Journal ArticleDOI
Second-order scalar-tensor field equations in a four-dimensional space
TLDR
In this article, the second-order Euler-Lagrange tensors are derived from a Lagrangian which is at most of second order in the derivatives of the field functions.Abstract:
Lagrange scalar densities which are concomitants of a pseudo-Riemannian metric-tensor, a scalar field and their derivatives of arbitrary order are considered. The most general second-order Euler-Lagrange tensors derivable from such a Lagrangian in a four-dimensional space are constructed, and it is shown that these Euler-Lagrange tensors may be obtained from a Lagrangian which is at most of second order in the derivatives of the field functions.read more
Citations
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Journal ArticleDOI
Instability of hairy black holes in shift-symmetric Horndeski theories
TL;DR: In this paper, the authors developed a black hole perturbation theory for shift-symmetric scalar-tensor theories and computed the quadratic action of odd-parity perturbations.
Journal ArticleDOI
Phenomenology of dark energy: general features of large-scale perturbations
Louis Perenon,Louis Perenon,Federico Piazza,Federico Piazza,Christian Marinoni,Christian Marinoni,Lam Hui +6 more
TL;DR: In this article, the authors present a systematic exploration of dark energy and modified gravity models containing a single scalar field non-minimally coupled to the metric, and exploit an effective field theory (EFT) formulation and by imposing simple physical constraints such as stability conditions and (sub-)luminal propagation of perturbations.
Journal ArticleDOI
Inflation, quintessence, and the origin of mass
TL;DR: In this paper, the history of the universe describes a crossover from a scale invariant "past fixed point" where all particles are massless, to a future fixed point for which spontaneous breaking of the exact scale symmetry generates the particle masses.
Book ChapterDOI
The Effective Field Theory of Inflation/Dark Energy and the Horndeski Theory
TL;DR: The effective field theory of cosmological perturbations is a useful framework to deal with the low-energy degrees of freedom present for inflation and dark energy as mentioned in this paper, and the Lagrangian of curvature perturbation and gravitational waves with a single scalar degree of freedom.
Journal ArticleDOI
Evolution of Dark Energy Reconstructed from the Latest Observations
TL;DR: In this paper, the authors reconstruct the evolution of the dark energy (DE) density using a nonparametric Bayesian approach from a combination of the latest observational data, and find a 3.7σ preference for an evolving effective DE density with interesting features.
References
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Journal ArticleDOI
Mach's principle and a relativistic theory of gravitation
Carl H. Brans,R. H. Dicke +1 more
TL;DR: In this paper, the role of Mach's principle in physics is discussed in relation to the equivalence principle and the difficulties encountered in attempting to incorporate Mach's principles into general relativity are discussed.
Journal ArticleDOI
The Einstein Tensor and Its Generalizations
TL;DR: In this paper, the number of independent tensors of this type depends crucially on the dimension of the space, and, in the four dimensional case, the only tensors with these properties are the metric and the Einstein tensors.
Journal ArticleDOI
Comments on the scalar-tensor theory
TL;DR: In this article, the ponderomotive laws of a scalar-tensor theory are constructed free of approximations in the form of integral laws, and the integrals are extended over two-and three-dimensional domains that lie entirely in empty space but surround the regions containing matter.
Journal ArticleDOI
The uniqueness of the einstein field equations in a four-dimensional space.
TL;DR: In this article, the Euler-Lagrange equations corresponding to a Lagrange density which is a function of g ≥ 2 and its first two derivatives are investigated and necessary and sufficient conditions for these equations to be of second order are obtained and it is shown that in a four-dimensional space the Einstein field equations (with cosmological term) are the only permissible second order Euler Lagrange equations.
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