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Different versions of consistent canonical realizations of hypersurface deformations of spherically symmetric space-times have been derived in models of loop quantum gravity, modifying the classical dynamics and sometimes also the structure…

General Relativity and Quantum Cosmology · Physics 2020-02-13 Martin Bojowald , Suddhasattwa Brahma , Ding Ding , Michele Ronco

In the investigation and resolution of the cosmological constant problem the inclusion of the dynamics of quantum gravity can be a crucial step. In this work we suggest that the quantum constraints in a canonical theory of gravity can…

High Energy Physics - Theory · Physics 2013-04-23 Jan Govaerts , Simone Zonetti

The problem of topology change transitions in quantum gravity is investigated from the Wheeler-de Witt wave function point of view. It is argued that for all theories allowing wormhole effects the wave function of the universe is…

General Relativity and Quantum Cosmology · Physics 2015-06-25 O. Yu. Shvedov

Pure gauge theories for de Sitter, anti de Sitter and orthogonal groups, in four-dimensional Euclidean spacetime, are studied. It is shown that, if the theory is asymptotically free and a dynamical mass is generated, then an effective…

High Energy Physics - Theory · Physics 2012-12-13 R. F. Sobreiro , A. A. Tomaz , V. J. Vasquez Otoya

We consider degrees of freedom for a quantum de Sitter spacetime. The problem is studied from both a Lorentzian and a Euclidean perspective. From a Lorentzian perspective, we compute dynamical properties of the static patch de Sitter…

High Energy Physics - Theory · Physics 2023-01-31 Dionysios Anninos , Damián A. Galante , Beatrix Mühlmann

We investigate the quantum Ricci curvature, which was introduced in earlier work, in full, four-dimensional quantum gravity, formulated nonperturbatively in terms of Causal Dynamical Triangulations (CDT). A key finding of the CDT approach…

High Energy Physics - Theory · Physics 2020-12-02 N. Klitgaard , R. Loll

We argue that the instability of Euclidean Einstein gravity is an indication that the vacuum is non perturbative and contains a condensate of the metric tensor in a manner reminiscent of Yang-Mills theories. As a simple step toward the…

High Energy Physics - Theory · Physics 2009-11-10 Janos Polonyi , Eniko Regos

The cosmological constant problem is usually considered an inevitable feature of any effective theory capturing well-tested gravitational and matter physics, without regard to the details of short-distance gravitational couplings. In this…

High Energy Physics - Theory · Physics 2009-09-15 Raman Sundrum

de Sitter symmetry on quantum level implies that operators describing a given system satisfy commutation relations of the de Sitter algebra. This approach gives a new perspective on fundamental notions of quantum theory. We discuss…

High Energy Physics - Theory · Physics 2012-04-04 Felix M. Lev

We are studying the dynamics of a one-dimensional field in a non-commutative Euclidean space. The non-commutative space we consider is the one that emerges in the context of three dimensional Euclidean quantum gravity: it is a deformation…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Karim Noui

We show how it is possible to formulate Euclidean two-dimensional quantum gravity as the scaling limit of an ordinary statistical system by means of dynamical triangulations, which can be viewed as a discretization in the space of…

High Energy Physics - Theory · Physics 2009-10-28 J. Ambjorn , J. Jurkiewicz , Y. Watabiki

We employ Riesz's fractional derivative into the Wheeler--DeWitt equation for a closed de Sitter geometry and obtain the no-boundary and tunneling wavefunctions. From the corresponding probability distributions, the event horizon of the…

General Relativity and Quantum Cosmology · Physics 2022-07-05 S. Jalalzadeh , E. W. Oliveira Costa , P. V. Moniz

In this note we study nonequilibrium fluctuations in gravitational algebras within de Sitter space. An essential aspect of this study is quantum measurement theory, which allows us to access the dynamical fluctuations of observables via a…

High Energy Physics - Theory · Physics 2024-11-18 Michele Cirafici

Quantum gravity in 2+1 dimensions with a positive cosmological constant can be represented as an SL(2,C) Chern-Simons gauge theory. The symmetric vacuum of this theory is a degenerate configuration for which the gauge fields and spacetime…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Juan M. Maldacena , Andrew Strominger

The evolution of the universe is determined by its quantum state. The wave function of the universe obeys the constraints of general relativity and in particular the Wheeler-DeWitt equation (WDWE). For non-zero \Lambda, we show that…

High Energy Physics - Theory · Physics 2015-06-05 James B. Hartle , S. W. Hawking , Thomas Hertog

We apply the recently proposed transfer matrix formalism to 2-dimensional quantum gravity coupled to $(2, 2k-1)$ minimal models. We find that the propagation of a parent universe in geodesic (Euclidean) time is accompanied by continual…

High Energy Physics - Theory · Physics 2009-10-22 Steven S. Gubser , Igor R. Klebanov

A finite and unitary nonlocal formulation of quantum gravity is applied to the cosmological constant problem. The entire functions in momentum space at the graviton-standard model particle loop vertices generate an exponential suppression…

General Relativity and Quantum Cosmology · Physics 2016-02-08 J. W. Moffat

Coherent solutions of the classical Liouville equation for the rigid rotator are presented as positive phase-space distributions associated with the Lagrangian submanifolds of Hamilton-Jacobi theory. These solutions become Wigner-type…

Quantum Physics · Physics 2025-11-13 M. Grigorescu

Perturbative gravity about a de Sitter background motivates a global picture of quantum dynamics in `eternal de Sitter space,' the theory of states which are asymptotically de Sitter to both future and past. Eternal de Sitter physics is…

High Energy Physics - Theory · Physics 2008-11-26 Steven B. Giddings , Donald Marolf

We consider a discrete model of euclidean quantum gravity in four dimensions based on a summation over random simplicial manifolds. The action used is the Einstein-Hilbert action plus an $R^2$-term. The phase diagram as a function of the…

High Energy Physics - Theory · Physics 2009-10-22 J. Ambjorn , J. Jurkiewicz , C. F. Kristjansen