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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Behind Horndeski: structurally robust higher derivative EFTs
TL;DR: In this article, a complete classification of higher derivative scalar interactions can be found, which can yield sizeable effects without introducing ghosts and, at the same time, define an effective field theory robust under the inclusion of quantum corrections.
Journal ArticleDOI
Fab 5: Noncanonical Kinetic Gravity, Self Tuning, and Cosmic Acceleration
TL;DR: In this paper, a nonlinear combination of purely kinetic gravity terms can give rise to an accelerating universe without the addition of extra propagating degrees of freedom on cosmological backgrounds.
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Black-Hole Models in Loop Quantum Gravity
TL;DR: In this article, the authors derived a new space-time structure which is covariant in a generalized sense, which is consistent with both generalized covariance and low-curvature determinism.
Journal ArticleDOI
Caustic free completion of pressureless perfect fluid and k-essence
TL;DR: In this article, the authors show that the free massive/self-interacting complex scalar reproduces dynamics of pressureless perfect fluid/shift-symmetric k-essence under certain initial conditions in the limit of large mass/sharp selfinteracting potential.
Journal ArticleDOI
Spatially covariant gravity with velocity of the lapse function: the Hamiltonian analysis
Xian Gao,Zhi-Bang Yao +1 more
TL;DR: In this article, a large class of gravity theories that respect spatial covariance, and involve kinetic terms for both the spatial metric and the lapse function, were investigated, and the condition requiring the kinetic terms to be degenerate is not sufficient to evade the unwanted scalar mode in general.
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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