Symmetries are the daily bread of modern particle physicists. In a variety of scenarios their breaking is associated with the formation and expansion of bubbles of true vacuum in what is called a first order phase transition. In this context, Electroweak Baryogenesis, a mechanism proposed over 40 years ago, takes advantage of Electroweak symmetry breaking and offers a way to address the baryon asymmetry of the universe, as all three Sakharov conditions can be realised on the walls of said bubbles. Additionally, the dynamics of bubble collisions could provide interesting gravitational waves signals that could be detected in the years to come.
Although the Standard Model contains all required ingredients, it has long been established that the electroweak phase transition does not proceed via nucleation of bubbles, rather it is a smooth crossover. Additionally, the smallness of the CP violation in SM is insufficient to account for the observed baryon asymmetry.
Extending the SM scalar sector can, however, drastically modify the dynamics of symmetry breaking and provide a richer vacuum structure. In this talk, I will analyse one such extension, the Zee model, first proposed to generating neutrino masses at loop level via the introduction of additional scalar degrees of freedom. We shall show how in this framework the electroweak phase transition actually proceeds via bubble nucleation, and how it could be strong enough to generate the observed baryon asymmetry of the universe.