A two-field dark energy model with cubic contractions of the Riemann tensor

TL;DR

This paper introduces a complex two-field dark energy model involving cubic Riemann tensor contractions, revealing diverse phase space structures that could explain different cosmic evolution stages and address dark energy.

Contribution

It presents a novel two-field dark energy model with cubic Riemann tensor invariants and analyzes its stability and phase space structure in a quintom scenario.

Findings

Complex phase space with multiple stationary points

Existence of scaling solutions for dark energy

Potential explanation for matter and accelerated epochs

Abstract

The paper proposes a novel cosmological model based on a two-field scenario, where the two fields are independently coupled with a specific invariant, based on cubic contractions of the Riemann tensor. After obtaining the modified Friedmann equations and the specific Klein-Gordon relations, the investigation studies the corresponding physical features by adopting the linear stability theory in a quintom scenario case where the coupling functions and potential energies have an exponential behavior. The corresponding investigation revealed a high complexity of the phase space structure, with various stationary points which can explain different aspects in the evolution of our Universe, the matter dominated epoch, and the late time accelerated stage. The present model can represent a viable solution to the dark energy problem due to the high complexity of the phase space and the existence of the scaling solutions.