We study the bipartite entanglement per bond to determine characteristic features of the phase diagram of various quantum spin models in different spatial dimensions. The bipartite entanglement is obtained from a tensor network representation of the ground state wave-function. Three spin-1/2 models (Ising, XY, XXZ, all in a transverse field) are investigated. Infinite imaginary-time evolution (...

The t(11;14)(q13;q32) translocation is considered to be the cytogenetic hallmark of mantle cell lymphoma. This report describes a case of leukaemic mantle cell lymphoma in which conventional cytogenetics on stimulated peripheral blood cells showed a 46,XY, t(1;12)(p21;q23)/46,XY karyotype. Fluorescence in situ hybridisation analysis using a dual colour immunoglobulin heavy chain (IgH)/CCND1 pro...

We study the zero temperature phase diagram of hard-core bosons in two dimensions subjected to three types of background potentials: staggered, uniform, and random. In all three cases there is a quantum phase transition from a superfluid (at small potential) to a normal phase (at large potential), but with different universality classes. As expected, the staggered case belongs to the XY univers...

We explore ensemble inequivalence in long-range interacting systems by studying an XY model of classical spins with ferromagnetic and nematic coupling. We demonstrate the inequivalence by mapping the microcanonical phase diagram onto the canonical one, and also by doing the inverse mapping. We show that the equilibrium phase diagrams within the two ensembles strongly disagree within the regions...

New developments concerning the extension of the Feynman diagram analyzer DIANA are presented. We discuss new graphics facilities, different approaches to automation of momenta distribution and parallel processing facilities. Furthermore applications to t ¯ t production and Bhabha scattering are shortly discussed. The project called DIANA (DIagram ANA-lyzer)[1] for the evaluation of Feynman dia...

We investigate the inversion phenomenon between the XXZ anisotropies of the Hamiltonian and the wave function in quantum spin chains, mainly focusing on the S = 1/2 trimerized XXZ model with the next-nearest-neighbor interactions. We have obtained the ground-state phase diagram by use of the degenerate perturbation theory and the level spectroscopy analysis of the numerical data calculated by t...

The phase diagram of the frustrated 2D classical and 1D quantum XY models is calculated analytically. Four transitions are found: the vortex unbinding transitions triggered by strong fluctuations occur above and below the chiral transition temperature. Vortex interaction is short range on small and logarithmic on large scales. The chiral transition, though belonging to the Ising universality cl...

We investigate a class of one-dimensional, exactly solvable anisotropic XY spin-1/2 models in an alternating transverse magnetic field from an entanglement perspective. We find that a physically motivated Lie-algebraic generalized entanglement measure faithfully portraits the static phase diagram – including secondand fourth-order quantum phase transitions belonging to distinct universality cla...

The one dimensional S = 1 XXZ model with the next-nearest-neighbor interaction α and the anisotropy ∆ is studied by the numerical diagonalization. We study the ground state phase diagram of this model by the level spectroscopy method with the twisted boundary method, the phenomenological renormalization group method, the spin wave theory, the nonlinear σ model and the renormalization group. We ...

In this article, the correlated basis-function (CBF) method is applied for the first time to the quantum spin-half XY model on the linear chain, the square lattice, and the simple cubic lattice. In this treatment of the quantum spin-half XY model a Jastrow ansatz is utilised to approximate the ground-state wave function. Results for the ground-state energy and the sublattice magnetisation are p...