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Modified gravity and cosmology
Physics Reports, 2012 In this review we present a thoroughly comprehensive survey of recent work on modified theories of gravity and their cosmological consequences. Amongst other things, we cover General Relativity, Scalar-Tensor, Einstein-Aether, and Bimetric theories, as well as TeVeS, f(R), general higher-order theories, Horava-Lifschitz gravity, Galileons, Ghost ...
Clifton, T. +7 more
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Causal hierarchy in modified gravity
Journal of High Energy Physics, 2020 We investigate the causal hierarchy in various modified theories of gravity. In general relativity the standard causal hierarchy, (key elements of which are chronology, causality, strong causality, stable causality, and global hyperbolicity), is well ...
Raúl Carballo-Rubio +3 more
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ON EXPONENTIAL MODIFIED GRAVITY [PDF]
International Journal of Modern Physics A, 2013 A modified theory of gravity with the function F(R) = R exp (αR) instead of Ricci scalar R in the Einstein–Hilbert action is considered and analyzed. The action of the model is converted into Einstein–Hilbert action at small value of the parameter α. From local tests we obtain a bound on the parameter α ≤ 10-6 cm 2.
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Cosmological bound from the neutron star merger GW170817 in scalar–tensor and F(R) gravity theories
Physics Letters B, 2018 We consider the evolution of cosmological gravitational waves in scalar–tensor theory and F(R) gravity theory as typical models of the modified gravity. Although the propagation speed is not changed from the speed of light, the propagation phase changes ...
Shin'ichi Nojiri, Sergei D. Odintsov
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Probing the existence of the ZTF Casimir wormholes in the framework of f(R) gravity
Nuclear Physics B, 2022 For the spherically symmetric static traversable wormholes, supported by the Casimir energy in f(R)=R+αR2 Quadratic, f(R)=f0Rn power-law Modified Gravity (MOG) theories we investigate energy conditions and dynamical stability of the wormhole solutions ...
Oleksii Sokoliuk +2 more
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Formalizing anisotropic inflation in modified gravity
Nuclear Physics B, 2022 Motivated by the fact that the pre-inflationary era may evolve in an exotic way, in this work we formalize anisotropic evolution in the context of modified gravity, focusing on pre-inflationary and near the vicinity of the inflationary epochs.
S. Nojiri +3 more
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Matter Instability in Theories with Modified Induced Gravity
Advances in High Energy Physics, 2012 Matter stability is a necessary condition to have a cosmologically viable model. Modified gravity in the spirit of f(R) theories suffers from matter instability in some subdomains of the model parameter space.
Kourosh Nozari, Faeze Kiani
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Generalized gravity from modified DFT
Journal of High Energy Physics, 2017 Recently, generalized equations of type IIB supergravity have been derived from the requirement of classical kappa-symmetry of type IIB superstring theory in the Green-Schwarz formulation.
Yuho Sakatani +2 more
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Classical and Quantum GravityAbstract A complete canonical formulation of general covariance makes it possible to construct new modified theories of gravity that are not of higher-curvature form, as shown here in a spherically symmetric setting. The usual uniqueness theorems are evaded by using a crucial and novel ingredient, allowing for fundamental fields of ...
Martin Bojowald, Erick I Duque
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Born–Infeld-type modified gravity [PDF]
International Journal of Geometric Methods in Modern Physics, 2019 We propose and investigate the modified Born–Infeld-type gravity model with the function [Formula: see text]. At different values of the dimensionless parameter [Formula: see text], the action is converted into some models including general relativity ([Formula: see text]), the Starobinsky model ([Formula: see text]), the exponential model of gravity (
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