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We construct new classes of exact solutions in metric--affine gravity (MAG) with string corrections by the antisymmetric $H$--field. The solutions are parametrized by generic off--diagonal metrics possessing noncommutative symmetry…

High Energy Physics - Theory · Physics 2007-05-23 Sergiu I. Vacaru , Evghenii Gaburov

We study the geometric and physical foundations of Finsler gravity theories with metric compatible connections defined on tangent bundles, or (pseudo) Riemannian manifolds). There are analyzed alternatives to Einstein gravity (including…

Mathematical Physics · Physics 2013-03-15 Sergiu I. Vacaru

We introduce a new type of generating theorems in General Relativity for anisotropic, static, spherically symmetric solutions of the Einstein field equations. The results are used to derive a class of solutions that can serve as new models…

General Relativity and Quantum Cosmology · Physics 2026-04-14 Paulo Luz , Sante Carloni

We present solution generating techniques which permit to construct exact inhomogeneous and anisotropic cosmological solutions to a four-dimensional low energy limit of string theory containing non-minimally interacting electromagnetic and…

High Energy Physics - Theory · Physics 2009-10-31 Stoytcho Yazadjiev

We study new classes of generic off-diagonal and diagonal cosmological solutions for effective Einstein equations in modified gravity theories, MGTs, with modified dispersion relations, MDRs, encoding possible violations of (local) Lorentz…

General Physics · Physics 2021-06-02 Panayiotis Stavrinos , Sergiu I. Vacaru

We apply the method of moving anholonomic frames, with associated nonlinear connections, in (pseudo) Riemannian spaces and examine the conditions when various types of locally anisotropic (la) structures (Lagrange, Finsler like and more…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Heinz Dehnen , Sergiu I. Vacaru

Nonholonomic distributions and adapted fame structures on (pseudo) Riemannian manifolds of even dimension are employed to build structures equivalent to almost Kahler geometry and which allows to perform a Fedosov-like quantization of…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Sergiu I. Vacaru

We construct new classes of solutions describing generic off-diagonal deformations of regular Schwarzschild black holes (BHs) in general relativity (GR). Examples of such (primary) diagonal metrics reducing the Einstein equations to…

General Physics · Physics 2025-05-27 Sergiu I. Vacaru , Elşen Veli Veliev

A new method of construction of integral varieties of Einstein equations in three dimensional (3D) and 4D gravity is presented whereby, under corresponding redefinition of physical values with respect to anholonomic frames of reference with…

General Relativity and Quantum Cosmology · Physics 2010-02-03 Sergiu I. Vacaru

In this work we implement the Minimal Geometric Deformation method to obtain the isotropic sector and the decoupler matter content of any anisotropic solution of the Einstein field equations with cosmological constant in $2+1$ dimensional…

General Relativity and Quantum Cosmology · Physics 2019-06-28 Ernesto Contreras

We develop the method of anholonomic frames with associated nonlinear connection (in brief, N--connection) structure and show explicitly how geometries with local anisotropy (various type of Finsler--Lagrange--Cartan--Hamilton geometry) can…

High Energy Physics - Theory · Physics 2007-05-23 Sergiu I. Vacaru

We elaborate on nonmetric geometric flow theory and metric-affine gravity with applications in modern cosmology. Two main motivations for our research follow from the facts that 1) cosmological models for $f(Q)$ modified gravity theories,…

General Relativity and Quantum Cosmology · Physics 2024-10-08 L. Bubuianu , E. Nurlan , J. O. Seti , S. Vacaru , E. V. Veliev

We develop an approach to the theory nonholonomic relativistic stochastic processes on curved spaces. The Ito and Stratonovich calculus are formulated for spaces with conventional horizontal (holonomic) and vertical (nonholonomic) splitting…

Mathematical Physics · Physics 2012-03-27 Sergiu I. Vacaru

We construct solutions of higher-dimensional Einstein gravity coupled to nonlinear $\sigma$-model with cosmological constant. The $\sigma$-model can be perceived as exterior configuration of a spontaneously-broken $SO(D-1)$ global…

General Relativity and Quantum Cosmology · Physics 2017-08-30 Ilham Prasetyo , Handhika S. Ramadhan

We investigate the behaviour on approach to the initial singularity in higher-order extensions of general relativity by finding exact cosmological solutions for a wide class of models in which the Lagrangian is allowed to depend nonlinearly…

General Relativity and Quantum Cosmology · Physics 2014-11-21 Jonathan Middleton

Beginning with a special form of the Einstein-Rosen metric, we find new cosmological solutions of the Einstein equations, having two hypersurface-orthogonal Killing vectors , with ideal fluid. The equation of state is in the most cases of…

General Relativity and Quantum Cosmology · Physics 2007-05-23 D. Kamani , R. Mansouri

We study the fractional gravity for spacetimes with non-integer dimensions. Our constructions are based on a geometric formalism with the fractional Caputo derivative and integral calculus adapted to nonolonomic distributions. This allows…

Mathematical Physics · Physics 2012-04-20 Sergiu I. Vacaru

This article deals with a nonrelativistic cosmological model based on Galilean covariance, formulated within a five-dimensional Galilean manifold. Within this framework, we construct an isotropic and homogeneous metric analogous to the…

General Relativity and Quantum Cosmology · Physics 2025-11-17 R. G. G. Amorim , A. F. Santos , K. V. S. Araújo , S. C. Ulhoa

We study Einstein's equations with an isotropic but inhomogeneous metric in the cosmic rest frame. The equations are solved perturbatively in the late Universe. The leading plus next-to-leading order results agree with observations without…

Cosmology and Nongalactic Astrophysics · Physics 2016-02-23 Günter Scharf

Among the general class of metric-affine theories of gravity, there is a special class conformed by those endowed with a projective symmetry. Perhaps the simplest manner to realise this symmetry is by constructing the action in terms of the…

General Relativity and Quantum Cosmology · Physics 2021-04-23 Jose Beltrán Jiménez , Daniel de Andrés , Adrià Delhom