61,452 research outputs found
Probing States in the Mott Insulator Regime
We propose a method to probe states in the Mott insulator regime produced
from a condensate in an optical lattice. We consider a system in which we
create time-dependent number fluctuations in a given site by turning off the
atomic interactions and lowering the potential barriers on a nearly pure Mott
state to allow the atoms to tunnel between sites. We calculate the expected
interference pattern and number fluctuations from such a system and show that
one can potentially observe a deviation from a pure Mott state. We also discuss
a method in which to detect these number fluctuations using time-of-flight
imaging.Comment: 4 pages, 3 figures. Send correspondence to
[email protected]
Aspects of Dynamical Chiral Symmetry Breaking
Dynamical chiral symmetry breaking is a nonperturbative phenomenon that may
be studied using QCD's gap equation. Model-independent results can be obtained
with a nonperturbative and symmetry preserving truncation. The gap equation
yields the massive dressed-quark propagator, which has a spectral
representation when considered as a function of the current-quark mass. This
enables an explication of the connection between the infrared limit of the QCD
Dirac operator's spectrum and the quark condensate appearing in the operator
product expansion.Comment: 11, LaTeX2e, ws-procs9x6; contribution to proceedings of the "5th
International Conference on Quark Confinement and the Hadron Spectrum,"
Gargnano, Italy, 10-14/Sept./0
Differences between heavy and light quarks
The quark Dyson-Schwinger equation shows that there are distinct differences
between light and heavy quarks. The dynamical mass function of the light quarks
is characterised by a sharp increase below 1 GeV, whereas the mass function of
the heavy quarks is approximately constant in this infrared region. As a
consequence, the heavy-meson masses increase linearly with the current-quark
masses, whereas the light pseudoscalar meson masses are proportional to the
square root of the current-quark masses.Comment: 4 pages, 3 figures, Contribution to the IVth International Workshop
on Progress in Heavy Quark Physics, 20-22 Sept. 1997, Rostoc
Continuum Strong QCD: Confinement and Dynamical Chiral Symmetry Breaking
Continuum strong QCD is the application of models and continuum quantum field
theory to the study of phenomena in hadronic physics, which includes; e.g., the
spectrum of QCD bound states and their interactions. Herein I provide a
Dyson-Schwinger equation perspective, focusing on qualitative aspects of
confinement and dynamical chiral symmetry breaking in cold, sparse QCD, and
also elucidating consequences of the axial-vector Ward-Takahashi identity and
features of the heavy-quark limit.Comment: 28 pages, 12 figures, LaTeX2e; Contribution to the proceedings of the
"Confinement" Research Program at the Erwin Schroedinger International
Institute for Mathematical Physics, Vienna, Austria, Coordinated by W. Lucha,
A. Martin and F. Schoeberl, May-July, 200
Thermodynamic properties of a simple, confining model
We study the equilibrium thermodynamics of a simple, confining, DSE-model of
2-flavour QCD at finite temperature and chemical potential. The model has two
phases: one characterised by confinement and dynamical chiral symmetry
breaking; and the other by their absence. The phase boundary is defined by the
zero of the vacuum-pressure difference between the confined and deconfined
phases. Chiral symmetry restoration and deconfinement are coincident with the
transition being of first order, except for , where it is second order.
Nonperturbative modifications of the dressed-quark propagator persist into the
deconfined domain and lead to a dispersion law modified by a
dynamically-generated, momentum-dependent mass-scale. This entails that the
Stefan-Boltzmann limit for the bulk thermodynamic quantities is attained only
for large values of temperature and chemical potential.Comment: 11 pages, LaTeX, epsfig.sty, elsart.st
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