Results 11 to 20 of about 634,467 (244)

f(R) Theories

Living Reviews in Relativity, 2010
Over the past decade, f(R) theories have been extensively studied as one of the simplest modifications to General Relativity. In this article we review various applications of f(R) theories to cosmology and gravity – such as inflation, dark energy, local
Antonio De Felice, Shinji Tsujikawa
doaj   +2 more sources

k-essence f(R) gravity inflation

Nuclear Physics B, 2019
In this work we study a modified version of f(R) gravity in which higher order kinetic terms of a scalar field are added in the action of vacuum f(R) gravity. This type of theory is a type of k-essence f(R) gravity, and it belongs to the general class of
S. Nojiri, S.D. Odintsov, V.K. Oikonomou
doaj   +1 more source

Pre-inflationary bounce effects on primordial gravitational waves of f(R) gravity

Physics Letters B, 2022
In this work we shall study a possible pre-inflationary scenario for our Universe and how this might be realized by f(R) gravity. Specifically, we shall introduce a scenario in which the Universe in the pre-inflationary era contracts until it reaches a ...
S.D. Odintsov, V.K. Oikonomou
doaj   +1 more source

Massive white dwarfs in $$f(\mathtt {R,L_m})$$ f ( R , L m ) gravity

European Physical Journal C: Particles and Fields, 2022
In this work, we investigate the equilibrium configurations of massive white dwarfs (MWD) in the context of modified gravity, namely $$f(\mathtt {R,L_m})$$ f ( R , L m ) gravity, where $$\mathtt {R}$$ R stands for the Ricci scalar and $$\mathtt {L_m}$$ L
R. V. Lobato, G. A. Carvalho, N. G. Kelkar, M. Nowakowski   +3 more
doaj   +1 more source

Cosmological viability of f(R)-gravity as an ideal fluid and its compatibility with a matter dominated phase [PDF]

, 2006
We show that f(R)-gravity can, in general, give rise to cosmological viable models compatible with a matter-dominated epoch evolving into a late accelerated phase.
A. Troisi, Abdalla, Allemandi, Amarzguioui, Amendola, Amendola, Bahcall, Barrow, Barrow, Birrell, Buchbinder, Capozziello, Capozziello, Capozziello, Capozziello, Capozziello, Capozziello, Capozziello, Capozziello, Capozziello, Capozziello, Capozziello, Capozziello, Cardone, Carloni, Carroll, Cembranos, Cho, Clifton, Cole, Copeland, Crooks, Dominguez, Faraoni, Faraoni, Gorini, Hannestad, Hannestad, Hwang, Hwang, Hwang, Hwang, Jassal, Kalara, Kerner, Koivisto, Krauss, Melchiorri, Meng, Navarro, Nojiri, Nojiri, Nojiri, Odintsov, Odintsov, Odintsov, Olmo, Padmanabhan, Perivolaropoulos, Riess, S. Capozziello, S. Nojiri, S.D. Odintsov, Schmidt, Shao, Sotiriou, Sotiriou, Sotiriou, Spergel, Starobinsky, Turyshev, Will, Will, Woodard   +73 more
core   +2 more sources

A study of cylindrically symmetric solutions in $$f(R, \phi , X)$$ f ( R , ϕ , X ) theory of gravity

European Physical Journal C: Particles and Fields, 2022
In this article, we aim to investigate some cylindrically symmetric solutions in a very well known modified theory named as $$f(R, \phi , X)$$ f ( R , ϕ , X ) theory of gravity, where the terms R, $$\phi $$ ϕ and X are clarified as Ricci Scalar, scalar ...
Adnan Malik, Ayesha Nafees, Akram Ali, Muhammad Naeem Butt   +3 more
doaj   +1 more source

Neutron stars in $$f(\mathtt {R,L_m})$$ f ( R , L m ) gravity with realistic equations of state: joint-constrains with GW170817, massive pulsars, and the PSR J0030+0451 mass-radius from NICER data

European Physical Journal C: Particles and Fields, 2021
In this work, we investigate neutron stars (NS) in $$f(\mathtt {R,L_m})$$ f ( R , L m ) theory of gravity for the case $$f(\mathtt {R,L_m})= \mathtt {R}+ \mathtt {L_m}+ \sigma \mathtt {R}\mathtt {L_m}$$ f ( R , L m ) = R + L m + σ R L m , where $$\mathtt
R. V. Lobato, G. A. Carvalho, C. A. Bertulani   +2 more
doaj   +1 more source

Ghost-free F(R) gravity with Lagrange multiplier constraint

Physics Letters B, 2017
We propose two new versions of ghost-free generalized F(R) gravity with Lagrange multiplier constraint. The first version of such theory for a particular degenerate choice of the Lagrange multiplier, corresponds to mimetic F(R) gravity.
S. Nojiri, S.D. Odintsov, V.K. Oikonomou
doaj   +1 more source

FRW Cosmology in F(R,T) gravity

, 2012
In this paper, we consider a theory of gravity with a metric-dependent torsion namely the $F(R,T)$ gravity, where $R$ is the curvature scalar and $T$ is the torsion scalar. We study a geometric root of such theory. In particular we give the derivation of
Myrzakulov, Ratbay
core   +1 more source

The post-Newtonian limit of hybrid f(R)-gravity

EPJ Web of Conferences, 2018
The post-Newtonian formalism is developed for hybrid f(R)-gravity. The model is tested in the weak field regime of the Solar System. Using scalartensor representation of hybrid f(R)-gravity we impose restrictions on the parameters of the theory and show ...
Dyadina Polina, Labazova Sofya
doaj   +1 more source