Effective description of higher-order scalar-tensor theories

D Langlois, M Mancarella, K Noui… - Journal of Cosmology …, 2017 - iopscience.iop.org
Most existing theories of dark energy and/or modified gravity, involving a scalar degree of
freedom, can be conveniently described within the framework of the Effective Theory of Dark …

Extended scalar-tensor theories of gravity

M Crisostomi, K Koyama… - Journal of Cosmology and …, 2016 - iopscience.iop.org
We study new consistent scalar-tensor theories of gravity recently introduced by Langlois
and Noui with potentially interesting cosmological applications. We derive the conditions for …

Dark energy and modified gravity in degenerate higher-order scalar–tensor (DHOST) theories: A review

D Langlois - International Journal of Modern Physics D, 2019 - World Scientific
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 …

Effective field theory of modified gravity with two scalar fields: dark energy and dark matter

LÁ Gergely, S Tsujikawa - Physical Review D, 2014 - APS
We present a framework for discussing the cosmology of dark energy and dark matter based
on two scalar degrees of freedom. An effective field theory of cosmological perturbations is …

Reconstructing Horndeski theories from phenomenological modified gravity and dark energy models on cosmological scales

J Kennedy, L Lombriser, A Taylor - Physical Review D, 2018 - APS
Recently we have derived a set of mapping relations that enables the reconstruction of the
family of Horndeski scalar-tensor theories which reproduce the background dynamics and …

Essential building blocks of dark energy

J Gleyzes, D Langlois, F Piazza… - Journal of Cosmology …, 2013 - iopscience.iop.org
We propose a minimal description of single field dark energy/modified gravity within the
effective field theory formalism for cosmological perturbations, which encompasses most …

Modified gravity and cosmology with nonminimal direct or derivative coupling between matter and the Einstein tensor

P Asimakis, S Basilakos, A Lymperis, M Petronikolou… - Physical Review D, 2023 - APS
We construct new classes of modified theories in which the matter sector couples with the
Einstein tensor, namely we consider direct couplings of the latter to the energy-momentum …

Mimetic gravity as DHOST theories

D Langlois, M Mancarella, K Noui… - Journal of Cosmology …, 2019 - iopscience.iop.org
We show that theories of mimetic gravity can be viewed as degenerate higher-order scalar-
tensor (DHOST) theories that admit an extra local (gauge) symmetry in addition to the usual …

Cosmology in new gravitational scalar-tensor theories

EN Saridakis, M Tsoukalas - Physical Review D, 2016 - APS
We investigate the cosmological applications of new gravitational scalar-tensor theories,
which are novel modifications of gravity possessing 2+ 2 propagating degrees of freedom …

Effective action approach to cosmological perturbations in dark energy and modified gravity

RA Battye, JA Pearson - Journal of Cosmology and Astroparticle …, 2012 - iopscience.iop.org
In light of upcoming observations modelling perturbations in dark energy and modified
gravity models has become an important topic of research. We develop an effective action to …