Effective temperatures out of equilibriumWe describe some interesting effects observed during the evolution of nonequilibrium systems, using domain growth and glassy systems as examples. We breafly discuss the analytical tools that have…Leticia F. Cugliandolo·Mar 16, 1999SaveLearn
First-Order Lagrangians and Path-Integral Quantization in the t-J ModelBy using the supersymmetric version of the Faddeev-Jackiw symplectic formalism, a family of first-order constrained Lagrangians for the t-J model is found. In this approach the Hubbard $…A. Foussats, A. Greco, O. S. Zandron·Mar 16, 1999SaveLearn
Novel metallic behavior in two dimensionsExperiments on a sufficiently disordered two-dimensional (2D) electron system in silicon reveal a new and unexpected kind of metallic behavior, where the conductivity decreases as…X. G. Feng, Dragana Popovic, S. Washburn et al.·Mar 15, 1999SaveLearn
From the Liouville Equation to the Generalized Boltzmann Equation for Magnetotransport in the 2D Lorentz ModelWe consider a system of non-interacting charged particles moving in two dimensions among fixed hard scatterers, and acted upon by a perpendicular magnetic field. Recollisions between charged…A. V. Bobylev, Alex Hansen, J. Piasecki et al.·Mar 15, 1999SaveLearn
Minority game with arbitrary cutoffsWe study a model of a competing population of N adaptive agents, with similar capabilities, repeatedly deciding whether to attend a bar with an arbitrary cutoff L. Decisions are based upon past…N. F. Johnson, P. M. Hui, Dafang Zheng et al.·Mar 15, 1999SaveLearn
A Closed Class of Hydrodynamical Solutions for the Collective Excitations of a Bose-Einstein CondensateA trajectory approach is taken to the hydrodynamical treatment of collective excitations of a Bose-Einstein condensate in a harmonic trap. The excitations induced by linear deformations of the trap…Pippa Storey, Maxim Olshanii·Mar 12, 1999SaveLearn
Phase Diagrams from Topological Transitions: The Hubbard Chain with Correlated HoppingThe quantum phase diagram of the Hubbard chain with correlated hopping is accurately determined through jumps in π in the charge and spin Berry phases. The nature of each thermodynamic phase, and…A. A. Aligia, K. Hallberg, C. D. Batista et al.·Mar 12, 1999SaveLearn
Pseudogap Formation in an Electronic System with d-wave Attraction at Low-densityOn the basis of an electronic model with separable attractive interaction, the precursors at high temperature and strong coupling of the d-wave superconducting state are investigated in the…Takashi Hotta, Matthias Mayr, Elbio Dagotto·Mar 12, 1999SaveLearn
On the equivalence between the Barkhausen effect and directed Abelian sandpile modelsThe existence of self-organized criticality in the Barkhausen effect and its analogy with sandpile models is investigated. It is demonstrated that a model recently introduced to describe the dynamics…Alexei Vazquez, Oscar Sotolongo-Costa·Mar 12, 1999SaveLearn
Symmetry Constraints and Variational Principles in Diffusion Quantum Monte Carlo Calculations of Excited-State EnergiesFixed-node diffusion Monte Carlo (DMC) is a stochastic algorithm for finding the lowest energy many-fermion wave function with the same nodal surface as a chosen trial function. It has proved itself…W. M. C. Foulkes, Randolph Q. Hood, R. J. Needs·Mar 12, 1999SaveLearn
Open t-J chain with boundary impuritiesWe study integrable boundary conditions for the supersymmetric t-J model of correlated electrons which arise when combining static scattering potentials with dynamical impurities carrying an internal…Gerald Bedürftig, Holger Frahm·Mar 12, 1999SaveLearn
Exact Ground States and Excited States of Net Spin ModelsWe study a set of exactly soluble net spin models. There exist two kinds of ground state, one is a complete dimerized state, and the other one is the ground state of corresponding spin-1 model. For…H. Q. Lin, J. L. Shen·Mar 12, 1999SaveLearn
