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A locally-built, LLM-digested index of recent arXiv papers in quant finance, geometry/topology, and statistical ML — keyword search served straight from SQLite on this machine.

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48 results for Einstein space-times

The paper examines properties of WW-curvature tensor in relativistic space-times.

problem Investigating the properties and implications of the WW-curvature tensor in relativistic space-times.
method Analyzing the semi-symmetry and divergence properties of the energy-momentum tensor in relation to the WW-curvature tensor.
result Space-times with specific properties of the WW-curvature tensor are classified as Einstein or Codazzi type.

Study finds conditions for certain warped product manifolds to be quasi-Einstein.

problem Conditions for quasi-Einstein sequential warped product manifolds.
method Investigated necessary and sufficient conditions for specific types of manifolds.
result Identified conditions for sequential warped product manifolds to be quasi-Einstein.

Proves stability of Minkowski space-time for Einstein-Yang-Mills equations.

problem Stability of Minkowski space-time for perturbations governed by Einstein-Yang-Mills equations.
method Proves exterior energy estimates for tensorial non-linear wave equations in Minkowski space-time.
result Proves exterior stability of Minkowski space-time for Einstein-Yang-Mills equations.

The study examines a semi-symmetric metric connection in perfect fluid space-time and phantom barriers.

problem Investigating the properties of semi-symmetric metric connections in perfect fluid space-time.
method Using concircularly semi-symmetric metric connections, the study derives conditions for quasi-Einstein manifolds and examines the scalar curvature of perfect fluid space-times.
result The study proves that in a perfect fluid space-time, the scalar curvature is constant and represents a phantom barrier.

Proves stability of Minkowski space-time in Einstein-Yang-Mills system.

problem Stability of Minkowski space-time governed by Einstein-Yang-Mills system.
method Null frame decomposition, well-posedness of Cauchy development, convergence to Minkowski space-time.
result Exterior stability of Minkowski space-time in Lorenz gauge without spherical symmetry.

Essentially, some conditions for the Riemannian factor and the warping function of a standard static space-time are obtained in order to guarantee that no nontrivial warping function on the Riemannian factor can make the standard static space-time Einstein.

2004-06-03abs ↗pdf ↗

Stability of Minkowski space-time in higher dimensions proven for arbitrary small perturbations.

problem Stability of Minkowski space-time solution to Einstein-Yang-Mills equations in higher dimensions.
method Global stability proof for arbitrary small perturbations using wave coordinates and gauge invariant norms.
result Global stability of Minkowski space-time in higher dimensions n5n \geq 5 for arbitrary small perturbations.

This paper explores Lorentzian manifolds with specific connections and their symmetries.

problem Characterizing Lorentzian manifolds with concircularly semi-symmetric metric connections.
method Investigates the properties of Lorentzian manifolds equipped with a concircularly semi-symmetric metric connection under specific conditions.
result Derives necessary and sufficient conditions for the manifold to be Einstein and proves that a perfect fluid space-time with a semi-symmetric metric PP-connection is Ricci pseudo-symmetric manifold of constant type.

The notion of maximal extension of a globally hyperbolic space-time arises from the notion of maximal solutions of the Cauchy problem associated to the Einstein's equations of general relativity. In 1969 Choquet-Bruhat and Geroch proved that if the Cauchy problem has a local solution, this solution has a unique maximal…

2013-06-17abs ↗pdf ↗

Stability of Minkowski space-time in Einstein-Yang-Mills system proven.

problem Stability of Minkowski space-time in Einstein-Yang-Mills system.
method Null frame decomposition, wave coordinates, dispersive estimates.
result Solutions converge to zero Yang-Mills curvature and Minkowski space-time.

The paper explores Kaluza-Klein theories without assuming a fibration structure.

problem Exploring Kaluza-Klein theories without assuming a fibration structure.
method Variational formulations of gauge theories and Einstein--Yang-Mills equations.
result Classical solutions allow the construction of a manifold XX of dimension 4 as physical space-time, leading to solutions of the Einstein--Yang-Mills systems.

In this paper, we study Ricci-flat and Einstein Lorentzian multiply warped products. We also consider the case of having constant scalar curvatures for this class of warped products. Finally, after we introduce a new class of spacetimes called as generalized Kasner space-times, we apply our results to this kind of spac…

2004-06-02abs ↗pdf ↗

The paper explores stable surfaces in Einstein-Maxwell theory, proving mass bounds and nonexistence results.

problem Exploring stable surfaces in static Einstein-Maxwell space-time.
method Using mean-stable surfaces theory to prove properties of lapse functions and mass bounds.
result Proves ADM mass is bounded by Hawking quasi-local mass.

The paper examines conditions for Einstein-like classes in doubly warped product manifolds.

problem Conditions for a factor manifold to be in the same Einstein-like class as the entire doubly warped product manifold.
method Analysis of the Ricci tensor and warping functions.
result Sufficient and necessary conditions for a factor manifold to inherit the Einstein-like class of the entire manifold.

In this paper, based on an intrinsic definition of asymptotically AdS space-times, we show that the standard anti-de Sitter space-time is the unique strictly stationary asymptotically AdS solution to the vacuum Einstein equations with negative cosmological constant in dimension less than 7. Instead of using the positiv…

2003-10-18abs ↗pdf ↗

We prove theorems about the Ricci and the Weyl tensors on generalized Robertson-Walker space-times of dimension n3n\ge 3. In particular, we show that the concircular vector introduced by Chen decomposes the Ricci tensor as a perfect fluid term plus a term linear in the contracted Weyl tensor. The Weyl tensor is harmoni…

2016-08-03abs ↗pdf ↗

Unified method for constructing non-vacuum initial data sets in general relativity.

problem Constructing solutions of Einstein constraint equations with coupled matter sources.
method Phase space representation and scaling of matter fields.
result Semi-decoupling of conformal constraint equations for constant-mean curvature initial data.

