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In loop quantum gravity, the quantum geometry of a black hole horizon consist of discrete non-perturbative quantum geometric excitations (or punctures) labeled by spins, which are responsible for the quantum area of the horizon. If these…

General Relativity and Quantum Cosmology · Physics 2016-11-07 Abhishek Majhi

We consider cosmological solution for Einstein gravity with massive fermions with a four-fermion coupling, which emerges from the Holst action and is related to the Barbero-Immirzi (BI) parameter. This gravitational action is an important…

General Relativity and Quantum Cosmology · Physics 2015-06-03 G. de Berredo-Peixoto , L. Freidel , I. L. Shapiro , C. A. de Souza

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

This article presents an "in-a-nutshell" yet self-contained introductory review on loop quantum gravity (LQG) -- a background-independent, nonperturbative approach to a consistent quantum theory of gravity. Instead of rigorous and…

General Relativity and Quantum Cosmology · Physics 2014-12-30 Dah-Wei Chiou

We study and compare the spectra of geometric operators (length and area) in the quantum kinematics of two formulations of three-dimensional Lorentzian loop quantum gravity. In the SU(2) Ashtekar-Barbero framework, the spectra are discrete…

General Relativity and Quantum Cosmology · Physics 2014-05-07 Jibril Ben Achour , Marc Geiller , Karim Noui , Chao Yu

When gauge field theory coherent states for loop quantum gravity (LQG) were introduced, an optimized semiclassical proper length emerged, corresponding to the edge length $\epsilon$ of a graph embedded in a given classical geometry. Here…

General Relativity and Quantum Cosmology · Physics 2014-02-20 Paul G. N. de Vegvar

In loop quantum gravity in the connection representation, the quantum configuration space $\bar{\mathcal{A}/\mathcal{G}}$, which is a compact space, is much larger than the classical configuration space $\mathcal{A}/% \mathcal{G}$ of…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Andreas Doering , Hans F. de Groote

With a semiclassical polymerization in the loop quantum gravity (LQG), the interior of Schwarzschild black holes provides a captivating single-horizon regular black hole spacetime. The shortage of rotating black hole models in loop quantum…

General Relativity and Quantum Cosmology · Physics 2022-11-23 Jitendra Kumar , Shafqat Ul Islam , Sushant G. Ghosh

We give an account of the state of the art about black hole entropy in Loop Quantum Gravity. This chapter contains a historical summary and explains how black hole entropy is described by relying on the concept of isolated horizon, with an…

General Relativity and Quantum Cosmology · Physics 2022-12-29 J. Fernando Barbero G. , Daniele Pranzetti

We present a manifestly Lorentz-covariant description of the phase space of general relativity with the Immirzi parameter. This formulation emerges after solving the second-class constraints arising in the canonical analysis of the Holst…

General Relativity and Quantum Cosmology · Physics 2018-01-17 Merced Montesinos , Jorge Romero , Mariano Celada

Considering the possibility of `renormalization' of the gravitational constant on the horizon, leading to a dependence on the level of the associated Chern-Simons theory, a rescaled area spectrum is proposed for the non-rotating black hole…

General Relativity and Quantum Cosmology · Physics 2018-04-04 Abhishek Majhi

Loop quantum gravity is one of the leading candidate theory to non-perturbatively quantize gravity. In this framework, holonomy corrections to the equation of propagation of gravitons in a FLRW background have been derived. We investigate…

General Relativity and Quantum Cosmology · Physics 2008-05-06 A. Barrau , J. Grain

D = 2+1 gravity with a cosmological constant has been shown by Bonzom and Livine to present a Barbero-Immirzi like ambiguity depending on a parameter. We make use of this fact to show that, for positive cosmological constant, the Lorentzian…

General Relativity and Quantum Cosmology · Physics 2015-06-04 Rodrigo M. S. Barbosa , Clisthenis P Constantinidis , Zui Oporto , Olivier Piguet

The appearance of the big bounce (BB) in the evolution of the universe is analyzed in the setting of loop quantum cosmology (LQC). Making use of an idea of a minimum length turns classical Big Bang into BB. We argue why the spectrum of the…

General Relativity and Quantum Cosmology · Physics 2015-03-13 Piotr Dzierzak , Jacek Jezierski , Przemyslaw Malkiewicz , Wlodzimierz Piechocki

Within loop quantum gravity we construct a coarse-grained approximation for the Einstein-Maxwell theory that yields effective Maxwell equations in flat spacetime comprising Planck scale corrections. The corresponding Hamiltonian is defined…

High Energy Physics - Theory · Physics 2009-11-07 Jorge Alfaro , Hugo A. Morales-Técotl , Luis F. Urrutia

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

Using non-extensive statistical mechanics, the Bekenstein-Hawking area law is obtained from microstates of black holes in loop quantum gravity, for arbitrary real positive values of the Barbero-Immirzi parameter$(\gamma)$. The arbitrariness…

General Relativity and Quantum Cosmology · Physics 2017-10-31 Abhishek Majhi

We study the coupling of the gravitational action, which is a linear combination of the Hilbert-Palatini term and the quadratic torsion term, to the action of Dirac fermions. The system possesses local Poincare invariance and hence belongs…

General Relativity and Quantum Cosmology · Physics 2013-10-02 Jian Yang , Kinjal Banerjee , Yongge Ma

In the context of Loop Quantum Gravity (LQG), we study the fate of Thiemann complexifier in homogeneous and isotropic FRW cosmology. The complexifier is the dilatation operator acting on the canonical phase space for gravity and generates…

General Relativity and Quantum Cosmology · Physics 2017-09-27 Jibril Ben Achour , Etera R. Livine

An outstanding open issue in our quest for physics beyond Einstein is the unification of general relativity (GR) and quantum physics. Loop quantum gravity (LQG) is a leading approach toward this goal. At its heart is the central lesson of…

General Relativity and Quantum Cosmology · Physics 2021-04-12 Abhay Ashtekar , Eugenio Bianchi
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