The non-linear dynamics inherent in the axial coupling between massless gauge fields and a pseudo-scalar during inflation have been thoroughly investigated, and some features of the strong backreaction regime can be captured using simple analytical expressions for the interaction terms. In this talk, I will show some preliminary work on the extension of the mechanism to the case of massive Abelian gauge fields, which are expected from thermalisation or from a Stückelberg mechanism. Analytical formulas for the comoving energy density of gauge fields and for the helicity are derived. An estimation of the enhancement in the power spectrum of the scalar perturbations in the gauge-induced slow-roll phase will also be provided.
Organized by: Catarina Cosme