Closed Inhomogeneous String Cosmologies

TL;DR

This paper introduces a comprehensive algorithm for constructing inhomogeneous string cosmology solutions in four dimensions, utilizing a sequence of transformations to generate models with key string theory features, and discusses their properties and implications.

Contribution

The paper presents a novel algorithm combining conformal, T-duality, SL(2,R) rotations, and Geroch transformations to generate inhomogeneous string cosmology solutions.

Findings

Constructed an inhomogeneous string cosmology with S^3 topology.

Analyzed properties and subtleties of homogeneity and isotropy in string cosmology.

Demonstrated the algorithm's ability to produce solutions with string theory remnants.

Abstract

We present a general algorithm which permits to construct solutions in string cosmology for heterotic and type-IIB superstrings in four dimensions. Using a chain of transformations applied in sequence: conformal, T-duality and SL(2,R) rotations, along with the usual generating techniques associated to Geroch transformations in Einstein frame, we obtain solutions with all relevant low-energy remnants of the string theory. To exemplify our algorithm we present an inhomogeneous string cosmology with S^3 topology of spatial sections, discuss some properties of the solution and point out some subtleties involved in the concept of homogeneity and isotropy in string cosmology.