D-branes, String Cosmology and Large Extra Dimensions

TL;DR

This paper explores how D-branes in string theory with large extra dimensions influence cosmological models, proposing new mechanisms for inflation, stabilization, and addressing cosmological singularities and baryon asymmetry.

Contribution

It introduces a novel approach to string cosmology where brane dynamics and extra dimensions drive inflation and resolve key cosmological issues.

Findings

Inflation can be driven by large extra dimensions and brane fluctuations.

Stabilization of extra dimensions is linked to the graceful exit problem.

Brane fluctuations may lead to brane-driven inflation and help smooth cosmological singularities.

Abstract

D-branes are fundamental in all scenarios where there are large extra dimensions and the string scale is much smaller than the four-dimensional Planck mass. We show that this current picture leads to a new approach to string cosmology where inflation on our brane is driven by the large extra dimensions and the issue of the graceful exit becomes inextricably linked to the problem of the stabilization of the extra dimensions, suggesting the possibility of a common solution. We also show that branes may violently fluctuate along their transverse directions in curved spacetime, possibly leading to a period of brane-driven inflation. This phenomenon plays also a crucial role in many other cosmological issues, such as the smoothing out of the cosmological singularities and the generation of the baryon asymmetry on our three brane.