Enhanced winnings in a mixed-ability population playing a minority gameWe study a mixed population of adaptive agents with small and large memories, competing in a minority game. If the agents are sufficiently adaptive, we find that the average winnings per agent can…N. F. Johnson, P. M. Hui, D. Zheng et al.·Mar 10, 1999SaveLearn
Geometric Phase TransitionsA model in statistical mechanics, characterised by the corresponding Gibbs measure, is a subset of the totality of probability distributions on the phase space. The shape of this subset, i.e., the…D. C. Brody, A. Ritz·Mar 10, 1999SaveLearn
Metal-insulator transition in the one-dimensional Holstein model at half fillingWe study the one-dimensional Holstein model with spin-1/2 electrons at half-filling. Ground state properties are calculated for long chains with great accuracy using the density matrix…Eric Jeckelmann, Chunli Zhang, Steven R. White·Mar 9, 1999SaveLearn
The interaction of surface acoustic waves with an array of quantum wiresWe describe the interaction of surface acoustic waves with electrons in an array of quantum wires, patterned out of a two dimensional electron gas. Two specific geometries are considered, in which…Michal Rokni, Y. Levinson·Mar 9, 1999SaveLearn
Thermodynamics of binary mixture glassesWe compute the thermodynamic properties of the glass phase in a binary mixture of soft spheres. Our approach is a generalization to mixtures of the replica strategy, recently proposed by Mezard and…Barbara Coluzzi, Marc Mezard, Giorgio Parisi et al.·Mar 8, 1999SaveLearn
Spontaneous emission of polaritons from a Bose-Einstein condensateWe study the spontaneous emission of a partially excited Bose-Einstein condensate composed of two-level atoms. The formation of polaritons induced by the ground-state part of the condensate leads to…Karl-Peter Marzlin, Weiping Zhang·Mar 8, 1999SaveLearn
Experiments in Dilute Atomic Bose-Einstein CondensationBoth theoretical and experimental activity in BEC has expanded dramatically in the three years since the first observation of BEC in a dilute atomic gas. One is tempted to ask, why? Why is there so…Eric A. Cornell, Jason R. Ensher, Carl E. Wieman·Mar 5, 1999SaveLearn
Two lifetimes and the pseudogap in the orbital magnetoresistance of Zn-substituted La1.85Sr0.15CuO4The effect of zinc doping on the anomalous temperature dependence of the magnetoresistance and the Hall effect in the normal state was studied in a series of La1.85Sr0.15Cu1-yZnyO4 films,…A. Malinowski, A. Krickser, Marta Z. Cieplak et al.·Mar 4, 1999SaveLearn
X-ray phase determination by the principle of minimum chargeWhen the charge density in a crystal or a quasicrystal is reconstructed from its Fourier modes, the global minimum value of the density is sensitively dependent on the relative phases of the modes.…Veit Elser·Mar 3, 1999SaveLearn
Systematic Analytical Approach to Correlation Functions of Resonances in Quantum Chaotic ScatteringWe solve the problem of resonance statistics in systems with broken time-reversal invariance by deriving the joint probability density of all resonances in the framework of a random matrix approach…Yan V. Fyodorov, B. A. Khoruzhenko·Mar 2, 1999SaveLearn
Quantum Group based Modelling for the description of high temperature superconductivity and antiferromagnetismFollowing our recent conjecture to model the phenomenona of antiferromagnetism and superconductivity by quantum symmetry groups, we propose in the present note three toy models, namely, one based on…Sher Alam·Mar 2, 1999SaveLearn
Dynamics of Vortices in Two-Dimensional MagnetsTheories, simulations and experiments on vortex dynamics in quasi-two-dimensional magnetic materials are reviewed. These materials can be modelled by the classical two-dimensional anisotropic…F. G. Mertens, A. R. Bishop·Mar 2, 1999SaveLearn
Floppy MembranesFloppy membranes are tensionless surfaces without extrinsic stiffness, whose fluctuations are governed by fourth-order bending elasticity. This suppresses spiky superstructures and ensures that…M. C. Diamantini, H. Kleinert, C. A. Trugenberger·Mar 1, 1999SaveLearn