ON THE NATURE OF THE MAGNETIC-FIELDS GENERATED DURING THE ELECTROWEAKPHASE-TRANSITION

In this letter we reanalyse the question of the origin of magnetic fie lds during the electroweak phase transition. We show that their format ion is intimately connected to some semiclassical configurations of th e gauge fields, such as electroweak Z-strings and W-condensates. We de scribe the formation of these semiclassical configurations during a fi rst order phase transition and argue that they might be generated also in the case of a second order phase transition. We suggest that the i nstability of electroweak strings does not imply the disappearance of the embedded magnetic field. (C) 1998 Elsevier Science B.V.