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astro-ph/9206004
Dynamics of the Intermediate-Age Elliptical LMC Cluster NGC 1978
In this paper we investigate the internal dynamics of the LMC cluster NGC 1978 through the use of Photometric (CCD images) and kinematic (stellar radial velocities) data. We apply a variety of dynamical models to this data, including multi-mass King-Michie models and rotating and non-rotating oblate spheroid models. We...
1992-06-23
2009-10-22
[ "astro-ph" ]
Philippe Fischer, Douglas L. Welch, and Mario Mateo
astro-ph/9206003
Gamma Ray Signatures from Ordinary Cosmic Strings
We calculate the flux of ultra high energy photons from individual ordinary (i.e. non-superconducting) cosmic strings and compare the results with the sensitivity of current and proposed TeV and EeV telescopes. Our calculations give only upper limits for the gamma ray flux, since the source of the photons, jets from pa...
1992-06-19
2009-10-22
[ "astro-ph", "hep-ph" ]
Jane H. MacGibbon (NASA/Goddard) and Robert H. Brandenberger (Brown)
astro-ph/9206002
Primordial Nucleosynthesis and the Abundances of Beryllium and Boron
The ability to now make measurements of Be and B as well as put constraints on \lisix\ abundances in metal-poor stars has led to a detailed reexamination of Big Bang Nucleosynthesis in the $A\groughly6$ regime. The nuclear reaction network has been significantly expanded with many new rates added. It is demonstrated th...
1992-06-18
2009-09-15
[ "astro-ph" ]
David Thomas, David N. Schramm, Keith A. Olive, Brian D. Fields
astro-ph/9206001
Electroweak Baryogenesis with Electroweak Strings
If stable electroweak strings are copiously produced during the electroweak phase transition, they may contribute significantly to the presently observed baryon to entropy ratio of the Universe. This analysis establishes the feasibility of implementing an electroweak baryogenesis scenario without a first order phase tr...
1992-06-16
2010-11-01
[ "astro-ph", "hep-ph" ]
Robert H. Brandenberger (Brown) and Anne-Christine Davis (DAMTP, Cambridge)
astro-ph/9205006
Can the Quark-Gluon Plasma in the Early Universe be supercooled?
The quark-hadron phase transition in the early universe can produce inhomogeneities in the distribution of nucleons, which in turn affect the primordial nucleosynthesis. In all the investigations of this problem it has been assumed that the degree of supercooling of the quark-gluon plasma after the phase transition is ...
1992-05-13
2009-10-22
[ "astro-ph", "hep-lat" ]
B. Banerjee and R. V. Gavai
astro-ph/9205005
Chaotic Dark Matter
A very weakly coupled scalar field with mass $m$ and initial vacuum expectation value $V$ will provide enough mass to close the universe provided $V\simeq (3\times 10^8\gev)(100\gev/m)^{1/4}$. We discuss possible models in which such a field could arise.
1992-05-09
2009-10-22
[ "astro-ph" ]
R. Rangarajan and M. Srednicki
astro-ph/9205004
The Spatial Distribution of Nearby Galaxy Clusters in the Northern and Southern Galactic Hemispheres
We compare the spatial distributions of galaxy clusters in the northern and southern galactic hemispheres, and the Abell and ACO clusters distributions. We perform a statistical (correlation and cluster) analysis of a sample of Abell and ACO galaxy clusters in the southern galactic hemisphere. We compare these results ...
1992-05-08
2011-05-23
[ "astro-ph" ]
A. Cappi & S. Maurogordato
astro-ph/9205003
Particle Acceleration in (by) Accretion Discs
I present a model for acceleration of protons by the second-order Fermi process acting on randomly scrambled magnetic flux arches above an accretion disc. The accelerated protons collide with thermal protons in the disc, producing degraded energetic protons, charged and neutral pions, and neutrons. The pions produce ga...
1992-05-04
2009-10-22
[ "astro-ph" ]
J. I. Katz
astro-ph/9205002
Giant Molecular Cloud Formation through the Parker Instability in a Skewed Magnetic Field
The effect of the magnetic skew on the Parker instability is investigated by means of the linear stability analysis for a gravitationally stratified gas layer permeated by a horizontal magnetic field. When the magnetic field is skewed (i.e., the field line direction is a function of the height), the wavelength of the m...
1992-05-02
2009-10-22
[ "astro-ph" ]
T. Hanawa, R. Matsumoto and K. Shibata
astro-ph/9205001
Nonstationary Gravitational Lenses and the Fermat Principle
We apply Perlick's (1990a) rigorous formulation of the Fermat principle in arbitrary spacetimes to prove the correctness of the description of gravitational lensing by gravitational waves, given in the literature using the scalar and vector formalisms. We obtain an expression for the time delay due to such nonstationar...
1992-05-01
2011-07-19
[ "astro-ph" ]
Valerio Faraoni
astro-ph/9204006
Nova Dust Nucleation: Kinetics and Photodissociation
Dust is observed to form in nova ejecta. The grain temperature is determined by the diluted nova radiation field rather than the gas kinetic temperature, making classical nucleation theory inapplicable. We used kinetic equations to calculate the growth of carbon nuclei in these ejecta. For expected values of the parame...
1992-04-30
2009-10-22
[ "astro-ph" ]
D. J. Johnson, M. W. Friedlander, J. I. Katz
astro-ph/9204005
Radiation Transfer in Gamma-Ray Bursts
We have calculated gamma-ray radiative transport in regions of high energy density, such as gamma-ray burst source regions, using a discrete ordinate, discrete energy group method. The calculations include two-photon pair production and annihilation, as well as three-photon pair annihilation. The radiation field itself...
1992-04-30
2009-10-22
[ "astro-ph" ]
B. J. Carrigan and J. I. Katz
astro-ph/9204004
Expanding Photospheres of Type II Supernovae and the Extragalactic Distance Scale
We use the Expanding Photosphere Method to determine distances to 10 type II supernovae. The effects of asymmetries, extinction, and flux dilution are explored. Using empirical evidence and time-independent, spherical models which treat H and He in non-LTE, we show that blackbody corrections caused by flux dilution are...
