Cosmology and Gravitation Theories

We analyze a class of product geometries of the form $\mathbb{R}^{1,1}\times Σ_2$ supported by electric, magnetic, or dyonic flux in the Einstein-Maxwell-$Λ$ theory. These spacetimes belong to a unified family of direct products $(dS_2,\mathbb{R}^{1,1},AdS_2)\times Σ_2$ distinguished solely by the sign of the Lorentzi…

We analyze a class of product geometries of the form $\mathbb{R}^{1,1}\times Σ_2$ supported by electric, magnetic, or dyonic flux in the Einstein-Maxwell-$Λ$ theory. These spacetimes belong to a unified family of direct products $(dS_2,\mathbb{R}^{1,1},AdS_2)\times Σ_2$ distinguished solely by the sign of the Lorentzi…

A metric is called universal if every symmetric conserved rank-two tensor constructed locally from the metric, the curvature, and covariant derivatives of the curvature is proportional to the metric. Such a metric solves arbitrary metric-based higher-curvature field equations after, at most, a change in the effective…

This preprint introduces the geometric framework of "Causal Accessibility" (D) as a unified origin for both classical relativistic limits (the light-speed barrier, event horizons) and galactic-scale kinematics. By treating these phenomena as regime-dependent manifestations of outward causal reach, we provide a paramet…

Abstract We investigate the Chern–Simons-like formulation of 3D MMG-like massive gravity models that are “third-way consistent”. Building on previous work on exotic massive gravities, we analyze a class of MMG-like theories characterized by a specific parity structure and an auxiliary field hierarchy. Focusing on the…

We investigate the Chern-Simons-like formulation of 3D MMG-like massive gravity models that are "third-way consistent". Building on previous work on exotic massive gravities, we analyze a class of MMG-like theories characterized by a specific parity structure and an auxiliary field hierarchy. Focusing on the simplest…

We investigate the Chern-Simons-like formulation of 3D MMG-like massive gravity models that are "third-way consistent". Building on previous work on exotic massive gravities, we analyze a class of MMG-like theories characterized by a specific parity structure and an auxiliary field hierarchy. Focusing on the simplest…

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In this study, we consider a cosmological model based on Rényi holographic dark energy within the context of an anisotropic Bianchi type III spacetime geometry. The dark energy density is taken as a modified function of the Hubble parameter, which enables us to express the Einstein field equations in a closed dynamica…

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