Preheating in radiative corrections to $\phi^4$ inflation with non-minimal coupling in Palatini formulation

TL;DR

This paper examines how preheating affects radiative corrections in non-minimally coupled $phi^4$ inflation within Palatini gravity, revealing efficient reheating via tachyonic instability and compatibility with observational data.

Contribution

It introduces the analysis of preheating effects on radiative corrections in Palatini $phi^4$ inflation with non-minimal coupling, highlighting a rapid reheating mechanism and observational consistency.

Findings

Reheating occurs in less than one e-fold due to tachyonic instability.

Spectral index and tensor-to-scalar ratio are compatible with Planck and BICEP2 data.

The average equation of state during reheating approaches -1, differing from standard models.

Abstract

We discuss the impact of the preheating stage in radiative corrections due to interaction of the inflaton to fermions to $\phi^4$ inflation with non-minimal coupling in Palatini formulation. In Palatini inflation with large non-minimal coupling the field is allow to return to the plateau region during the reheating stage, so the average equation of state per oscillations is closer to $-1$ than to $1/3$. The incursion in the plateau leads, however, to a highly efficient tachyonic instability able to reheat the Universe in less than one e-fold. By taking into account prescription II discussed in the literature, in the wide range of $\kappa-\xi$, we figure out spectral index $n_s$ and tensor-to-scalar ratio $r$ which are compatible with the data given by the Keck Array/BICEP2 and Planck collaborations.