Zobrazeno 1 - 10
of 56
pro vyhledávání: '"Shahab Shahidi"'
Autor:
Tiberiu Harko, Shahab Shahidi
Publikováno v:
European Physical Journal C: Particles and Fields, Vol 84, Iss 5, Pp 1-22 (2024)
Abstract We consider the cosmological implications of the Weyl geometric gravity theory. The basic action of the model is obtained from the simplest conformally invariant gravitational action, constructed, in Weyl geometry, from the square of the Wey
Externí odkaz:
https://doaj.org/article/ffb12aa9128449dca65ae41a1826c5ea
Publikováno v:
European Physical Journal C: Particles and Fields, Vol 82, Iss 12, Pp 1-28 (2022)
Abstract We consider numerical black hole solutions in the Weyl conformal geometry and its associated conformally invariant Weyl quadratic gravity. In this model, Einstein gravity (with a positive cosmological constant) is recovered in the spontaneou
Externí odkaz:
https://doaj.org/article/2c6870f7eb6a4f85ad38c7e743e993ca
Palatini formulation of the conformally invariant $$f\left( R,L_m\right) $$ f R , L m gravity theory
Autor:
Tiberiu Harko, Shahab Shahidi
Publikováno v:
European Physical Journal C: Particles and Fields, Vol 82, Iss 11, Pp 1-18 (2022)
Abstract We investigate the field equations of the conformally invariant models of gravity with curvature-matter coupling, constructed in Weyl geometry, using the Palatini formalism. We consider the case in which the Lagrangian is given by the sum of
Externí odkaz:
https://doaj.org/article/617a97584a5543789cbe61f4d98ee337
Autor:
Tiberiu Harko, Shahab Shahidi
Publikováno v:
European Physical Journal C: Particles and Fields, Vol 82, Iss 3, Pp 1-22 (2022)
Abstract We investigate the coupling of matter to geometry in conformal quadratic Weyl gravity, by assuming a coupling term of the form $$L_m{\tilde{R}}^2$$ L m R ~ 2 , where $$L_m$$ L m is the ordinary matter Lagrangian, and $${\tilde{R}}$$ R ~ is t
Externí odkaz:
https://doaj.org/article/6302306a01ec4afc998ee14cd100d0e0
Autor:
Shahab Shahidi, Nima Khosravi
Publikováno v:
European Physical Journal C: Particles and Fields, Vol 82, Iss 3, Pp 1-9 (2022)
Abstract Recently a new 4D Einstein–Gauss–Bonnet theory has been introduced (Glavan and Lin in Phys Rev Lett 124: 081301, 2020) with a serious debate that it does not possess a covariant equation of motion in 4D. This feature, makes impossible to
Externí odkaz:
https://doaj.org/article/7c7c7cad85304c4da0c4b8c6c8754dbb
Publikováno v:
European Physical Journal C: Particles and Fields, Vol 81, Iss 8, Pp 1-33 (2021)
Abstract We consider the cosmological evolution in an osculating point Barthel–Randers type geometry, in which to each point of the space-time manifold an arbitrary point vector field is associated. This Finsler type geometry is assumed to describe
Externí odkaz:
https://doaj.org/article/286800e370934438a0f6b13db3e31a1f
Autor:
Shahab Shahidi
Publikováno v:
European Physical Journal C: Particles and Fields, Vol 81, Iss 4, Pp 1-10 (2021)
Abstract We consider a gravitational theory with an additional non-minimal coupling between baryonic matter fields and geometry. The coupling is second order in the energy momentum tensor and can be seen as a generalization of the energy–momentum s
Externí odkaz:
https://doaj.org/article/122f5899452846aca4144d6cb63acfa2
Publikováno v:
European Physical Journal C: Particles and Fields, Vol 81, Iss 2, Pp 1-19 (2021)
Abstract We consider the geodesic deviation equation, describing the relative accelerations of nearby particles, and the Raychaudhuri equation, giving the evolution of the kinematical quantities associated with deformations (expansion, shear and rota
Externí odkaz:
https://doaj.org/article/87b8e1e56fc04e1089fadaebbd85baf9
Publikováno v:
European Physical Journal C: Particles and Fields, Vol 80, Iss 5, Pp 1-22 (2020)
Abstract We consider an f(Q, T) type gravity model in which the scalar non-metricity $$Q_{\alpha \mu \nu }$$ Qαμν of the space-time is expressed in its standard Weyl form, and it is fully determined by a vector field $$w_{\mu }$$ wμ . The field e
Externí odkaz:
https://doaj.org/article/96e974ca50794b5da98897851c271b8b
Publikováno v:
European Physical Journal C: Particles and Fields, Vol 80, Iss 2, Pp 1-20 (2020)
Abstract The possible existence of naked singularities, hypothetical astrophysical objects, characterized by a gravitational singularity without an event horizon is still an open problem in present day astrophysics. From an observational point of vie
Externí odkaz:
https://doaj.org/article/9f791278aae845a6874cdde33eff94b7