Degenerate higher order scalar-tensor theories beyond Horndeski and disformal transformations
read the original abstract
We consider all degenerate scalar-tensor theories that depend quadratically on second order derivatives of a scalar field, which we have identified in a previous work. These theories, whose degeneracy in general ensures the absence of Ostrogradski instability, include the quartic Horndenski Lagrangian as well as its quartic extension beyond Horndeski, but also other families of Lagrangians. We study how all these theories transform under general conformal-disformal transformations and find that they can be separated into three main classes that are stable under these transformations. This leads to a complete classification modulo conformal-disformal transformations. Finally, we show that these higher order theories include mimetic gravity and some particular khronometric theories. They also contain theories that do not correspond, to our knowledge, to already studied theories, even up to field redefinitions.
This paper has not been read by Pith yet.
Forward citations
Cited by 8 Pith papers
-
Covariant scalar-tensor theories beyond second derivatives
A new covariant foliation-based construction of scalar-tensor theories up to four derivatives of the scalar field that extends DHOST and U-DHOST without unitary gauge and propagates three degrees of freedom.
-
Gravitational wave constraints on the Paneitz operator
The Paneitz operator in 4D belongs to extended mimetic gravity and is constrained by gravitational wave propagation speed.
-
Rotating Black Holes with Primary Scalar Hair: Shadow Signatures in Beyond Horndeski Gravity
Rotating black holes with primary scalar hair in beyond Horndeski gravity produce shadows whose diameter increases for negative Q and whose distortion increases for positive Q, with EHT bounds on M87* restricting but ...
-
Degenerate higher-order scalar-tensor theories in metric-affine gravity
A metric-affine version of quadratic DHOST theories is derived and reduced to a one-function family that satisfies degeneracy conditions and light-speed gravitational wave propagation.
-
Imperfect dark matter with higher derivatives
Higher-derivative extension of dark matter yields an imperfect fluid that matches pressureless dust on homogeneous backgrounds but generates acceleration and vorticity to avoid caustic singularities in inhomogeneous c...
-
Dynamical system analysis of the cosmological phases in Palatini $k$-essence gravity
Dynamical systems analysis of a Palatini k-essence model identifies fixed points for quasi-de-Sitter epochs, scaling solutions, and quintessence phases connected by heteroclinic orbits in flat FLRW cosmology.
-
Spherical collapse and cluster number counts in DHOST theories that pass the constraints from gravitational waves
In DHOST theories consistent with GW observations, deviations from GR suppress high-redshift galaxy cluster abundance relative to ΛCDM when using spherical collapse and analytic mass functions matched to eROSITA data.
-
Noncanonical Approaches To Inflation
A review thesis covering Mukhanov parametrization, general scalar-tensor theories, and new slow-roll techniques for canonical and noncanonical inflation observables.
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.