Speaker
Description
According to the standard model of cosmology, the Universe at its very beginning underwent a phase of rapid expansion, followed by a reheating period. During this epoch, the energy density, initially accumulated in the oscillations of the inflaton field, was injected into the visible sector, eventually setting the initial conditions for the hot big bang. In this talk, I will discuss the perturbative production of the Standard Model (SM) and dark matter (DM) particles during the reheating phase, assuming a non-standard expansion history. In particular, I will explore a scenario in which reheating is induced by a cubic interaction of the inflaton $\phi$ with the SM Higgs doublet $\bf{h}$ of the form $g_{h \phi} M_{\rm Pl} \phi |\mathbf{h}|^2$. In the presence of such interaction, the Higgs field acquires a $\phi$-dependent mass which generates a vacuum expectation value that oscillates in time and breaks the SM gauge symmetry. Furthermore, the non-zero mass of the Higgs field leads to a time-dependent inflaton decay rate and generates a non-trivial phase-space suppression of the SM radiation production. As a consequence, the reheating phase is prolonged, and the maximal temperature of the SM thermal bath is reduced. This, in turn, has non-trivial consequences for the dark sector, especially for the UV freeze-in DM scenario.
