Results 31 to 40 of about 68,602 (263)
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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, 2013 added references; made some clarifications; 8 ...
Dimitrijevic, Ivan +3 more
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Early modified gravity: Implications for cosmology [PDF]
Physical Review D, 2014 We study the effects of modifications of gravity after Big Bang Nucleosynthesis (BBN) which would manifest themselves mainly before recombination. We consider their effects on the Cosmic Microwave Background (CMB) radiation and on the formation of large scale structure.
Brax, Philippe +4 more
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GRAVITY FROM A MODIFIED COMMUTATOR [PDF]
International Journal of Modern Physics D, 2005 We show that a suitably chosen position-momentum commutator can elegantly describe many features of gravity, including the IR/UV correspondence and dimensional reduction ("holography"). Using the most simplistic example based on dimensional analysis of black holes, we construct a commutator which qualitatively exhibits these novel properties of ...
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Cosmological tests of modified gravity [PDF]
Reports on Progress in Physics, 2016 82 pages, 28 figures. This review is partly based on arXiv:1304.0601, arXiv:1305.0279 and arXiv:1503.06673.
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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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Charged gravastars in modified gravity [PDF]
Physical Review D, 2019 In this paper, we investigate the effects of electromagnetic field on the isotropic spherical gravastar models in metric $f(R,T)$ gravity. For this purpose, we have explored singularity-free exact models of relativistic spheres with a specific equation of state.
Yousaf, Z. +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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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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