Journal
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
Volume 28, Issue 5, Pages -Publisher
WORLD SCIENTIFIC PUBL CO PTE LTD
DOI: 10.1142/S0218271819420069
Keywords
Alternative gravity theories; modified gravity; dark energy
Categories
Ask authors/readers for more resources
This paper reviews scalar-tensor theories characterized by a Lagrangian that, despite the presence of second-order derivatives, contains a single scalar degree of freedom. These theories, known as Degenerate Higher-Order Scalar-Tensor (DHOST) theories, include Horndeski and Beyond Horndeski theories. They propagate a single scalar mode as a consequence of the degeneracy of their Lagrangian and, therefore, are not plagued by an Ostrogradsky instability. They have been fully classified up to cubic order in second-order derivatives. The study of their phenomenological consequences restricts the subclass of DHOST theories that are compatible with observations. In cosmology, these theories can be described in the language of the unified effective approach to dark energy and modified gravity. Compact objects in the context of DHOST theories are also discussed.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available