I discuss the importance of CP violation (CPV) in cosmology and give some common arguments why it is believed that the CPV of the Standard Model cannot be sufficient to explain the observed baryon asymmetry. Then I go on to argue why these arguments might fail in an effective approach where the quarks have been integrated out. I discuss in detail how to obtain the corresponding bosonic effective theory by using the worldline formalism with special emphasis on CP-violating operators. Finally I comment on the use of this effective theory in baryogenesis calculations.