A Study of Accelerating Cosmologies from Superstring/M theories

TL;DR

This paper investigates how accelerating cosmologies can emerge from superstring/M theory compactifications, analyzing parameter effects, internal space geometries, and comparing different brane models, highlighting both possibilities and challenges.

Contribution

It provides a detailed analysis of accelerating universe solutions from superstring/M theories, including effects of internal space geometry and brane model relations.

Findings

Accelerating expansion can arise from spherical internal spaces.

Solutions eventually enter a contracting phase.

Potential issues are identified in SD2-brane models.

Abstract

We study aspects of the accelerating cosmologies obtained from the compactification of vacuum solution and S2-branes of superstring/M theories. Parameter dependence of the resulting expansion of our universe and internal space is examined for all cases. We find that accelerating expansions are obtained also from spherical internal spaces, albeit the solution enters into contracting phase eventually. The relation between the models of SM2- and SD2-branes are also discussed, and a potential problem with SD2-brane model is noted.