Evaporation of charged bosonic condensate in cosmology

Cosmological evolution of equilibrium plasma with a condensate of U(1)-charged bosonic field is considered. It is shown that the evaporation of the condensate is very much different from naive expectations, discussed in the literature, as well as from evaporation of non-equilibrium neutral condensate. The charged condensate evaporates much slower than the decay of the corresponding bosons. The evaporation rate is close to that of the cosmological expansion. The plasma temperature, in contrast, drops much faster than usually, namely as the third power of the cosmological scale factor. As a result the universe becomes very cold and the cosmological charge asymmetry reaches a huge value.