Nonlinear definition of the shadowy mode in higher-order scalar-tensor theories
General Relativity and Quantum Cosmology
2021-12-13 v2 High Energy Physics - Theory
Abstract
We study U-DHOST theories, i.e., higher-order scalar-tensor theories which are degenerate only in the unitary gauge and yield an apparently unstable extra mode in a generic coordinate system. We show that the extra mode satisfies a three-dimensional elliptic differential equation on a spacelike hypersurface, and hence it does not propagate. We clarify how to treat this "shadowy" mode at both the linear and the nonlinear levels.
Keywords
Cite
@article{arxiv.2110.03194,
title = {Nonlinear definition of the shadowy mode in higher-order scalar-tensor theories},
author = {Antonio De Felice and Shinji Mukohyama and Kazufumi Takahashi},
journal= {arXiv preprint arXiv:2110.03194},
year = {2021}
}
Comments
10 pages