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Operator Spin Foam Models [PDF]
Classical and Quantum Gravity, 2010 The goal of this paper is to introduce a systematic approach to spin foams. We define operator spin foams, that is foams labelled by group representations and operators, as the main tool.
Alesci E Bianchi E Magliaro E Perini C +33 more
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Causal Structure in Spin Foams
UniverseThe metric field of general relativity is almost fully determined by its causal structure. Yet, in spin foam models of quantum gravity, the role played by the causal structure is still largely unexplored.
Eugenio Bianchi, Pierre Martin-Dussaud
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The Construction of Spin Foam Vertex Amplitudes [PDF]
Symmetry, Integrability and Geometry: Methods and Applications, 2013 Spin foam vertex amplitudes are the key ingredient of spin foam models for quantum gravity. These fall into the realm of discretized path integral, and can be seen as generalized lattice gauge theories.
Eugenio Bianchi, Frank Hellmann
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Spin-Foam Models and the Physical Scalar Product [PDF]
Physical Review D, 2008 This paper aims at clarifying the link between Loop Quantum Gravity and Spin-Foam models in four dimensions. Starting from the canonical framework, we construct an operator P acting on the space of cylindrical functions Cyl($\Gamma$), where $\Gamma$ is ...
Alesci, Emanuele +2 more
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The Holst spin foam model via cubulations [PDF]
New Journal of Physics, 2012 Spin foam models are an attempt at a covariant or path integral formulation of canonical loop quantum gravity. The construction of such models usually relies on the Plebanski formulation of general relativity as a constrained BF theory and is based on ...
Aristide Baratin +2 more
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Positivity of spin foam amplitudes [PDF]
Classical and Quantum Gravity, 2002 The amplitude for a spin foam in the Barrett-Crane model of Riemannian quantum gravity is given as a product over its vertices, edges and faces, with one factor of the Riemannian 10j symbols appearing for each vertex, and simpler factors for the edges and faces. We prove that these amplitudes are always nonnegative for closed spin foams. As a corollary,
John C. Baez, J. Daniel Christensen
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Four-Dimensional Spin Foam Perturbation Theory [PDF]
Symmetry, Integrability and Geometry: Methods and Applications, 2011 We define a four-dimensional spin-foam perturbation theory for the BF-theory with a B∧B potential term defined for a compact semi-simple Lie group G on a compact orientable 4-manifold M.
João Faria Martins, Aleksandar Mikovic
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The Feynman propagator for spin foam quantum gravity [PDF]
Physical Review Letters, 2004 We link the notion causality with the orientation of the 2-complex on which spin foam models are based. We show that all current spin foam models are orientation-independent, pointing out the mathematical structure behind this independence.
C. Rovelli +12 more
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Spin Foam Perturbation Theory [PDF]
, 1999 We study perturbation theory for spin foam models on triangulated manifolds. Starting with any model of this sort, we consider an arbitrary perturbation of the vertex amplitudes, and write the evolution operators of the perturbed model as convergent ...
Baez, John C.
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Spin foam diagrammatics and topological invariance [PDF]
Classical and Quantum Gravity, 2002 20 pages, latex with AMS macros and eps ...
Florian Girelli +2 more
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