1992-04-30
2009-10-22
[ "astro-ph" ]
B P Schmidt, R P Kirshner, R G Eastman
astro-ph/9204003
The Ptolemaic Gamma-Ray Burst Universe
The BATSE experiment on GRO has demonstrated the isotropic arrival directions and flat $\log N$ {\it vs.} $\log S$ of cosmic gamma-ray bursts. These data are best explained if the burst sources are distributed throughout an extended spherical Galactic halo, as previously suggested by Jennings. The halo's radius is at l...
1992-04-29
2009-10-22
[ "astro-ph" ]
J. I. Katz
astro-ph/9204002
Gravitational Lensing and the Variability of G
The four observables associated with gravitational lensing of distant quasars by intervening galaxies: image splittings, relative amplifications, time delays, and optical depths, provide separate measures of the strength of the gravitational constant $G$ at cosmological distances. These allow one, in principle, to fact...
1992-04-26
2009-08-18
[ "astro-ph" ]
Lawrence Krauss and Martin White
astro-ph/9204001
Gamma-Ray Bursts as the Death Throes of Massive Binary Stars
It is proposed that gamma-ray bursts are created in the mergers of double neutron star binaries and black hole neutron star binaries at cosmological distances. Bursts with complex profiles and relatively long durations are the result of magnetic flares generated by the Parker instability in a post-merger differentially...
1992-04-13
2009-10-22
[ "astro-ph" ]
Ramesh Narayan, Bohdan Paczy\'nski, and Tsvi Piran
cond-mat/9212036
Dimerization structures on the metallic and semiconducting fullerene tubules
The Kekule patterns are realized in the metallic tubules and chain-like distortions occur in the semiconducting tubules.
1992-12-31
2007-05-23
[ "cond-mat" ]
Kikuo Harigaya (1) and Mitsutaka Fujita (2) ((1)Department of Physics, University of Sheffield, United Kingdom, (2) Institute of Materials Science, University of Tsukuba, Japan)
cond-mat/9212035
On flux phase and N\'eel antiferromagnetism in the {\em t}-{\em J}-model}}
We reanalyse the mathematical formulation of the flux-state problem within the $t$-$J$ model. The analysis of different parametrizations in the functional representation shows that (i) calculations which take into account constraints for the number of on-site-available states are describing quasiparticles in terms of w...
1992-12-29
2007-05-23
[ "cond-mat" ]
I.S. Sandalov, M. Richter
cond-mat/9212034
Hierarchical Wave Functions of Fractional Quantum Hall Effect on the Torus
One kind of the hierarchical wave functions of Fractional Quantum Hall Effect on the torus is constructed. We find that the wave functions closely relate to the wave functions of generalized Abelian Chern-Simons theory.
1992-12-28
2008-11-26
[ "cond-mat", "hep-th" ]
Dingping Li
cond-mat/9212033
Hierarchical Wave Functions and Fractional Statistics in Fractional Quantum Hall Effect on the Torus
One kind of hierarchical wave functions of Fractional Quantum Hall Effect (FQHE) on the torus are constructed. The multi-component nature of anyon wave functions and the degeneracy of FQHE on the torus are very clear reflected in this kind of wave functions. We also calculate the braid statistics of the quasiparticles ...
1992-12-28
2015-06-25
[ "cond-mat", "hep-th" ]
Dingping Li
cond-mat/9212032
Spatial Correlation of Conduction Electrons in Metal with Complicated Geometry Of The Fermi Surface
The "density-density" correlation function of conduction electrons in metal is investigated. It is shown, that the asymptotic behaviour of the CF depends on the shape and the local geometry of the Fermi surface. In particular, the exponent of power law which describes the damping of Friedel oscillations at large r (-4 ...
1992-12-25
2009-10-22
[ "cond-mat" ]
D.I.Golosov and M.I.Kaganov
cond-mat/9212031
Spin Gap and Superconductivity in the One-Dimensional t-J Model with Coulomb Repulsion
The one-dimensional t-J model with density-density repulsive interactions is investigated using exact diagonalization and quantum Monte Carlo methods. A short-range repulsion pushes phase separation to larger values of J/t, and leads to a widened precursor region in which a spin gap and strengthened superconducting cor...
1992-12-23
2007-05-23
[ "cond-mat" ]
M.Troyer, H. Tsunetsugu, T.M. Rice, J. Riera and E. Dagotto
cond-mat/9212030
Gapless Spin-Fluid Ground State in a Random Quantum Heisenberg Magnet
We examine the spin-$S$ quantum Heisenberg magnet with Gaussian-random, infinite-range exchange interactions. The quantum-disordered phase is accessed by generalizing to $SU(M)$ symmetry and studying the large $M$ limit. For large $S$ the ground state is a spin-glass, while quantum fluctuations produce a spin-fluid sta...
1992-12-21
2009-01-23
[ "cond-mat" ]
Subir Sachdev and Jinwu Ye
cond-mat/9212029
Super Lax Pairs and Infinite Symmetries in The $1/r^2$ System
We present an algebraic structure that provides an interesting and novel link between supersymmetry and quantum integrability. This structure underlies two classes of models that are exactly solvable in 1-dimension and belong to the $1/r^2 $ family of interactions. The algebra consists of the commutation between a ``Su...
1992-12-19
2025-07-03
[ "cond-mat" ]
B. Sriram Shastry (AT & T Bell Laboratories, Murray Hill, N.J.) and Bill Sutherland (Department of Physics, University of Utah, Salt Lake City)
cond-mat/9212028
Solution of Some Integrable One-Dimensional Quantum Systems
In this paper, we investigate a family of one-dimensional multi-component quantum many-body systems. The interaction is an exchange interaction based on the familiar family of integrable systems which includes the inverse square potential. We show these systems to be integrable, and exploit this integrability to comple...
1992-12-18
2009-10-22
[ "cond-mat" ]
Bill Sutherland, B. Sriram Shastry (Physics Department, AT&T Bell Labs, Murray Hill, NJ and University of Utah, Salt Lake City, UT)
cond-mat/9212027
A Solvable Spin-Glass of Quantum Rotors
We examine a model of $M$-component quantum rotors coupled by Gaussian-distributed random, infinite-range exchange interactions. A complete solution is obtained at $M=\infty$ in the spin-glass and quantum-disordered phases. The quantum phase transition separating them is found to possess logarithmic violations of scali...
