• Publications
  • Influence
Degenerate higher derivative theories beyond Horndeski: evading the Ostrogradski instability
Theories with higher order time derivatives generically suffer from ghost-like instabilities, known as Ostrogradski instabilities. This fate can be avoided by considering "degenerate" Lagrangians,Expand
  • 317
  • 23
  • PDF
Healthy theories beyond Horndeski
Jérôme Gleyzes, 2 David Langlois, Federico Piazza, 4 and Filippo Vernizzi CEA, Institut de Physique Théorique, F-91191 Gif-sur-Yvette cédex, CNRS, Unité de recherche associée-2306, F-91191Expand
  • 224
  • 21
  • PDF
Brane cosmological evolution in a bulk with cosmological constant
Abstract We consider the cosmology of a “3-brane universe” in a five dimensional (bulk) space-time with a cosmological constant. We show that Einstein's equations admit a first integral, analogous toExpand
  • 759
  • 17
  • PDF
Exploring gravitational theories beyond Horndeski
We have recently proposed a new class of gravitational scalar-tensor theories free from Ostrogradski instabilities, in arXiv:1404.6495. As they generalize Horndeski theories, or "generalized"Expand
  • 270
  • 15
  • PDF
Non-conventional cosmology from a brane-universe
Abstract We consider “brane universes”, where energy density is confined to four-dimensional hypersurfaces (three-branes) whereas one extra compact dimension is felt by gravity only. We show that theExpand
  • 756
  • 14
  • PDF
Hamiltonian formalism and gauge invariance for linear perturbations in inflation
A Hamiltonian treatment of gauge-invariant cosmological perturbations is presented. In this framework the gauge-invariant perturbations as well as their evolution equations are obtained with minimalExpand
  • 85
  • 12
Essential Building Blocks of Dark Energy
We propose a minimal description of single field dark energy/modified gravity within the effective field theory formalism for cosmological perturbations, which encompasses most existing models. WeExpand
  • 238
  • 10
  • PDF
Degenerate higher order scalar-tensor theories beyond Horndeski and disformal transformations
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, whoseExpand
  • 171
  • 10
  • PDF
Curvature and isocurvature perturbations in two-field inflation
We study cosmological perturbations in two-field inflation, allowing for non-standard kinetic terms. We calculate analytically the spectra of curvature and isocurvature modes at Hubble crossing, upExpand
  • 146
  • 9
  • PDF
A unifying description of dark energy
We review and extend a novel approach that we introduced recently, to describe general dark energy or scalar-tensor models. Our approach relies on an ADM formulation based on the hypersurfaces whereExpand
  • 153
  • 8
  • PDF