Work

Fresh Look at Shift Symmetric Modified Gravity

Year: 2026

Type: preprint

Abstract: Shift symmetric Horndeski gravity can be a simple, well posed theory with protection against quantum corrections. Overturning conventional thought that such a theory cannot cross the phantom divide ($w=-1$) we present both analytic and numerical proof that it can. We carry out a detailed dynamical systems analysis showing the evolution of ghost free and stable regions within the model family, identify the fixed point and dynamical attractor structure, and derive the interaction of the $w=-1$ curve with these phase space structures. This reveals two mechanisms for cosmologies crossing the phantom divide while preserving shift symmetry.

Source: arXiv (Cornell University)

DOI: 10.48550/arxiv.2610.36063

Authors: Calderon, Rodrigo, Linder, Eric V.

Institutions: FZU - Institute of Physics of the Czech Academy of Sciences, Lawrence Berkeley National Laboratory, University of California System, University of California, Berkeley

Language: English

Topic: Cosmology and Gravitation Theories

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: green

Funder: Ministerstvo Školství, Mládeže a Tělovýchovy

Awards: G1935710221, G545007060, G8140083606

OpenAlex ID: W7224086142

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