65 research outputs found
The Massive Schwinger Model in a Fast Moving Frame
We present a non-perturbative study of the massive Schwinger model. We use a
Hamiltonian approach, based on a momentum lattice corresponding to a fast
moving reference frame, and equal time quantization.Comment: contribution to Lattice'98 including: 2 style files
(espcrc2.sty,psfig.sty) + text file (LaTeX) + 3 figures (ps) + complete
paper(ps
Reply to ``Comment on `Properties of the massive Thirring model from the XYZ spin chain' "
We elaborate in more details why lattice calculation in [Kolanovic et al,
Phys. Rev. D 62, 025021 (2000)] was done correctly and argue that incresing the
number of sites is not expected to change our conclusions on the mass spectrum.Comment: 2 pages, revtex 4, to be published in Phys. Rev.
Strong Coupling Limit of Bethe Ansatz Solutions in Massive Thirring Model
We study the strong coupling limit of the Bethe ansatz solutions in the
massive Thirring model. We find analytical expressions for the energy
eigenvalues for the vacuum state as well as n-particle n- hole states. This
formula is compared with the numerical results and is found to achieve a very
good agreement.
Also, it is found that the 2-particle 2- hole and higher particle-hole states
describe n- free bosons states in this limit. The behaviors of the strong
coupling limit of the boson mass for various model calculations are examined.
We discuss an ambiguity of the coupling constant normalization due to the
current regularization.Comment: 15 pages, to appear in Ann. Phys. 281 (2000), Ma
Non-equivalence between Heisenberg XXZ spin chain and Thirring model
The Bethe ansatz equations for the spin 1/2 Heisenberg XXZ spin chain are
numerically solved, and the energy eigenvalues are determined for the
anti-ferromagnetic case. We examine the relation between the XXZ spin chain and
the Thirring model, and show that the spectrum of the XXZ spin chain is
different from that of the regularized Thirring model.Comment: 10 pages. 2figure
Oscillatory Tunneling between Quantum Hall Systems
Electron tunneling between quantum Hall systems on the same two dimensional
plane separated by a narrow barrier is studied. We show that in the limit where
inelastic scattering time is much longer than the tunneling time, which can be
achieved in practice, electrons can tunnel back and forth through the barrier
continously, leading to an oscillating current in the absence of external
drives. The oscillatory behavior is dictated by a tunneling gap in the energy
spectrum. We shall discuss ways to generate oscillating currents and the
phenomenon of natural ``dephasing" between the tunneling currents of edge
states. The noise spectra of these junctions are also studied. They contain
singularites reflecting the existence of tunneling gaps as well as the inherent
oscillation in the system. (Figures will be given upon requests).Comment: 20 pages, OS
Interacting Electrons on a Square Fermi Surface
Electronic states near a square Fermi surface are mapped onto quantum chains.
Using boson-fermion duality on the chains, the bosonic part of the interaction
is isolated and diagonalized. These interactions destroy Fermi liquid behavior.
Non-boson interactions are also generated by this mapping, and give rise to a
new perturbation theory about the boson problem. A case with strong repulsions
between parallel faces is studied and solved. There is spin-charge separation
and the square Fermi surface remains square under doping. At half-filling,
there is a charge gap and insulating behavior together with gapless spin
excitations. This mapping appears to be a general tool for understanding the
properties of interacting electrons on a square Fermi surface.Comment: 25 pages, Nordita preprint 94/22
A new class of exactly solvable interacting fermion models in one dimension
We investigate a model containing two species of one-dimensional fermions
interacting via a gauge field determined by the positions of all particles of
the opposite species. The model can be solved exactly via a simple unitary
transformation. Nevertheless, correlation functions exhibit nontrivial
interaction-dependent exponents. A similar model defined on a lattice is
introduced and solved. Various generalizations, e.g. to the case of internal
symmetries of the fermions, are discussed. The present treatment also clarifies
certain aspects of Luttinger's original solution of the ``Luttinger model''.Comment: 11 pages, revtex 3.0, no figures, some typos correcte
Finite size corrections in massive Thirring model
We calculate for the first time the finite size corrections in the massive
Thirring model. This is done by numerically solving the equations of periodic
boundary conditions of the Bethe ansatz solution. It is found that the
corresponding central charge extracted from the term is around 0.4 for
the coupling constant of and decreases down to zero when
. This is quite different from the predicted central
charge of the sine-Gordon model.Comment: 8 pages, Latex, 2 figure
The Vacuum in Light-Cone Field Theory
This is an overview of the problem of the vacuum in light-cone field theory,
stressing its close connection to other puzzles regarding light-cone
quantization. I explain the sense in which the light-cone vacuum is
``trivial,'' and describe a way of setting up a quantum field theory on null
planes so that it is equivalent to the usual equal-time formulation. This
construction is quite helpful in resolving the puzzling aspects of the
light-cone formalism. It furthermore allows the extraction of effective
Hamiltonians that incorporate vacuum physics, but that act in a Hilbert space
in which the vacuum state is simple. The discussion is fairly informal, and
focuses mainly on the conceptual issues. [Talk presented at {\sc Orbis
Scientiae 1996}, Miami Beach, FL, January 25--28, 1996. To appear in the
proceedings.]Comment: 20 pages, RevTeX, 4 Postscript figures. Minor typos correcte
The Influence of Higher Fock States in Light-Cone Gauge Theories
In the light-cone Fock state expansion of gauge theories, the influence of
non-valence states may be significant in precision non-perturbative
calculations. In two-dimensional gauge theories, it is shown how these states
modify the behaviour of the light-cone wavefunction in significant ways
relative to endemic choices of variational ansatz. Similar effects in
four-dimensional gauge theories are briefly discussed.Comment: 4 pages, REVTE
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