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arXiv research

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.

169,291 papers · 148 categories

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18355370 · Jun 202019922001200920182026
48 results for modified Einstein gravity

Proposes new conformal parametrizations for modified Einstein gravity.

problem Initial data in modified Einstein gravity theories.
method Proposes conformal parametrizations that lead to conformally covariant systems.
result Some conformal parametrizations give rise to conformally covariant systems.

The paper introduces and analyzes pseudo generalized Ricci-recurrent spacetimes in modified gravity.

problem Characterizing and analyzing pseudo generalized Ricci-recurrent spacetimes in modified gravity.
method Introducing and characterizing pseudo generalized Ricci-recurrent spacetimes, proving their properties, and studying their impact under modified gravity scenarios.
result Pseudo generalized Ricci-recurrent spacetimes represent specific spacetime types under modified gravity scenarios.

Study on generalized mm-Kropina metrics in modified gravity and cosmology.

problem Understanding the geometric properties and applications of generalized mm-Kropina metrics.
method Proving the rationality of Finslerian geometric objects and studying the conditions for Einstein metrics.
result Conditions for a generalized mm-Kropina metric to be an exact solution in modified gravity and cosmology.

Contravariant gravity on Poisson manifolds is linked to Einstein gravity.

problem Exploring the relationship between Poisson gravity and Einstein gravity.
method Investigating the compatibility of Poisson and Riemann structures to define a unique connection and derive the contravariant gravity theory.
result The contravariant gravity theory can be described as an equivalent system of Einstein gravity coupled to matter.

We simplify and extend a 6D conformal gravity theory to 8D, linking it to Q-curvature.

problem Constructing and understanding conformal gravity actions in different dimensions.
method Streamlined construction of 6D action, proving existence of 8D action, relating to Q-curvature.
result A unique 8D conformal gravity action exists with Einstein metrics as solutions.

This work presents the foundations of Singular Semi-Riemannian Geometry and Singular General Relativity, based on the author's research. An extension of differential geometry and of Einstein's equation to singularities is reported. Singularities of the form studied here allow a smooth extension of the Einstein field eq…

2013-01-10abs ↗pdf ↗

We use conformal, but ghostful, Weyl gravity to study its ghost-free, second derivative, partially massless (PM) spin 2 component in presence of Einstein gravity with positive cosmological constant. Specifically, we consider both gravitational- and self- interactions of PM via the fully non-linear factorization of conf…

2012-08-07abs ↗pdf ↗

A theory of gravitation is proposed, modeled after the notion of a Ricci flow. In addition to the metric an independent volume enters as a fundamental geometric structure. Einstein gravity is included as a limiting case. Despite being a scalar-tensor theory the coupling to matter is different from Jordan-Brans-Dicke gr…

2006-02-14abs ↗pdf ↗

The study characterizes spacetimes with specific solitons in f(R)f(\mathcal{R})-gravity.

problem Characterizing spacetimes with specific solitons in f(R)f(\mathcal{R})-gravity.
method Analyzing ηη-Ricci solitons, gradient ηη-Ricci solitons, gradient Einstein Solitons, and gradient mm-quasi Einstein solitons in perfect fluid spacetimes obeying f(R)f(\mathcal{R})-gravity.
result Established conditions for the behavior of ηη-Ricci solitons and derived significant theorems about dark matter.

The article introduces pseudo generalized Ricci-recurrent spacetimes and their applications in modified gravity.

problem Characterizing and understanding pseudo generalized Ricci-recurrent spacetimes.
method Introduced and characterized pseudo generalized Ricci-recurrent spacetimes, provided examples, and studied their implications in modified gravity.
result Pseudo generalized Ricci-recurrent spacetimes represent perfect fluid spacetimes and can model dark energy epochs or static spacetimes.

Einstein-Kropina metrics extend Einstein condition to all signatures and classify Finsler gravity solutions.

problem Einstein-Kropina metrics in Finsler gravity
method Generalize Einstein condition and classify solutions
result All Einstein-Kropina solutions to the ΛΛ-vacuum equation are Berwald and Ricci-flat, with vanishing cosmological constant.

