1,032 research outputs found
On Dirac sheet configurations of SU(2) lattice fields
Finite temperature Euclidean SU(2) lattice gauge fields close to the
deconfinement phase transition are subjected to cooling. We find relatively
stable or absolutely stable configurations with an action below the
one-instanton action both in the deconfinement and the
confinement phases. In this paper we attempt an interpretation of these lowest
action configurations. Their action is purely magnetic and amounts to
, where () is the timelike (spacelike)
lattice size, while the topological charge vanishes. In the confined phase part
of the corresponding lattice configurations turns out to be absolutely stable
with respect to the cooling process in which case Abelian projection reveals a
homogeneous, purely Abelian magnetic field closed over the "boundary" in one of
the spatial directions. Referring to the dyonic structure established for the
confinement phase near and based on the observation made for this phase
that such events below the instanton action emerge from
dyon-antidyon annihilation, the question of stability (metastability) is
discussed for both phases. The hypothetically different dyonic structure of the
deconfinement phase, inaccessible by cooling, could explain the metastability.Comment: 14 pages, 7 figure
Yang-Mills streamlines and semi-classical confinement
Semi-classical configurations in Yang-Mills theory have been derived from
lattice Monte Carlo configurations using a recently proposed constrained
cooling technique which is designed to preserve every Polyakov line (at any
point in space-time in any direction). Consequently, confinement was found
sustained by the ensemble of semi-classical configurations. The existence of
gluonic and fermionic near-to-zero modes was demonstrated as a precondition for
a possible semi-classical expansion around the cooled configurations as well as
providing the gapless spectrum of the Dirac operator necessary for chiral
symmetry breaking. The cluster structure of topological charge of the
semi-classical streamline configurations was analysed and shown to support the
axial anomaly of the right size, although the structure differs from the
instanton gas or liquid. Here, we present further details on the space-time
structure and the time evolution of the streamline configurations.Comment: Invited talk presented at the conference "Quark confinement and the
hadron spectrum IX", Madrid, Aug 30 - Sept 3, 201
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.
Physics of the Electroweak Phase Transition at M_H <= 70 GeV in a 3-dimensional SU(2)-Higgs Model
Physical parameters of the electroweak phase transition in a 3d effective
lattice SU(2)-Higgs model are presented. The phase transition temperatures,
latent heats and continuum condensate discontinuities are measured at Higgs
masses of about 70 and 35 GeV. Masses and Higgs condensates are compared to
perturbation theory in the broken phase. In the symmetric phase bound states
and the static force are determined.Comment: Talk presented at LATTICE96(electroweak), 4 pages, 5 figure
An SU(2) KvBLL caloron gas model and confinement
A semi-classical model is developed to describe pure SU(2) Yang-Mills
gluodynamics at finite temperature as a dilute, non-interacting gas of
Kraan-van Baal-Lee-Lu calorons including the case of non-trivial holonomy.
Temperature dependent parameters of the model (asymptotic caloron holonomy,
caloron density and caloron size distribution) are discussed from the point of
view of lattice observations and of in-medium modifications of the one-loop
caloron amplitude. Space-like string tensions running into plateaux at
distances R \approx 0.8 - 1.3 fm are obtained and compared to lattice results
in order to find more precisely the average caloron size. Then, the
quark-antiquark free energy as predicted by the model is considered. In the
confined phase a linear rise with the separation can be observed up to R
\approx 4 fm, whereas it runs into plateaux above T_c. Screening effects in the
adjoint potentials are observed together with an approximate Casimir scaling of
the caloron contribution to the fundamental and adjoint forces. In Abelian
projection, space-like percolation of monopoles is found in the confined phase
only. Thus, taking the non-trivial holonomy into account, confinement
properties of pure SU(2) Yang-Mills gluodynamics can be described by a
semi-classical approach up to distances one order of magnitude larger than the
caloron size.Comment: 26 pages, 14 figures, textheight change
- …