Electroweak Baryogenesis and the Standard Model Effective Field Theory
  We investigate electroweak baryogenesis within the framework of the Standard
Model Effective Field Theory. The Standard Model Lagrangian is supplemented by
dimension-six operators that facilitate a strong first-order electroweak phase
transition and provide sufficient CP violation. Two explicit scenarios are
studied that are related via the classical equations of motion and are
therefore identical at leading order in the effective field theory expansion.
We demonstrate that formally higher-order dimension-eight corrections lead to
large modifications of the matter-antimatter asymmetry. The effective field
theory expansion breaks down in the modified Higgs sector due to the
requirement of a first-order phase transition. We investigate the source of the
breakdown in detail and show how it is transferred to the CP-violating sector.
We briefly discuss possible modifications of the effective field theory
framework.
