Hilltop curvatons

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 mσ=cH, where the coefficient varies within 0.2⩽c⩽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.