1992-12-18
2009-01-23
[ "cond-mat" ]
Jinwu Ye, Subir Sachdev, and N. Read
cond-mat/9212025
Fractional Quantum Hall States in Narrow Channels
A model system is considered where two dimensional electrons are confined by a harmonic potential in one direction, and are free in the other direction. Ground state in strong magnetic fields is investigated through numerical diagonalization of the Hamiltonian. It is shown that the fractional quantum Hall states are re...
1992-12-17
2009-10-22
[ "cond-mat" ]
Daijiro Yoshioka
cond-mat/9212026
On Oscillations in Cellular Automata
We investigate cellular automata where some global quantity varies periodically or quasiperiodically with time. We find that these systems are highly predictable, and can be rather well described by a set of mean-field variables. We conclude that this is not a collective phenomenon - where different subsystems are supp...
1992-12-17
2009-10-22
[ "cond-mat" ]
Jan Hemmingsson and Hans J. Herrmann
cond-mat/9212024
Multiscaling analysis and width of the active zone of large off-lattice DLA
We measure the multiscaling behavior of large off-lattice diffusion limited aggregates (DLA). In contrast to previous studies we now find a continuous dependence of the multiscaling dimensions $D(x)$ on the relative distance $x=r/R_g$ to the center of the cluster. This result agrees with measurements on smaller cluster...
1992-12-16
2009-10-22
[ "cond-mat" ]
Peter Ossadnik
cond-mat/9212023
Scaling Exponents for Kinetic Roughening in Higher Dimensions
We discuss the results of extensive numerical simulations in order to estimate the scaling exponents associated with kinetic roughening in higher dimensions, up to d=7+1. To this end, we study the restricted solid - on - solid growth model, for which we employ a novel fitting {\it ansatz} for the spatially averaged hei...
1992-12-16
2009-10-22
[ "cond-mat" ]
T. Ala-Nissila, T. Hjelt, J. M. Kosterlitz, and O. Ven\"al\"ainen
cond-mat/9212022
Electronic interactions in fullerene spheres
The electron-phonon and Coulomb interactions inC$_{60}$, and larger fullerene spheres are analyzed. The coupling between electrons and intramolecular vibrations give corrections $\sim 1 - 10$ meV to the electronic energies for C$_{60}$, and scales as $R^{-4}$ in larger molecules. The energies associated with electrosta...
1992-12-15
2009-10-22
[ "cond-mat" ]
F. Guinea, J. Gonzalez and M.A. H. Vozmediano
cond-mat/9212021
Test of Conformal Invariance in One-Dimensional Quantum Liquid with Long-Range Interaction
We numerically study the momentum distribution of one-dimensional Bose and Fermi systems with long-range interaction $g/r^2$ for the ``special'' values $g= -\frac{1}{2}, 0, 4$, singled out by random matrix theory. The critical exponents are shown to be independent of density and in excellent agreement with estimates ob...
1992-12-15
2014-09-02
[ "cond-mat", "hep-th" ]
Rudolf A. R\"omer and Bill Sutherland
cond-mat/9212020
Spin-Wave Theory and Finite-Size Scaling for the Heisenberg Antiferromagnet
Spin-wave perturbation theory for the Heisenberg antiferromagnet at zero temperature is used to compute the finite-lattice corrections to the ground state energy, the staggered magnetization and the energy gap. The dispersion relation, the spin-wave velocity and the bulk ground state energy to order $O(1/S^2)$ are also...
1992-12-14
2009-10-22
[ "cond-mat" ]
Zheng Weihong and C.J. Hamer
cond-mat/9212019
The $1/N$ Expansion and Spin Correlations in Constrained Wavefunctions
We develop a large-N expansion for Gutzwiller projected spin states. We consider valence bonds singlets, constructed by Schwinger bosons or fermions, which are variational ground states for quantum antiferromagnets. This expansion is simpler than the familiar expansions of the quantum Heisenberg model, and thus more in...
1992-12-14
2009-10-22
[ "cond-mat" ]
Maxim Raykin (Physics Department, Boston University, Boston, USA) and Assa Auerbach (Physics Department, Technion, Haifa, Israel and Physics Department, Boston University, Boston, USA)
cond-mat/9212018
Spin Tunneling, Berry phases and Doped Antiferromagnets
Interference effects between Berry phase factors in spin tunneling systems have been discussed in recent Letters by Loss, DiVincenzo and Grinstein and von Delft and Henley. This Comment points out that Berry phases in spin tunneling are important in another interesting case: the two dimensional doped antiferromagnet. I...
1992-12-10
2009-10-22
[ "cond-mat" ]
Assa Auerbach
cond-mat/9212015
Theory of Anisotropic Superexchange in Insulating Cuprates
Spin-orbit corrections to superexchange are calculated using the method of Moriya [T.\ Moriya, {\it Phys.\ Rev.}~{\bf 120} 91, (1960)] for two of the insulating parent compounds of the cuprate superconductors: (1) La$_{2-x}$Nd$_x$CuO$_4$ where the CuO$_6$ octahedra forming each Cu-O layer are tilted in staggered fashio...
1992-12-09
2009-10-22
[ "cond-mat" ]
N.E. Bonesteel
cond-mat/9212014
Dynamical Properties of a Haldane Gap Antiferromagnet
We study the dynamic spin correlation function of a spin one antiferromagnetic chain with easy-plane single-ion anisotropy. We use exact diagonalization by the Lancz\H os method for chains of lengths up to N=16 spins. We show that a single-mode approximation is an excellent description of the dynamical properties. A va...
1992-12-09
2009-10-22
[ "cond-mat", "hep-lat" ]
O. Golinelli, Th. Jolicoeur, R. Lacaze
cond-mat/9212012
Exact Correlation Function at the Lifshitz Points of the Spherical Model
The spin-spin correlation function of the spherical model being precisely at an anisotropic Lifshitz point of arbitrary order is calculated exactly. The results are in agreement with scaling. The scaling function is shown to be universal. The direction-dependent long-range correlations may change from ferromagnetic to ...
