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The implementation of the dynamics in Loop Quantum Gravity (LQG) is still an open problem. Here, we discuss a tentative dynamics for the simplest class of graphs in LQG: Two vertices linked with an arbitrary number of edges. We use the…

General Relativity and Quantum Cosmology · Physics 2015-05-20 Enrique F. Borja , Jacobo Díaz-Polo , Iñaki Garay , Etera R. Livine

We start with the Hamiltonian formulation of the first order action of pure gravity with a full $\mathfrak{sl}(2,\mathbb C)$ internal gauge symmetry. We make a partial gauge-fixing which reduces $\mathfrak{sl}(2,\mathbb C)$ to its…

General Relativity and Quantum Cosmology · Physics 2017-06-28 Hongguang Liu , Karim Noui

We apply the reduced phase space quantization to the Kasner universe. We construct the kinematical phase space, find solutions to the Hamilton equations of motion, identify Dirac observables and arrive at physical solutions in terms of…

General Relativity and Quantum Cosmology · Physics 2015-05-28 Przemyslaw Malkiewicz

An inhomogeneous (1+1)-dimensional model of the quantum gravity is considered. It is found, that this model corresponds to a string propagating against some curved background space. The quantization scheme including the Wheeler-DeWitt…

General Relativity and Quantum Cosmology · Physics 2015-05-28 S. L. Cherkas , V. L. Kalashnikov

In this paper we calculated the spectral dimension of loop quantum gravity (LQG) using the scaling property of the area operator spectrum on spin-network states and using the scaling property of the volume and length operators on Gaussian…

General Relativity and Quantum Cosmology · Physics 2009-05-19 Leonardo Modesto

By applying loop quantum gravity techniques to 3D gravity with a positive cosmological constant $\Lambda$, we show how the local gauge symmetry of the theory, encoded in the constraint algebra, acquires the quantum group structure of…

High Energy Physics - Theory · Physics 2016-12-09 Francesco Cianfrani , Jerzy Kowalski-Glikman , Daniele Pranzetti , Giacomo Rosati

We perform a LQC-quantization of the FRW cosmological model with nonminimally coupled scalar field. Making use of a canonical transformation, we recast the theory in the minimally coupled form (Einstein frame), for which standard LQC…

General Relativity and Quantum Cosmology · Physics 2013-05-21 Michal Artymowski , Andrea Dapor , Tomasz Pawlowski

We embark on the vast program of integrating the dynamics of Loop Quantum Gravity (LQG). Adopting the strategy of decomposing spin network states into small blocks of (quantum) geometry which can later be glued back together, we focus on…

General Relativity and Quantum Cosmology · Physics 2026-01-30 Mehdi Assanioussi , Etera R. Livine

We continue our work on the study of spherically symmetric loop quantum gravity coupled to two spherically symmetric scalar fields, one that acts as a clock. As a consequence of the presence of the latter, we can define a true Hamiltonian…

General Relativity and Quantum Cosmology · Physics 2024-02-07 Rodolfo Gambini , Jorge Pullin

This article sheds new light on the problem of cosmological reduction in Loop Quantum Gravity. We critically analyze Quantum Reduced Loop Gravity -- an attempt to extract the cosmological sector of the full theory. We reconsider the…

General Relativity and Quantum Cosmology · Physics 2021-01-12 Jakub Bilski , Antonino Marciano

Loop quantum gravity and cosmology are reviewed with an emphasis on evaluating the dynamics, rather than constructing it. The three crucial parts of such an analysis are (i) deriving effective equations, (ii) controlling the theory's…

General Relativity and Quantum Cosmology · Physics 2011-01-31 Martin Bojowald

In this article we propose a new construction of the spatial scalar curvature operator in (1+3)-dimensional LQG based on the twisted geometry. The starting point of the construction is to express the holonomy of the spin connection on a…

General Relativity and Quantum Cosmology · Physics 2024-12-02 Gaoping Long , Hongguang Liu

We formulate quantum field theory in triangulated spacetime using compositional quantum field theory and tensor network methods. We show that gravitational interactions emerge as a low-energy effective phenomenon in this framework. For…

High Energy Physics - Theory · Physics 2025-05-13 Matti Raasakka

It is discussed a truncation of the kinematical Hilbert space of Loop Quantum Gravity, which describes the dynamical system associated with an inhomogeneous cosmological model.

General Relativity and Quantum Cosmology · Physics 2013-03-04 Francesco Cianfrani

A rigorous implementation of the Wheeler-Dewitt equations was derived in the context of Loop Quantum Gravity (LQG) and was coined Quantum Spin Dynamics (QSD). The Hamiltonian constraint of QSD was criticised as being too local and to…

General Relativity and Quantum Cosmology · Physics 2021-12-09 Thomas Thiemann , Madhavan Varadarajan

In a previous work [arXiv:2009.03428] we proposed a new model for Quantum GRavity(QGR) and cosmology, dubbed $SU(\infty)$-QGR. One of the axioms of this model is that Hilbert spaces of the Universe and its subsystems represent $SU(\infty)$…

General Relativity and Quantum Cosmology · Physics 2022-01-04 Houri Ziaeepour

We study gravity coupled to a scalar field in spherical symmetry using loop quantum gravity techniques. Since this model has local degrees of freedom, one has to face ``the problem of dynamics'', that is, diffeomorphism and Hamiltonian…

General Relativity and Quantum Cosmology · Physics 2009-11-19 Rodolfo Gambini , Jorge Pullin , Saeed Rastgoo

The study of toy models in loop quantum gravity (LQG), defined as truncations of the full theory, is relevant to both the development of the LQG phenomenology, in cosmology and astrophysics, and the progress towards the resolution of the…

General Relativity and Quantum Cosmology · Physics 2022-07-13 Eneko Aranguren , Iñaki Garay , Etera R. Livine

In the framework of loop quantum gravity, we define a new Hilbert space of states which are solutions of a large number of components of the diffeomorphism constraint. On this Hilbert space, using the methods of Thiemann, we obtain a family…

General Relativity and Quantum Cosmology · Physics 2015-03-05 Jerzy Lewandowski , Hanno Sahlmann

We introduce a new framework for loop quantum gravity: mimicking the spinfoam quantization procedure we propose to study the symmetric sectors of the theory imposing the reduction weakly on the full kinematical Hilbert space of the…

General Relativity and Quantum Cosmology · Physics 2015-06-12 Emanuele Alesci , Francesco Cianfrani