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We analyze a fully geometric approach to dark energy in the framework of $F(R,{\cal G})$ theories of gravity, where $R$ is the Ricci curvature scalar and ${\cal G}$ is the Gauss-Bonnet topological invariant. The latter invariant naturally…

General Relativity and Quantum Cosmology · Physics 2020-11-09 Micol Benetti , Simony Santos da Costa , Salvatore Capozziello , Jailson S. Alcaniz , Mariafelicia De Laurentis

We give a novel definition of gravitational energy for an arbitrary theory of gravity including quadratic-curvature corrections to Einstein equations. We focus on the theory in four dimensions, in presence of negative cosmological constant,…

High Energy Physics - Theory · Physics 2018-09-12 Gaston Giribet , Olivera Miskovic , Rodrigo Olea , David Rivera-Betancour

The gravitational lensing of relativistic and nonrelativistic neutral massive particles in the black-bounce-Schwarzschild black hole spacetime is investigated in the strong deflection limit. Beginning with the explicit equations of motion…

General Relativity and Quantum Cosmology · Physics 2026-02-05 Guansheng He , Jiaxu Huang , Zhongwen Feng , Ghulam Mustafa , Wenbin Lin

There are constructed exact solutions of the quantum-mechanical Dirac equation for a spin S=1/2 particle in Riemannian space of constant negative curvature, hyperbolic Lobachevsky space, in presence of an external magnetic field, analogue…

Mathematical Physics · Physics 2011-08-30 E. M. Ovsiyuk , V. V. Kisel , V. M. Red'kov

In quantum field theory there exist states for which the energy density is negative. It is important that these negative energy densities satisfy constraints, such as quantum inequalities, to minimize possible violations of causality, the…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Dan N. Vollick

A derivation is presented of the quantummechanical wave equations based upon the Equity Principle of Einstein's General Relativity Theory. This is believed to be more generic than the common derivations based upon Einstein's energy…

General Physics · Physics 2007-07-19 Engel Roza

Two of the major open questions in particle physics are: (1) Why are the elementary fermionic particles that are so far observed have such low mass-energy compared to the Planck energy scale? And (2), what mechanical energy may be…

General Relativity and Quantum Cosmology · Physics 2022-02-13 Carl F. Diether , Joy Christian

Exact solution of Dirac equation for a particle whose potential energy and mass are inversely proportional to the distance from the force centre has been found. The bound states exist provided the length scale $a$ which appears in the…

Quantum Physics · Physics 2009-11-11 I. O. Vakarchuk

A modified extremal Reissner-Nordstrom geometry, void of singularities, is proposed in this work, by means of an exponential factor depending on a positive constant $k$. All the metric coefficients are positive and finite and the spacetime…

General Relativity and Quantum Cosmology · Physics 2023-03-15 Hristu Culetu

Three theoretical criteria for gravitational theories beyond general relativity are considered: obtaining the cosmological constant as an integration constant, deriving the energy conservation law as a consequence of the field equations,…

General Relativity and Quantum Cosmology · Physics 2023-08-17 Junpei Harada

Is "Gravity" a deformation of "Electromagnetism"? Deformation theory suggests quantizing Special Relativity: formulate Quantum Information Dynamics $SL(2,C)_h$-gauge theory of dynamical lattices, with unifying gauge ``group'' the quantum…

General Physics · Physics 2010-05-20 Lucian M Ionescu

A problem of self-energy and self-force for a charged point-like particle in a higher dimensional homogeneous gravitational field is considered. We study two cases, when a particle has usual electric charge and a case when it has a scalar…

High Energy Physics - Theory · Physics 2015-06-22 Valeri P. Frolov , Andrei Zelnikov

In this paper, we introduce a class of spacetimes $\left(\mathcal{M},g\right)$ which satisfy the vacuum Einstein equations and dynamically approach a Schwarzschild solution of mass $M$, a class we shall call \emph{ultimately…

General Relativity and Quantum Cosmology · Physics 2010-10-18 Gustav Holzegel

The Lagrangian density of standard relativistic mean-field (RMF) models with density-dependent meson-nucleon coupling vertices is modified by introducing couplings of the meson fields to derivative nucleon densities. As a consequence, the…

Nuclear Theory · Physics 2007-05-23 S. Typel

A Friedmann--Robertson--Walker Universe is studied with a dark energy component represented by a quintessence field. The Lagrangian for this system, hereafter called the Friedmann--Robertson--Walker--quintessence (FRWq) system, is…

General Relativity and Quantum Cosmology · Physics 2017-08-23 Sergio A. Hojman , Felipe A. Asenjo , Carlos A. Rubio

The energy of gravitating systems has been an issue since Einstein proposed general relativity: considered to be ill defined, having no proper local density. Energy-momentum is now regarded as \emph{quasi-local} (associated with a closed…

General Relativity and Quantum Cosmology · Physics 2018-11-15 Chiang-Mei Chen , Jian-Liang Liu , James M. Nester

Relativistic energy shifts of the low energy levels of Fe have been calculated using the Dirac-Hartree-Fock and configuration interaction techniques. The results are to be used in the search for the space-time variation of the fine…

Atomic Physics · Physics 2009-11-13 V. A. Dzuba , V. V. Flambaum

In this continuation paper, we apply the general relativistic quantum theory for one particle systems, derived in paper II of this series, to a simple problem: the quantum Schwartzchild problem, where one particle of mass {\it m% }…

Quantum Physics · Physics 2008-02-03 L. S. F. Olavo

Recently the global variation of the Planck mass in the General Relativistic Einstein-Hilbert action was proposed as a self-tuning mechanism of the cosmological constant preventing vacuum energy from freely gravitating. We show that this…

General Relativity and Quantum Cosmology · Physics 2020-08-12 Daniel Sobral-Blanco , Lucas Lombriser

Utilizing various gauges of the radial coordinate, we give a General Relativistic (GR) description of static spherically symmetric spacetimes with a massive point source and vacuum outside this singularity. We show that in GR there exists a…

General Relativity and Quantum Cosmology · Physics 2019-11-13 Plamen P. Fiziev