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We construct a well-defined lattice-regularized quantum theory formulated in terms of fundamental fermion and gauge fields, the same type of degrees of freedom as in the Standard Model. The theory is explicitly invariant under local Lorentz…

High Energy Physics - Theory · Physics 2013-05-30 Alexey A. Vladimirov , Dmitri Diakonov

We use the method of embedding a subsystem (i.e. its observable algebra) into a larger quantum system to extract a cosmological sector from full Loop Quantum Gravity. The application of this method provides a setting for a systematic study…

General Relativity and Quantum Cosmology · Physics 2007-11-08 Tim A. Koslowski

Effective equations are often useful to extract physical information from quantum theories without having to face all technical and conceptual difficulties. One can then describe aspects of the quantum system by equations of classical type,…

High Energy Physics - Theory · Physics 2008-11-26 Martin Bojowald , Aureliano Skirzewski

We investigate the ambiguities in the Fock quantization of the scalar perturbations of a Friedmann-Lema\^{i}tre-Robertson-Walker model with a massive scalar field as matter content. We consider the case of compact spatial sections (thus…

General Relativity and Quantum Cosmology · Physics 2012-06-21 Mikel Fernández-Méndez , Guillermo A. Mena Marugán , Javier Olmedo , José M. Velhinho

We study one loop quantum gravitational corrections to the long range force induced by the exchange of a massless scalar between two massive scalars. The various diagrams contributing to the flat space S-matrix are evaluated in a general…

General Relativity and Quantum Cosmology · Physics 2017-11-22 S. P. Miao , T. Prokopec , R. P. Woodard

Loop quantum cosmology predicts that quantum gravity effects resolve the big-bang singularity and replace it by a cosmic bounce. Furthermore, loop quantum cosmology can also modify the form of primordial cosmological perturbations, for…

General Relativity and Quantum Cosmology · Physics 2017-06-28 Edward Wilson-Ewing

Loop quantum cosmology is an application of recent developments for a non-perturbative and background independent quantization of gravity to a cosmological setting. Characteristic properties of the quantization such as discreteness of…

Astrophysics · Physics 2009-11-13 Martin Bojowald

The framework of quantum symmetry reduction is applied to loop quantum gravity with respect to transitively acting symmetry groups. This allows to test loop quantum gravity in a large class of minisuperspaces and to investigate its features…

General Relativity and Quantum Cosmology · Physics 2010-11-19 Martin Bojowald

Our review is devoted to three promising research lines in quantum cosmology and the physics of the early universe. The nonperturbative renormalization programme is making encouraging progress that we here assess from the point of view of…

General Relativity and Quantum Cosmology · Physics 2016-11-15 Giampiero Esposito

We present a complete quantization of an approximately homogeneous and isotropic universe with small scalar perturbations. We consider the case in which the matter content is a minimally coupled scalar field and the spatial sections are…

General Relativity and Quantum Cosmology · Physics 2013-10-16 Mikel Fernández-Méndez , Guillermo A. Mena Marugán , Javier Olmedo

We construct and study Loop Quantum Cosmology (LQC) when the Barbero-Immirzi parameter takes the complex value $\gamma=\pm i$. We refer to this new quantum cosmology as complex Loop Quantum Cosmology. We proceed in making an analytic…

General Relativity and Quantum Cosmology · Physics 2015-06-22 Jibril Ben Achour , Julien Grain , Karim Noui

A powerful strategy to treat quantum field theories beyond perturbation theory is by putting them on a lattice. However, the dynamical and symmetry structure of general relativity have for a long time stood in the way of a well-defined…

High Energy Physics - Theory · Physics 2024-01-18 J. Ambjørn , R. Loll

We study spherical charged black holes in the presence of a cosmological constant with corrections motivated by the theory of loop quantum gravity. The effective theory is constructed at the Hamiltonian level by introducing certain…

General Relativity and Quantum Cosmology · Physics 2023-04-12 Asier Alonso-Bardaji , David Brizuela , Raül Vera

We consider the loop quantum theory of the spherically symmetric model of gravity coupled to Gaussian dust fields, where the Gaussian dust fields provide a material reference frame of the space and time to deparameterize gravity. This…

General Relativity and Quantum Cosmology · Physics 2022-02-25 Cong Zhang

Quantum cosmology is traditionally formulated in a minisuperspace setting, implicitly averaging fields over space to obtain homogeneous models. For universal reasons related to the uncertainty principle, quantum corrections then depend on…

General Relativity and Quantum Cosmology · Physics 2019-06-05 Martin Bojowald

We explore the potential application of quantum computers to the examination of lattice holography, which extends to the strongly-coupled bulk theory regime. With adiabatic evolution, we compute the ground state of a spin system on a…

High Energy Physics - Lattice · Physics 2023-12-19 Ying-Ying Li , Muhammad Omer Sajid , Judah Unmuth-Yockey

We analyse cosmological perturbations around a homogeneous and isotropic background for scalar-tensor, vector-tensor and bimetric theories of gravity. Building on previous results, we propose a unified view of the effective parameters of…

General Relativity and Quantum Cosmology · Physics 2018-03-28 Macarena Lagos , Emilio Bellini , Johannes Noller , Pedro G. Ferreira , Tessa Baker

While homogeneous cosmologies have long been studied in the group field theory (GFT) approach to quantum gravity, including a quantum description of cosmological perturbations is highly non-trivial. Here we apply a recent proposal for…

General Relativity and Quantum Cosmology · Physics 2025-11-18 Steffen Gielen , Lisa Mickel

The concept of effective dynamics has proven successful in LQC, a loop-inspired quantization of cosmological spacetimes. We apply the same idea of its derivation in LQC to the full theory, by computing the expectation value of the scalar…

General Relativity and Quantum Cosmology · Physics 2018-09-17 Andrea Dapor , Klaus Liegener

The alternative dynamics of loop quantum cosmology is examined by the path integral formulation. We consider the spatially flat FRW models with a massless scalar field, where the alternative quantization inherit more features from full loop…

General Relativity and Quantum Cosmology · Physics 2015-06-05 Li Qin , Guo Deng , Yongge Ma