1992-12-09
2011-09-26
[ "cond-mat", "hep-lat", "hep-th", "math-ph", "math.MP" ]
Laurent Frachebourg and Malte Henkel
cond-mat/9212013
Bosonic Mean Field Theory of the Spiral Phases of Heisenberg Antiferromagnets on a Chain
We develop a novel bosonic mean field theory to describe the spiral phases of a Heisenberg antiferromagnet on a one-dimensional chain, in terms of three bosons at each site. The ground state is disordered and for large values of the spin $S$, two different and exponentially small energy gaps are found. The spin-spin co...
1992-12-09
2009-10-22
[ "cond-mat" ]
Sumathi Rao and Diptiman Sen
cond-mat/9212017
Flux Pinning and Phase Transitions in Model High-Temperature Superconductors with Columnar Defects
We calculate the degree of flux pinning by defects in model high-temperature superconductors (HTSC's). The HTSC is modeled as a three-dimensional network of resistively-shunted Josephson junctions in an external magnetic field, corresponding to a HTSC in the extreme Type-II limit. Disorder is introduced either by rando...
1992-12-09
2009-10-22
[ "cond-mat" ]
K. H. Lee, D. Stroud, and S. M. Girvin
cond-mat/9212016
Tunneling Conductance Between Parallel Two Dimensional Electron Systems
We derive and evaluate expressions for the low temperature {\it dc} equilibrium tunneling conductance between parallel two-dimensional electron systems. Our theory is based on a linear-response formalism and on impurity-averaged perturbation theory. The disorder broadening of features in the dependence of tunneling con...
1992-12-09
2009-10-22
[ "cond-mat" ]
Lian Zheng and A.H. MacDonald
cond-mat/9212011
Translational Correlations in the Vortex Array at the Surface of a Type-II Superconductor
We discuss the statistical mechanics of magnetic flux lines in a finite-thickness slab of type-II superconductor. The long wavelength properties of a flux-line liquid in a slab geometry are described by a hydrodynamic free energy that incorporates the boundary conditions on the flux lines at the sample's surface as a s...
1992-12-08
2009-10-22
[ "cond-mat" ]
M.C. Marchetti (Syracuse University) and D.R. Nelson (Harvard University)
cond-mat/9212005
Length-scale competition in the damped sine-Gordon chain
It is shown that there are two different regimes for the damped sine-Gordon chain driven by the spatio-temporal periodic force $\Gamma sin(\omega t - k_{n} x)$ with a flat initial condition. For $\Gamma_{c}(n)$ to a translating {\em 2-breather} excitation from a state locked to the driver. For $\omega < k_{n}$, the exc...
1992-12-07
2007-05-23
[ "cond-mat" ]
David Cai (1), A.R. Bishop (1), and Angel Sanchez (1,2) ((1) Theoretical Division and CNLS, Los Alamos National Laboratory, (2) Escuela Politecnica Superior, Universidad Carlos III de Madrid)
cond-mat/9212010
Dynamical Properties of a Single Hole in an Antiferromagnet
A finite size scaling analysis of the spectral function and of the optical conductivity of a single hole moving in an antiferromagnetic background is performed. It is shown that both the low energy quasiparticle peak and the broad higher energy structure are robust with increasing cluster size from $4\times 4$ to $\sqr...
1992-12-07
2009-10-22
[ "cond-mat" ]
Didier Poilblanc, Timothy Ziman, H.J. Schulz and Elbio Dagotto
cond-mat/9212008
Indications of d_{x^2 - y^2} Superconductivity in the Two Dimensional t-J Model
Superconducting correlations in the two dimensional ${\rm t-J}$ model at zero temperature are evaluated using numerical techniques. At the fermionic density $\langle n \rangle \sim 1/2$, strong signals of $\dx2y2$ superconductivity were observed in the ground state. These conclusions are based on a study of static pair...
1992-12-07
2009-10-22
[ "cond-mat" ]
Elbio Dagotto and Jose Riera
cond-mat/9212007
Low Temperature Transport through a Quantum Dot: The Anderson Model out of Equilibrium
NEC technical report 92-079-2-0077-1.
1992-12-07
2009-10-22
[ "cond-mat" ]
Y. Meir, N. S. Wingreen and P. A. Lee
cond-mat/9212006
A determination of the low energy parameters of the 2-d Heisenberg antiferromagnet
We perform numerical simulations of the 2-d antiferromagnetic quantum Heisenberg model using an efficient cluster algorithm. Comparing the finite size and finite temperature effects of various quantities with recent results from chiral perturbation theory we are able to determine the low energy parameters of the system...
1992-12-07
2007-05-23
[ "cond-mat", "hep-lat" ]
U.-J. Wiese and H.-P. Ying, (Bern University)
cond-mat/9212009
Basis Set Reduction Applied to the Two Dimensional t-Jz Model
A simple variation of the Lanczos method is discussed. The new technique is based on a systematic reduction of the size of the Hilbert space of the model under consideration. As an example, the two dimensional ${\rm t-J_z}$ model of strongly correlated electrons is studied. Accurate results for the ground state energy ...
1992-12-07
2009-10-22
[ "cond-mat" ]
Jose Riera and Elbio Dagotto
cond-mat/9212004
Fractal Properties of the Distribution of Earthquake Hypocenters
We investigate a recent suggestion that the spatial distribution of earthquake hypocenters makes a fractal set with a structure and fractal dimensionality close to those of the backbone of critical percolation clusters, by analyzing four different sets of data for the hypocenter distributions and calculating the dynami...
1992-12-04
2009-10-22
[ "cond-mat" ]
Hisao Nakanishi, Muhammad Sahimi, Michelle C. Robertson, Charles C. Sammis and Mark D. Rintoul
cond-mat/9212003
Recurrent Clogging and Density Waves in Granular Material Flowing through a Narrow Pipe
We report on density waves in granular material, investigated both experimentally and numerically. When granular material falls through a long narrow pipe one observes recurrent clogging. The kinetic energy of the falling particles increases up to a characteristic threshold corresponding to the onset of recurrent clogg...
