CP violation at the finite temperature

In this letter we explore the CP violation at the finite temperature. We show that a spontaneous CP-violating phase φ may arise at the temperature of the electroweak phase transition, and φ can provide a source term for generating the matter-antimatter asymmetry of the universe via the electroweak baryogenesis mechanism (EWBG) whenever the domain wall relating to ±φ vacua is collapsed by a small explicit Z2-breaking term. Therefore no extra CP violation is needed! We further point out that this CP symmetry can be restored after the electroweak phase transition, such that there will be no constraint from the electric dipole moment (EDM) measurements. This study solves the tension between the non-observation of EDMs in precision measurement experiments and the requirement of a large CP violation by the EWBG.