Magnetic Seed Field Generation from Electroweak Bubble Collisions, with
  Bubble Walls of Finite Thickness
  Building on earlier work, we develop an equation-of-motion method for
calculating magnetic seed fields generated from currents arising from charged W
fields in bubble collisions during a first-order primordial electroweak phase
transition allowed in some proposed extensions of the standard model. The novel
feature of our work is that it takes into account, for the first time, the
dynamics of the bubble walls in such collisions. We conclude that for bubbles
with sufficiently thin surfaces the magnetic seed fields may be comparable to,
or larger than, those found in earlier work. Thus, our results strengthen the
conclusions of previous studies that cosmic magnetic fields observed today may
originate from seeds created during the electroweak phase transition, and
consequently that these fields may offer a clue relevant to extensions of the
standard model.
