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          Institute: MPI für Gravitationsphysik     Collection: Quantum Gravity and Unified Theories     Display Documents

ID: 3358.0, MPI für Gravitationsphysik / Quantum Gravity and Unified Theories
Non-perturbative 3d Lorentzian Quantum Gravity
Authors:Ambjörn, Jan; Jurkiewicz, Jerzy; Loll, Renate
Date of Publication (YYYY-MM-DD):2001
Title of Journal:Physical Review D
Sequence Number of Article:044011
Review Status:Peer-review
Audience:Not Specified
Abstract / Description:We have recently introduced a discrete model of Lorentzian quantum gravity, given as a regularized non-perturbative state sum over simplicial Lorentzian space-times, each possessing a unique Wick rotation to Euclidean signature. We investigate here the phase structure of the Wick-rotated path integral in three dimensions with the aid of computer simulations. After fine-tuning the cosmological constant to its critical value, we find a whole range of the gravitational coupling constant $k_0$ for which the functional integral is dominated by non-degenerate three-dimensional space-times. We therefore have a situation in which a well-defined ground state of extended geometry is generated dynamically from a non-perturbative state sum of fluctuating geometries. Remarkably, its macroscopic scaling properties resemble those of a semi-classical spherical universe. Measurements so far indicate that $k_0$ defines an overall scale in this extended phase, without affecting the physics of the continuum limit. These findings provide further evidence that discrete {it Lorentzian} gravity is a promising candidate for a non-trivial theory of quantum gravity
External Publication Status:published
Document Type:Article
Communicated by:Hermann Nicolai
Affiliations:MPI für Gravitationsphysik/Quantum Gravity and Unified Theories
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