Hilltop Curvatons

TL;DR

This paper investigates hilltop curvatons on convex potentials, focusing on their evolution under Hubble-induced mass terms and the resulting impact on low-scale inflation energy bounds.

Contribution

It analyzes the behavior of hilltop curvatons with Hubble-induced potentials, highlighting the fluctuation enhancement and its implications for inflation models.

Findings

Negative mass terms can enhance curvaton fluctuations.

The fluctuation enhancement affects the energy bounds for low-scale inflation.

The study demonstrates the generality of fluctuation enhancement in a simple curvaton model.

Abstract

We study ``hilltop'' curvatons that evolve on a convex potential. Hilltop curvatons evolving on the Hubble-induced potential are generic if supergravity is assumed in the theory. We do not consider curvatons whose potential is protected from $O(H)$ corrections, where $H$ is the Hubble parameter. We assume that the effective mass of a curvaton is expressed as $m_\sigma = c H$, where the coefficient varies within $0.2 \le c \le 5$ depending on the circumstances. A negative mass term may lead to enhancement of curvaton fluctuation, which has a significant impact on the energy bound for low-scale inflation. Using a simple curvaton model and following the conventional curvaton hypothesis, we demonstrate the generality of this enhancement.