The Second-Level Preheating

TL;DR

This paper explores a two-stage preheating process for the inflaton field non-minimally coupled to gravity, analyzing the efficiency of particle production and implications for primordial black hole formation.

Contribution

It introduces a dual-regime preheating model with a suppression mechanism for particle production and evaluates reheating temperatures based on preheating efficiency.

Findings

Preheating is efficient in the quadratic regime despite higher-dimensional operator suppression.

Non-renormalizable operators are ineffective in the quartic regime.

Small particle momentum during preheating influences primordial black hole abundance.

Abstract

This paper proposes two levels of preheating for the inflaton that is non-minimally coupled with gravity. The first level, later named by the quadratic regime, corresponds to the matter-dominated era and is responsible for draining the inflaton's energy density. The second level, which we will call the quartic regime, corresponds to the radiation-dominated era and is responsible for the reheating of the universe. We investigate the behavior of non-renormalizable higher dimension operators in both the quadratic and quartic regimes. In the quadratic regime, the preheating is also efficient, even though it is less than the lower dimension. On the other hand, the non-renormalizable higher dimension operators in the quartic regime are extremely inefficient. In our work, we also introduce a simple mechanism controlled by the characteristic momentum $\alpha$ to suppress the particle production during preheating. Additionally, we emphasized the significance of the small momentum of the particles produced during preheating for the abundance of primordial black holes. This result supports the efficient preheating in the quadratic regime. Finally, we evaluate two modes of the reheating temperature, which differ based on the preheating efficiency during the quadratic regime.