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2 results on '"attractor: de Sitter"'

1. Phenomenology of minimal theory of quasidilaton massive gravity

Author

Shinji Mukohyama, Antonio De Felice, Michele Oliosi, Institut Denis Poisson (IDP), Centre National de la Recherche Scientifique (CNRS)-Université de Tours-Université d'Orléans (UO), Fédération de recherche Denis Poisson (FDP), Université d'Orléans (UO)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université de Tours (UT)-Université d'Orléans (UO)

Subjects
High Energy Physics - Theory, Cosmology and Nongalactic Astrophysics (astro-ph.CO), General relativity, perturbation, attractor: de Sitter, kinetic, Perturbation (astronomy), FOS: Physical sciences, alternative theories of gravity, Kinetic term, General Relativity and Quantum Cosmology (gr-qc), attractor: stability, gravitation: potential, 01 natural sciences, General Relativity and Quantum Cosmology, photon: velocity, Gravitational potential, De Sitter universe, 0103 physical sciences, Attractor, gravitation: massive, 010306 general physics, Physics, 010308 nuclear & particles physics, Gravitational wave, symmetry: violation, polarization: tensor, [PHYS.HTHE]Physics [physics]/High Energy Physics - Theory [hep-th], gravitational radiation, velocity: acoustic, violation: Lorentz, Massive gravity, Classical mechanics, High Energy Physics - Theory (hep-th), dilaton: massive, [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], symmetry: Lorentz, dilaton: scalar, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], simplex, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The minimal theory of quasidilaton massive gravity with or without a Horndeski-type kinetic term for the quasidilaton field propagates only three physical modes: the two massive tensor polarizations and one scalar mode. This reduced number of degrees of freedom is realized by a Lorentz symmetry violation at cosmological scales and the presence of appropriate constraints that remove unwanted modes. Vacuum cosmological solutions have been considered in a previous work, and it has been shown that the late-time de Sitter attractor is stable under inhomogeneous perturbations. In this work, we explore the stability of cosmological solutions in the presence of matter fields. Assuming for simplicity that the quasidilaton scalar is on an attractor at the level of the background, we derive stability conditions in the subhorizon limit, and find the scalar sound speeds, as well as the modification with respect to general relativity to the gravitational potential in the quasistatic approximation. We also find that the speed limit of gravitational waves coincides with the speed of light for any homogeneous and isotropic cosmological background, on or away from the attractor., Comment: 14 pages

Published
2019
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2. Cosmological evolution in DHOST theories

Author

David Langlois, Marco Crisostomi, Karim Noui, Kazuya Koyama, Daniele A. Steer, Institut de Physique Théorique - UMR CNRS 3681 (IPHT), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Laboratoire de Physique Théorique d'Orsay [Orsay] (LPT), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), AstroParticule et Cosmologie (APC (UMR_7164)), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Laboratoire de Mathématiques et Physique Théorique (LMPT), Université de Tours-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université de Tours

Subjects
High Energy Physics - Theory, Cosmology and Nongalactic Astrophysics (astro-ph.CO), perturbation, gr-qc, scalar tensor, attractor: de Sitter, Perturbation (astronomy), FOS: Physical sciences, General Relativity and Quantum Cosmology (gr-qc), Fixed point, coupling: minimal, System of linear equations, 01 natural sciences, General Relativity and Quantum Cosmology, symbols.namesake, Theoretical physics, De Sitter universe, 0103 physical sciences, Attractor, STFC, Physics, 010308 nuclear & particles physics, [PHYS.HTHE]Physics [physics]/High Energy Physics - Theory [hep-th], hep-th, Degenerate energy levels, RCUK, Astronomy and Astrophysics, stability, ghost, High Energy Physics - Theory (hep-th), fixed point, Homogeneous, symbols, astro-ph.CO, [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], ST/N000668/1, k-essence, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Lagrangian, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

In the context of Degenerate Higher-Order Scalar-Tensor (DHOST) theories, we study cosmological solutions and their stability properties. In particular, we explicitly illustrate the crucial role of degeneracy by showing how the higher order homogeneous equations in the physical frame (where matter is minimally coupled) can be recast in a system of equations that do not involve higher order derivatives. We study the fixed points of the dynamics, finding the conditions for having a de Sitter attractor at late times. Then we consider the coupling to matter field (described for convenience by a k-essence Lagrangian) and find the conditions to avoid gradient and ghost instabilities at linear order in cosmological perturbations, extending previous work. Finally, we apply these results to a simple subclass of DHOST theories, showing that de Sitter attractor conditions, no ghost and no gradient instabilities conditions (both in the self-accelerating era and in the matter dominated era) can be compatible., 17 pages, 2 figures. V2: error corrected in the effective dark energy equation of state

Published
2019
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