Effective field theory, electric dipole moments and electroweak baryogenesis

TL;DR

This paper uses effective field theory to connect electric dipole moment constraints with the baryon asymmetry generated during electroweak baryogenesis, highlighting the role of derivative operators and reclassifying relevant dimension six operators.

Contribution

It provides a model-independent analysis linking EDM constraints to baryogenesis, emphasizing the importance of derivative operators and reclassifying dimension six operators relevant to the phase transition.

Findings

Derivative operators contribute to BAU via Higgs vev derivatives.

Non-derivative operators lack such contributions.

BAU calculations relate to EDM constraints and bubble wall parameters.

Abstract

Negative searches for permanent electric dipole moments (EDMs) heavily constrain models of baryogenesis utilising various higher dimensional charge and parity violating (CPV) operators. Using effective field theory, we create a model independent connection between these EDM constraints and the baryon asymmetry of the universe (BAU) produced during a strongly first order electroweak phase transition. The thermal aspects of the high scale physics driving the phase transition are paramaterised by the usual kink solution for the bubble wall profile. We find that operators involving derivatives of the Higgs field yield CPV contributions to the BAU containing derivatives of the Higgs vev, while non-derivative operators lack such contributions. Consequently, derivative operators cannot be eliminated in terms of non-derivative operators (via the equations of motion) if one is agnostic to the new physics that leads to the phase transition. Thus, we re-classify the independent dimension six operators, restricting ourselves to third generation quarks, gauge bosons and the Higgs. Finally, we calculate the BAU (as a function of the bubble wall width and the cutoff) for a derivative and a non-derivative operator, and relate it to the EDM constraints.