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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Gravitational Wave Decay into Dark Energy
TL;DR: In this article, the decay of gravitational waves into dark energy fluctuations was studied through the processes of gamma-to-pi/pi-pi decay, made possible by the spontaneous breaking of Lorentz invariance.
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Generalized SU(2) Proca theory reconstructed and beyond
TL;DR: In this paper, the generalized SU(2) Proca theory (GSU2P) was constructed from the Lagrangian degeneration and removed one degree of freedom from the vector field in accordance with the irreducible representations of the Poincar\'e group.
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Stability of Geodesically Complete Cosmologies
TL;DR: In this article, the stability of spatially flat FRW solutions which are geodesically complete is studied, i.e. for which one can follow null (graviton) geodesics both in the past and in the future without ever encountering singularities.
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Positivity bounds on dark energy: when matter matters
TL;DR: In this article, it was shown that the existence of a standard UV completion requires that gravitational waves must travel superluminally on cosmological backgrounds, which leads to further constraints on the dark energy parameter space.
Journal ArticleDOI
Consistency relations for large-scale structure in modified gravity and the matter bispectrum
TL;DR: In this paper, the perturbation theory for large-scale structure in the most general scalar-tensor theories propagating a single scalar degree of freedom, including Horndeski theories and beyond, is studied.
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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