The Preheating Stage on The Starobinsky Inflation after ACT

TL;DR

This paper revisits the Starobinsky inflation model in light of recent ACT data, emphasizing the need for a spectator field to achieve efficient preheating and adjusting reheating parameters accordingly.

Contribution

It introduces a viable preheating mechanism involving a spectator field and non-minimal coupling, aligning the model with recent observational constraints.

Findings

Reheating temperature decreases with ACT data constraints

Spectator field is necessary for efficient preheating

Potential collider signatures for daughter fields

Abstract

In this paper, we reinvestigate the Starobinsky inflation model and its reheating features in light of the recent ACT results. To make the Starobinsky model consistent with the ACT data at the $68\%$ confidence level, the number of e-folds must increase while the reheating temperature decreases. We find that the Starobinsky model requires a spectator field to achieve efficient preheating. The preheating stage and the reheating temperature must be significantly adjusted to accommodate the lower temperature. In this paper, the favored non-minimal coupling of the produced particles is approximately $10$ or slightly lower. We also present viable parameter sets that fit the preferred reheating mechanism in this model. For certain parameter choices, the daughter fields could potentially be detected in future collider experiments such as the LHC or the ILC. Furthermore, our proposed mechanism can reproduce the lower reheating temperature, but it fails when the temperature falls below $1$ GeV.