Results 21 to 30 of about 338,003 (249)

A study of traversable wormhole solutions in extended teleparallel theory of gravity with matter coupling

European Physical Journal C: Particles and Fields, 2021
This study is devoted to explore the physical aspects of wormhole geometry under embedded class-1 spacetime in $$f(T,\tau )$$ f ( T , τ ) gravity, where $$\tau $$ τ denotes the trace of the energy-momentum tensor and T is the torsion.
Allah Ditta, Ibrar Hussain, G. Mustafa, Abdelghani Errehymy, Mohammed Daoud   +4 more
doaj   +1 more source

Energy Conditions in Palatini Approach to Modified $f(R)$ Gravity

Journal of High Energy Physics, Gravitation and Cosmology, 2018
In this paper, we review modified $f(R)$ theories of gravity in Palatini formalism. In this framework, , we use the Raychaudhuri's equation along with the requirement that the gravity is attractive, which holds for any geometrical theory of gravity to discuss the energy conditions. Then, to derive these conditions, we obtain an expression for effective
openaire   +4 more sources

Irreversible Geometrothermodynamics of Open Systems in Modified Gravity

Entropy, 2023
In this work, we explore the formalism of the irreversible thermodynamics of open systems and the possibility of gravitationally generated particle production in modified gravity.
Miguel A. S. Pinto, Tiberiu Harko, Francisco S. N. Lobo   +2 more
doaj   +1 more source

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

Crossing the Phantom Divide [PDF]

, 2006
We consider fluid perturbations close to the "phantom divide" characterised by p = -rho and discuss the conditions under which divergencies in the perturbations can be avoided.
Domenico Sapone, H. Kodama, Martin Kunz, R. Durrer   +3 more
core   +3 more sources

Study of anisotropic compact stars with quintessence field and modified chaplygin gas in f(T) gravity

European Physical Journal C: Particles and Fields, 2019
In this work, we get an idea of the existence of compact stars in the background of f(T) modified gravity where T is a scalar torsion. We acquire the equations of motion using anisotropic property within the spherically compact star with electromagnetic ...
Pameli Saha, Ujjal Debnath
doaj   +1 more source

Reconstruction of energy conditions from observations and implications for extended theories of gravity

European Physical Journal C: Particles and Fields, 2019
The attempt to describe the recent accelerated expansion of the Universe includes different propositions for dark energy models and modified gravity theories.
M. Penna-Lima, S. D. P. Vitenti, M. E. S. Alves, J. C. N. de Araujo, F. C. Carvalho   +4 more
doaj   +1 more source

Modified f(G) gravity models with curvature-matter coupling

, 2012
A modified f(G) gravity model with coupling between matter and geometry is proposed, which is described by the product of the Lagrange density of the matter and an arbitrary function of the Gauss-Bonnet term.
A.D. Dolgov, A.D. Dolgov, A.D. Felice, A.D. Felice, A.D. Felice, A.G. Riess, B.J. Li, B.J. Li, C. Brans, C.G. Boehmer, D. Rapetti, Dvali, E. Komatsu, E.J. Copeland, E.R. Harrison, G. Cognola, G. Cognola, J. Sadeghi, J. Santos, J. Wang, J. Wang, J.D. Bekenstein, J.D. Brown, J.H. Kung, J.H. Kung, Jian-Bo Lu, K. Bamba, L. Amendola, Liang-Liang Lin, M. Alimohammadi, M. Visser, M. Visser, N. Goheer, N.M. Garcia, O. Bertolami, O. Bertolami, O. Bertolami, O. Bertolami, O. Bertolami, P. Landsberg, R. Maartens, S. Capozziello, S. Capozziello, S. Capozziello, S. Nojiri, S. Nojiri, S. Nojiri, S. Nojiri, S. Nojiri, S. Nojiri, S. Nojiri, S. Perlmutter, S. Tsujikawa, S.E.P. Bergliaffa, S.M. Carroll, S.W. Hawking, S.Y. Zhou, T. Harko, T. Jacobson, T.P. Sotiriou, T.P. Sotiriou, V. Faraoni, V. Faraoni, V. Faraoni, Wei-Li Han, Y.B. Wu, Ya-Bo Wu, Yue-Yue Zhao, Zhuo Zhang   +68 more
core   +1 more source

Probing the geometries of wormholes: A comparative study of f(R,T) and f(Q,T) theories in the presence of BEC matter

Nuclear Physics B
This study explores wormhole solutions within two distinct modified gravity theories, namely f(R,T) gravity and f(Q,T) gravity, incorporating Bose-Einstein condensate (BEC) dark matter to analyze their geometric properties.
Chaitra Chooda Chalavadi, H. Aruna Kumara, V. Venkatesha   +2 more
doaj   +1 more source

Energetics in Condensate Star and Wormholes

, 2008
It is known that the total gravitational energy in localized sources having static spherical symmetry and satisfying energy conditions is negative (attractive gravity).
A. Panchenko, C. W. Misner, I. Z. Fisher, K. K. Nandi, K. A. Bronnikov, K. A. Bronnikov, L. Flamm, M. Visser, R. G. Cai, R. M. Wald, Y. Z. Zhang   +10 more
core   +1 more source