1992-12-03
2007-05-23
[ "cond-mat", "hep-lat" ]
Thorsten Poeschel
cond-mat/9212002
Weak-Localization and Integrability in Ballistic Cavities
We demonstrate the existence of an interference contribution to the average magnetoconductance, G(B), of ballistic cavities and use it to test the semiclassical theory of quantum billiards. G(B) is qualitatively different for chaotic and regular cavities, an effect explained semiclassically by the differing classical d...
1992-12-02
2009-01-23
[ "cond-mat" ]
H. U. Baranger, R. A. Jalabert, and A. D. Stone
cond-mat/9212001
The Mass Gap of the Nonlinear Sigma Model through the Finite Temperature Effective Action
The $O(3)$ nonlinear $\sigma$ model is studied in the disordered phase, using the techniques of the effective action and finite temperature field theory. The nonlinear constraint is implemented through a Lagrange multiplier. The finite temperature effective potential for this multiplier is calculated at one loop. The e...
1992-12-01
2009-10-22
[ "cond-mat" ]
D. Senechal
cond-mat/9211021
Magnetic Oscillations of a Fractional Hall Dot
We show that a quantum dot in the fractional Hall regime exhibits mesoscopic magnetic oscillations with a period which is a multiple of the period for free electrons. Our calculations are performed for parabolic quantum dots with hard-core electron-electron interactions and are exact in the strong field limit for $k_B ...
1992-11-30
2009-10-22
[ "cond-mat" ]
A.H.MacDonald and M.D. Johnson
cond-mat/9211020
Diffusion and spectral dimension on Eden tree
We calculate the eigenspectrum of random walks on the Eden tree in two and three dimensions. From this, we calculate the spectral dimension $d_s$ and the walk dimension $d_w$ and test the scaling relation $d_s = 2d_f/d_w$ ($=2d/d_w$ for an Eden tree). Finite-size induced crossovers are observed, whereby the system cros...
1992-11-27
2009-10-22
[ "cond-mat" ]
Hisao Nakanishi and Hans J. Herrmann
cond-mat/9211019
Quantum Mechanics and Superconductivity in a Magnetic Field
The influence of a magnetic field on superconductivity is usually described either phenomenologically, using Ginzburg-Landau theory, or semiclassically using Gor'kov theory. In this article we discuss the influence of magnetic fields on the mean-field theory of the superconducting instability from a completely quantum ...
1992-11-25
2015-06-25
[ "cond-mat" ]
A. H. MacDonald, Hiroshi Akera and M.R. Norman
cond-mat/9211018
I-V Characteristics of High Temperature Superconductors with Columnar Defects
The vortex glass transition in the presence of columnar defects is studied by Monte Carlo simulations of a vortex loop model, suggested by the analogy to the $T=0$ superconductor-insulator transition for dirty bosons in (2+1)D. From finite-size scaling analysis of the $I$-$V$ characteristic we find two dynamical expone...
1992-11-24
2009-10-22
[ "cond-mat" ]
M. Wallin and S. M. Girvin
cond-mat/9211017
Possible Quantum Spin Liquid States on the Triangular and Kagome Lattices
The frustrated spin-one-half Heisenberg model on triangualr and Kagome Lattices is mapped onto a single specis of fermion carrying statistical flux. The corresponding Chern-Simons gauge theory is analyzed at the Gaussian level and found to be massive. This provides a new motivation for the spin-liquid Kalmeyer-Laughlin...
1992-11-24
2016-08-31
[ "cond-mat" ]
Kun Yang, K. L. Warman, and S. M. Girvin
cond-mat/9211016
Angle of Repose and Angle of Marginal Stability: Molecular Dyanmics of Granular Particles
We present an implementation of realistic static friction in molecular dynamics (MD) simulations of granular particles. In our model, to break contacts between two particles, one has to apply a finite amount of force, determined by the Coulomb criterion. Using a two dimensional model, we show that piles generated by av...
1992-11-23
2009-10-22
[ "cond-mat" ]
Jysoo Lee and Hans J. Herrmann
cond-mat/9211015
Cellular automaton for the fracture of disordered media
We study numerically the growth of a crack in an elastic medium under the influence of a travelling shockwave. We describe the implementation of a fast algorithm which is perfectly suited for a data parallel computer. Using large scale simulations on the Connection Machine we generate cracks with more than 10000 sites ...
1992-11-21
2015-06-25
[ "cond-mat" ]
Peter Ossadnik
cond-mat/9211014
Spin-Peierls ground states and frustration in a multi-band Peierls-Hubbard model
We discuss the consequences of including both electron-phonon and electron-electron couplings in multi-band models, focusing on numerical studies of a one-dimensional two-band model in the intermediate regime for both coupling strengths. Spin-Peierls as well as long-period, frustrated ground states are identified, remi...
1992-11-21
2009-10-22
[ "cond-mat" ]
H. Roeder, A.R. Bishop, and J. Tinka Gammel
cond-mat/9211012
Second-Order Dynamics in the Collective Evolution of Coupled Maps and Automata
We review recent numerical studies and the phenomenology of spatially synchronized collective states in many-body dynamical systems. These states exhibit thermodynamic noise superimposed on the collective, quasiperiodic order parameter evolution with typically one basic irrational frequency. We concentrate on the descr...
1992-11-20
2014-10-13
[ "cond-mat", "hep-lat" ]
P.-M. Binder, V. Privman
cond-mat/9211013
Granular Material Flowing Down an Inclined Chute: A Molecular Dynamics Simulation
Two-dimensional Molecular Dynamics simulations are used to model the free surface flow of spheres falling down an inclined chute. The interaction between the particles in our model is assumed to be subjected to the Hertzian contact force and normal as well as shear friction. The stream of particles shows a characterist...
1992-11-20
2009-10-22
[ "cond-mat", "hep-lat" ]
Thorsten Poeschel
cond-mat/9211011
On the Thermodynamics of Granular Media
A thermodynamic formulation for moving granular material is proposed. The fluctuations due to the constant flux and dissipation of energy are controlled in a `granular' ensemble by a pressure $\wp$ (`compression') which is conjugate to a contact volume (`contactopy'). The corresponding response function (`dissipativity...
