1,395 research outputs found
On the Phase Structure of the Schwinger Model with Wilson Fermions
We study the phase structure of the massive one flavour lattice Schwinger
model on the basis of the finite size scaling behaviour of the partition
function zeroes. At we observe and discuss a possible discrepancy
with results obtained by a different method.Comment: 3 pages (2 figures), POSTSCRIPT-file (174 KB), Contribution to
Lattice 93, preprint UNIGRAZ-UTP 19-11-9
Properties of the Soliton-Lattice State in Double-Layer Quantum Hall Systems
Application of a sufficiently strong parallel magnetic field produces a soliton-lattice (SL) ground state in a double-layer quantum
Hall system. We calculate the ground-state properties of the SL state as a
function of for total filling factor , and obtain the
total energy, anisotropic SL stiffness, Kosterlitz-Thouless melting
temperature, and SL magnetization. The SL magnetization might be experimentally
measurable, and the magnetic susceptibility diverges as .Comment: 4 pages LaTeX, 1 EPS figure. Proceedings of the 12th International
Conference on the Electronic Properties of Two-Dimensional Electron Systems
(EP2DS-12), to be published in Physica B (1998
Strong Coupling Lattice Schwinger Model on Large Spherelike Lattices
The lattice regularized Schwinger model for one fermion flavor and in the
strong coupling limit is studied through its equivalent representation as a
restricted 8-vertex model. The Monte Carlo simulation on lattices with
torus-topology is handicapped by a severe non-ergodicity of the updating
algorithm; introducing lattices with spherelike topology avoids this problem.
We present a large scale study leading to the identification of a critical
point with critical exponent , in the universality class of the Ising
model or, equivalently, the lattice model of free fermions.Comment: 16 pages + 7 figures, gzipped POSTSCRIPT fil
Bias-voltage induced phase-transition in bilayer quantum Hall ferromagnets
We consider bilayer quantum Hall systems at total filling factor in
presence of a bias voltage which leads to different filling factors
in each layer. We use auxiliary field functional integral approach to study
mean-field solutions and collective excitations around them. We find that at
large layer separation, the collective excitations soften at a finite wave
vector leading to the collapse of quasiparticle gap. Our calculations predict
that as the bias voltage is increased, bilayer systems undergo a phase
transition from a compressible state to a phase-coherent state {\it
with charge imbalance}. We present simple analytical expressions for
bias-dependent renormalized charge imbalance and pseudospin stiffness which are
sensitive to the softening of collective modes.Comment: 12 pages, 5 figures. Minor changes, one reference adde
Resonance Scattering Phase Shifts in a 2-d Lattice Model
We study a simple 2-d model representing two fields with different mass and a
3-point coupling term. The phase shift in the resonating 2-particle channel is
determined from the energy spectrum obtained in Monte Carlo simulations on
finite lattices. Masses and wave function renormalization constants of the
fields as well as mass and width of the resonance are determined and discussed.
The representation of scattering states in terms of the considered operators is
analysed.Comment: 24 p + 8 PS-figures, UNIGRAZ-UTP-04-05-9
Scaling Behavior of Transverse Kinetic Energy Distributions in Au+Au Collisions at GeV
With the experimental data from STAR on the centrality dependence of
transverse momentum spectra of pions and protons in Au+Au collisions at
, we investigate the scaling properties of
transverse energy distributions at different centralities. In the
framework of cluster formation and decay mechanism for particle production, the
universal transverse energy distributions for pion and proton can be described
separately but not simultaneously.Comment: 5 pages, 5 eps figures included, to be appeared in Nucl. Phys.
Lee-Yang zeroes and logarithmic corrections in the Φ44 theory
The leading mean-field critical behaviour of φ 4 4-theory is modified by multiplicative logarithmic corrections. We analyse these corrections both analytically and numerically. In particular we present a finite-size scaling theory for the Lee-Yang zeroes and temperature zeroes, both of which exhibit logarithmic corrections. On lattices from size 8 4 to 24 4, Monte-Carlo cluster methods and multi-histogram techniques are used to determine the partition function zeroes closest to the critical point. Finite-size scaling behaviour is verified and the logarithmic corrections are found to be in good agreement with our analytical predictions. 1
The zeros of the QCD partition function
We establish a relationship between the zeros of the partition function in
the complex mass plane and the spectral properties of the Dirac operator in
QCD. This relation is derived within the context of chiral Random Matrix Theory
and applies to QCD when chiral symmetry is spontaneously broken. Further, we
introduce and examine the concept of normal modes in chiral spectra. Using this
formalism we study the consequences of a finite Thouless energy for the zeros
of the partition function. This leads to the demonstration that certain
features of the QCD partition function are universal.Comment: 13 page
Solitons in polarized double layer quantum Hall systems
A new manifestation of interlayer coherence in strongly polarized double
layer quantum Hall systems with total filling factor
in the presence of a small or zero tunneling is theoretically
predicted. It is shown that moving (for small tunneling) and spatially
localized (for zero tunneling) stable pseudospin solitons develop which could
be interpreted as mobile or static charge-density excitations.
The possibility of their experimental observation is also discussed.Comment: Phys. Rev. B (accepted
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