On the numerical evaluation of the `exact' Post-Newtonian parameters in Brans-Dicke and Entangled Relativity theories

Fuente: arXiv
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Main Authors: Chehab, Thomas, Minazzoli, Olivier
Format: Preprint
Published: 2026
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author Chehab, Thomas
Minazzoli, Olivier
author_facet Chehab, Thomas
Minazzoli, Olivier
contents In context of Brans-Dicke scalar-tensor theories of gravity, it has recently been obtained that the post-Newtonian parameters should be generalized in the context of strongly gravitating bodies, and that its generalization -- the so-called $\textit{exact parameters}$ -- actually depends on the pressure and energy density of a considered celestial body. Here we develop two new methods to numerically obtain the $\textit{exact parameters}$ by means of usual Tolman-Oppenheimer-Volkoff computation, and find that the difference with the value of standard post-Newtonian parameters can be more than 80% in some situations. We also provide the connection with the Damour-Esposito Farèse non-pertubative parameter $α_{DEF}$. We then apply the methodology to the case of Entangled Relativity, and derive these exact parameters for the Sun and the Earth, as well as for neutron stars. We argue that current and foreseeable experiments are likely able to constrain the theory under the assumption that $\mathcal{L}_m=-ρ$, where $ρ$ is the total energy density. If $\mathcal{L}_m=T$ instead, as often advocated in the literature, then there is no deviation with respect to General Relativity and the prospects of testing Entangled Relativity become much more remote in time, as only compact objects with extreme electric or magnetic fields could lead to some deviation from General Relativity.
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id arxiv_https___arxiv_org_abs_2602_11811
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle On the numerical evaluation of the `exact' Post-Newtonian parameters in Brans-Dicke and Entangled Relativity theories
Chehab, Thomas
Minazzoli, Olivier
General Relativity and Quantum Cosmology
In context of Brans-Dicke scalar-tensor theories of gravity, it has recently been obtained that the post-Newtonian parameters should be generalized in the context of strongly gravitating bodies, and that its generalization -- the so-called $\textit{exact parameters}$ -- actually depends on the pressure and energy density of a considered celestial body. Here we develop two new methods to numerically obtain the $\textit{exact parameters}$ by means of usual Tolman-Oppenheimer-Volkoff computation, and find that the difference with the value of standard post-Newtonian parameters can be more than 80% in some situations. We also provide the connection with the Damour-Esposito Farèse non-pertubative parameter $α_{DEF}$. We then apply the methodology to the case of Entangled Relativity, and derive these exact parameters for the Sun and the Earth, as well as for neutron stars. We argue that current and foreseeable experiments are likely able to constrain the theory under the assumption that $\mathcal{L}_m=-ρ$, where $ρ$ is the total energy density. If $\mathcal{L}_m=T$ instead, as often advocated in the literature, then there is no deviation with respect to General Relativity and the prospects of testing Entangled Relativity become much more remote in time, as only compact objects with extreme electric or magnetic fields could lead to some deviation from General Relativity.
title On the numerical evaluation of the `exact' Post-Newtonian parameters in Brans-Dicke and Entangled Relativity theories
topic General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2602.11811