Bubble nucleation and growth in very strong cosmological phase
  transitions
  Strongly first-order phase transitions, i.e., those with a large order
parameter, are characterized by a considerable supercooling and high velocities
of phase transition fronts. A very strong phase transition may have important
cosmological consequences due to the departures from equilibrium caused in the
plasma. In general, there is a limit to the strength, since the metastability
of the old phase may prevent the transition to complete. Near this limit, the
bubble nucleation rate achieves a maximum and thus departs from the widely
assumed behavior in which it grows exponentially with time. We study the
dynamics of this kind of phase transitions. We show that in some cases a
gaussian approximation for the nucleation rate is more suitable, and in such a
case we solve analytically the evolution of the phase transition. We compare
the gaussian and exponential approximations with realistic cases and we
determine their ranges of validity. We also discuss the implications for cosmic
remnants such as gravitational waves.
