The observed matter–antimatter asymmetry of the Universe remains one of the fundamental puzzles in modern cosmology. Conventional baryogenesis mechanisms rely on the Sakharov conditions, including departure from thermal equilibrium. However, a time-dependent scalar background can bias particle and antiparticle populations, enabling baryogenesis even when the relevant interactions remain in thermal equilibrium.
In this talk, I will discuss this possibility within a minimal dynamical scotogenic framework, where neutrino masses are generated radiatively and a spontaneously broken global U(1)B-L symmetry gives rise to a Nambu–Goldstone boson, the Majoron. A rolling Majoron field induces an effective chemical potential for B-L, allowing a lepton asymmetry to develop through rapid lepton-number-violating interactions without requiring a decay-induced CP asymmetry. This mechanism enables successful leptogenesis at relatively low right-handed neutrino mass scales. I will also discuss its implications for neutrino masses and multicomponent dark matter, connecting particle physics with early-Universe cosmology.
