arXiv subjects

M. Feurstein

Publications and source records attributed to M. Feurstein.

7 recordsLinked to original sources

arXiv1997

Topology at the Deconfinement Transition Uncovered by Inverse Blocking in SU(2) Pure Gauge Theory with Fixed Point Action

Renormalization group transformations as discussed recently in deriving fixed point actions are used to analyse the vacuum structure near to the deconfinement temperature. Monte Carlo configurations are generated using the fixed point action. We compare equilibrium configurations with configurations obtained by inverse blocking from a coarser lattice. The absence of short range vacuum fluctuations in the latter does not influence the string tension. For the inversely blocked configurations we find the following: (i) the topological susceptibility chi_top is consistent with the phenomenological value in the confinement phase, (ii) chi_top drops across the deconfinement transition, (iii) density and size of instantons are estimated, (iv) the topological density is found to be correlated to Abelian monopole currents and (v) the density of spacelike monopole currents becomes a confinement order parameter.

hep-lat↗

arXiv1997

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.

hep-lat↗

arXiv1997

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 $σ\approx 0.2$ fm. The correlation length between monopoles and instantons is $ζ\approx 0.25$ 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.

hep-lat↗

arXiv1997

Instantons and monopoles in lattice QCD

We analyze the interplay of topological objects in four-dimensional QCD on the lattice. The distributions of color magnetic monopoles in the maximum abelian gauge are computed around instantons in both pure and full QCD. We find an enhanced probability for monopoles inside the core of an instanton on gauge field average. This feature is independent of the topological charge definition used. For specific gauge field configurations we visualize the situation graphically. Moreover we investigate how monopole loops and instantons are correlated with the chiral condensate. Strong evidence is found that clusters of the quark condensate and topological objects coexist locally on individual configurations.

hep-lat↗

arXiv1996

Correlation functions between topological objects -- field theoretic versus geometric definitions

We analyze topological objects in pure gluonic $SU(2)$ lattice gauge theory and compute correlation functions between instantons and monopoles. Concerning the instantons we use geometric and field theoretic definitions of the topological charge. On a $12^3\times 4$ lattice it turns out that topological quantities have a non-trivial local correlation. The auto-correlation functions of the topological charge depend on cooling for both definitions. We fit the correlation functions to exponentials and obtain screening masses.

hep-lat↗

arXiv1996

Visualization of topological objects in QCD

Recently evidence appeared that instantons and monopoles have a certain local correlation in four-dimensional pure $SU(2)$ and $SU(3)$ gauge theory. We visualize several specific gauge field configurations and show directly that there is an enhanced probability for finding maximally projected abelian monopole loops in the vicinity of instantons. This feature is independent of the topological charge definition used.

hep-lat↗

arXiv1996

Relations Between Monopoles, Instantons and Chiral Condensate

We analyze the interplay of topological objects in four dimensional QCD. The distributions of color magnetic monopoles obtained in the maximum abelian gauge are computed around instantons in both pure and full QCD. We find an enhanced probability of encountering monopoles inside the core of an instanton on gauge field average. For specific gauge field configurations we visualize the situation graphically. Moreover we investigate how monopole loops and instantons are locally correlated with the chiral condensate.

hep-lat↗