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A model for quantized gravity coupled to matter in the form of a single scalar field is investigated in four dimensions. For the metric degrees of freedom we employ Regge's simplicial discretization, with the scalar fields defined at the…

High Energy Physics - Theory · Physics 2009-10-22 Herbert W. Hamber , Ruth M. Williams

In loop quantum gravity, matter fields can have support only on the `polymer-like' excitations of quantum geometry, and their algebras of observables and Hilbert spaces of states can not refer to a classical, background geometry. Therefore,…

General Relativity and Quantum Cosmology · Physics 2017-08-23 Abhay Ashtekar , Jerzy Lewandowski , Hanno Sahlmann

Treating the gravitational force on the same footing as the electroweak and strong forces, we present a quantum field theory of gravity based on spin and scaling gauge symmetries. A biframe spacetime is initiated to describe such a quantum…

High Energy Physics - Theory · Physics 2016-01-20 Yue-Liang Wu

We consider the emergence from quantum entanglement of spacetime geometry in a bulk region. For certain classes of quantum states in an appropriately factorized Hilbert space, a spatial geometry can be defined by associating areas along…

High Energy Physics - Theory · Physics 2018-04-11 ChunJun Cao , Sean M. Carroll

Loop Quantum Gravity heavily relies on a connection formulation of General Relativity such that 1. the connection Poisson commutes with itself and 2. the corresponding gauge group is compact. This can be achieved starting from the Palatini…

General Relativity and Quantum Cosmology · Physics 2013-02-13 Norbert Bodendorfer , Thomas Thiemann , Andreas Thurn

We generalize the Hamiltonian picture of General Relativity coupled to classical matter, known as geometrodynamics, to the case where such matter is described by a Quantum Field Theory in Curved Spacetime, but gravity is still described by…

General Relativity and Quantum Cosmology · Physics 2024-03-20 J. L. Alonso , C. Bouthelier-Madre , J. Clemente-Gallardo , D. Martínez-Crespo

We introduce a new framework for loop quantum gravity: mimicking the spinfoam quantization procedure we propose to study the symmetric sectors of the theory imposing the reduction weakly on the full kinematical Hilbert space of the…

General Relativity and Quantum Cosmology · Physics 2015-06-12 Emanuele Alesci , Francesco Cianfrani

We study the role of the Barbero-Immirzi parameter $\gamma$ and the choice of connection in the construction of (a symmetry-reduced version of) loop quantum gravity. We start with the four-dimensional Lorentzian Holst action that we reduce…

General Relativity and Quantum Cosmology · Physics 2015-05-19 Jibril Ben Achour , Marc Geiller , Karim Noui , Chao Yu

In order to study 3d loop quantum gravity coupled to matter, we consider a simplified model of abelian quantum gravity, the so-called U(1)^3 model. Abelian gravity coupled to a scalar field shares a lot of commonalities with parameterized…

General Relativity and Quantum Cosmology · Physics 2019-05-01 Christoph Charles

The "problem of time" in canonical quantum gravity refers to the difficulties involved in defining a Hilbert space structure on states -- and local observables on this Hilbert space -- for a theory in which the spacetime metric is treated…

General Relativity and Quantum Cosmology · Physics 2009-12-30 Robert M. Wald

The talk is devoted to the "extended phase space" approach to Quantum Geometrodynamics. The premises that have led to the formulation of this approach are briefly reviewed, namely, non-trivial topology of the Universe which implies the…

General Relativity and Quantum Cosmology · Physics 2011-01-18 T. P. Shestakova

Quantum gravity is studied nonperturbatively in the case in which space has a boundary with finite area. A natural set of boundary conditions is studied in the Euclidean signature theory, in which the pullback of the curvature to the…

General Relativity and Quantum Cosmology · Physics 2010-04-06 Lee Smolin

Twenty years ago, by extending the Wightman axiom framework, it has been found possible to quantize only a conformal factor of the gravitational field. Gravitons being excluded from this quantum scalar field theory, numerous attempts were…

General Relativity and Quantum Cosmology · Physics 2007-05-23 G. Burdet , M. Perrin

We study the separability of the state space of loop quantum gravity. In the standard construction, the kinematical Hilbert space of the diffeomorphism-invariant states is nonseparable. This is a consequence of the fact that the knot-space…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Winston Fairbairn , Carlo Rovelli

We consider single graviton loop corrections to the effective field equation of a massless, minimally coupled scalar on de Sitter background in the simplest gauge. We find a large temporal logarithm in the approach to freeze-in at late…

General Relativity and Quantum Cosmology · Physics 2022-03-16 D. Glavan , S. P. Miao , T. Prokopec , R. P. Woodard

We perform the manifestly covariant quantization of a scale invariant gravity with a scalar field, which is equivalent to the well-known Brans-Dicke gravity via a field redefinition of the scalar field, in the de Donder gauge condition (or…

High Energy Physics - Theory · Physics 2022-03-14 Ichiro Oda

We construct a model of quantum gravity in which dimension, topology and geometry of spacetime are dynamical. The microscopic degree of freedom is a real rectangular matrix whose rows label internal flavours, and columns label spatial…

High Energy Physics - Theory · Physics 2020-12-14 Sung-Sik Lee

In recent years several ideas for experimental searches of effects induced by quantum properties of space-time have been discussed. Some of these ideas concern the role in quantum spacetime of the ordinary Lorentz symmetry of classical flat…

Astrophysics · Physics 2007-05-23 Giovanni Amelino-Camelia

The quantization of the Hamiltonian for a scalar field is performed in the framework of Quantum Reduced Loop Gravity. We outline how the regularization can be performed by using the analogous tools adopted in full Loop Quantum Gravity and…

General Relativity and Quantum Cosmology · Physics 2015-12-23 Jakub Bilski , Emanuele Alesci , Francesco Cianfrani

Motivated by the ideas of Jacob Bekenstein concerning gravity-assisted symmetry breaking, we consider a non-canonical model of f(R)=R+R^2 extended gravity coupled to neutral scalar "inflaton", as well as to SU(2)xU(1) multiplet of fields…

General Relativity and Quantum Cosmology · Physics 2018-04-24 Eduardo Guendelman , Emil Nissimov , Svetlana Pacheva
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