. Sphalerons are shown to be related to monopolium bound states. 
M.N.Chernodub, F.V.Gubarev, E.-M.Ilgenfritz and A.Schiller