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A bouncing scenario of a flat homogeneous and isotropic universe is explored by using the reconstruction technique for the power-law parametrization of the Hubble parameter in a modified gravity theory with higher-order curvature and trace…

General Relativity and Quantum Cosmology · Physics 2023-04-03 J. K. Singh , Harshna Balhara , Kazuharu Bamba , J. Jena

We present a detailed analysis of a quantum model for Loop Quantum Cosmology based on strict application of the Thiemann regularization algorithm for the Hamiltonian in Loop Quantum Gravity, extending the results presented previously in our…

General Relativity and Quantum Cosmology · Physics 2019-10-09 Mehdi Assanioussi , Andrea Dapor , Klaus Liegener , Tomasz Pawlowski

In this paper, we consider a gravitational action containing a combination of the Ricci scalar, $R$, and the topological Gauss--Bonnet term, $G$. Specifically, we study the cosmological features of a particular class of modified gravity…

General Relativity and Quantum Cosmology · Physics 2023-03-15 Francesco Bajardi , Rocco D'Agostino

Recently the so-called mimetic gravity approach has been used to obtain corrections to Friedmann equation of General Relativity similar to the ones present in loop quantum cosmology. In this paper, we propose an alternative way to derive…

General Relativity and Quantum Cosmology · Physics 2017-09-06 Stefano Chinaglia , Aimeric Colleaux , Sergio Zerbini

A modification of General Relativity that is based on the gravitational Standard-Model Extension and incorporates nondynamical background fields has recently been studied via the ADM formalism. Our objective in this paper is to develop a…

General Relativity and Quantum Cosmology · Physics 2023-05-15 Carlos M. Reyes , Marco Schreck

We offer a new proposal for cosmic singularity resolution based upon a quantum cosmology with a unitary bounce. This proposal is illustrated via a novel quantization of a mini-superspace model in which there can be superpositions of the…

General Relativity and Quantum Cosmology · Physics 2018-12-17 Sean Gryb , Karim P. Y. Thébault

We develop a Gauss-Bonnet extension of Loop Quantum Cosmology, by introducing holonomy corrections in modified $F(\mathcal{G})$ theories of gravity. Within the context of our formalism, we provide a perturbative expansion in the critical…

General Relativity and Quantum Cosmology · Physics 2015-12-16 J. Haro , A. N. Makarenko , A. N. Myagky , S. D. Odintsov , V. K. Oikonomou

We derive new functional renormalisation group flows for quantum gravity, in any dimension. The key new achievement is that the equations apply for any theory of gravity whose underlying Lagrangian $\sim f(R_{\mu\nu\rho\sigma})$ is a…

High Energy Physics - Theory · Physics 2022-12-07 Yannick Kluth , Daniel F. Litim

The cosmology of metric-affine gravity is studied for the general, parity preserving action quadratic in curvature, torsion and non-metricity. The model contains 27 a priori independent couplings in addition to the Einstein constant. Linear…

General Relativity and Quantum Cosmology · Physics 2024-12-23 Thomas Dyer , Will Barker , Damianos Iosifidis

A new approach for embedding the renormalization group running of Newton's constant and cosmological constant in gravity is proposed. This approach is based on a gravitational Lagrangian that gives rise to a new class of modified gravity…

General Relativity and Quantum Cosmology · Physics 2025-10-28 Alfio Bonanno , Konstantinos F. Dialektopoulos , Vasilios Zarikas

When general relativity is augmented by quadratic gravity terms, it becomes a renormalisable theory of gravity. This theory may admit a non-Gaussian fixed point as envisaged in the asymptotic safety program, rendering the theory trustworthy…

High Energy Physics - Theory · Physics 2019-11-06 Jean-Luc Lehners , K. S. Stelle

The goal of this work is to elaborate on new geometric methods of constructing exact and parametric quasiperiodic solutions for anamorphic cosmology models in modified gravity theories, MGTs, and general relativity, GR. There exist…

General Relativity and Quantum Cosmology · Physics 2017-10-24 Marcelo M. Amaral , Raymond Aschheim , Laurenţiu Bubuianu , Klee Irwin , Sergiu I. Vacaru , Daniel Woolridge

In this paper, we study the phase space of cosmological models in the context of Einstein-Gauss-Bonnet theory. More specifically, we consider a generalized dynamical system that encapsulates the main features of the theory and for the cases…

General Relativity and Quantum Cosmology · Physics 2020-07-15 N. Chatzarakis , V. K. Oikonomou

A scale-dependent cosmological constant $\Lambda$ and the Newton constant G emerge naturally in quantum field theory in a curved space-time background leading to renormalization group running cosmologies. A scale-setting procedure is…

General Relativity and Quantum Cosmology · Physics 2007-07-27 Branko Guberina

Cosmologies with a time dependent Newton constant and cosmological constant are investigated. The scale dependence of $G$ and $\Lambda$ is governed by a set of renormalization group equations which is coupled to Einstein's equation in a…

Astrophysics · Physics 2014-10-13 A. Bonanno , M. Reuter

We provide a detailed analysis of Friedmann-Robertson-Walker universes in a wide range of scalar-tensor theories of gravity. We apply solution-generating methods to three parametrised classes of scalar-tensor theory which lead naturally to…

General Relativity and Quantum Cosmology · Physics 2009-10-28 John D. Barrow , Paul Parsons

We present a non-perturbative framework for the dynamics of slow-roll inflation that consistently incorporates quantum corrections, based on an alternative functional renormalisation group (RG) approach. We derive the coupled Friedmann-RG…

High Energy Physics - Theory · Physics 2025-11-10 Jean Alexandre , Lucien Heurtier , Silvia Pla

The discovery of the accelerated expansion of the universe highlighted General Relativity's inability to naturally account for dark energy without invoking a finely tuned cosmological constant. In response, a wide range of alternative…

General Relativity and Quantum Cosmology · Physics 2025-11-11 P. A. G. Monteiro , C. J. A. P. Martins

We construct a class of generalized non-local gravity (GNLG) model which is the modified theory of general relativity (GR) obtained by adding a term $m^{2n-2} R\Box^{-n}R$ to the Einstein-Hilbert action. Concretely, we not only study the…

General Relativity and Quantum Cosmology · Physics 2016-11-23 Xue Zhang , Ya-Bo Wu , Song Li , Yu-Chen Liu , Bo-Hai Chen , Yun-Tian Chai , Shuang Shu

The cosmological reconstruction scheme for modified $F(R)$ gravity is developed in terms of e-folding (or, redshift). It is demonstrated how any FRW cosmology may emerge from specific $F(R)$ theory. The specific examples of well-known…

High Energy Physics - Theory · Physics 2014-11-20 Shin'ichi Nojiri , Sergei D. Odintsov , Diego Saez-Gomez