Cosmological magnetic dynamo in the early Universe

We study the behavior of large-scale magnetic fields in the early Universe influenced by an instability associated with breaking of mirror symmetry in weak interactions. It is shown that the magnetic field, whose present scale reaches about 500 m, which is negligible for galactic sizes, increases considerably if we correctly take into account the dynamics of the Universe. We conclude that this magnetic field is unlikely to provide the seed field for galactic dynamos, nearly independent of the particular instability considered.