Effective Theory of Resonant Leptogenesis in the Closed-Time-Path
  Approach
  We describe mixing scalar particles and Majorana fermions using
Closed-Time-Path methods. From the Kadanoff-Baym equations, we obtain the
charge asymmetry, that is generated from decays and inverse decays of the
mixing particles. Within one single formalism, we thereby treat Leptogenesis
from oscillations and recover as well the standard results for the asymmetry in
Resonant Leptogenesis, which apply when the oscillation frequency is much
larger than the decay rate. Analytic solutions for two mixing neutral particles
in a constant-temperature background illustrate our results qualitatively. We
also perform the modification of the kinetic equations that is necessary in
order to take account of the expansion of the Universe and the washout of the
asymmetry.
