Instanton Cosmology and Domain Walls from M-theory and String Theory

TL;DR

This paper derives exact cosmological solutions from M-theory and string theory compactifications, exploring instantons, domain walls, and supersymmetry preservation, contributing to understanding open inflationary universe models.

Contribution

It provides explicit Lagrangians from M-theory/string theory compactifications and analyzes their cosmological and domain-wall solutions, including supersymmetric cases.

Findings

Exact solutions for Lagrangians from M-theory compactifications.

Existence of supersymmetric domain-wall solutions approaching AdS.

Detailed cosmological solutions from S^7 compactification.

Abstract

The recent proposal by Hawking and Turok for obtaining an open inflationary universe from singular instantons makes use of low-energy effective Lagrangians describing gravity coupled to scalars and non-propagating antisymmetric tensors. In this paper we derive some exact results for Lagrangians of this type, obtained from spherical compactifications of M-theory and string theory. In the case of the S^7 compactification of M-theory, we give a detailed discussion of the cosmological solutions. We also show that the lower-dimensional Lagrangians admit domain-wall solutions, which preserve one half of the supersymmetry, and which approach AdS spacetimes near their horizons.