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The non-factorizing nature of the Hilbert space in Loop Quantum Gravity (LQG) due to gauge invariance requires a generalized definition of entanglement entropy. This work employs the framework of von Neumann algebras to investigate the…

General Relativity and Quantum Cosmology · Physics 2025-11-04 Muxin Han

Inhomogeneities are introduced in loop quantum cosmology using regular lattice states, with a kinematical arena similar to that in homogeneous models considered earlier. The framework is intended to encapsulate crucial features of…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Martin Bojowald

Given a smooth compact Riemannian manifold $M$ and a Hamiltonian $H$ on the cotangent space $T^*M$, strictly convex and superlinear in the momentum variables, we prove uniqueness of certain ergodic invariant Lagrangian graphs within a given…

Dynamical Systems · Mathematics 2010-12-13 Albert Fathi , Alessandro Giuliani , Alfonso Sorrentino

We discuss a covariant setting for Hamiltonian formalism in a relativistic field theory and we use this to obtain again the properties of Hamilton principal functional in Newtonian mechanics, relativistic mechanics, Klein-Gordon,…

General Relativity and Quantum Cosmology · Physics 2026-02-06 Lorenzo Fatibene , Marco Ferraris , Andrea Orizzonte

We propose a new derivation from the full Loop Quantum Gravity (LQG) to the Loop Quantum Cosmology (LQC) improved $\bar{\mu}$-scheme effective dynamics, based on the reduced phase space formulation of LQG and a proposal of effective…

General Relativity and Quantum Cosmology · Physics 2020-09-30 Muxin Han , Hongguang Liu

The basic framework for this article is the causal set approach to discrete quantum gravity (DQG). Let $Q_n$ be the collection of causal sets with cardinality not greater than $n$ and let $K_n$ be the standard Hilbert space of…

General Relativity and Quantum Cosmology · Physics 2012-04-23 Stan Gudder

We briefly report our application of a version of noncommutative geometry to the quantum Euclidean space $R^N_q$, for any $N \ge 3$; this space is covariant under the action of the quantum group $SO_q(N)$, and two covariant differential…

Quantum Algebra · Mathematics 2007-05-23 B. L. Cerchiai , G. Fiore , J. Madore

A non-perturbative quantum field theory of General Relativity is presented which leads to a new realization of the theory of Covariant Quantum-Gravity (CQG-theory). The treatment is founded on the recently-identified Hamiltonian structure…

General Relativity and Quantum Cosmology · Physics 2017-05-24 Claudio Cremaschini , Massimo Tessarotto

Content: 1. Introduction 2. Regge calculus and dynamical triangulations Simplicial manifolds and piecewise linear spaces - dual complex and volume elements - curvature and Regge action - topological invariants - quantum Regge calculus -…

High Energy Physics - Theory · Physics 2016-09-06 F. David

Recently, a generally covariant reformulation of 2 dimensional flat spacetime free scalar field theory known as Parameterised Field Theory was quantized using Loop Quantum Gravity (LQG) type `polymer' representations. Physical states were…

General Relativity and Quantum Cosmology · Physics 2015-01-30 Alok Laddha , Madhavan Varadarajan

We explore how to extract effective dynamics from loop quantum gravity and spinfoams truncated to a finite fixed graph, with the hope of modeling symmetry-reduced gravitational systems. We particularize our study to the 2-vertex graph with…

General Relativity and Quantum Cosmology · Physics 2013-07-09 Etera R. Livine , Mercedes Martín-Benito

Quantum General Relativity (QGR), sometimes called Loop Quantum Gravity, has matured over the past fifteen years to a mathematically rigorous candidate quantum field theory of the gravitational field. The features that distinguish it from…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Thomas Thiemann

We recast the action of pure gravity into a form that is invariant under a twofold Lorentz symmetry. To derive this representation, we construct a general parameterization of all theories equivalent to the Einstein-Hilbert action up to a…

High Energy Physics - Theory · Physics 2017-01-31 Clifford Cheung , Grant N. Remmen

We consider a discrete model of euclidean quantum gravity in four dimensions based on a summation over random simplicial manifolds. The action used is the Einstein-Hilbert action plus an $R^2$-term. The phase diagram as a function of the…

High Energy Physics - Theory · Physics 2009-10-22 J. Ambjorn , J. Jurkiewicz , C. F. Kristjansen

We introduce a class of states characterized by proposed conditions of homogeneity and isotropy in loop quantum gravity and construct concrete examples given by Bell-network states on a special class of homogeneous graphs. Such states…

General Relativity and Quantum Cosmology · Physics 2023-03-29 Bekir Baytas , Nelson Yokomizo

We study the quantum fermions+gravity system, that is, the gravitational counterpart of QED. We start from the standard Einstein-Weyl theory, reformulated in terms of Ashtekar variables; and we construct its non- perturbative quantum theory…

General Relativity and Quantum Cosmology · Physics 2009-10-22 H A Marales-Tecotl , C Rovelli

We introduce a new regularization scheme for Quantum Cosmology in Loop Quantum Gravity (LQG) using the tools of Quantum Reduced Loop Gravity (QRLG). It is obtained considering density matrices for superposition of graphs based on…

General Relativity and Quantum Cosmology · Physics 2019-01-23 Emanuele Alesci , Gioele Botta , Gabriele V. Stagno

In this paper we construct the Hamiltonian constraint operator of loop quantum cosmology using holonomies defined for arbitrary irreducible SU(2) representations labeled by spin J. We show that modifications to the effective semi-classical…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Kevin Vandersloot

We present a systematic approach to the kinematics of quantum-reduced loop gravity, a model originally proposed by Alesci and Cianfrani as an attempt to probe the physical implications of loop quantum gravity. We implement the quantum…

General Relativity and Quantum Cosmology · Physics 2024-12-03 Ilkka Mäkinen

Based on a recent purely geometric construction of observables for the spatial diffeomorphism constraint, we propose two distinct quantum reductions to spherical symmetry within full 3+1-dimensional loop quantum gravity. The construction of…

General Relativity and Quantum Cosmology · Physics 2015-05-28 Norbert Bodendorfer , Jerzy Lewandowski , Jedrzej Świeżewski