Affleck–Dine baryogenesis via mass splitting

Abstract

We introduce a class of non-supersymmetric models explaining baryogenesis a la Affleck–Dine, which use a decay of two superheavy scalar fields with close masses. These scalars acquire non-zero expectation values during inflation through linear couplings to a function of an inflaton. After the inflaton decay, the model possesses approximate U(1)-invariance, explicitly broken by a small mass splitting. This splitting leads to the baryogenesis in the early Universe. Resulting baryon asymmetry is automatically small for the scalars with the masses about the Grand Unification scale and larger. It is fully determined by the inflaton dynamics and the Lagrangian parameters, i.e., is independent of initial pre-inflationary conditions for the scalars. As a consequence, baryon perturbations are purely adiabatic. We point out a possible origin of the mass splitting: masses of scalars degenerate at some large energy scale may acquire different loop corrections due to the interaction with the inflaton. Compared to electroweak baryogenesis and conventional Affleck–Dine scenarios, our mechanism generically leads to the proton decay suppressed by the powers of the superheavy scalar masses, which makes this scenario potentially testable.