254 research outputs found
Quark Confinement Physics in Quantum Chromodynamics
We study abelian dominance and monopole condensation for the quark
confinement physics using the lattice QCD simulations in the MA gauge. These
phenomena are closely related to the dual superconductor picture of the QCD
vacuum, and enable us to construct the dual Ginzburg-Landau (DGL) theory as an
useful effective theory of nonperturbative QCD. We then apply the DGL theory to
the studies of the low-lying hadron structure and the scalar glueball
properties.Comment: Talk given at 15th International Conference on Particle and Nuclei
(PANIC 99), Uppsala, Sweden, 10-16 Jun 1999, 4 page
Confinement and Topological Charge in the Abelian Gauge of QCD
We study the relation between instantons and monopoles in the abelian gauge.
First, we investigate the monopole in the multi-instanton solution in the
continuum Yang-Mills theory using the Polyakov gauge. At a large instanton
density, the monopole trajectory becomes highly complicated, which can be
regarded as a signal of monopole condensation. Second, we study instantons and
monopoles in the SU(2) lattice gauge theory both in the maximally abelian (MA)
gauge and in the Polyakov gauge. Using the lattice, we find
monopole dominance for instantons in the confinement phase even at finite
temperatures. A linear-type correlation is found between the total
monopole-loop length and the integral of the absolute value of the topological
density (the total number of instantons and anti-instantons) in the MA gauge.
We conjecture that instantons enhance the monopole-loop length and promote
monopole condensation.Comment: 3 pages, LaTeX, Talk presented at LATTICE96(topology
Stretching in a model of a turbulent flow
Using a multi-scaled, chaotic flow known as the KS model of turbulence, we
investigate the dependence of Lyapunov exponents on various characteristics of
the flow. We show that the KS model yields a power law relation between the
Reynolds number and the maximum Lyapunov exponent, which is similar to that for
a turbulent flow with the same energy spectrum. Our results show that the
Lyapunov exponents are sensitive to the advection of small eddies by large
eddies, which can be explained by considering the Lagrangian correlation time
of the smallest scales. We also relate the number of stagnation points within a
flow to the maximum Lyapunov exponent, and suggest a linear dependence between
the two characteristics.Comment: 7 pages, 10 figure
Instanton, Monopole Condensation and Confinement
The confinement mechanism in the nonperturbative QCD is studied in terms of
topological excitation as QCD-monopoles and instantons. In the 't Hooft abelian
gauge, QCD is reduced into an abelian gauge theory with monopoles, and the QCD
vacuum can be regarded as the dual superconductor with monopole condensation,
which leads to the dual Higgs mechanism. The monopole-current theory extracted
from QCD is found to have essential features of confinement. We find also close
relation between monopoles and instantons using the lattice QCD. In this
framework, the lowest glueball (1.5 1.7GeV) can be identified
as the QCD-monopole or the dual Higgs particle.Comment: Talk presented by H.Suganuma at the 5th Topical Seminar on The
Irresistible Rise of the Standard Model, San Miniato al Todesco, Italy, 21-25
April 1997 5 pages, Plain Late
Association between ultrasound assessment of glenohumeral subluxation and shoulder pain, muscle strength, active range of movement and upper limb function in people with stroke
Background: Glenohumeral subluxation (GHS) is a commonly reported post-stroke complication which has a negative effect on rehabilitation. Objective: To explore the association between GHS and other clinical outcomes in people with post-stroke hemiplegia. Methods: Patients with post-stroke hemiplegia (n=105, 71±11 years, median time since stroke 5.6 weeks), who gave informed consent, were recruited. GHS was assessed by the ultrasound method. Assessment of shoulder pain (visual analogue scale), active range of movement (AROM), muscle strength (Medical Research Council Scale), muscle tone (Modified Ashworth Scale) and the upper limb section of the Motor Assessment Scale (MAS) was undertaken. Results: GHS was present in 65 (62%) patients. There was a moderate negative correlation between GHS and muscle strength (r=-0.54,
The Maximal Abelian Gauge, Monopoles, and Vortices in SU(3) Lattice Gauge Theory
We report on calculations of the heavy quark potential in SU(3) lattice gauge
theory. Full SU(3) results are compared to three cases which involve
gauge-fixing and projection. All of these start from the maximal abelian gauge
(MAG), in its simplest form. The first case is abelian projection to U(1)xU(1).
The second keeps only the abelian fields of monopoles in the MAG. The third
involves an additional gauge-fixing to the indirect maximal center gauge
(IMCG), followed by center projection to Z(3). At one gauge
fixing/configuration, the string tensions calculated from MAG U(1)xU(1), MAG
monopoles, and IMCG Z(3) are all less than the full SU(3) string tension. The
projected string tensions further decrease, by approximately 10%, when account
is taken of gauge ambiguities. Comparison is made with corresponding results
for SU(2). It is emphasized that the formulation of the MAG is more subtle for
SU(3) than for SU(2), and that the low string tensions may be caused by the
simple MAG form used. A generalized MAG for SU(3) is formulated.Comment: 22 pages, latex, 2 postscript figures. Replaced version has added
data at beta=6.0, analysis of Gribov ambiguities, extended tables of results,
discussion of scalin
Weyl Invariant Formulation of Flux-Tube Solution in the Dual Ginzburg-Landau Theory
The flux-tube solution in the dual Ginzburg-Landau (DGL) theory in the
Bogomol'nyi limit is studied by using the manifestly Weyl invariant form of the
DGL Lagrangian. The dual gauge symmetry is extended to , and
accordingly, there appear three different types of the flux-tube. The string
tension for each flux-tube is calculated analytically and is found to be the
same owing to the Weyl symmetry. It is suggested that the flux-tube can be
treated in quite a similar way with the Abrikosov-Nielsen-Olesen vortex in the
U(1) Abelian Higgs theory except for various types of flux-tube.Comment: 12 pages, revtex, no figur
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