Late Inflation and the Moduli Problem of Sub-Millimeter Dimensions

TL;DR

This paper examines a model with sub-millimeter extra dimensions where the radion acts as an inflaton, but finds that late inflation cannot adequately reheat the universe to solve the moduli problem.

Contribution

It analyzes the viability of late inflation in a model with extra dimensions and shows its limitations in reheating the universe.

Findings

Late inflation fails to reheat the universe sufficiently.

Radion as inflaton leads to potential overclosure issues.

Second inflationary phase does not solve the moduli problem.

Abstract

We consider a recent model with sub-millimeter sized extra dimensions, where the field that determines the size of the extra dimensions (the radion) also acts as an inflaton. The radion is also a stable modulus, and its coherent oscillations can potentially overclose the Universe. It has been suggested that a second round of late inflation can solve this problem, however we find that this scenario does not allow for sufficient reheating of the Universe.