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In this paper, a new Hamiltonian constraint operator for loop quantum cosmology is constructed by using the Chern-Simons action. The quantum dynamics of the $k=0$ cosmological model with respect to a massless scalar field as an emergent…

General Relativity and Quantum Cosmology · Physics 2019-09-23 Jinsong Yang , Cong Zhang , Yongge Ma

In this article we introduce a new operator representing the three-dimensional scalar curvature in loop quantum gravity. Our construction does not apply to the entire kinematical Hilbert space of loop quantum gravity; instead, the operator…

General Relativity and Quantum Cosmology · Physics 2023-06-02 Jerzy Lewandowski , Ilkka Mäkinen

The scheme of using the Chern-Simons action to regularize the gravitational Hamiltonian constraint is extended to including the Lorentzian term in the $k=0$ cosmological model. The Euclidean term and the Lorenzian term are thus regularized…

General Relativity and Quantum Cosmology · Physics 2020-10-12 Jinsong Yang , Cong Zhang , Yongge Ma

In a remarkable paper, T. Koslowski introduced kinematical representations for loop quantum gravity in which there is a non-degenerate spatial background metric present. He also considered their properties, and showed that Gauss and…

General Relativity and Quantum Cosmology · Physics 2010-10-27 Hanno Sahlmann

In a previous article we have introduced an operator representing the three-dimensional scalar curvature in loop quantum gravity. In this article we examine the new curvature operator in the setting of quantum-reduced loop gravity. We…

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

The Hamiltonian constraint remains an elusive object in loop quantum gravity because its action on spinnetworks leads to changes in their corresponding graphs. As a result, calculations in loop quantum gravity are often considered…

General Relativity and Quantum Cosmology · Physics 2025-07-28 Thiago L. M. Guedes , Guillermo A. Mena Marugán , Markus Müller , Francesca Vidotto

Using a Hamiltonian formulation of the spherically symmetric gravity-scalar field theory adapted to flat spatial slicing, we give a construction of the reduced Hamiltonian operator. This Hamiltonian, together with the null expansion…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Viqar Husain , Oliver Winkler

We first recall a fact which is well-known among mathematical physicists although lesser-known among theoretical physicists that the standard quantum mechanics over a complex Hilbert space, is a Hamiltonian mechanics, regarding the Hilbert…

Quantum Physics · Physics 2022-01-05 Seyed Ebrahim Akrami

Dirac's quantization of the (2+1)-dimensional analog of Ashtekar's approach to quantum gravity is investigated. After providing a diffeomorphism-invariant regularization of the Hamiltonian constraint, we find a set of solutions to this…

General Relativity and Quantum Cosmology · Physics 2009-10-28 Kiyoshi Ezawa

A covariant spin-foam formulation of quantum gravity has been recently developed, characterized by a kinematics which appears to match well the one of canonical loop quantum gravity. In this paper we reconsider the implementation of the…

General Relativity and Quantum Cosmology · Physics 2014-11-21 You Ding , Carlo Rovelli

Variables adapted to the quantum dynamics of spherically symmetric models are introduced, which further simplify the spherically symmetric volume operator and allow an explicit computation of all matrix elements of the Euclidean and…

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

We relate three-dimensional loop quantum gravity to the combinatorial quantisation formalism based on the Chern-Simons formulation for three-dimensional Lorentzian and Euclidean gravity with vanishing cosmological constant. We compare the…

General Relativity and Quantum Cosmology · Physics 2012-02-07 C. Meusburger , K. Noui

Loop quantum cosmology is a symmetry reduced quantization of cosmological spacetimes based on loop quantum gravity. While it has been successful in resolution of various cosmological singularities and connecting Planck scale physics to…

General Relativity and Quantum Cosmology · Physics 2019-12-25 Klaus Liegener , Parampreet Singh

The flat, homogeneous, and isotropic universe with a massless scalar field is a paradigmatic model in Loop Quantum Cosmology. In spite of the prominent role that the model has played in the development of this branch of physics, there still…

General Relativity and Quantum Cosmology · Physics 2010-09-23 Mercedes Martin-Benito , Guillermo A. Mena Marugan , Javier Olmedo

We generalize the idea of Vassiliev invariants to the spin network context, with the aim of using these invariants as a kinematical arena for a canonical quantization of gravity. This paper presents a detailed construction of these…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Cayetano Di Bartolo , Rodolfo Gambini , Jorge Griego , Jorge Pullin

Given a symmetry group acting on a principal fibre bundle, symmetric states of the quantum theory of a diffeomorphism invariant theory of connections on this fibre bundle are defined. These symmetric states, equipped with a scalar product…

High Energy Physics - Theory · Physics 2015-06-26 M. Bojowald , H. A. Kastrup

This series of lectures gives a simple and self-contained introduction to the non-perturbative and background independent loop approach of canonical quantum gravity. The Hilbert space of kinematical quantum states is constructed and a…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Marcus Gaul , Carlo Rovelli

We introduce the Quantum Holonomy-Diffeomorphism *-algebra, which is generated by holonomy-diffeomorphisms on a 3-dimensional manifold and translations on a space of SU(2)-connections. We show that this algebra encodes the canonical…

General Relativity and Quantum Cosmology · Physics 2016-04-12 Johannes Aastrup , Jesper M. Grimstrup

We construct the holonomy-flux operator algebra in the recently developed spinor formulation of loop gravity. We show that, when restricting to SU(2)-gauge invariant operators, the familiar grasping and Wilson loop operators are written as…

General Relativity and Quantum Cosmology · Physics 2013-11-08 Etera R. Livine , Johannes Tambornino

We use the recently introduced U(N) framework for loop quantum gravity to study the dynamics of spin network states on the simplest class of graphs: two vertices linked with an arbitrary number N of edges. Such graphs represent two regions,…

General Relativity and Quantum Cosmology · Physics 2011-03-28 Enrique F. Borja , Jacobo Diaz-Polo , Iñaki Garay , Etera R. Livine