1992-11-18
2009-10-22
[ "cond-mat" ]
H.J. Herrmann
cond-mat/9211010
The half-filled Hubbard model in the pair approximation of the Cluster Variation Method
The half filled Hubbard model is studied in the pair approximation of the Cluster Variation Method. The use of the $SO(4)$ symmetry of the model makes possible to give a complete analytical characterization of the ground state, by means of explicit expressions for the double occupancy and the nearest neighbor correlati...
1992-11-18
2009-10-22
[ "cond-mat" ]
Alessandro Pelizzola
cond-mat/9211009
The fermion sign problem: A new decoupling transformation, and a new simulation algorithm
We discuss the Fermion sign problem and, by examining a very general Hubbard-Stratonovich (HS) transformation, argue that the sign problem cannot be solved with such methods. We propose a different kind of transformation which, while not solving the sign problem, shows more detailed information about the system. With o...
1992-11-17
2011-08-11
[ "cond-mat", "hep-lat" ]
Ghassan George Batrouni and Philippe de Forcrand
cond-mat/9211007
Singularity spectrum of self-organized criticality
I introduce a simple continuous probability theory based on the Ginzburg-Landau equation that provides for the first time a common analytical basis to relate and describe the main features of two seemingly different phenomena of condensed-matter physics, namely self-organized criticality and multifractality. Numerical ...
1992-11-16
2008-12-24
[ "cond-mat" ]
E. Canessa (ICTP-Trieste, Italy)
cond-mat/9211006
Cluster Algorithm for Vertex Models
We present a new type of cluster algorithm that strongly reduces critical slowing down in simulations of vertex models. Since the clusters are closed paths of bonds, we call it the {\em loop algorithm}. The basic steps in constructing a cluster are the break-up and the freezing of vertices. We concentrate on the case o...
1992-11-16
2009-01-23
[ "cond-mat", "hep-lat" ]
H.G. Evertz, G. Lana and M. Marcu
cond-mat/9211008
Rigid Chiral Membranes
Statistical ensembles of flexible two-dimensional fluid membranes arise naturally in the description of many physical systems. Typically one encounters such systems in a regime of low tension but high stiffness against bending, which is just the opposite of the regime described by the Polyakov string. We study a class ...
1992-11-16
2016-08-31
[ "cond-mat", "hep-th" ]
Philip Nelson and Thomas Powers
cond-mat/9211005
Spin-Wave Theory of the Spiral Phase of the t-J Model
A graded H.P,realization of the SU(2|1) algebra is proposed.A spin-wave theory with a condition that the sublattice magnetization is zero is discussed.The long-range spiral phase is investigated.The spin-spin correlator is calculated.
1992-11-10
2009-10-22
[ "cond-mat" ]
N.I.Karchev and T.S.Hristov
cond-mat/9211003
Infinite-Scale Percolation in a New Type of Branching Diffusion Processes
We give an account of matter and (basically) a solution of a new class of problems synthesizing percolation theory and branching diffusion processes. They led us to realizing a novel type of stochastic processes, namely branching processes with diffusion on the space of parameters distinguishing the branching `particle...
1992-11-04
2011-12-08
[ "cond-mat", "hep-lat" ]
A.Mezhlumian and S.A.Molchanov
cond-mat/9211004
Level repulsion in integrable and almost-integrable quantum spin models
The repartition of the separation between energy levels of various isotropic S=1/2 antiferromagnetic chains is studied numerically with the aim of investigating the transition from integrable to non-integrable systems. We begin by displaying the level separation distribution of the integrable Bethe chain. Then two non-...
1992-11-04
2009-10-22
[ "cond-mat" ]
Theodore C. Hsu and J.C. Angles d'Auriac
cond-mat/9211001
Exact Solution of an Electronic Model of Superconductivity in 1+1 Dimensions
We study a superconducting integrable model of strongly correlated electrons in 1+1 dimensions. We construct all six Bethe Ans\"atze for the model and give explicit expressions for lowest conservation laws. We also prove a lowest weight theorem for the Bethe-Ansatz states.
1992-11-03
2015-06-25
[ "cond-mat" ]
Fabian H.L. Essler, Vladimir E. Korepin, Kareljan Schoutens
cond-mat/9211002
Spin tunneling in the Kagom\'e antiferromagnet
The collective tunneling of a small cluster of spins between two degenerate ground state configurations of the Kagom\'{e}-lattice quantum Heisenberg antiferromagnet is \mbox{studied}. The cluster consists of the six spins on a hexagon of the lattice. The resulting tunnel splitting energy $\Delta$ is calculated in detai...
1992-11-03
2009-10-22
[ "cond-mat" ]
Jan von Delft and Christopher L. Henley (Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY)
cond-mat/9210028
The Third Virial Coefficient of Free Anyons
We use a path integral representation for the partition function of non-interacting anyons confined in a harmonic oscillator potential in order to prove that the third virial coefficient of free anyons is finite, and to calculate it numerically. Our results together with previously known results are consistent with a r...
1992-10-30
2009-10-22
[ "cond-mat", "hep-th" ]
Jan Myrheim and K{\aa}re Olaussen
cond-mat/9210027
Absence of Definite Scaling Laws in Raman Scattering from Fractals
The frequency dependence of the Raman coupling coefficient $C(\omega)$ is calculated numerically for square and cubic percolation clusters. No general scaling law in terms of the macroscopic parameters such as the fractal dimension $D$ or the spectral dimension $\overline d$ is found. $C(\omega)$ is sensitive to the mi...
1992-10-30
2007-05-23
[ "cond-mat" ]
P.Benassi, O.Pilla, G.Viliani, G.Ruocco, G.Signorelli, V.Mazzacurati and M.Montagna
cond-mat/9210026
Narrow band noise as a model of time-dependent accelerations: study of the stability of a fluid surface in a microgravity environment
We introduce a stochastic model to analyze in quantitative detail the effect of the high frequency components of the residual accelerations onboard spacecraft (often called g-jitter) on fluid motion. The residual acceleration field is modeled as a narrow band noise characterized by three independent parameters: its int...
