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We present the construction of a physical Hamiltonian operator in the deparametrized model of loop quantum gravity coupled to a free scalar field. This construction is based on the use of the recently introduced curvature operator, and on…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Emanuele Alesci , Mehdi Assanioussi , Jerzy Lewandowski , Ilkka Mäkinen

We study the homogeneous but anisotropic cosmological models of Bianchi in presence of a massive scalar field using the ADM Hamiltonian formalism. We begin to describe the main steps to find the ADM Hamiltonian of the General Relativity…

General Relativity and Quantum Cosmology · Physics 2014-04-15 Stephane Fay

Following the idea of a field quantization of gravity as realized in group field theory, we construct a minisuperspace model where the wavefunction of canonical quantum cosmology (either Wheeler-DeWitt or loop quantum cosmology) is promoted…

General Relativity and Quantum Cosmology · Physics 2012-05-02 Gianluca Calcagni , Steffen Gielen , Daniele Oriti

We analyze the Bianchi I cosmology in the presence of a massless scalar field and describe its dynamics via a semiclassical and quantum polymer approach. We study the morphology of the Big Bounce by adopting three different sets of…

General Relativity and Quantum Cosmology · Physics 2022-03-09 E. Giovannetti , G. Montani , S. Schiattarella

In this paper, we discuss the properties of one-parameter sequences that arise when solving the Hamiltonian constraint in Bianchi I loop quantum cosmology using a separation of variables method. In particular, we focus on finding an…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Daniel Cartin , Gaurav Khanna

We derive a canonical analysis of a double null 2+2 Hamiltonian description of General Relativity in terms of complex self-dual 2-forms and the associated SO(3) connection variables. The algebra of first class constraints is obtained and…

General Relativity and Quantum Cosmology · Physics 2009-11-11 R. A. d'Inverno , P Lambert , J. A. Vickers

The Hamiltonian constraint of scalar-tensor theories in the Jordan frame is quantised using three quantisation prescriptions in loop quantum cosmology, from which we obtain three different effective Hamiltonian constraints. The…

General Relativity and Quantum Cosmology · Physics 2022-12-08 Yu Han

We investigate some properties of geometric operators in canonical quantum gravity in the connection approach \`a la Ashtekar, which are associated with volume, area and length of spatial regions. We motivate the construction of analogous…

General Relativity and Quantum Cosmology · Physics 2009-10-28 R. Loll

The two-loop (order $\alpha'$) $\beta$-function equations, which are equivalent to the equations of motion of $\alpha'$-corrected string effective action, are considered for anisotropic homogeneous space-times. These equations are solved…

High Energy Physics - Theory · Physics 2017-10-19 F. Naderi , A. Rezaei-Aghdam

A brief review of various numerical techniques used in loop quantum cosmology and results is presented. These include the way extensive numerical simulations shed insights on the resolution of classical singularities, resulting in the key…

General Relativity and Quantum Cosmology · Physics 2013-07-11 Parampreet Singh

This article describes the theory of cosmological perturbations around a homogeneous and anisotropic universe of the Bianchi I type. Starting from a general parameterisation of the perturbed spacetime a la Bardeen, a complete set of gauge…

Astrophysics · Physics 2008-11-26 Thiago S. Pereira , Cyril Pitrou , Jean-Philippe Uzan

A quantum damped-polariton model is constructed for an inhomogeneous anisotropic linear dielectric with arbitrary dispersion in space and time. The model Hamiltonian is completely diagonalized by determining the creation and annihilation…

Quantum Physics · Physics 2018-08-16 L. G. Suttorp

We analyze the quantum dynamics of the non-relativistic two-dimensional isotropic harmonic oscillator in Heisenberg's picture. Such a system is taken as toy model to analyze some of the various quantum theories that can be built from the…

Quantum Physics · Physics 2009-11-10 Merced Montesinos , G. F. Torres del Castillo

We study the role of non-perturbative quantum gravity effects in the Ekpyrotic/Cyclic model using the effective framework of loop quantum cosmology in the presence of anisotropies. We show that quantum geometric modifications to the…

General Relativity and Quantum Cosmology · Physics 2010-04-30 Thomas Cailleteau , Parampreet Singh , Kevin Vandersloot

In the loop approach to the quantisation of gravity, one uses a Hilbert space which is too singular for some operators to be realised as derivatives. This is usually addressed by instead using finite difference operators at the Planck…

General Relativity and Quantum Cosmology · Physics 2009-12-17 Robert C. Helling

In this paper canonical quantum gravity on noncommutative space-time is considered. The corresponding generalized classical theory is formulated by using the moyal star product, which enables the representation of the field quantities…

General Relativity and Quantum Cosmology · Physics 2016-09-02 Martin Kober

We propose a quantum symmetry reduction of loop quantum gravity to Bianchi I spacetimes. To this end, we choose the diagonal metric gauge for the spatial diffeomorphism constraint at the classical level, leading to an…

General Relativity and Quantum Cosmology · Physics 2015-04-16 Norbert Bodendorfer

Coherent state functional integral for the minisuperspace model of loop quantum cosmology is studied. By the well-established canonical theory, the transition amplitude in the path integral representation of loop quantum cosmology with…

General Relativity and Quantum Cosmology · Physics 2012-06-07 Li Qin , Yongge Ma

This work explores the behaviour of a noncommutative harmonic oscillator in a time-dependent background, as previously investigated in [1]. Specifically, we examine the system when expressed in terms of commutative variables, utilizing a…

Quantum Physics · Physics 2024-07-10 Manjari Dutta , Shreemoyee Ganguly , Sunandan Gangopadhyay

We consider the quantization of a general spatially homogeneous space-time belonging to an arbitrary but fixed Class A Bianchi type. Exploiting the information furnished by the quantum version of the momentum constraints, we use as…

General Relativity and Quantum Cosmology · Physics 2011-07-19 T. Christodoulakis , E. Korfiatis , E. C. Vagenas