Results 31 to 40 of about 47,027 (304)
, 2016 I discuss how to impose causality on spin-foam models, separating forward and backward propagation, turning a given triangulation to a 'causal set', and giving asymptotically the exponential of the Regge action, not a cosine. I show the equivalence of the prescriptions which have been proposed to achieve this.
Giorgio Immirzi
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Invited review: The new spin foam models and quantum gravity [PDF]
Papers in Physics, 2012 In this article, we give a systematic definition of the recently introduced spin foam models for four-dimensional quantum gravity, reviewing the main results on their semiclassical limit on fixed discretizations.
Alejandro Perez
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Coarse Graining Spin Foam Quantum Gravity—A Review
Frontiers in Physics, 2020 In quantum gravity, we envision renormalization as the key tool for bridging the gap between microscopic models and observable scales. For spin foam quantum gravity, which is defined on a discretization akin to lattice gauge theories, the goal is to ...
Sebastian Steinhaus
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Quantum gravity at the fifth root of unity
Physics Open, 2022 We consider quantum transition amplitudes, partition functions and observables for 3D spin foam models within SU(2)quantum group deformation symmetry, where the deformation parameter is postulated to be a complex fifth root of unity.
Marcelo Amaral +2 more
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Diffeomorphisms and spin foam models [PDF]
Nuclear Physics B, 2003 19 ...
David Louapre +2 more
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Spin foam quantization and anomalies [PDF]
General Relativity and Gravitation, 2009 32 ...
Bojowald, Martin, Perez, Alejandro
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Towards a phase diagram for spin foams [PDF]
Classical and Quantum Gravity, 2017 37+11 ...
Clement Delcamp, Bianca Dittrich
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Spin Foam Models from the Tetrad Integration [PDF]
, 2005 We describe a class of spin foam models of four-dimensional quantum gravity which is based on the integration of the tetrad one-forms in the path integral for the Palatini action of General Relativity.
Mikovic, A.
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The Hessian in Spin Foam Models [PDF]
Annales Henri Poincaré, 2019 Abstract We fill one of the remaining gaps in the asymptotic analysis of the vertex amplitudes of the Engle–Pereira–Rovelli–Livine (EPRL) spin foam models: We show that the Hessian is nondegenerate for the stationary points that corresponds to geometric nondegenerate 4 simplices. Our analysis covers the case when all faces are spacelike.
Wojciech Kamiński, Hanno Sahlmann
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Classical and Quantum Gravity, 1998 While the use of spin networks has greatly improved our understanding of the kinematical aspects of quantum gravity, the dynamical aspects remain obscure. To address this problem, we define the concept of a `spin foam' going from one spin network to another. Just as a spin network is a graph with edges labeled by representations and vertices labeled by
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