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
Cosmological constraints on Brans-Dicke theory.
A. Avilez,Constantinos Skordis +1 more
TL;DR: Constraints on the Brans-Dicke (BD) theory of gravity using cosmic microwave background data from Planck have greater validity than for the BD theory and are valid for any Horndeski theory, the most general second-order scalar-tensor theory, which approximates theBD theory on cosmological scales.
Journal ArticleDOI
Matter creation in a nonsingular bouncing cosmology
TL;DR: In this paper, the authors examined Parker particle production in the two-field matter bounce cosmological model and showed that it is sufficient to reheat the universe to high temperatures.
Journal ArticleDOI
Extended vector-tensor theories
TL;DR: In this paper, a degeneracy condition of the Lagrangian in the context of ADM decomposition of space-time to eliminate an unwanted mode was introduced, and a new class of massive vector theories where five degrees of freedom can propagate, corresponding to three for massive vector modes and two for massless tensor modes.
Journal ArticleDOI
Effective Theory of Interacting Dark Energy
Jérôme Gleyzes,Jérôme Gleyzes,David Langlois,Michele Mancarella,Michele Mancarella,Filippo Vernizzi +5 more
TL;DR: In this paper, a unified treatment of dark energy and modified gravity is presented, where distinct conformal-disformal couplings of matter species to the gravitational sector are derived.
Journal ArticleDOI
A simplified approach to general scalar-tensor theories
TL;DR: In this article, it was shown that for linear perturbations about a Friedmann-Robertson-Walker background, the theory is completely specified by only six functions of time, two of which are constrained by the background evolution.
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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