95 research outputs found
Coexistence of monopoles and instantons for different topological charge definitions and lattice actions
We compute instanton sizes and study correlation functions between instantons
and monopoles in maximum abelian projection within SU(2) lattice QCD at finite
temperature. We compare several definitions of the topological charge,
different lattice actions and methods of reducing quantum fluctuations. The
average instanton size turns out to be fm. The correlation
length between monopoles and instantons is fm and hardly
affected by lattice artifacts as dislocations. We visualize several specific
gauge field configurations and show directly that there is an enhanced
probability for finding monopole loops in the vicinity of instantons. This
feature is independent of the topological charge definition used.Comment: 10 pages, LaTeX, uses elsart.sty and elsart12.sty, 16 eps files, 4
figures, published, for corresponding movies (MPEG) see
http://www.tuwien.ac.at/e142/Lat/qcd.htm
Topology without cooling: instantons and monopoles near to deconfinement
In an attempt to describe the change of topological structure of pure SU(2)
gauge theory near deconfinement a renormalization group inspired method is
tested. Instead of cooling, blocking and subsequent inverse blocking is applied
to Monte Carlo configurations to capture topological features at a well-defined
scale. We check that this procedure largely conserves long range physics like
string tension. UV fluctuations and lattice artefacts are removed which
otherwise spoil topological charge density and Abelian monopole currents. We
report the behaviour of topological susceptibility and monopole current
densities across the deconfinement transition and relate the two faces of
topology to each other. First results of a cluster analysis are described.Comment: 6 pages, 8 figures, LaTeX with espcrc2.sty. Talk and poster presented
at Lattice97, Edinburgh, 22-26 July 1997, to appear in Nucl. Phys. B
(Proc.Suppl.
Abelian Monopole and Center Vortex Views at the Multi-Instanton Gas
We consider full non-Abelian, Abelian and center projected lattice field
configurations built up from random instanton gas configurations in the
continuum. We study the instanton contribution to the force with
respect to ({\it i}) instanton density dependence, ({\it ii}) Casimir scaling
and ({\it iii}) whether various versions of Abelian dominance hold. We check
that the dilute gas formulation for the interaction potential gives an reliable
approximation only for densities small compared to the phenomenological value.
We find that Casimir scaling does not hold, confirming earlier statements in
the literature. We show that the lattice used to discretize the instanton gas
configurations has to be sufficiently coarse ( compared
with the instanton size ) such that maximal Abelian gauge
projection and center projection as well as the monopole gas contribution to
the force reproduce the non-Abelian instanton-mediated force in the
intermediate range of linear quasi-confinement. We demonstrate that monopole
clustering also depends critically on the discretization scale confirming
earlier findings based on monopole blocking.Comment: 21 pages, 22 Postscript figure
Abelian Monopoles in SU(2) Lattice Gauge Theory as Physical Objects
By numerical calculations we show that the abelian monopole currents are
locally correlated with the density of SU(2) lattice action. The correlations
are larger by the order of magnitude in the maximal abelian projection than in
the projections which correspond to the diagonalization of Polyakov line and to
the diagonalization of the plaquette. These facts show that (at least) in the
maximal abelian projection the monopoles are the physical objects, they carry
the SU(2) action. The larger value of \beta, the larger the relative action
carried by monopole. Calculations on the asymmetric lattice show that this
correlation exists also in the deconfinement phase of gluodynamics.Comment: 6 pages, RevTeX, 3 figures, uses epsf.sty; to be published in
Phys.Rev.Lett., replaced to match version accepted for publicatio
Quark zero modes in intersecting center vortex gauge fields
The zero modes of the Dirac operator in the background of center vortex gauge
field configurations in and are examined. If the net flux in D=2
is larger than 1 we obtain normalizable zero modes which are mainly localized
at the vortices. In D=4 quasi-normalizable zero modes exist for intersecting
flat vortex sheets with the Pontryagin index equal to 2. These zero modes are
mainly localized at the vortex intersection points, which carry a topological
charge of . To circumvent the problem of normalizability the
space-time manifold is chosen to be the (compact) torus \T^2 and \T^4,
respectively. According to the index theorem there are normalizable zero modes
on \T^2 if the net flux is non-zero. These zero modes are localized at the
vortices. On \T^4 zero modes exist for a non-vanishing Pontryagin index. As
in these zero modes are localized at the vortex intersection points.Comment: 20 pages, 4 figures, LaTeX2e, references added, treatment of ideal
vortices on the torus shortene
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