Results 61 to 70 of about 32,011 (180)
Ghosts in metric-affine higher order curvature gravity
European Physical Journal C: Particles and Fields, 2019 We disprove the widespread belief that higher order curvature theories of gravity in the metric-affine formalism are generally ghost-free. This is clarified by considering a sub-class of theories constructed only with the Ricci tensor and showing that ...
Jose Beltrán Jiménez, Adria Delhom
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Instabilities in metric-affine theories of gravity with higher order curvature terms
European Physical Journal C: Particles and Fields, 2020 We discuss the presence of ghostly instabilities for metric-affine theories constructed with higher order curvature terms. We mainly focus on theories containing only the Ricci tensor and show the crucial role played by the projective symmetry.
Jose Beltrán Jiménez, Adrià Delhom
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A Note on the Geometry of RW Space-Times
Mathematics, 2023 A conformally flat GRW space-time is a perfect fluid RW space-time. In this note, we investigated the influence of many differential curvature conditions, such as the existence of recurrent and semi-symmetric curvature tensors.
Sameh Shenawy +2 more
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Wadi Alshatti University Journal of Pure and Applied SciencesThis paper presents and examines a new class of Finsler spaces known as Generalized BW-Four-Recurrent Finsler spaces - , in which a particular recurrence relation involving non-null covariant vector fields a_lmns and b_lmns is satisfied by the fourth ...
Adel Al-Qashbari +3 more
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Hierarchy of spaces of projective connection
Дифференциальная геометрия многообразий фигур, 2018 We consider the bundle of projective frames over a smooth manifold, i. e. the principal bundle whose typical fiber is the projective group. The giving fundamental-group connection in this bundle transforms it into a space of general projective connection.
Yu. Shevchenko
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Some Remarks on Fourth-Order Tensor Fields on Space-Times
MathematicsThis paper is a contribution to Einstein’s general relativity theory and is mostly a review of known work. It concentrates attention on four fourth-order tensors which arise on the space-time manifold describing this theory and which are very useful ...
Graham Hall
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On Almost C(α)-Manifold Satisfying Certain Curvature Conditions
Cumhuriyet Science JournalThis research article is about the geometry of the almost C(α)- manifold. Some important properties of the almost C(α)- manifold with respect to the W_3- curvature tensor, such as W_3-flat and W_3- semi-symmetry, are investigated.
Pakize Uygun +2 more
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Index of pseudo-projectively-symmetric semi-Riemannian manifolds
Karpatsʹkì Matematičnì Publìkacìï, 2015 The index of $\widetilde{\nabla}$-pseudo-projectively symmetric and in particular for $\widetilde{\nabla}$-projectively symmetric semi-Riemannian manifolds, where $\widetilde{\nabla}$ is Ricci symmetric metric connection, are discussed.
P. Gupta
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Some Identities for Generalized Curvature Tensors in 𝓑-Recurrent Finsler Space
Journal of New Theory, 2020 The purpose of the present paper is to consider and study a certain identities for some generalized curvature tensors in ℬ-recurrent Finsler space 𝐹𝑛 in which Cartan’s second curvature tensor 𝑃𝑗𝑘ℎ𝑖 satisfies the generalized of recurrence condition with ...
Adel Mohammed Ali Al-qashbari
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University of Aden Journal of Natural and Applied Sciences, 2019 In this paper, we defined a Finsler space \(F_n\) for which Weyl’s projective curvature tensor \(W_{jkh}^i\) satisfies the generalized-birecurrence condition with respect to Cartan’s connection parameters \(\Gamma_{kh}^{*i}\) , given by the condition ...
A. Al-Qashbari
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