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The semi-classical back reaction to black hole evaporation (wherein the renormalized energy momentum tensor is taken as source of Einstein's equations) is analyzed in detail. It is proven that the mass of a Schwarzshild black hole decreases…

General Relativity and Quantum Cosmology · Physics 2010-11-01 S. Massar

We propose a quantum bosonic qubit model on a fcc lattice to obtain mimetic dark matter. The general relativity contribution is implemented similarly to other works but it differs strongly on the implementation of the constraint equations…

High Energy Physics - Theory · Physics 2020-01-01 Luis Lozano , Hugo Garcia-Compean

We consider the growth rate of matter perturbations in the Einstein dark energy theory. The theory consists of the Einstien-Hilbert Lagrangian plus the trace of the energy momentum tensor, coupled non-minimally to a dynamical vector field.…

General Relativity and Quantum Cosmology · Physics 2021-04-26 Zahra Haghani

The hypothesis of low entropy in the initial state of the universe usually explains the observed entropy increase is in only one time direction: the thermodynamic arrow of time. The Hamiltonian formalism is commonly used in the context of…

General Relativity and Quantum Cosmology · Physics 2024-08-27 Jackie C. H. Liu

$\tilde{\delta}$ Gravity is a gravitational field model, where the geometry is governed by two symmetric tensors, $g_{\mu \nu}$ and $\tilde{g}_{\mu \nu}$, and new matter fields ($\tilde{\delta}$ Matter fields) are added to the original…

General Relativity and Quantum Cosmology · Physics 2017-12-08 Jorge Alfaro , Pablo González

Dark matter self-scattering is one of key ingredients for small-scale structure of the Universe, while dark matter annihilation is important for the indirect measurements. There is a strong correlation between the velocity-dependent…

High Energy Physics - Phenomenology · Physics 2024-03-22 Ayuki Kamada , Takumi Kuwahara , Ami Patel

We investigate the possibility of dark matter being a pure geometrical effect, rather than a particle or a compact object, by exploring a specific modified gravity model: mimetic dark matter. We present an alternative formulation of the…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-18 Ali Rida Khalifeh , Nicola Bellomo , José Luis Bernal , Raul Jimenez

In this work the phenomenology of models possessing a non-minimal coupling between matter and geometry is discussed, with a particular focus on the possibility of describing the flattening of the galactic rotation curves as a dynamically…

Astrophysics of Galaxies · Physics 2015-05-18 Orfeu Bertolami , Jorge Páramos

The question about the appearance of time in the semiclassical limit of quantum gravity continues to be discussed in the literature. It is believed that a temporal Schrodinger equation for matter fields on the background of a classical…

General Relativity and Quantum Cosmology · Physics 2025-07-24 R. I. Ayala Oña , M. B. Kalmykov , D. P. Kislyakova , T. P. Shestakova

One of the major problems in quantum gravity research is the lack of signals at the reach of present or near-future experimental facilities. In this paper, we show that this is not the case. Contrary to previous claims, the quantum decay of…

General Relativity and Quantum Cosmology · Physics 2025-07-22 Bernard Carr , Piero Nicolini , Athanasios G. Tzikas

Within the standard cosmological scenario the Universe is found to be filled by obscure components (dark matter and dark energy) for ~95% of its energy budget. In particular, almost all the matter content in the Universe is given by dark…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Crescenzo Tortora , Philippe Jetzer , Nicola R. Napolitano

We explore the possibility that part of what we call dark matter may be the mark of a preferred frame, revealing a breakdown of diffeomorphism invariance. In the non-relativistic limit this appears as a deviant matter source capable of…

General Relativity and Quantum Cosmology · Physics 2025-05-08 Raymond Isichei , Joao Magueijo

We investigate the shadow of an exact black hole solution of Einstein's equations recently proposed by Cardoso et al., to describe a supermassive black hole immersed in a dark matter halo. We analyze and discuss the light rings and the…

General Relativity and Quantum Cosmology · Physics 2023-04-03 Sérgio V. M. C. B. Xavier , Haroldo C. D. Lima Junior , Luís C. B. Crispino

We model pseudo-Finsler geometries, with pseudo-Euclidean signatures of metrics, for two classes of four dimensional nonholonomic manifolds: a) tangent bundles with two dimensional base manifolds and b) pseudo-Riemannian/ Einstein…

General Relativity and Quantum Cosmology · Physics 2013-04-09 Sergiu I. Vacaru

The problem of explaining the acceleration of the expansion of the universe and the observational and theoretical difficulties associated with dark matter and dark energy are discussed. The possibility that Einstein gravity does not…

Astrophysics · Physics 2007-05-23 J. W. Moffat

We show that dark energy and dark matter can be described simultaneously by ordinary Einstein gravity interacting with a single scalar field provided the scalar field Lagrangian couples in a symmetric fashion to two different spacetime…

General Relativity and Quantum Cosmology · Physics 2016-11-29 Eduardo Guendelman , Emil Nissimov , Svetlana Pacheva

The modification of Einstein gravity at high energies is mandatory from a quantum approach. In this work, we point out that this modification will necessarily introduce new degrees of freedom. We analyze the possibility that these new…

High Energy Physics - Phenomenology · Physics 2009-05-18 Jose A. R. Cembranos

In this article we find a four-dimensional metric for a large black hole immersed in dark matter. Specifically, we look for and find a static spherically symmetric black hole solution to the Einstein equations which gives, in the Newtonian…

General Relativity and Quantum Cosmology · Physics 2021-01-12 Fateen Haddad , Nidal Haddad

Motivated by the absence of signals of new physics in both searches for new particles at LHC and for a Weakly Interacting Massive Particle (WIMP) dark matter candidate, we consider a scenario where supersymmetry is broken at a scale above…

High Energy Physics - Phenomenology · Physics 2017-05-10 Karim Benakli , Yifan Chen , Emilian Dudas , Yann Mambrini

Classical particle-like solutions of field equations such as general relativity, could account for dark matter. Such particles would not interact quantum mechanically and would have negligible interactions apart from gravitation. As a relic…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Mark J Hadley
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