1992-10-28
2007-05-23
[ "cond-mat" ]
Jaume Casademunt, Wenbin Zhang, Jorge Vinals, R.F. Sekerka
cond-mat/9210025
Collective Effects in Random Sequential Adsorption of Diffusing Hard Squares
We study by Monte Carlo computer simulations random sequential adsorption (RSA) with diffusional relaxation, of lattice hard squares in two dimensions. While for RSA without diffusion the coverage approaches its maximum jamming value (large-time fractional coverage) exponentially, added diffusion allows the deposition ...
1992-10-24
2014-10-13
[ "cond-mat", "hep-lat" ]
J.-S. Wang, P. Nielaba, V. Privman
cond-mat/9210021
Static Response Function for Longitudinal and Transverse Excitations in Superfluid Helium
The sum rule formalism is used to evaluate rigorous bounds for the density and current static response functions in superfluid helium at zero temperature. Both lower and upper bounds are considered. The bounds are expressed in terms of ground state properties (density and current correlation funtions) and of the intera...
1992-10-23
2009-10-22
[ "cond-mat" ]
F.Dalfovo and S.Stringari
cond-mat/9210024
The Supercooling of a Nematic Liquid Crystal
We investigate the supercooling of a nematic liquid crystal using fluctuating non-linear hydrodynamic equations. The Martin-Siggia-Rose formalism is used to calculate renormalized transport coefficients to one-loop order. Similar theories for isotropic liquids have shown substantial increases of the viscosities as the ...
1992-10-23
2009-10-22
[ "cond-mat" ]
P.De, Robert Pelcovits, E. Vogel, J. Vogel
cond-mat/9210023
Uncertainty Principle and Off-Diagonal Long Range Order in the Fractional Quantum Hall Effect
A natural generalization of the Heisenberg uncertainty principle inequality holding for non hermitian operators is presented and applied to the fractional quantum Hall effect (FQHE). This inequality was used in a previous paper to prove the absence of long range order in the ground state of several 1D systems with cont...
1992-10-23
2009-10-22
[ "cond-mat" ]
L.Pitaevskii and S.Stringari
cond-mat/9210022
Correlaction Effects on the Band Gap of Conducting Polymers
By applying the projection technique to the computation of excitation energies, we study the correlation effects on the band gap of conducting polymers. In the presence of an additional electron or hole, the correlation induces a polarization cloud around the addi- tional particle, which forms a polaron. For the excita...
1992-10-23
2009-10-22
[ "cond-mat" ]
C.Q.Wu (Max-Planck-Institue f\"ur Festk\"orperforschung, Stuttgart, Germany)
cond-mat/9210020
Magnetic field effects on non-periodic superlattice structures
A simple numerical method to study the effect of an applied magnetic field on the energy spectrum of non-periodic superlattice structures is presented. The magnetic field could be either parallel or perpendicular to the growth direction. Our method is based on the transfer matrix technique and on the effective mass app...
1992-10-22
2009-10-22
[ "cond-mat" ]
H. Cruz, F. Piazza, and L. Pavesi
cond-mat/9210019
Response functions and Spectrum of Collective Excitations of Fractional Quantum Hall Effect Systems
We calculate the electromagnetic response functions of a Fractional Quantum Hall system within the framework of the fermion Chern-Simons theory for the Fractional Hall Effect (FQHE) which we developed before. Our results are valid in a semiclassical expansion around the average field approximation (AFA). We reexamine t...
1992-10-21
2009-10-22
[ "cond-mat" ]
Ana Lopez and Eduardo Fradkin
cond-mat/9210018
Hysteresis and hierarchies: dynamics of disorder-driven first-order phase transformations
We use the zero-temperature random-field Ising model to study hysteretic behavior at first-order phase transitions. Sweeping the external field through zero, the model exhibits hysteresis, the return-point memory effect, and avalanche fluctuations. There is a critical value of disorder at which a jump in the magnetizat...
1992-10-20
2009-01-23
[ "cond-mat" ]
James P. Sethna, Karin Dahmen, Sivan Kartha, James A. Krumhansl, Bruce W. Roberts, and Joel D. Shore
cond-mat/9210017
Biharmonic pattern selection
A new model to describe fractal growth is discussed which includes effects due to long-range coupling between displacements $u$. The model is based on the biharmonic equation $\nabla^{4}u =0$ in two-dimensional isotropic defect-free media as follows from the Kuramoto-Sivashinsky equation for pattern formation -or, alte...
1992-10-20
2009-10-22
[ "cond-mat" ]
Wei Wang and E. Canessa (Condensed Matter Group, ICTP, Trieste, Italy)
cond-mat/9210016
Spin-Charge separation in a model of two coupled chains
A model of interacting electrons living on two chains coupled by a transverse hopping $t_\perp$, is solved exactly by bosonization technique. It is shown that $t_\perp$ does modify the shape of the Fermi surface also in presence of interaction, although charge and spin excitations keep different velocities $u_\rho$, $u...
1992-10-19
2009-10-22
[ "cond-mat" ]
M. Fabrizio and A. Parola
cond-mat/9210015
Many Body Theory of Charge Transfer in Hyperthermal Atomic Scattering
We use the Newns-Anderson Hamiltonian to describe many-body electronic processes that occur when hyperthermal alkali atoms scatter off metallic surfaces. Following Brako and Newns, we expand the electronic many-body wavefunction in the number of particle-hole pairs (we keep terms up to and including a single particle-h...
1992-10-17
2009-10-22
[ "cond-mat" ]
J. B. Marston, D. R. Andersson, E. R. Behringer, B. H. Cooper, C. A. DiRubio, G. A. Kimmel, and C. Richardson
cond-mat/9210012
Ordering and finite-size effects in the dynamics of one-dimensional transient patterns
We introduce and analyze a general one-dimensional model for the description of transient patterns which occur in the evolution between two spatially homogeneous states. This phenomenon occurs, for example, during the Freedericksz transition in nematic liquid crystals.The dynamics leads to the emergence of finite domai...
1992-10-16
2009-10-22
[ "cond-mat" ]
A. Amengual, E. Hernandez-Garcia, and M. San Miguel
cond-mat/9210013
Numerical studies of tunneling in a nonharmonic time-dependent potential
Azbel' has recently carried out a WKB-analysis of the effects of a nonharmonic time-dependent perturbation embedded in an opaque potential barrier. He suggests the existence of three different transmission regimes: direct tunneling, activation assisted tunneling, and elevator resonant activation. We address the same pr...
