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Classical nonlinear theories are highly successful in describing far-from-equilibrium dynamics of magnets, encompassing phenomena such as parametric resonance, ultrafast switching, and even chaos. However, at ultrashort length and time…

Mesoscale and Nanoscale Physics · Physics 2025-12-15 Lukas Körber , Pim Coenders , Johan H. Mentink

In this work, we define quasicrystalline spin networks as a subspace within the standard Hilbert space of loop quantum gravity, effectively constraining the states to coherent states that align with quasicrystal geometry structures. We…

General Relativity and Quantum Cosmology · Physics 2023-06-06 Marcelo Amaral , Richard Clawson , Klee Irwin

We review the basic steps in building the asymptotic analysis of the Euclidean sector of new spin foam models using coherent states, for Immirzi parameter less than one. We focus on conceptual issues and by so doing omit peripheral proofs…

General Relativity and Quantum Cosmology · Physics 2015-05-14 John W. Barrett , Richard J. Dowdall , Winston J. Fairbairn , Henrique Gomes , Frank Hellmann

We study the semiclassical behavior of Lorentzian Engle-Pereira-Rovelli-Livine (EPRL) spinfoam model, by taking into account of the sum over spins in the large spin regime. The large spin parameter \lambda and small Barbero-Immirzi…

General Relativity and Quantum Cosmology · Physics 2013-09-09 Muxin Han

Tuning interactions in the spin singlet and quintet channels of two colliding atoms could change the symmetry of the one-dimensional spin-3/2 fermionic systems of ultracold atoms while preserving the integrability. Here we find a novel…

Quantum Gases · Physics 2015-05-20 Yuzhu Jiang , Xiwen Guan , Junpeng Cao , Hai-Qing Lin

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…

General Relativity and Quantum Cosmology · Physics 2024-02-27 Pietro Dona , Francesco Gozzini , Giorgio Sarno

The amplitude for the 4-simplex in a spin foam model for quantum gravity is defined using a graphical calculus for the unitary representations of the Lorentz group. The asymptotics of this amplitude are studied in the limit when the…

General Relativity and Quantum Cosmology · Physics 2014-11-20 John W. Barrett , Richard J. Dowdall , Winston J. Fairbairn , Frank Hellmann , Roberto Pereira

We present an exact solution for an itinerant hole added into the oxygen orbitals of a CuO$_{3}$-like ferromagnetic chain. Using the Green's function method, the quantum polarons obtained for the Heisenberg SU(2) interaction between…

Strongly Correlated Electrons · Physics 2014-10-31 Krzysztof Bieniasz , Andrzej M. Oleś

The stationary phase technique is used to calculate asymptotic formulae for SO(4) Relativistic Spin Networks. For the tetrahedral spin network this gives the square of the Ponzano-Regge asymptotic formula for the SU(2) 6j symbol. For the…

General Relativity and Quantum Cosmology · Physics 2017-08-23 John W Barrett , Christopher M Steele

We explore the geometry and asymptotics of extended Racah coeffecients. The extension is shown to have a simple relationship to the Racah coefficients for the positive discrete unitary representation series of SU(1,1) which is explicitly…

General Relativity and Quantum Cosmology · Physics 2011-08-17 Stefan Davids

In this work we give an explicit isomorphism between the usual spin network basis and the direct quantization of the reduced phase space of tetrahedra. The main outcome is a formula that describes the space of SU(2) invariant states by an…

General Relativity and Quantum Cosmology · Physics 2010-01-15 Florian Conrady , Laurent Freidel

We present two results on the recently proposed new spin foam models. First, we show how a (slightly modified) restriction on representations in the EPRL model leads to the appearance of the Ashtekar-Barbero connection, thus bringing this…

General Relativity and Quantum Cosmology · Physics 2012-10-12 Sergei Alexandrov

Calculations in Loop Quantum Gravity (LQG) and spin-foams theory rely heavily on group theory of SU(2) and SL(2,C). Even though many monographs exist devoted to this theory, the different tools needed (e.g. representation theory, harmonic…

Mathematical Physics · Physics 2022-11-21 Pierre Martin-Dussaud

We study the problem of semiclassical limit of Loop Quantum Gravity theory defined by the new spin foam models. This is done by analyzing the large-spin asymptotics of the Hartle-Hawking wavefunction. By using the stationary phase method we…

General Relativity and Quantum Cosmology · Physics 2011-08-01 Aleksandar Mikovic , Marko Vojinovic

We show that the path integral for the three-dimensional SU(2) BF theory with a Wilson loop or a spin network function inserted can be understood as the Rovelli-Smolin loop transform of a wavefunction in the Ashtekar connection…

General Relativity and Quantum Cosmology · Physics 2009-01-16 A. Mikovic

Spin-foam models are hoped to provide a dynamics for loop quantum gravity. These start from the Plebanski formulation of gravity, in which gravity is obtained from a topological field theory, BF theory, through constraints, which, however,…

General Relativity and Quantum Cosmology · Physics 2015-06-03 Jonathan Engle

Starting from the defining transformations of complex matrices for the $SO(4,R)$ group, we construct the fundamental representation and the tensor and spinor representations of the group $SO(4,R)$. Given the commutation relations for the…

General Relativity and Quantum Cosmology · Physics 2008-04-29 P. Kramer , M. Lorente

Tensor products of standard model bosons and fermions form a spin-2 self-realization of SU(5), and because every quark can be interpreted as a lepton that has coupled to an appropriate element of this adjoint representation, and inversely,…

General Physics · Physics 2007-05-23 J. Towe

We develop a semi-classical approximation to electron spin resonance in quantum spin systems, based on the rotor or non-linear sigma model. The classical time evolution is studied using molec- ular dynamics while random initial conditions…

Strongly Correlated Electrons · Physics 2011-11-22 Shunsuke C. Furuya , Masaki Oshikawa , Ian Affleck

So far spin foam models are hardly understood beyond a few of their basic building blocks. To make progress on this question, we define analogue spin foam models, so called spin nets, for quantum groups $\text{SU}(2)_k$ and examine their…

General Relativity and Quantum Cosmology · Physics 2014-08-06 Bianca Dittrich , Mercedes Martin-Benito , Sebastian Steinhaus