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We propose a toy model of quantum gravity in two dimensions with Euclidean signature. The model is given by a kind of discretization which is different from the dynamical triangulation. We show that there exists a continuum limit and we can…

High Energy Physics - Theory · Physics 2017-08-28 Marcello Rotondo , Shin'ichi Nojiri

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

We consider two-dimensional quantum gravity coupled to matter fields which are renormalizable, but not conformal invariant. Questions concerning the $\b$ function and the effective action are addressed, and the effective action and the…

High Energy Physics - Theory · Physics 2009-10-22 Jan Ambjorn , Kazuo Ghoroku

A generalised canonical formulation of gravity is devised for foliations of spacetime with codimension $n\ge1$. The new formalism retains n-dimensional covariance and is especially suited to 2+2 decompositions of spacetime. It is also…

General Relativity and Quantum Cosmology · Physics 2009-10-30 James D. E. Grant , Ian G. Moss

A potentially powerful approach to quantum gravity has been developed over the last few years under the name of Causal Dynamical Triangulations. Numerical simulations have given very interesting results in the cases of two, three and four…

General Relativity and Quantum Cosmology · Physics 2007-09-05 Dario Benedetti

Loop quantum cosmology(LQC) is the symmetric model of loop quantum gravity. In this paper, we generalize the structure of loop quantum cosmology to the theories with arbitrary spacetime dimensions. The isotropic and homogenous cosmological…

General Relativity and Quantum Cosmology · Physics 2016-10-13 Xiangdong Zhang

Doubly special relativity has been studied for the last twenty years as a way to go beyond the special relativistic kinematics, trying to capture residual effects of a quantum gravity theory. In particular, in doubly special relativity the…

General Relativity and Quantum Cosmology · Physics 2022-07-19 J. J. Relancio

We descry and discuss a duality in 2-dimensional dilaton gravity.

High Energy Physics - Theory · Physics 2008-11-26 D. Grumiller , R. Jackiw

In this work we investigate the canonical quantization of 2+1 gravity with cosmological constant $\Lambda>0$ in the canonical framework of loop quantum gravity. The unconstrained phase space of gravity in 2+1 dimensions is coordinatized by…

General Relativity and Quantum Cosmology · Physics 2012-08-15 Karim Noui , Alejandro Perez , Daniele Pranzetti

In this thesis we consider the problem of dynamics in canonical loop quantum gravity, primarily in the context of deparametrized models, in which a scalar field is taken as a physical time variable for the dynamics of the gravitational…

General Relativity and Quantum Cosmology · Physics 2021-01-01 Ilkka Mäkinen

We investigate rotation and rotating structures in (2+1)-dimensional Einstein gravity. We show that rotation generally leads to pathological physical situations.

General Relativity and Quantum Cosmology · Physics 2010-04-06 N. J. Cornish , N. E. Frankel

For spacetimes with the topology $\IR\!\times\!T^2$, the action of (2+1)-dimensional gravity with negative cosmological constant $\La$ is written uniquely in terms of the time-independent traces of holonomies around two intersecting…

General Relativity and Quantum Cosmology · Physics 2010-04-28 S. Carlip , J. E. Nelson

The Hamiltonian structure of spacetimes with two commuting Killing vector fields is analyzed for the purpose of addressing the various problems of time that arise in canonical gravity. Two specific models are considered: (i) cylindrically…

General Relativity and Quantum Cosmology · Physics 2009-10-28 Joseph D. Romano , Charles G. Torre

Borrowing techniques from cosmology, I compute the power spectrum of quantum fluctuations in (2+1)-dimensional causal dynamical triangulations, a promising discrete path integral approach to quantum gravity. The results agree with those of…

General Relativity and Quantum Cosmology · Physics 2011-11-03 Michael K. Sachs

Despite their diversity, many of the most prominent candidate theories of quantum gravity share the property to be effectively lower-dimensional at small scales. In particular, dimension two plays a fundamental role in the finiteness of…

High Energy Physics - Theory · Physics 2015-03-17 Gianluca Calcagni

This is a summary of a talk delivered at the workshop ``Quantum gravity in the Southern Cone II''. We present a very brief review of current results on canonical quantization of general relativity using Ashtekar's variables and loop…

General Relativity and Quantum Cosmology · Physics 2011-04-15 Jorge Pullin

There is a number of completely integrable gravity theories in two dimensions. We study the metric-affine approach on a 2-dimensional spacetime and display a new integrable model. Its properties are described and compared with the known…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Yuri N. Obukhov

Canonical quantization of gravity in general relativity is greatly simplified by the artificial decomposition of space and time into a 3+1 formalism. Such a simplification may appear to come at the cost of general covariance. This requires…

General Relativity and Quantum Cosmology · Physics 2025-11-03 Cooper Watson , William Julius , Patrick Brown , Donald Salisbury , Gerald Cleaver

Loop quantum gravity is a physical theory which aims at unifying general relativity and quantum mechanics. It takes general relativity very seriously and modifies it via a quantisation. General relativity describes gravity in terms of…

General Relativity and Quantum Cosmology · Physics 2022-02-02 J. Manuel García-Islas

In two space-time dimensions, there is a theory of Lorentzian quantum gravity which can be defined by a rigorous, non-perturbative path integral and is inequivalent to the well-known theory of (Euclidean) quantum Liouville gravity. It has a…

High Energy Physics - Theory · Physics 2009-10-31 R. Loll , J. Ambjorn , K. N. Anagnostopoulos