Nonlinear definition of the shadowy mode in higher-order scalar-tensor theories
説明
<jats:title>Abstract</jats:title> <jats:p>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.</jats:p>
収録刊行物
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- Journal of Cosmology and Astroparticle Physics
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Journal of Cosmology and Astroparticle Physics 2021 (12), 020-, 2021-12-01
IOP Publishing