Preheating in radiatively corrected 𝝓𝟒𝟒 inflation with non-minimal coupling in Palatini formulation

Abstract

We discuss the impact of the preheating stage due to the interaction of the inflaton to fermions in Palatini formulation. In Palatini inflation with large non-minimal coupling, the field is allowed to return to the plateau region during the reheating stage, therefore the average equation of state per oscillations is closer to −1 rather than 1/3. The incursion in the plateau, however, leads to a highly efficient tachyonic instability, which is able to reheat the Universe in less than one e-fold. By taking prescription II into account, which is discussed in the literature, we calculate the spectral index ns and the tensor-to-scalar ratio r in the wide range of κ − ξ. We will show the results which are compatible with the data given by the Keck Array/BICEP2 and Planck collaborations.