Smooth Cosmologies from M-theory

TL;DR

This paper reviews methods from M-theory to derive smooth cosmological models that transition between two de Sitter phases, supporting inflationary expansion with potential implications for early universe cosmology.

Contribution

It introduces new smooth cosmological solutions from M-theory via hyperbolic reductions, enabling models with inflationary expansion.

Findings

Supports smooth transition between de Sitter phases in higher-dimensional theories

Solutions exhibit inflation-like expansion with higher early universe rate

Derived from superpotential-based first-order systems

Abstract

We review two ways in which smooth cosmological evolution between two de Sitter phases can be obtained from M/string-theory. Firstly, we perform a hyperbolic reduction of massive IIA* theory to D=6 N=(1,1) SU(2)xU(1) gauged de Sitter supergravity, which supports smooth cosmological evolution between dS_4 x S^2 and a dS_6-type geometry. Secondly, we obtain four-dimensional de Sitter gravity with SU(2) Yang-Mills gauge fields from a hyperbolic reduction of standard eleven-dimensional supergravity. The four-dimensional theory supports smooth cosmological evolution between dS_2 x S^2 and a dS_4-type geometry. Although time-dependent, these solutions arise from a first-order system via a superpotential construction. For appropriate choices of charges, these solutions describe an expanding universe whose expansion rate is significantly larger in the past than in the future, as required for an inflationary model.