Speaker
Description
We investigate the theory of spontaneous baryogenesis, considering two extensions to the scalar paradigm and proposing a vectorial and LIV version of the model. Concerning the scalar paradigm, firstly we generalize the minimal theory introducing a non-minimal coupling between the inflaton field and the scalar curvature. This modifies the effective mass squared of the inflaton and accordingly changes its decay amplitude into fermion-antifermion pairs. We show that this mechanism can significantly increase the baryon asymmetry, providing a value compatible with experimental data. In the second place, we introduce a complex scalar spectator field non-minimally coupled to gravity and interacting with the inflaton through a bilinear quadratic term. Also in this case, the overall baryogenesis process turns out to be more efficient, even though the enhancement is not yet sufficient to account for the observed matter-antimatter asymmetry. Finally, we propose a vectorial version of spontaneous baryogenesis. We reformulate the model from scratch, substituting the complex scalar field with a complex vector field. We start from the unbroken phase Lagrangian and discuss the mechanism of spontaneous symmetry breaking with a vector field, yielding a spontaneous violation of Lorentz symmetry further than $U(1)_B$. In this picture, the pseudo-Nambu-Goldstone boson arising from the $U(1)_B$-breaking is the global phase of the vector field and plays the role of the inflaton. The baryon asymmetry is then produced through the same mechanism as in the scalar model. The crucial difference lies in the mixing between fermions, here acting on their spatial momenta rather than on the masses. This provides a non-null mixing factor even for massless fermions and allows larger values of the coupling constant. The net baryon asymmetry is accordingly modified and may reproduce experimental data.