Rolling Galileons: Evolving Braiding Strength for Viable Dark Energy
Abstract
Motivated by growing observational indications that dark energy may be dynamical, we introduce Rolling Galileon gravity: a minimal shift-symmetry-breaking extension of the cubic Galileon in which the coupling coefficients are allowed to vary, giving rise to an evolving braiding strength. The full theory space, shown to be closed under field redefinitions, is characterised by two functions. We derive analytical conditions to satisfy three phenomenological requirements: i) a phantom-crossing equation of state at late times, ii) a positive integrated Sachs-Wolfe signature, and iii) absence of pathologies in the screened scalar force in cosmic voids. We show that these conditions are collectively satisfied by an increasing braiding strength relative to the kinetic sector. A Bayesian analysis of minimal Rolling Galileon models finds that they can satisfy the viability requirements i)-iii) whilst providing an acceptable fit to expansion-history data.
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BibTeX
@misc{hallam2026rolling,
title = {{Rolling Galileons: Evolving Braiding Strength for Viable Dark Energy}},
author = {James Hallam and Krishna Naidoo and Sergi Sirera and Tessa Baker},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2607.16395},
eprint = {2607.16395},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.16395},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Rolling Galileons: Evolving Braiding Strength for Viable Dark Energy
AU - James Hallam
AU - Krishna Naidoo
AU - Sergi Sirera
AU - Tessa Baker
PY - 2026
DA - 2026/09/01
PB - arXiv
DO - 10.48550/arxiv.2607.16395
UR - https://arxiv.org/abs/2607.16395
AB - Motivated by growing observational indications that dark energy may be dynamical, we introduce Rolling Galileon gravity: a minimal shift-symmetry-breaking extension of the cubic Galileon in which the coupling coefficients are allowed to vary, giving rise to an evolving braiding strength. The full theory space, shown to be closed under field redefinitions, is characterised by two functions. We derive analytical conditions to satisfy three phenomenological requirements: i) a phantom-crossing equation of state at late times, ii) a positive integrated Sachs-Wolfe signature, and iii) absence of pathologies in the screened scalar force in cosmic voids. We show that these conditions are collectively satisfied by an increasing braiding strength relative to the kinetic sector. A Bayesian analysis of minimal Rolling Galileon models finds that they can satisfy the viability requirements i)-iii) whilst providing an acceptable fit to expansion-history data.
ER -