Conditions and evidence for non-integrability in the Friedmann-Robertson-Walker Hamiltonian

TL;DR

This paper applies algebraic methods to analyze the non-integrability of the Friedmann-Robertson-Walker Hamiltonian, providing new conditions that simplify proofs of non-integrability in cosmological models.

Contribution

It introduces a formalization of variational systems and an alternative method to establish non-integrability conditions for the FRW Hamiltonian.

Findings

Derived sufficient conditions for non-integrability.

Simplified proofs of non-integrability for the complete Hamiltonian.

Addressed a specific open case attracting recent interest.

Abstract

This is an example of application of Ziglin-Morales-Ramis algebraic studies in Hamiltonian integrability, more specifically the result by Morales, Ramis and Sim\'o on higher-order variational equations, to the well-known Friedmann-Robertson-Walker cosmological model. A previous paper by the author formalises said variational systems in such a way allowing the simple expression of notable elements of the differential Galois group needed to study integrability. Using this formalisation and an alternative method already used by other authors, we find sufficient conditions whose fulfillment would entail very simple proofs of non-integrability -- both for the complete Hamiltonian, a goal already achieved by other means by Coelho et al, and for a special open case attracting recent attention.