  The role of CP-violating decay and annihilation processes have been
extensively studied in the context of generating cosmological
particle-antiparticle asymmetries, both as sources of the asymmetry and its
subsequent wash-out. In the scenarios for which the lowest order source of
CP-violation is scattering processes, we highlight the role of additional
CP-conserving annihilations in indirectly affecting the asymmetry generation.
This stems from the strong dependence of the relevant out-of-equilibrium number
densities on the rate of CP-conserving reactions. The net asymmetry generated,
in turn, is proportional to the out-of-equilibrium number densities and the
rate of CP-violation. Such CP-conserving scatterings occur naturally in
scenarios of baryogenesis, leptogenesis and asymmetric dark matter production
through scattering, as we illustrate through several examples. We find that the
asymmetric yields for relevant particle-antiparticle systems can vary by orders
of magnitude depending upon the relative size of the CP-conserving and
violating reaction rates.
