Warm Inflection

TL;DR

This paper investigates how dissipative effects in warm inflation can reduce the fine-tuning problem near inflection points in scalar potentials, by damping inflaton motion and maintaining a thermal bath.

Contribution

It demonstrates that dissipation can alleviate fine-tuning in inflection point inflation and analyzes the minimal dissipation needed to sustain a thermal bath during inflation.

Findings

Dissipation reduces the fine-tuning requirement for inflection point inflation.

The minimum dissipation needed is largely independent of potential flatness.

The dissipation depends on the field value at the inflection point.

Abstract

While ubiquitous in supersymmetric and string theory models, inflationary scenarios near an inflection point in the scalar potential generically require a severe fine-tuning of a priori unrelated supersymmetry breaking effects. We show that this can be significantly alleviated by the inclusion of dissipative effects that damp the inflaton's motion and produce a nearly-thermal radiation bath. We focus on the case where the slow-rolling inflaton directly excites heavy virtual modes that then decay into light degrees of freedom, although our main qualitative results should apply in other regimes. Furthermore, our analysis shows that the minimum amount of dissipation required to keep the temperature of the radiation bath above the Hubble rate during inflation is largely independent of the degree of flatness of the potential, although it depends on the field value at the inflection point. We then discuss the relevance of this result to warm inflation model building.