Zobrazeno 1 - 10
of 514
pro vyhledávání: '"MOLINARI, Luca"'
We derive the analog of the Tolman-Oppenheimer-Volkoff equation in conformal Killing gravity in a static spherically symmetric spacetime, sourced by perfect fluid matter. It differs from the original by `dark terms' associated to the conformal Killin
Externí odkaz:
http://arxiv.org/abs/2409.18663
Publikováno v:
Physical Review D 110, 044025 (2024)
We identify an anisotropic divergence-free conformal Killing tensor $K_{jl}$ for static spherically symmetric spacetimes, and write the conformal Killing gravity equations as Einstein equations augmented by this tensor. The field equations are of sec
Externí odkaz:
http://arxiv.org/abs/2406.12511
Publikováno v:
Physical Review D 110, 064041 (2024)
We introduce Sinyukov-like tensors, a special kind of conformal Killing tensors. In Robertson-Walker space-times they have the perfect-fluid form and only depend on two constants and the scale factor. They are the candidate for the dark term of the n
Externí odkaz:
http://arxiv.org/abs/2404.11468
We address in this article the criticism in a recently submitted article by Clement and Noiucer (arXiv:2312.17662 [gr-qc]) on "Cotton Gravity" (CG), a gravity theory alternative to General Relativity. These authors claim that CG is "not predictive" f
Externí odkaz:
http://arxiv.org/abs/2401.10479
Publikováno v:
Phys. Rev. D 109, 044059 (2024)
The Friedmann equations of Cotton gravity provide a simple parametrization to reproduce, by tuning a single function, the Friedmann equations of several extensions of gravity, such as f(R), modified Gauss-Bonnet f(G), teleparallel f(T), and more. It
Externí odkaz:
http://arxiv.org/abs/2312.02784
Publikováno v:
Phys. Rev. D 108, 124029 (2023)
We show that "Gravity at cosmological distances: Explaining the accelerating expansion without dark energy" recently proposed by J. Harada [6] is equivalent to the Einstein equation extended by the presence of an arbitrary conformal Killing tensor. T
Externí odkaz:
http://arxiv.org/abs/2308.06803
Publikováno v:
General Relativity and Gravitation, 2023 - open access
We present a covariant study of static space-times, as such and as solutions of gravity theories. By expressing the relevant tensors through the velocity and the acceleration vectors that characterise static space-times, the field equations provide a
Externí odkaz:
http://arxiv.org/abs/2306.05863
Publikováno v:
General Relativity and Gravitation, 2023 - open access
We study the geometric properties of certain Codazzi tensors for their own sake, and for their appearance in the recent theory of Cotton gravity. We prove that a perfect-fluid tensor is Codazzi if and only if the metric is a generalized Stephani univ
Externí odkaz:
http://arxiv.org/abs/2210.06173
Autor:
Molinari, Luca Guido
I conjecture three identities for the determinant of adjacency matrices of graphene triangles and trapezia with Bloch (and more general) boundary conditions. For triangles, the parametric determinant is equal to the characteristic polynomial of the s
Externí odkaz:
http://arxiv.org/abs/2206.14428
Autor:
Molinari, Luca Guido
Publikováno v:
Fundamental Journal of Mathematics and Applications 5 (4) (2022) 266-272
I reconsider the approximation of Bessel functions with finite sums of trigonometric functions, in the light of recent evaluations of Neumann-Bessel series with trigonometric coefficients. A proper choice of the angle allows for an efficient choice o
Externí odkaz:
http://arxiv.org/abs/2206.05334