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In this paper, we address a foundational challenge in quantum field theory on curved spacetime by developing a consistent framework within loop quantum gravity. We introduce a methodology for defining meaningful superpositions of quantum…

General Relativity and Quantum Cosmology · Physics 2026-02-17 Gaoping Long , Cong Zhang

We summarize the main ideas behind TGFT condensate cosmology and sketch the technical steps that bring from the fundamental theory to the effective cosmological dynamics. This framework is presented as an explicit illustration of (and…

General Relativity and Quantum Cosmology · Physics 2022-02-10 Daniele Oriti

We offer a perspective on some recent results obtained in the context of the group field theory approach to quantum gravity, on top of reviewing them briefly. These concern a natural mechanism for the emergence of non-commutative field…

High Energy Physics - Theory · Physics 2009-07-24 Daniele Oriti

We continue our work on the study of spherically symmetric loop quantum gravity coupled to two spherically symmetric scalar fields, one that acts as a clock. As a consequence of the presence of the latter, we can define a true Hamiltonian…

General Relativity and Quantum Cosmology · Physics 2024-02-07 Rodolfo Gambini , Jorge Pullin

This research establishes an operational measurement way to express the quantum field theory in a geometrical form. In four-dimensional spacetime continuum, the orthogonal rotation is defined. It forms two sets of equations: one set is…

General Physics · Physics 2007-05-23 Jianhua Xiao

Apart from the flat space with an angular deficit, Einstein general relativity possesses another cylindrically symmetric solution. Because this configuration displays circles whose "circumferences" tend to zero when their "radius" go to…

High Energy Physics - Theory · Physics 2007-05-23 M. Lubo

We present the case for a fundamentally discrete quantum spacetime and for Group Field Theories as a candidate consistent description of it, briefly reviewing the key properties of the GFT formalism. We then argue that the outstanding…

High Energy Physics - Theory · Physics 2008-11-26 Daniele Oriti

Some mathematical aspects of using the translation group as an internal symmetry group in a gauge field theory are presented and discussed. The traditional manner in which gravitation can be accounted for by the introduction of a global…

General Relativity and Quantum Cosmology · Physics 2007-05-23 David Delphenich

Three theoretical criteria for gravitational theories beyond general relativity are considered: obtaining the cosmological constant as an integration constant, deriving the energy conservation law as a consequence of the field equations,…

General Relativity and Quantum Cosmology · Physics 2023-08-17 Junpei Harada

General 2d dilaton theories, containing spherically symmetric gravity and hence the Schwarzschild black hole as a special case, are quantized by an exact path integral of their geometric (Cartan-) variables. Matter, represented by minimally…

High Energy Physics - Theory · Physics 2009-10-31 W. Kummer , H. Liebl , D. V. Vassilevich

We derive an effective dynamics for scalar cosmological perturbations from quantum gravity, in the framework of group field theory (GFT) condensate cosmology. The emergent spacetime picture is obtained from the mean field hydrodynamic…

General Relativity and Quantum Cosmology · Physics 2022-07-19 Luca Marchetti , Daniele Oriti

We present an effective theory to describe the quantization of spherically symmetric vacuum in loop quantum gravity. We include anomaly-free holonomy corrections through a canonical transformation of the Hamiltonian of general relativity,…

General Relativity and Quantum Cosmology · Physics 2023-04-18 Asier Alonso-Bardaji , David Brizuela , Raül Vera

In the search for exact solutions to Einstein's field equations the main simplification tool is the introduction of spacetime symmetries. Motivated by this fact we develop a method to write the field equations for general matter in a form…

General Relativity and Quantum Cosmology · Physics 2014-11-17 E. Zafiris

We extend previous results in spherically symmetric gravitational systems coupled with a massless scalar field within the loop quantum gravity framework. As starting point, we take the Schwarzschild spacetime. The results presented here…

General Relativity and Quantum Cosmology · Physics 2015-06-03 Enrique F. Borja , Iñaki Garay , Eckhard Strobel

Group field theories are a generalization of matrix models which provide both a second quantized reformulation of loop quantum gravity as well as generating functions for spin foam models. While states in canonical loop quantum gravity, in…

General Relativity and Quantum Cosmology · Physics 2018-08-01 Johannes Thürigen

In this paper we use the AdS/CFT correspondence to refine and then establish a set of old conjectures about symmetries in quantum gravity. We first show that any global symmetry, discrete or continuous, in a bulk quantum gravity theory with…

High Energy Physics - Theory · Physics 2019-06-07 Daniel Harlow , Hirosi Ooguri

We construct a generalized class of quantum gravity condensate states, that allows the description of continuum homogeneous quantum geometries within the full theory. They are based on similar ideas already applied to extract effective…

General Relativity and Quantum Cosmology · Physics 2015-11-24 Daniele Oriti , Daniele Pranzetti , James P. Ryan , Lorenzo Sindoni

For more than 80 years theoretical physicists have been trying to develop a theory of quantum gravity which would successfully combine the tenets of Einstein's theory of general relativity (GR) together with those of quantum field theory.…

General Relativity and Quantum Cosmology · Physics 2019-03-20 Andreas G. A. Pithis

Four-dimensional gravity admits many equivalent formulations - metric, Einstein-Cartan, teleparallel, McDowell-Mansouri, among others - each offering distinct advantages, particularly, in view of quantization. We propose a new formulation…

General Relativity and Quantum Cosmology · Physics 2026-03-13 Maïté Dupuis , Florian Girelli , Oleksandra Hrytseniak , Wolfgang Wieland

Close to the Planck energy scale, the quantum nature of space-time reveals itself and all forces, including gravity, should be unified so that all interactions correspond to just one underlying symmetry. In the absence of a full quantum…

High Energy Physics - Theory · Physics 2015-03-17 Mairi Sakellariadou