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Loop Quantum Cosmology (LQC), mainly due to Bojowald, is not the cosmological sector of Loop Quantum Gravity (LQG). Rather, LQC consists of a truncation of the phase space of classical General Relativity to spatially homogeneous situations…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Johannes Brunnemann , Thomas Thiemann

The volume operator plays a pivotal role for the quantum dynamics of Loop Quantum Gravity (LQG), both in the full theory and in truncated models adapted to cosmological situations coined Loop Quantum Cosmology (LQC). It is therefore crucial…

General Relativity and Quantum Cosmology · Physics 2008-12-09 C. Flori , T. Thiemann

We continue the semiclassical analysis of the Loop Quantum Gravity (LQG) volume operator that was started in the companion paper [23]. In the first paper we prepared the technical tools, in particular the use of complexifier coherent states…

General Relativity and Quantum Cosmology · Physics 2009-04-22 Cecilia Flori

In this paper we investigate the properties of gauge-invariant coherent states for Loop Quantum Gravity, for the gauge group U(1). This is done by projecting the corresponding complexifier coherent states, which have been applied in…

General Relativity and Quantum Cosmology · Physics 2009-02-12 Benjamin Bahr , Thomas Thiemann

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

An open issue in loop quantum gravity (LQG) is the introduction of a non-vanishing cosmological constant $\Lambda$. In 3d, Chern-Simons theory provides some guiding lines: $\Lambda$ appears in the quantum deformation of the gauge group. The…

General Relativity and Quantum Cosmology · Physics 2014-12-03 Maïté Dupuis , Florian Girelli

We examine the singularity resolution issue in quantum gravity by studying a new quantization of standard Friedmann-Robertson-Walker geometrodynamics. The quantization procedure is inspired by the loop quantum gravity programme, and is…

General Relativity and Quantum Cosmology · Physics 2009-11-10 V. Husain , O. Winkler

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 find an…

General Relativity and Quantum Cosmology · Physics 2015-05-30 Enrique F. Borja , Jacobo Diaz-Polo , Laurent Freidel , Iñaki Garay , Etera R. Livine

We present a separable version of Loop Quantum Gravity (LQG) based on an inductive system of cubic lattices. We construct semi-classical states for which the LQG operators -- the flux, the area and the volume operators -- have the right…

General Relativity and Quantum Cosmology · Physics 2009-11-24 Johannes Aastrup , Jesper M. Grimstrup

We adopt a novel approach to combine path integral methods with Loop Quantum Gravity (LQG). Our approach builds upon the recently developed coherent state path integral formulation of LQG to compute the one-loop effective action. We compare…

General Relativity and Quantum Cosmology · Physics 2025-02-12 Renata Ferrero , Muxin Han , Hongguang Liu

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 the lattice approach to Loop Quantum Gravity on a fixed graph computations tend to be involved and are rarely analytically manageable. But, when interested in the expectation values of coherent states on the lattice which are sharply…

General Relativity and Quantum Cosmology · Physics 2021-11-01 Klaus Liegener , Łukasz Rudnicki

The present paper is the companion of [1] in which we proposed a scheme that tries to derive the Quantum Field Theory (QFT) on Curved Spacetimes (CST) limit from background independent Quantum General Relativity (QGR). The constructions of…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Hanno Sahlmann , Thomas Thiemann

In loop quantum cosmology the quantum dynamics is well understood. We approximate the full quantum dynamics in the infinite dimensional Hilbert space by projecting it on a finite dimensional submanifold thereof, spanned by suitably chosen…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Victor Taveras

A manifestly Lorentz-covariant formulation of Loop Quantum Gravity (LQG) is given in terms of finite-dimensional representations of the Lorentz group. The formulation accounts for discrete symmetries, such as parity and time-reversal, and…

General Relativity and Quantum Cosmology · Physics 2021-12-08 Francesco Cianfrani

A new routine is proposed to relate Loop Quant Cosmology (LQC) to Loop Quantum Gravity (LQG) from the perspective of effective dynamics. We derive the big-bang singularity resolution and big bounce from the first principle of full canonical…

General Relativity and Quantum Cosmology · Physics 2020-02-12 Muxin Han , Hongguang Liu

One of the main achievements of LQG is the consistent quantization of the Wheeler-DeWitt equation which is free of UV problems. However, ambiguities associated to the intermediate regularization procedure lead to an apparently infinite set…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Alejandro Perez

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

Working within the framework of Loop Quantum Gravity (LQG), we construct a set of three operators suitable for identifying coordinate-like quantities on a spin-network configuration. In doing so, we rely on known properties of operators for…

High Energy Physics - Theory · Physics 2018-07-19 Suddhasattwa Brahma , Antonino Marcianò , Michele Ronco

We introduce a new top down approach to canonical quantum gravity, called Algebraic Quantum Gravity (AQG):The quantum kinematics of AQG is determined by an abstract $*-$algebra generated by a countable set of elementary operators labelled…

General Relativity and Quantum Cosmology · Physics 2008-11-26 K. Giesel , T. Thiemann
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