Work

Alleviating cosmological strong coupling with torsion in regularized 4D Einstein-Gauss-Bonnet gravity

Year: 2026

Type: preprint

Abstract: The four-dimensional scalar-tensor theory obtained by conformally regularizing the Gauss-Bonnet term has a vanishing kinetic term for the scalar perturbation mode on its late-time de Sitter attractor, signaling strong coupling. We show that, when the regularization is carried out in Riemann-Cartan geometry, the resulting theory admits de Sitter attractors with trace torsion on which this kinetic term remains nonvanishing. On spatially flat FLRW backgrounds with trace torsion, the quadratic actions for perturbations describe one scalar mode and two tensor modes, while the vector perturbations are nondynamical. We identify a nonempty parameter region admitting de Sitter attractors whose scalar and tensor perturbations are free of ghost and gradient instabilities at all momenta.

Source: arXiv (Cornell University)

DOI: 10.48550/arxiv.2610.23628

Authors: Qiu, Jianhui, Luo, Ling-Wei, Liu, Chunhui, Geng, Chao-Qiang

Institutions: University of Chinese Academy of Sciences, Hunan Normal University

Language: English

Topic: Cosmology and Gravitation Theories

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: green

Funder: National Natural Science Foundation of China

Award: G2712368410

OpenAlex ID: W7222943243

Cites: 52

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Related to: 10