Results 41 to 50 of about 540,486 (189)
Viscosity in Modified Gravity [PDF]
Entropy, 2012 A bulk viscosity is introduced in the formalism of modified gravity. It is shownthat, based on a natural scaling law for the viscosity, a simple solution can be found forquantities such as the Hubble parameter and the energy density. These solutions mayincorporate a viscosity-induced Big Rip singularity.
openaire +4 more sources
Solar System experiments do not yet veto modified gravity models [PDF]
, 2006 The dynamical equivalence between modified and scalar-tensor gravity theories is revisited and it is concluded that it breaks down in the limit to general relativity.
C. L. Bennett +8 more
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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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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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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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Modified gravity and coupled quintessence
, 2014 The distinction between modified gravity and quintessence or dynamical dark energy is difficult. Many models of modified gravity are equivalent to models of coupled quintessence by virtue of variable transformations.
Wetterich, C.
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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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Dynamical stability of Minkowski space in higher order gravity
, 2015 We discuss the Minkowski stability problem in modified gravity by using dynamical system approach. The method to investigate dynamical stability of Minkowski space was proposed.
Tretyakov, Petr V.
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