Results 61 to 70 of about 1,109,861 (332)
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
core +3 more sources
Spin-Foam Models and the Physical Scalar Product [PDF]
, 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
core +2 more sources
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
doaj +1 more source
Searching for classical geometries in spin foam amplitudes: a numerical method [PDF]
Classical and quantum gravity, 2019 We develop a numerical method to investigate the semiclassical limit of spin foam amplitudes with many vertices. We test it using the Ponzano–Regge model, a spin foam model for three-dimensional euclidean gravity, and a transition amplitude with three ...
P. Donà, F. Gozzini, Giorgio Sarno
semanticscholar +1 more source
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
openaire +3 more sources
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
doaj +1 more source
, 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 ...
openaire +2 more sources
Numerical methods for EPRL spin foam transition amplitudes and Lorentzian recoupling theory [PDF]
General Relativity and Gravitation, 2018 The intricated combinatorial structure and the non-compactness of the Lorentz group have always made the computation of $$SL(2,\mathbb {C})$$SL(2,C) EPRL spin foam transition amplitudes a very hard and resource demanding task.
P. Donà, Giorgio Sarno
semanticscholar +1 more source
Spin foam diagrammatics and topological invariance [PDF]
Classical and Quantum Gravity, 2002 20 pages, latex with AMS macros and eps ...
Girelli, Florian +2 more
openaire +3 more sources
An Overview of the Effectiveness of Bicycle Helmet Designs in Impact Testing
Frontiers in Bioengineering and Biotechnology, 2021 Cycling accidents are the leading cause of sports-related head injuries in the US. Conventional bicycle helmets typically consist of polycarbonate shell over Expanded Polystyrene (EPS) foam and are tested with drop tests to evaluate a helmet’s ability to
Javid Abderezaei +5 more
doaj +1 more source