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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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Spin Foam Models with Finite Groups [PDF]
Journal of Gravity, 2013 Spin foam models, loop quantum gravity, and group field theory are discussed as quantum gravity candidate theories and usually involve a continuous Lie group. We advocate here to consider quantum gravity-inspired models with finite groups, firstly as a test bed for the full theory and secondly as a class of new lattice theories possibly featuring an ...
Bahr, Benjamin +2 more
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Renormalization of Group Field Theories for Quantum Gravity: New Computations and Some Suggestions
Frontiers in Physics, 2021 We discuss motivation and goals of renormalization analyses of group field theory models of simplicial 4d quantum gravity, and review briefly the status of this research area.
Marco Finocchiaro +2 more
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Quantum Field Theory of Open Spin Networks and New Spin Foam Models [PDF]
, 2002 We describe how a spin-foam state sum model can be reformulated as a quantum field theory of spin networks, such that the Feynman diagrams of that field theory are the spin-foam amplitudes. In the case of open spin networks, we obtain a new type of state-
A. Miković +3 more
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2-Group Representations for Spin Foams [PDF]
AIP Conference Proceedings, 2009 8 pages; to appear in proceedings of the XXV Max Born Symposium: "The Planck Scale", Wroclaw ...
Aristide Baratin +4 more
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Expansions in spin foam cosmology [PDF]
Physical Review D, 2011 We discuss the expansions used in spin foam cosmology. We point out that already at the one vertex level arbitrarily complicated amplitudes contribute, and discuss the geometric asymptotics of the five simplest ones. We discuss what type of consistency conditions would be required to control the expansion.
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, 2023 Spinfoams provide a framework for the dynamics of loop quantum gravity that is manifestly covariant under the full four-dimensional diffeomorphism symmetry group of general relativity. In this way they complete the ideal of three-dimensional diffeomorphism covariance that consistently motivates loop quantum gravity at every step. Specifically, spinfoam
Engle, Jonathan, Speziale, Simone
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Recurrence relations for spin foam vertices [PDF]
Classical and Quantum Gravity, 2010 We study recurrence relations for various Wigner 3nj-symbols and the non-topological 10j-symbol. For the 6j-symbol and the 15j-symbols which correspond to basic amplitudes of 3d and 4d topological spin foam models, recurrence relations are obtained from the invariance under Pachner moves and can be interpreted as quantizations of the constraints of the
Simone Speziale +3 more
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Multiple Functions of Malpighian Tubules in Insects: A Review
Insects, 2022 The Malpighian Tubules (MTs) are the main excretory organs in most insects. They play a key role in the production of primary urine and osmoregulation, selectively reabsorbing water, ions, and solutes.
Priscilla Farina +2 more
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, 2014 The spin foam framework provides a way to define the dynamics of canonical loop quantum gravity in a spacetime covariant way, by using a path integral over histories of quantum states which can be interpreted as `quantum space-times'. This chapter provides a basic introduction to spin foams aimed principally at beginning graduate students and, where ...
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