Warm hilltop inflation

TL;DR

This paper analyzes warm hilltop inflation at low temperatures, providing an analytic description of the entire inflationary period and exploring regimes that satisfy observational constraints and address common inflation issues.

Contribution

It offers an analytic framework for low-temperature warm hilltop inflation, covering both weak and strong dissipative regimes and their implications for inflationary scale and particle physics.

Findings

Low-scale inflation with Hubble scale as low as 1 GeV in weak dissipative regime.

Model satisfies spectral index observational constraints with mild parameter tuning.

Potential overproduction of gravitinos unless particle content is large.

Abstract

We study the low-temperature limit of warm inflation in a hilltop model. This limit remains valid up to the end of inflation, allowing an analytic description of the entire inflationary stage. In the weak dissipative regime, if the kinetic density of the inflaton dominates after inflation, low scale inflation is attained with Hubble scale as low as 1 GeV. In the strong dissipative regime, the model satisfies the observational requirements for the spectral index with a mild tuning of the model parameters, while also overcoming the $\eta$-problem of inflation. However, there is some danger of gravitino overproduction unless the particle content of the theory is large.