2,493 research outputs found
String breaking
We numerically investigate the transition of the static quark-antiquark
string into a static-light meson-antimeson system. Improving noise reduction
techniques, we are able to resolve the signature of string breaking dynamics
for Nf=2 lattice QCD at zero temperature. We discuss the lattice techniques
used and present results on energy levels and mixing angle of the static
two-state system. We visualize the action density distribution in the region of
string breaking as a function of the static colour source-antisource
separation. The results can be related to properties of quarkonium systems.Comment: 8 pages, Talk given at the Workshop on Computational Hadron Physics,
Nicosia, Cyprus, 14--17 September 200
Glueball and gluelump spectrum in abelian projected QCD
We study glueball and gluelump spectra calculated after abelian projection in
both quenched and full QCD. The abelian projection is made after MA
gauge fixing. We demonstrate that both spectra can be recovered despite the
problem with positivity. We suggest the interpretation of some of the gluelump
states in the language of the abelian projected theory.Comment: Lattice 2001(confinement), 3 page
Vortex structure of the vacuum and confinement
We discuss the recently published numerical computations of the vortex free
energy. They dramatically demonstrate that the excitation probability for a
sufficiently thick vortex approaches unity at large beta, i.e. that thick
vortices `condense' in the vacuum. This is known to imply confinement. An
analytical approach for exploring this phenomenon is also outlined.Comment: LATTICE2000 (Topology and Vacuum), 4 pages, 1 epsf figure, LaTe
A Ginzburg-Landau Analysis of the Colour Electric Flux Tube
In a simulation of SU(2) gauge theory we investigate, after maximal Abelian
projection, the dual Maxwell equations for colour field and monopole current
distributions around a static quark-antiquark pair Q_ Q in vacuo. Within the
dual superconductor picture we carry out a Ginzburg-Landau type analysis of the
flux tube profile. As a result we can determine the coherence length of the GL
wave function related to the monopole condensate, xi = .25(3) fm, to be
compared to the penetration length, lambda = >.15(2) fm (scaled with the string
tension).Comment: 3 pages, 5 figures, corrected typos, LATTICE98(confine
The Gribov Ambiguity for Maximal Abelian and Center Gauges in SU(2) Lattice Gauge Theory
We present results for the fundamental string tension in SU(2) lattice gauge
theory after projection to maximal abelian and direct maximal center gauges. We
generate 20 Gribov copies/configuration. Abelian and center projected string
tensions slowly decrease as higher values of the gauge functionals are reached.Comment: 3 pages, latex, 1 postscript figure, presented at Lattice
2000(Topology and Vacuum
Abelian Monopoles and Action Density in SU(2) Gluodynamics on the Lattice
We show that the extended Abelian magnetic monopoles in the Maximal Abelian
projection of lattice SU(2) gluodynamics are locally correlated with the
magnetic and the electric parts of the SU(2) action density. These correlations
are observed in the confined and in the deconfined phases.Comment: 11 pages, LaTeX2e, 5 figures, uses epsf.sty; revision: Introduction
is extended and a few references are adde
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
Confining string and P-vortices in the indirect Z(2) projection of SU(2) lattice gauge theory
We study the distribution of P-vortices near the confining string in the
indirect Z(2) projection of SU(2) lattice gauge theory. It occurs that the
density of vortices is constant at large distances and strongly suppressed near
the line connecting the test quark-antiquark pair. This means that the
condensate of P-vortices is broken inside the confining string. We also find
that the width of the P-vortex density distribution is proportional to the
logarithm of the distance between the quark and antiquark.Comment: 3 pages, 4 figures, Lattice2002(topology), 2 references added, minor
change
The Spatial String Tension in the Deconfined Phase of the (3+1)-Dimensional SU(2) Gauge Theory
We present results of a detailed investigation of the temperature dependence
of the spatial string tension in SU(2) gauge theory. We show, for the first
time, that the spatial string tension is scaling on the lattice and thus is
non-vanishing in the continuum limit. It is temperature independent below Tc
and rises rapidly above. For temperatures larger than 2Tc we find a scaling
behaviour consistent with sigma_s(T) = 0.136(11) g^4(T) T^2, where g(T) is the
2-loop running coupling constant with a scale parameter determined as Lambda_T
= 0.076(13) Tc.Comment: 8 pages (Latex, shell archive, 3 PostScript figures), HLRZ-93-43,
BI-TP 93/30, FSU-SCRI-93-76, WUB 93-2
Scaling of the critical temperature and quark potential with a renormalization group improved SU(3) gauge action
We study the scaling property of the ratio of the critical temperature
to the square root of the string tension in the SU(3) pure gauge
theory using a renormalization group improved action. We first determine the
critical coupling on lattices with temporal extension and 6,
and then calculate the static quark potential at the critical couplings on
lattices at zero temperature. The values of in the
infinite volume limit are identical within errors, while they are slightly
larger than the value extrapolated to the continuum limit with the standard
action. We also note that the rotational invariance of the static quark
potential is remarkably restored in the both cases, and that the potential
in physical units scales in the whole region of investigated.Comment: 3 pages of Latex, 5 PostScript figures, Talk presented at
LATTICE96(finite temperature
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