Realization of quintom dark energy after DESI DR2 in Nieh-Yan modified teleparallel gravity

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Main Authors: Kang, Yuxuan, Li, Mingzhe, Yi, Changzhi
Format: Preprint
Published: 2026
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author Kang, Yuxuan
Li, Mingzhe
Yi, Changzhi
author_facet Kang, Yuxuan
Li, Mingzhe
Yi, Changzhi
contents Recent observations from the DESI Collaboration indicate a preference for quintom dark energy, i.e., its equation of state evolves across the cosmological constant boundary $w=-1$. It is well known that models with single perfect fluid or single scalar field minimally coupled to Einstein gravity develop perturbative instabilities around the crossing, thereby cannot realize the quintom scenario. In this paper, we propose a method to circumvent the instability problem of these models by considering the coupling of dark energy to the Nieh-Yan density within the framework of teleparallel gravity. We show that with this coupling the background evolution is not affected, but the dark energy perturbation is removed from the menu of dynamical degrees of freedom, thus avoiding the inherent difficulties in the old models. Furthermore, the Nieh-Yan coupling causes parity violation in gravitational waves, and this can be considered as a clear prediction of this mechanism.
format Preprint
id arxiv_https___arxiv_org_abs_2602_00506
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Realization of quintom dark energy after DESI DR2 in Nieh-Yan modified teleparallel gravity
Kang, Yuxuan
Li, Mingzhe
Yi, Changzhi
General Relativity and Quantum Cosmology
Cosmology and Nongalactic Astrophysics
High Energy Physics - Phenomenology
High Energy Physics - Theory
Recent observations from the DESI Collaboration indicate a preference for quintom dark energy, i.e., its equation of state evolves across the cosmological constant boundary $w=-1$. It is well known that models with single perfect fluid or single scalar field minimally coupled to Einstein gravity develop perturbative instabilities around the crossing, thereby cannot realize the quintom scenario. In this paper, we propose a method to circumvent the instability problem of these models by considering the coupling of dark energy to the Nieh-Yan density within the framework of teleparallel gravity. We show that with this coupling the background evolution is not affected, but the dark energy perturbation is removed from the menu of dynamical degrees of freedom, thus avoiding the inherent difficulties in the old models. Furthermore, the Nieh-Yan coupling causes parity violation in gravitational waves, and this can be considered as a clear prediction of this mechanism.
title Realization of quintom dark energy after DESI DR2 in Nieh-Yan modified teleparallel gravity
topic General Relativity and Quantum Cosmology
Cosmology and Nongalactic Astrophysics
High Energy Physics - Phenomenology
High Energy Physics - Theory
url https://arxiv.org/abs/2602.00506