We formulate an approach to the geometry of Riemann-Cartan spaces provided with nonholonomic distributions defined by generic off-diagonal and nonsymmetric metrics inducing effective nonlinear and affine connections. Such geometries can be modelled by moving nonholonomic frames on (pseudo) Riemannian manifolds and desc…

2008-06-24abs ↗pdf ↗

A differential calculus, differential geometry and the E-R Gravity theory are studied on noncommutative spaces. Noncommutativity is formulated in the star product formalism. The basis for the gravity theory is the infinitesimal algebra of diffeomorphisms. Considering the corresponding Hopf algebra we find that the defo…

2006-11-02abs ↗pdf ↗

Study on quasi-Einstein manifolds with boundary estimates and inequalities.

problem Understanding the geometry of compact quasi-Einstein manifolds with boundary.
method Sharp boundary estimates and characterization theorems for quasi-Einstein manifolds.
result New geometric inequalities and boundary estimates for quasi-Einstein manifolds.

Bayesian neural networks improve cosmic parameter estimation from modified gravity simulations.

problem Estimating cosmological parameters from large-scale structure data with modified gravity.
method Implement Bayesian neural networks (BNNs) with two cases: single BLL and FullB, trained on dark matter only particle mesh NN-body simulations.
result BNNs yield well-calibrated uncertainty estimates and accurately predict cosmological parameters for ΩmΩ_m and σ8σ_8.

The study characterizes spacetime and modified gravity models using projective curvature tensor.

problem Characterizing spacetime and modified gravity models with projective curvature tensor.
method Analyzing $f\left(R,G ight)$, $f\left(R,T ight)$, and $f\left(R,L_{m} ight)$-gravity models.
result Projectively flat perfect fluid spacetimes represent dark energy era and are locally isometric to Minkowski or de-Sitter spacetimes.

For (2+2)-dimensional nonholonomic distributions, the physical information contained into a spacetime (pseudo) Riemannian metric can be encoded equivalently into new types of geometric structures and linear connections constructed as nonholonomic deformations of the Levi-Civita connection. Such deformations and induced…

2009-02-05abs ↗pdf ↗

Study proves non-degeneracy of certain metrics in linearized gravity.

problem Proving non-degeneracy of Riemannian Schwarzschild-anti de Sitter metrics.
method Analyzing solutions of the linearized Einstein equations around Kottler metrics.
result Linearized Einstein operator is non-degenerate for open ranges of mass parameter.

In this paper we derive a differential identity for linearized gravity on the Kerr spacetime and more generally on vacuum spacetimes of Petrov type D. We show that a linear combination of second derivatives of the linearized Weyl tensor can be formed into a complex symmetric 2-tensor Mab\mathcal{M}_{ab} which solves the…

2016-01-22abs ↗pdf ↗

The 'anholonomic frame' method (see gr-qc/0005025, gr-qc/0001060 and hep-th/0110250) is applied for constructing new classes of exact solutions of vacuum Einstein equations with off-diagonal metrics in 4D and 5D gravity. We examine several black tori solutions generated by anholonomic transforms with non-trivial topolo…

2001-10-30abs ↗pdf ↗

The complete on-shell action of topological Einstein-Maxwell gravity in four-dimensions is presented. It is shown explicitly how this theory for SU(2) holonomy manifolds arises from four-dimensional Euclidean N=2 supergravity. The twisted local BRST symmetries and twisted local Lorentz symmetries are given and the acti…

2002-09-13abs ↗pdf ↗

The (2k)(2k)-th Gauss-Bonnet curvature is a generalization to higher dimensions of the (2k)(2k)-dimensional Gauss-Bonnet integrand, it coincides with the usual scalar curvature for k=1k=1. The Gauss-Bonnet curvatures are used in theoretical physics to describe gravity in higher dimensional space times where they are known a…

2007-09-27abs ↗pdf ↗

Proposes a new variational principle for Einstein gravity.

problem Formulating Einstein gravity as a gauge theory for the conformal group.
method First order formulation of conformal tractor geometry, variational principle based on abstract principal bundle.
result Provides first order field equations without requiring supplementary constraints.

We find exact solutions describing Ricci flows of four dimensional pp-waves nonlinearly deformed by two/three dimensional solitons. Such solutions are parametrized by five dimensional metrics with generic off-diagonal terms and connections with nontrivial torsion which can be related, for instance, to antisymmetric ten…

2006-02-07abs ↗pdf ↗

New approach to gravity theory sacrifices smoothness for ellipticity.

problem Developing a nonsmooth theory of gravity.
method Using a negative homogeneity p-d'Alembert operator to sacrifice linearity for ellipticity.
result Obtained a low-regularity splitting theorem.

A novel gravity theory based on Poisson Generalized Geometry is investigated. A gravity theory on a Poisson manifold equipped with a Riemannian metric is constructed from a contravariant version of the Levi-Civita connection, which is based on the Lie algebroid of a Poisson manifold. Then, we show that in Poisson Gener…

2015-08-24abs ↗pdf ↗