Cosmological evolution in DHOST theories

Abstract : In the context of Degenerate Higher-Order Scalar-Tensor (DHOST) theories, we study cosmological solutions and their stability properties. In particular, we explicitly illustrate the crucial role of degeneracy by showing how the higher order homogeneous equations in the physical frame (where matter is minimally coupled) can be recast in a system of equations that do not involve higher order derivatives. We study the fixed points of the dynamics, finding the conditions for having a de Sitter attractor at late times. Then we consider the coupling to matter field (described for convenience by a k-essence Lagrangian) and find the conditions to avoid gradient and ghost instabilities at linear order in cosmological perturbations, extending previous work. Finally, we apply these results to a simple subclass of DHOST theories, showing that de Sitter attractor conditions, no ghost and no gradient instabilities conditions (both in the self-accelerating era and in the matter dominated era) can be compatible.
Liste complète des métadonnées

https://hal.archives-ouvertes.fr/hal-01921720
Contributeur : Inspire Hep <>
Soumis le : mercredi 14 novembre 2018 - 09:13:25
Dernière modification le : mercredi 20 mars 2019 - 12:10:09

Lien texte intégral

Identifiants

Citation

M. Crisostomi, Kazuya Koyama, D. Langlois, K. Noui, D.A. Steer. Cosmological evolution in DHOST theories. JCAP, 2019, 01 (01), pp.030. 〈10.1088/1475-7516/2019/01/030〉. 〈hal-01921720〉

Partager

Métriques

Consultations de la notice

72