The paper studies φ\varphi-static perfect fluid space-times in Einstein's General Relativity.

problem Analyzing the geometry of φ\varphi-static perfect fluid space-times.
method Reduction of Einstein's Field Equations to the factors of a static warped product, introducing φ\varphi-curvatures.
result Sharp sufficient conditions for a compact φ\varphi-SPFST with boundary to be isometric to the standard hemisphere.

Many classical results in relativity theory concerning spherically symmetric space-times have easy generalizations to warped product space-times, with a two-dimensional Lorentzian base and arbitrary dimensional Riemannian fibers. We first give a systematic presentation of the main geometric constructions, with emphasis…

2017-07-05abs ↗pdf ↗

We show the existence of a Hawking vector field in a full neighborhood of a local, regular, bifurcate, non-expanding horizon embedded in a smooth Einstein-Maxwell space-time without assuming the underlying space-time is analytic. It extends one result of Friedrich, Rácz and Wald, which was limited to the interior of th…

2009-03-27abs ↗pdf ↗

Study of Einstein-Hilbert action on metric-affine spaces with connections.

problem Formulating and solving variational problems for mixed Einstein-Hilbert action.
method Developed variational formulas for extrinsic geometry, derived Euler-Lagrange equations, and characterized critical points.
result Derived new equations analogous to Einstein and Cartan equations, with a new Ricci type tensor.

In this paper, we study the structure of the limit space of a sequence of almost Einstein manifolds, which are generalizations of Einstein manifolds. Roughly speaking, such manifolds are the initial manifolds of some normalized Ricci flows whose scalar curvatures are almost constants over space-time in the L1L^1-sense,…

2012-02-14abs ↗pdf ↗

Causality violations are typically seen as unrealistic and undesirable features of a physical model. The following points out three reasons why causality violations, which Bonnor and Steadman identified even in solutions to the Einstein equation referring to ordinary laboratory situations, are not necessarily undesirab…

2006-09-15abs ↗pdf ↗

We study Einstein's equation in (m+n)D(m+n)D and (1+n)D(1+n)D warped spaces (Mˉ,gˉ)(\bar{M},\bar{g}) and classify all such spaces satisfying Einstein equations Gˉ=Λˉgˉ\bar{G}=-\barΛ\bar{g}. We show that the warping function not only can determine the cosmological constant Λˉ\barΛ but also it can determine the cosmological constant ΛΛ a…

2016-10-14abs ↗pdf ↗

We propose in this paper a new approach to the Kaluza-Klein idea of a five dimensional space-time unifying gravitation and electromagnetism, and extension to higher-dimensional space-time. By considering a natural geometric definition of a matter fluid and abandoning the usual requirement of a Ricci-flat five dimension…

2017-09-13abs ↗pdf ↗

Conformally quasi-recurrent (CQR)_n pseudo-Riemannian manifolds are investigated, and several new results are obtained. It is shown that the Ricci tensor and the gradient of the fundamental vector are Weyl compatible tensors (the notion was introduced recently by the authors and applies to significative space-times), (…

2013-05-22abs ↗pdf ↗

Minkowski space is a physically important space-time for which the finding an adequate holographic description is an urgent problem. In this paper we develop further the proposal made in hep-th/0303006 for the description as a duality between Minkowski space-time and a Conformal Field Theory defined on the boundary of …

2004-05-27abs ↗pdf ↗

Let $\M_*=\cup_{t\in [t_0, t_*)} Σ_t$ be a part of vacuum globally hyperbolic space-time $(\bM, \bg)$, foliated by constant mean curvature hypersurfaces ΣtΣ_t with t0<t<0t_0<t_*<0. We show that the foliation can be extended beyond tt_* if the second fundamental form kk and the lapse function nn satisfy $$ \int_{t_0}^{t_…

2010-04-17abs ↗pdf ↗

The paper presents new formulations of gauge and gravity theories using dynamical principal bundles.

problem Formulating gauge and gravity theories with a flexible principal bundle structure.
method Original variational formulations of Yang-Mills, Einstein's gravitation, and Kaluza-Klein theories with a dynamical principal bundle.
result The principal bundle structure and connection emerge from the dynamics, leading to solutions of Yang-Mills, Einstein-Cartan, or Yang-Mills-Einstein equations.

Study of four-dimensional Lorentzian manifolds with real Killing spinors.

problem Characterizing and understanding four-dimensional Lorentzian manifolds with Killing spinors.
method Differential geometry and topology, Killing spinor equations, flow equations.
result Proves that the evolution flow defined by a real Killing spinor preserves the Hamiltonian and momentum constraints of the Einstein equation with negative curvature.

In this paper, we study the Einstein warped products and multiply warped products with a quarter-symmetric connection. We also study warped products and multiply warped products with a quarter-symmetric connection with constant scalar curvature. Then apply our results to generalized Robertson-Walker spacetimes with a q…

2014-10-01abs ↗pdf ↗

We compute all 2-covariant tensors naturally constructed from a semiriemannian metric which are divergence-free and have weight greater than -2. As a consequence, it follows a characterization of the Einstein tensor as the only, up to a constant factor, 2-covariant tensor naturally constructed from a semiriemannian met…

2007-09-12abs ↗pdf ↗

The correspondence of stationary, axisymmetric, asymptotically flat space-times and bundles over a reduced twistor space has been established in four dimensions. The main impediment for an application of this correspondence to examples in higher dimensions is the lack of a higher-dimensional equivalent of the Ernst pot…

2012-06-30abs ↗pdf ↗