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In canonical gravity, covariance is implemented by brackets of hypersurface-deformation generators forming a Lie algebroid. Lie algebroid morphisms therefore allow one to relate different versions of the brackets that correspond to the same…

General Relativity and Quantum Cosmology · Physics 2016-11-15 Martin Bojowald , Suddhasattwa Brahma , Umut Buyukcam , Fabio D'Ambrosio

While homogeneous cosmologies have long been studied in the group field theory (GFT) approach to quantum gravity, including a quantum description of cosmological perturbations is highly non-trivial. Here we apply a recent proposal for…

General Relativity and Quantum Cosmology · Physics 2025-11-18 Steffen Gielen , Lisa Mickel

In this study, we developed the geometrically deformed compact objects in the $f(Q, T)$ gravity theory under an electric field through gravitational decoupling via. minimal geometric deformation (MGD) technique for the first time. The…

General Relativity and Quantum Cosmology · Physics 2024-08-06 Sneha Pradhan , Sunil Kumar Maurya , Pradyumn Kumar Sahoo , Ghulam Mustafa

We show that a geometric techniques can be elaborated and applied for constructing generic off-diagonal exact solutions in $f(R,T)$--modified gravity for systems of gravitational-Yang-Mills-Higgs equations. The corresponding classes of…

General Relativity and Quantum Cosmology · Physics 2014-11-12 Sergiu I. Vacaru , Elsen Veli Veliev , Enis Yazici

In this PhD thesis, we introduced a new strategy to investigate the kinematical and physical predictions of self dual Loop Quantum Gravity (LQG) and by-passed the old problem of implementing quantum mechanically the so called reality…

General Relativity and Quantum Cosmology · Physics 2015-11-24 Jibril Ben Achour

Inhomogeneous quantum cosmology is modeled as a dynamical system of discrete patches, whose interacting many-body equations can be mapped to a non-linear minisuperspace equation by methods analogous to Bose-Einstein condensation.…

General Relativity and Quantum Cosmology · Physics 2012-12-18 Martin Bojowald , Alexander L. Chinchilli , Christine C. Dantas , Matthew Jaffe , David Simpson

In this thesis we study two different approaches to holography, and comment on the possible relation between them. The first approach is an analysis of the high-energy regime of quantum gravity in the eikonal approximation, where the theory…

High Energy Physics - Theory · Physics 2016-09-06 Sebastian de Haro

We deal with quadratic metric-affine gravity (QMAG), which is an alternative theory of gravity and present a new explicit representation of the field equations of this theory. In our previous work we found new explicit vacuum solutions of…

General Relativity and Quantum Cosmology · Physics 2017-06-01 Vedad Pasic , Elvis Barakovic , Nermin Okicic

A crucial problem in quantum cosmology is a careful analysis of the one-loop semiclassical approximation for the wave function of the universe, after an appropriate choice of mixed boundary conditions. The results for Euclidean quantum…

High Energy Physics - Theory · Physics 2007-05-23 Giampiero Esposito , Alexander Yu. Kamenshchik

In the work, we present investigation on decoupling gravitational sources under the framework of $f(R,T)$ gravity. Basically the complete geometric deformation technique has been employed here which facilitates finding exact solutions to…

General Relativity and Quantum Cosmology · Physics 2024-03-21 S. K. Maurya , B. Mishra , Saibal Ray , Riju Nag

In this paper we work out in detail a new proposal to define rigorously a sector of loop quantum gravity at the diffeomorphism invariant level corresponding to homogeneous and isotropic cosmologies, and propose how to compare in detail the…

General Relativity and Quantum Cosmology · Physics 2017-11-22 Christopher Beetle , Jonathan Steven Engle , Matthew Ernest Hogan , Phillip Mendonca

We describe a new type of gravity-matter models where modified f(R)=R+R^2 gravity couples non-canonically to a scalar "inflaton", to the bosonic sector of the electroweak particle model and to a special nonlinear gauge field with a…

High Energy Physics - Theory · Physics 2019-03-27 Eduardo Guendelman , Emil Nissimov , Svetlana Pacheva

We describe an approach to the quantisation of (2+1)-dimensional gravity with topology R x T^2 and negative cosmological constant, which uses two quantum holonomy matrices satisfying a q-commutation relation. Solutions of diagonal and…

General Relativity and Quantum Cosmology · Physics 2009-10-31 J. E. Nelson , R. F. Picken

In the path integral formulation of the reduced phase space Loop Quantum Gravity (LQG), we propose a new approach to allow the spatial cubic lattice (graph) to change dynamically in the physical time evolution. The equations of motion of…

General Relativity and Quantum Cosmology · Physics 2021-07-14 Muxin Han , Hongguang Liu

This study investigates a cosmological scenario within the f(Q,L_m) gravity framework to explore whether one geometric model can simultaneously describe the early and late-time accelerated epochs. Motivated by the recently proposed f(Q,L_m)…

General Relativity and Quantum Cosmology · Physics 2026-05-13 Khandro K Chokyi , Abdel Nasser Tawfik , Surajit Chattopadhyay

In this paper, we propose a novel Quantum Spacetime Theory (QST) that reinterprets spacetime as an emergent structure, challenging the traditional block universe paradigm and aligning with research into emergent spacetime. Using a sphere…

General Physics · Physics 2025-05-06 Craig Philpot

We systematically study the field equations of $f(\mathbb Q)$ gravity for spherically symmetric and stationary metric-affine spacetimes. Such spacetimes are described by a metric as well as a flat and torsionless affine connection. In the…

General Relativity and Quantum Cosmology · Physics 2022-02-02 Fabio D'Ambrosio , Shaun D. B. Fell , Lavinia Heisenberg , Simon Kuhn

The vacuum expectation value of the non-minimally coupled Kalb-Ramond (KR) field leads to spontaneous local Lorentz symmetry violation, and static spherically symmetric solutions exist. In this study, we study the quasinormal modes (QNMs)…

General Relativity and Quantum Cosmology · Physics 2023-06-27 Anshuman Baruah , Ali Övgün , Atri Deshamukhya

We study a class of Hamiltonian deformations of the massless Einstein-Klein-Gordon system in spherical symmetry for which the Dirac constraint algebra closes. The system may be regarded as providing effective equations for quantum…

General Relativity and Quantum Cosmology · Physics 2012-04-24 Andreas Kreienbuehl , Viqar Husain , Sanjeev S. Seahra

We investigate the cosmological dynamics induced by nonlinear electrodynamics in a homogeneous and isotropic universe, focusing on the role of primordial electromagnetic fields with random spatial orientations. Building upon a…

General Relativity and Quantum Cosmology · Physics 2025-10-15 Alan G. Cesar , Mario Novello , Eduardo Bittencourt , Fernando A. Franco