On compatibility of the Kaluza-Klein approach with the COBE experiment

TL;DR

This paper investigates whether Kaluza-Klein multidimensional cosmological models can align with COBE data on cosmic microwave background anisotropies, finding that most models face restrictive limits, but some remain plausible under certain conditions.

Contribution

It analyzes the compatibility of Kaluza-Klein models with COBE data, deriving parameter limits and assessing their viability for early universe descriptions.

Findings

Most Kaluza-Klein models are incompatible with COBE limits.

Models with minimal gravitational wave contribution remain plausible.

String-inspired models are not ruled out if gravitational wave effects are small.

Abstract

Contributions of primordial gravitational waves to the large-angular-scale anisotropies of the cosmic microwave background radiation in multidimensional cosmological models (Kaluza-Klein models) are studied. We derive limits on free parameters of the models using results of the COBE experiment and other astrophysical data. It is shown that in principle there is a room for Kaluza-Klein models as possible candidates for the description of the Early Universe. However, the obtained limits are very restrictive. Assuming that the anisotropies are mostly due to gravitational waves, none of the concrete models, analyzed in the article, satisfy them. On the other hand, if the contribution of gravitational waves is very small then a string inspired model is not ruled out.