The anisotropic XY-model in a transverse field (s = 1/2) on the onedimensional alternating superlattice (closed chain) is considered. The solution of the model is obtained by introducing a generalized Jordan-Wigner transformation which maps the system onto a non-interacting fermion gas. The exact excitation spectrum is determined by reducing the problem to a diagonalization of a block matrix, a...

2014 Intercepts generated through granular packings by random 1D (line) sections may provide information on the geometry of the medium in a simpler way than metallographic cuts. The method, already tested on hard monosize spherical grain stackings, is used here to determine the average number of necks per grain of a classical model for slightly sintered materials. J. Phys. France 51 (1990) 1897...

A renormalization-group and bosonization approach for a multi-band Hubbard Hamiltonian in one dimension is described. Based on the limit of many bands, it is argued that this Hamiltonian with bare repulsive electron-electron interactions is scaled under specific conditions to a model in which superconducting fluctuations dominate. PACS numbers: 74.10.+v, 71.27.+a Typeset using REVTEX

Laboratory ultrasonics provides an ideal opportunity for studying wave propagation in random media. Models are relatively easy to construct and both the phase and amplitude of the wave field can be measured, so we can separate the coherent from the incoherent intensity. Here we show detailed measurements of wave propagation in a 1D strongly scattering medium that fit the theory of radiative tra...

We study the ground state properties of the one-dimensional t-J model using the Density Matrix Renormalization Group (DMRG), obtaining its phase diagram. By measuring the energy and correlations functions we have identified four different phases: metal, spin-gap with singlet superconductivity, superconductivity without spin-gap, and phase separation. We found at low densities that the phase sep...

We present numerical investigations of the short-time dynamics at criticality in the 1D Potts model with power-law decaying interactions of the form 1/r . The scaling properties of the magnetization, autocorrelation function and time correlations of the magnetization are studied. The dynamical critical exponents θ′ and z are derived in the cases q = 2 and q = 3 for several values of the paramet...

We study the dependence of complex-temperature phase diagrams on details of the Hamiltonian, focusing on the effect of non-nearest-neighbor spin-spin couplings. For this purpose, we consider a simple exactly solvable model, the 1D Ising model with nearest-neighbor (NN) and next-to-nearest-neighbor (NNN) couplings. We work out the exact phase diagrams for various values of Jnnn/Jnn and compare t...

Motivated by a recent application of the Kolmogorov-Johnson-Mehl-Avrami (KJMA) model to the study of DNA replication, we consider the one-dimensional (1D) version of this model. We generalize previous work to the case where the nucleation rate is an arbitrary function I (t) and obtain analytical results for the time-dependent distributions of various quantities (such as the island distribution)...