In this talk we deal with Bose-Einstein condensation in quantum field theory. The presence of such a condensate in the abelian U(1) sector leads to an oscillating and exponentially screened electrostatic interaction. In the whole electroweak sector, SU(2)xU(1), a condensate of W bosons may be realized in the primordial phases of the universe evolution, if lepton asymmetry is sufficiently large. When this condition is realized, the condensed Ws would act as a ferromagnet, that is, their spins would align. As a consequence, primordial magnetic fields at macroscopically large scales may be spontaneously generated. These fields could be seeds for the observed galactic and intergalactic magnetic fields.
Room 349, Theresienstr. 37
