On the stability of cosmological metrics in Einstein-Cartan cosmologies

TL;DR

This paper investigates the stability of cosmological metrics in Einstein-Cartan theory, revealing that both de Sitter and Friedmann metrics are unstable under small perturbations when considering spin-torsion and dilaton fields.

Contribution

It provides a detailed analysis of the stability of key cosmological metrics within Einstein-Cartan cosmology, highlighting their instability due to spin-torsion and dilaton effects.

Findings

De Sitter metric is unstable with spin-torsion and dilaton fields.

Friedmann metric is also unstable under small perturbations.

Both metrics exhibit instability in Einstein-Cartan cosmology.

Abstract

Two metric perturbations in Einstein-Cartan cosmology are examined.The first case is the scalar mode perturbation of de Sitter metric in Einstein-Cartan cosmology.In this case small perturbations of de Sitter metric shows that this metric is unstable for a universe with spin-torsion density and dilaton fields.In the second case we show that the Friedmann metric in the same space is also unstable under the small perturbations.