On the structural stability of a simple cosmological model in R + αR2 theory of gravity

The theory of gravity with a quadratic contribution of scalar curvature is investigated using a dynamical systems approach. The simplest Friedmann–Robertson–Walker metric is employed to formulate the dynamics in both the Jordan frame and the conformally transformed Einstein frame. We show that, in b...

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Main Author: Orest Hrycyna
Format: Article
Language:English
Published: Elsevier 2025-01-01
Series:Physics Letters B
Online Access:http://www.sciencedirect.com/science/article/pii/S037026932400755X
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author Orest Hrycyna
author_facet Orest Hrycyna
author_sort Orest Hrycyna
collection DOAJ
description The theory of gravity with a quadratic contribution of scalar curvature is investigated using a dynamical systems approach. The simplest Friedmann–Robertson–Walker metric is employed to formulate the dynamics in both the Jordan frame and the conformally transformed Einstein frame. We show that, in both frames, there are stable de Sitter states where the expansion of the Hubble function naturally includes terms corresponding to an effective dark matter component. Using the invariant centre manifold, we demonstrate that, in the Einstein frame, there exists a zero-measure set of initial conditions that lead from an unstable to a stable de Sitter state. Additionally, the initial de Sitter state is associated with a parallelly propagated singularity. We show that the formulations of the theory in the Jordan frame and the Einstein frame are physically nonequivalent.
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institution Kabale University
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series Physics Letters B
spelling doaj-art-95ec6a6f90ea4c6f8de37ce8b7ee955f2025-01-10T04:37:37ZengElsevierPhysics Letters B0370-26932025-01-01860139197On the structural stability of a simple cosmological model in R + αR2 theory of gravityOrest Hrycyna0Theoretical Physics Division, National Centre for Nuclear Research, Ludwika Pasteura 7, 02-093 Warszawa, PolandThe theory of gravity with a quadratic contribution of scalar curvature is investigated using a dynamical systems approach. The simplest Friedmann–Robertson–Walker metric is employed to formulate the dynamics in both the Jordan frame and the conformally transformed Einstein frame. We show that, in both frames, there are stable de Sitter states where the expansion of the Hubble function naturally includes terms corresponding to an effective dark matter component. Using the invariant centre manifold, we demonstrate that, in the Einstein frame, there exists a zero-measure set of initial conditions that lead from an unstable to a stable de Sitter state. Additionally, the initial de Sitter state is associated with a parallelly propagated singularity. We show that the formulations of the theory in the Jordan frame and the Einstein frame are physically nonequivalent.http://www.sciencedirect.com/science/article/pii/S037026932400755X
spellingShingle Orest Hrycyna
On the structural stability of a simple cosmological model in R + αR2 theory of gravity
Physics Letters B
title On the structural stability of a simple cosmological model in R + αR2 theory of gravity
title_full On the structural stability of a simple cosmological model in R + αR2 theory of gravity
title_fullStr On the structural stability of a simple cosmological model in R + αR2 theory of gravity
title_full_unstemmed On the structural stability of a simple cosmological model in R + αR2 theory of gravity
title_short On the structural stability of a simple cosmological model in R + αR2 theory of gravity
title_sort on the structural stability of a simple cosmological model in r   αr2 theory of gravity
url http://www.sciencedirect.com/science/article/pii/S037026932400755X
work_keys_str_mv AT oresthrycyna onthestructuralstabilityofasimplecosmologicalmodelinrar2theoryofgravity