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The field equations in modified gravity theories possess an important decoupling property with respect to certain classes of nonholonomic frames. This allows us to construct generic off--diagonal solutions depending on all spacetime…

General Relativity and Quantum Cosmology · Physics 2015-02-23 Sergiu I. Vacaru

The fundamental field equations in modified gravity (including general relativity; massive and bimetric theories; Ho\vrava-Lifshits, HL; Einstein--Finsler gravity extensions etc) posses an important decoupling property with respect to…

General Physics · Physics 2014-10-30 Sergiu I. Vacaru

We summarize some our recent results on encoding exact solutions of field equations in Einstein and modified gravity theories into solitonic hierarchies derived for nonholonomic curve flows with associated bi-Hamilton structure. We argue…

General Relativity and Quantum Cosmology · Physics 2015-05-20 Sergiu I. Vacaru

We show how the Einstein equations with cosmological constant (and/or various types of matter field sources) can be integrated in a very general form following the anholonomic deformation method for constructing exact solutions in four and…

General Physics · Physics 2017-10-19 Sergiu I. Vacaru

In this work, we apply the anholonomic deformation method for constructing new classes of anisotropic cosmological solutions in Einstein gravity and/or generalizations with nonholonomic variables. There are analyzed four types of, in…

Mathematical Physics · Physics 2015-05-18 Sergiu I. Vacaru

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…

General Relativity and Quantum Cosmology · Physics 2008-12-19 Sergiu I. Vacaru

We prove that the Einstein equations can be solved in a very general form for arbitrary spacetime dimensions and various types of vacuum and non-vacuum cases following a geometric method of anholonomic frame deformations for constructing…

General Relativity and Quantum Cosmology · Physics 2014-11-20 Sergiu I. Vacaru

Off-diagonal vacuum and nonvacuum configurations in Einstein gravity can mimic physical effects of modified gravitational theories of $f(R,T,R_{\mu \nu}T^{\mu \nu})$ type. To prove this statement, exact and approximate solutions are…

General Relativity and Quantum Cosmology · Physics 2015-07-01 Emilio Elizalde , Sergiu I. Vacaru

Certain off-diagonal vacuum and nonvacuum configurations in Einstein gravity can mimic physical effects of modified gravitational theories of $ f(R,T,R_{\mu\nu}T^{\mu\nu})$ type. We prove this statement by constructing exact and approximate…

Mathematical Physics · Physics 2015-06-30 Emilio Elizalde , Sergiu I. Vacaru

A new framework to perturbative quantum gravity is proposed following the geometry of nonholonomic distributions on (pseudo) Riemannian manifolds. There are considered such distributions and adapted connections, also completely defined by a…

General Relativity and Quantum Cosmology · Physics 2014-11-18 Sergiu I. Vacaru

This paper is concerned with giving the proof that there is a general decoupling property of vacuum and nonvacuum gravitational field equations in Einstein gravity and $f(R,T)$-modifications. The constructions are possible in terms of…

General Physics · Physics 2013-08-27 Sergiu I. Vacaru

The gravitational field equations in general relativity (GR) consist of a sophisticated system of nonlinear partial differential equations. Solving such equations in some generic off-diagonal forms is usually a hard analytic or numeric…

General Relativity and Quantum Cosmology · Physics 2025-08-18 Sergiu I. Vacaru , Elşen V. Veliev

We argue that generic off-diagonal vacuum and nonvacuum solutions for Einstein manifolds mimic physical effects in modified gravity theories (MGTs) and encode certain models of the $f(R,T,...)$, Ho\v{r}ava type with dynamical Lorentz…

High Energy Physics - Theory · Physics 2015-02-25 Tamara Gheorghiu , Olivia Vacaru , Sergiu Vacaru

A generalized geometric method is developed for constructing exact solutions of gravitational field equations in Einstein theory and generalizations. First, we apply the formalism of nonholonomic frame deformations (formally considered for…

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

We re-investigate how generic off-diagonal cosmological solutions depending, in general, on all spacetime coordinates can be constructed in massive and f-modified gravity using the anholonomic frame deformation method. There are constructed…

General Relativity and Quantum Cosmology · Physics 2015-05-06 Sergiu I. Vacaru

It is well known that Einstein's equations assume a simple polynomial form in the Hamiltonian framework based on a Yang-Mills phase space. We re-examine the gravitational dynamics in this framework and show that {\em time} evolution of the…

General Relativity and Quantum Cosmology · Physics 2021-01-14 Abhay Ashtekar , Madhavan Varadarajan

We prove the renormalizability of various theories of classical gravity coupled with interacting quantum fields. The models contain vertices with dimensionality greater than four, a finite number of matter operators and a finite or reduced…

High Energy Physics - Theory · Physics 2008-11-26 Damiano Anselmi , Milenko Halat

We derive Einstein's equations from a linear theory in flat space-time using free-field gauge invariance and universal coupling. The gravitational potential can be either covariant or contravariant and of almost any density weight. We adapt…

General Relativity and Quantum Cosmology · Physics 2008-11-26 J. Brian Pitts , W. C. Schieve

A gauge and diffeomorphism invariant theory in (2+1)-dimensions is presented in both first and second order Lagrangian form as well as in a Hamiltonian form. For gauge group $SO(1,2)$, the theory is shown to describe ordinary Einstein…

General Relativity and Quantum Cosmology · Physics 2009-10-22 Peter Peldan

Modified gravity theories (MGTs) have long been studied as alternatives to general relativity (GR) and the standard Lambda CDM cosmological model. For example, exponential f(R) models often yield better fits to observational data,…

General Physics · Physics 2026-05-01 Sergiu I. Vacaru
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