Disformal transformations of Friedmann-Lema\^itre-Robertson-Walker and Bianchi geometries are analyzed in the context of scalar-tensor gravity. Novel aspects discussed explicitly are the 3+1 splitting, the effective fluid equivalent of the gravitational scalar, Bianchi models, stealth solutions, and de Sitter solutions with non-constant scalar field (which are signatures of scalar-tensor gravity). Both pure disformal transformations and more general ones are discussed, including those containing higher derivatives of the scalar field recently introduced in the literature.
@article{arxiv.2401.00091,
title = {Disforming scalar-tensor cosmology},
author = {Valerio Faraoni and Carla Zeyn},
journal= {arXiv preprint arXiv:2401.00091},
year = {2024}
}
Comments
15 pages, latex. Added a section and an appendix on second order disformal transformation, extra discussion, bibliography expanded. Matches the version to appear in Phys. Rev. D