Using Cosmological Perturbation Theory to Distinguish between GR and Unimodular Gravity by Júlio C. Fabris, Marcelo H. Alvarenga, Hermano Velten

“…Unimodular gravity is one of the oldest geometric gravity theories and alternatives to general relativity. Essentially, it is based on the Einstein–Hilbert Lagrangian with an additional constraint on the determinant of the metric. …”
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Towards precise constraints in modified gravity: bounds on alternative coupling gravity using white dwarf mass-radius measurements by M. D. Danarianto, A. Sulaksono

“…We have shown that several alternatives to general relativity (GR), which modified GR only within matter, might be reduced to the well-known Poisson equation similar to that of Eddington-inspired Born Infeld (EiBI) and Minimal Exponential Measure (MEMe) gravity. …”
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Cosmological tests of general relativity by Baker, T, Theresa Baker

“…Inspired by the Parameterized Post-Newtonian framework I develop a new formalism, the Parameterized Post-Friedmann formalism, that aims to unify the linear cosmological perturbation theory of many alternatives to General Relativity.</p> <p>Having introduced the Parameterized Post-Friedmann formalism and demonstrated its application via a suite of examples, I examine several issues surrounding parameterized tests of gravity. …”

Impact of Lorentz Violation Models on Exoplanets’ Dynamics by Antonio Gallerati, Matteo Luca Ruggiero, Lorenzo Iorio

“…These variations are influenced by both Newtonian and non-Newtonian perturbations to the dominant inverse-square acceleration; accordingly, exoplanetary systems lend themselves to testing theories of gravity alternative to general relativity. In this paper, we consider the impact of the Standard Model Extension (a model that can be used to test all possible Lorentz violations) on the perturbation of radial velocity and suggest that suitable exoplanets’ configurations and improvements in detection techniques may contribute to obtaining new constraints on the model parameters.…”
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Nonminimal derivative coupling cosmology and the speed of gravitational waves by Isaac Torres, Felipe de Melo Santos

“…The so-called Nonminimal Derivative Coupling (NDC) is an alternative to General Relativity, which produces an asymptotic inflationary mechanism when applied to cosmology. …”
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DHOST gravity in ultra-diffuse galaxies – part I: the case of NGC1052-DF2 by Enrico Laudato, Vincenzo Salzano

“…Thus, we can conclude that even objects like NGC1052-DF2 are not in contrast, and are not obstacles, to the study and the definition of a reliable alternative to General Relativity.…”
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