Early Inflation and Cosmology in Theories with Sub-Millimeter Dimensions

TL;DR

This paper explores early universe cosmology within theories featuring sub-millimeter extra dimensions, focusing on inflation, density perturbations, and graviton production, with implications for the evolution of internal dimensions and the radion problem.

Contribution

It presents a detailed analysis of inflation and cosmological evolution in models with TeV-scale gravity and extra dimensions, highlighting new dynamics of internal dimensions and graviton production.

Findings

Inflation can occur while extra dimensions are still small.

Density perturbations depend on the size of extra dimensions.

Bulk graviton production affects cosmological evolution.

Abstract

We discuss early cosmology in theories where the fundamental Planck mass is close to the TeV scale. In such theories the standard model fields are localized to a (3+1)-dimensional wall with n new transverse sub-millimeter sized spatial dimensions. The topic touched upon include: early inflation that occurs while the size of the new dimensions are still small, the spectrum and magnitude of density perturbations, the post-inflation era of contraction of our world while the internal dimensions evolve to their final ``large'' radius, and the production of gravitons in the bulk during these two eras. The radion moduli problem is also discussed.