In a spirited attack, Dorothée Heisenberg takes issue with the emerging field of quantitatively-oriented European Union studies in general and the formal modelling tradition in the exploration of Council of Minister decisionmaking in particular. Drawing on her important article on the ‘culture of consensus’ (Heisenberg 2005), she argues in Chapter 14 above that rationalist scholarship is incapa...

In the recent article Phys. Lett. B 2016, 759, 424–429, a new class of field theories called Nonlinear Field Space Theory was proposed. In this approach, the standard field theories are considered as linear approximations to some more general theories characterized by nonlinear field phase spaces. The case of spherical geometry is especially interesting due to its relation with the spin physics...

A supersymmetric way of imposing the constraint of no double occupancy in models with strong on-site Coulomb repulsion is presented in this paper. In this formulation the physical operators in the constrainted Hilbert space are invariant under local unitary transformations mixing boson and fermion representations. To illustrate, the formulation is applied to the Heisenberg, t-J , and infinite-U...

We study the relationship among the XXZ Heisenberg model and three models obtained from it by various transformations. In particular, we emphasize the role of a non trivial central element t in the underlying algebra and its relationship with the twisted boundary conditions, S N+1 = t S 1 . Key-words: Quantum Groups; Quantum Spin Chains; Integrable Models.

It is shown that, with an appropriate scaling, the energy of low-lying excitations of the (1, 1,. .. , 1) interface in the d-dimensional quantum Heisenberg model are given by the spectrum of the d − 1-dimensional Lapla-cian on an suitable domain.

Recently a significant progress in matching the anomalous dimensions of certain class of operators in N=4 SYM and rotating strings was made. The correspondence was established mainly by using of Bethe ansatz technique applied to the spin s Heisenberg chain model. In a recent paper Kruczenski (hep-th/0311203) suggested to solve the Heisenberg model by using of sigma model approach. In this paper...

We compute the magnetic susceptibility and specific heat of the spin1 2 Heisenberg model on the kagome lattice with high-temperature expansions and exact diagonalizations. We compare the results with the experimental data on ZnCu3(OH)6Cl2 obtained by Helton et al. [Phys. Rev. Lett. 98, 107204 (2007)]. Down to kBT/J ' 0.2, our calculations reproduce accurately the experimental susceptibility, wi...

In this paper, we study the spin and energy dynamic correlations of the one dimensional spin 1/2 Heisenberg model, using mostly exact diagonalization numerical techniques. In particular, observing that the uniform spin and energy currents decay to finite values at long times, we argue for the absence of spin and energy diffusion in the easy plane anisotropic Heisenberg model.

Competing magnetically ordered structures in polymerized orthorhombic AC 60 are studied. A mean-field theory for the equilibrium phases is developed using an Ising model and a classical Heisenberg model to describe the competition between inter-and intra-chain magnetic order in the solid. In the Ising model, the limiting commensurate one-dimensional and three-dimensional phases are separated by...

It is shown that a certain representation of the Heisenberg type KricheverNovikov algebra gives rise to a state field correspondence that is quite similar to the vertex algebra structure of the usual Heisenberg algebra. Finally a definition of Krichever-Novikov type vertex algebras is proposed and its relation to the ”classical” vertex algebra is discussed.