A recent study investigates whether the observed baryon asymmetry of the Universe, the imbalance between matter and antimatter, can be explained by a baryogenesis mechanism known as sphalerogenesis within the Standard Model Effective Field Theory (SMEFT) framework. This mechanism posits that the baryon asymmetry is generated through a CP-asymmetric decoupling of electroweak (EW) sphaleron-like transitions.

Researchers introduced seven CP-violating dimension-8 operators constructed from the Higgs doublet and the SU(2)L gauge fields. They demonstrated that five of these operators can individually account for the observed baryon asymmetry while satisfying experimental constraints from particle colliders or electron electric dipole moment measurements. This finding suggests new avenues for understanding the origin of matter in the universe.

The study also examined the impact of these dimension-8 operators in the presence of a CP-violating dimension-6 operator. It was found that the dimension-8 contributions can be comparable to those from the dimension-6 operator when the former are generated at one loop. This result highlights that loop-order counting can be as crucial as canonical mass-dimension counting in sphalerogenesis models, offering a more nuanced perspective on the relevance of different operators in physics beyond the Standard Model.