1992-10-16
2009-10-22
[ "cond-mat" ]
J. A. St{\o}vneng and A.-P. Jauho
cond-mat/9210014
On the Scale-Invariant Distribution of the Diffusion Coefficient for Classical Particles Diffusing in Disordered Media.-
The scaling form of the whole distribution P(D) of the random diffusion coefficient D(x) in a model of classically diffusing particles is investigated. The renormalization group approach above the lower critical dimension d=0 is applied to the distribution P(D) using the n-replica approach. In the annealed approximatio...
1992-10-16
2009-10-22
[ "cond-mat", "hep-th" ]
Yan-Chr Tsai and Yonathan Shapir
cond-mat/9210011
Generalized spin density wave state of the Hubbard model on the C12 and C60 clusters
The one-band Hubbard model at half-filling on a truncated tetrahedron (C$_{12}$), and on the C$_{60}$ molecule is studied. Within the Hartree-Fock approximation, we find a magnetic-like instability of the `Fermi sea' towards a spin-ordered phase for an intermediate value of the coupling ${\rm (U/t)_c}\approx 2.6$. The ...
1992-10-14
2014-10-13
[ "cond-mat" ]
L. Bergomi, J. P. Blaizot, Th. Jolicoeur and E. Dagotto
cond-mat/9210008
String Defects in Condensed Matter Systems as Optical Fibers
We analyze the core structure of string defects in various condensed matter systems, such as nematic liquid crystals and superfluid helium, and argue that in certain cases the variation of the refractive index near the core is such that it can lead to total internal reflection of light travelling along the string core....
1992-10-14
2007-05-23
[ "cond-mat", "hep-ph" ]
Ajit Mohan Srivastava
cond-mat/9210010
Dimerization structures on the metallic and semiconducting fullerene tubules with half-filled electrons
Possible dimerization patterns and electronic structures in fullerene tubules as the one-dimensional pi-conjugated systems are studied with the extended Su-Schrieffer-Heeger model. We assume various lattice geometries, including helical and nonhelical tubules. The model is solved for the half-filling case of $\pi$-elec...
1992-10-14
2007-05-23
[ "cond-mat" ]
Kikuo Harigaya (Fundamental Physics Section, Physical Science Division, Electrotechnical Laboratory, Japan), Mitsutaka Fujita (Institute of Materials Science, University of Tsukuba, Japan)
cond-mat/9210009
Phase Ordering Dynamics in the Continuum q-state Clock Model
The order parameter correlation function of the nonconserved, continuum $q$-state clock model is evaluated in the asymptotic scaling limit, during the phase ordering process after a temperature quench. The short distance behavior of the order parameter scaling function exhibits explicit crossover from that characterist...
1992-10-14
2009-10-22
[ "cond-mat" ]
Fong Liu and Gene F. Mazenko
cond-mat/9210007
Bosonization and Fermion Liquids in Dimensions Greater Than One
(Revised, with postscript figures appended, corrections and added comments.) We develop and describe new approaches to the problem of interacting Fermions in spatial dimensions greater than one. These approaches are based on generalizations of powerful tools previously applied to problems in one spatial dimension. We b...
1992-10-10
2009-10-22
[ "cond-mat", "hep-th" ]
A. Houghton and J. B. Marston
cond-mat/9210006
Once again about interchain hopping
Renormalization group equations and a phase diagram are derived for a system of two chains with a single-electron hopping between chains in order to correct the results of a recent paper by F.~V.~Kusmartsev, A.~Luther, and A.~Nersesyan, Pis'ma v Zh.\ Exp.\ Teor.\ Fiz.\ {\bf 55}, 692 (1992) [JETP Lett.\ {\bf 55}, 724 (1...
1992-10-09
2008-02-03
[ "cond-mat" ]
Victor M. Yakovenko
cond-mat/9210005
Multicanonical Study of the 3D Ising Spin Glass
We simulated the Edwards-Anderson Ising spin glass model in three dimensions via the recently proposed multicanonical ensemble. Physical quantities such as energy density, specific heat and entropy are evaluated at all temperatures. We studied their finite size scaling, as well as the zero temperature limit to explore ...
1992-10-07
2009-10-22
[ "cond-mat", "hep-lat" ]
B.A.Berg, T.Celik and U.Hansmann
cond-mat/9210004
A new Proposal for a Quasielectron Trial Wavefunction for the FQHE on a Disk
In this letter, we propose a new quasielectron trial wavefunction for $N$ interacting electrons in two dimensions moving in a strong magnetic field in a disk geometry. Requiring that the trial wavefunction exhibits the correct filling factor of a quasielectron wavefunction, we obtain $N+1$ angular momentum eigenfunctio...
1992-10-06
2010-12-17
[ "cond-mat", "hep-th" ]
Marcus Kasner and Walter Apel (Physikalisch-Technische Bundesanstalt Braunschweig, PF 3345, D-W-3300 Braunschweig, Germany)
cond-mat/9210003
Pressure Induced Topological Phase Transitions in Membranes
Some highly unusual features of a lipid-water liquid crystal are revealed by high pressure x-ray diffraction, light scattering and dilatometric studies of the lamellar (bilayer $L_{\alpha}$) to nonlamellar inverse hexagonal ($H_{II}$) phase transition. (i) The size of the unit cell of the $H_{II}$ phase increases with ...
1992-10-04
2009-10-22
[ "cond-mat" ]
P.T.C. So, Sol M. Gruner and Shyamsunder Erramilli
cond-mat/9210002
Exact Solution of a Phase Separation Model with Conserved Order Parameter Dynamics
Pairwise particle-exchange model on a linear lattice is solved exactly by a new rate-equation method. Lattice sites are occupied by particles A and B which can exchange irreversibly provided the local energy in reduced. Thus, the model corresponds to a zero-temperature Kawasaki-type phase separation process. Due to loc...
1992-10-02
2014-10-13
[ "cond-mat", "hep-lat" ]
Vladimir Privman