Topological Content of the Electroweak Sphaleron on the Lattice

3D electroweak sphaleron configurations are studied by Abelian projection from the Maximal Abelian gauge. They all contain a symmetric array of Abelian monopoles and anti-monopoles connected by Abelian vortex strings. Gauge–invariant lattice definitions of the Nambu monopole and the Z–vortex string on the lattice are formulated. Looking for these new types of lattice topological defects, we demonstrate that the Abelian monopole structure of the sphalerons is related to the presence of one non–Abelian Nambu monopole–anti-monopole pair (connected by a Z-string) in the sphaleron core. In the unitary gauge (and related ones) the Nambu monopoles appear as Abelian monopoles. The additional Abelian monopole pairs and vortices are created by gauge–cooling towards the Maximal Abelian gauge. e-mail: [email protected] e-mail: [email protected] e-mail: [email protected]