Safe Phantom Divide Crossing from Unscreened Non-Minimal Coupling to Gravity
Abstract
Recent hints of dynamical dark energy, including a possible crossing of the phantom divide, have motivated the search for viable theoretical explanations. Scalar fields non-minimally coupled to gravity with a coupling of the form F(φ)=1+αφ2 have emerged as promising candidates, providing an improved fit to the data compared to ΛCDM and even the w0waCDM parametrization. However, in the absence of a screening mechanism, the regions of parameter space examined exhaustively so far (with α<0) violate stringent local constraints on the strength and time variation of gravity and enhance the matter growth rate at low redshifts, thereby compromising the viability of these solutions. In this work, we investigate a largely unexplored region of parameter space (with α>0) that realizes the crossing while remaining consistent with local constraints. This setup, which is subject to some fine-tuning, respects the BBN constraints and leads only to deviations of the effective gravitational coupling from Newton's constant below 0.3% in the past. We review the background and linear perturbation dynamics of the model, deriving analytical results that provide physical insight into its behavior, and update the constraints on the model using the latest cosmological data, including the DES-Dovekie supernova sample. We perform for the first time a full-fledged Monte Carlo analysis with α>0, studying the impact of the variation of G on the supernovae absolute luminosity, and compare the results with those obtained for α<0, using in both cases a linear potential. In the context of the model with non-minimal coupling and α<0, the standard model is excluded at the 2.50σ CL, whereas for α>0, the exclusion significance decreases to ∼ 2σ CL, indicating a moderate preference for these models over ΛCDM. [abridged]
Related
- Addressing the DESI DR2 phantom-crossing anomaly and enhanced H 0 tension with reconstructed scalar-tensor gravity
- Viable Phantom Crossing in Softly Broken Shift Symmetric Gravity
- Constraints on Horndeski gravity with phantom crossing
- Constraints on Horndeski gravity with phantom crossing
- Gravitational-Susceptibility Dip Behind DESI's results: Addressing the Phantom Crossing by Local limit of Nonlocal Gravity
BibTeX
@misc{argudopanes2026safe,
title = {{Safe Phantom Divide Crossing from Unscreened Non-Minimal Coupling to Gravity}},
author = {Joel Argudo-Panes and Alex González-Fuentes and Adrià Gómez-Valent},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.10133},
eprint = {2609.10133},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.10133},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Safe Phantom Divide Crossing from Unscreened Non-Minimal Coupling to Gravity
AU - Joel Argudo-Panes
AU - Alex González-Fuentes
AU - Adrià Gómez-Valent
PY - 2026
DA - 2026/09/09
PB - arXiv
DO - 10.48550/arxiv.2609.10133
UR - https://arxiv.org/abs/2609.10133
AB - Recent hints of dynamical dark energy, including a possible crossing of the phantom divide, have motivated the search for viable theoretical explanations. Scalar fields non-minimally coupled to gravity with a coupling of the form F(φ)=1+αφ^2 have emerged as promising candidates, providing an improved fit to the data compared to ΛCDM and even the w_0w_aCDM parametrization. However, in the absence of a screening mechanism, the regions of parameter space examined exhaustively so far (with α<0) violate stringent local constraints on the strength and time variation of gravity and enhance the matter growth rate at low redshifts, thereby compromising the viability of these solutions. In this work, we investigate a largely unexplored region of parameter space (with α>0) that realizes the crossing while remaining consistent with local constraints. This setup, which is subject to some fine-tuning, respects the BBN constraints and leads only to deviations of the effective gravitational coupling from Newton's constant below 0.3% in the past. We review the background and linear perturbation dynamics of the model, deriving analytical results that provide physical insight into its behavior, and update the constraints on the model using the latest cosmological data, including the DES-Dovekie supernova sample. We perform for the first time a full-fledged Monte Carlo analysis with α>0, studying the impact of the variation of G on the supernovae absolute luminosity, and compare the results with those obtained for α<0, using in both cases a linear potential. In the context of the model with non-minimal coupling and α<0, the standard model is excluded at the 2.50σ CL, whereas for α>0, the exclusion significance decreases to ∼ 2σ CL, indicating a moderate preference for these models over ΛCDM. [abridged]
ER -