Fri·Nov 25, 2005Friday·November 25, 2005

1. 01*

   Variational method for lattice spectroscopy with ghosts

   Tommy Burch🇩🇪 · Christof Gattringer🇦🇹 · Leonid Ya. Glozman🇦🇹 · Christian Hagen🇩🇪 · C.B. Lang🇦🇹

   We discuss the variational method used in lattice spectroscopy calculations. In particular we address the role of ghost contributions which appear in quenched or partially quenched simulations and have a non-standard euclidean time dependence. We show that the ghosts can be separated from the physical states. Our result is illustrated with numerical data for the scalar meson.

   hep-latPRD(2006)·37 citations
2. 02*

   High accuracy simulations of d=4 SU(3) qcd-string

   N.D. Hari Dass (IMSc, Chennai)🇮🇳 · Pushan Majumdar (University of Graz)🇦🇹

   We present here the results of our high accuracy simulations of $q\bar{q}$ potential in $d=4$ SU(3) Yang-Mills theory. We measure this quantity by measuring the {\it Polyakov Loop Correlators} using the {\it exponential variance reduction technique(multilevel)} of Luscher and Weisz. We further use numerical integration of the one-link integrals of SU(3) theory by adopting techniques proposed by de Forcrand and Roiesnell achieving significant speed-up in the process. Measurements were done at $\beta =5.7$ on $24^{3}x32$ as well as $32^4$ lattices for separations between the Polyakov loops in the range $r=2-9$ in lattice units. We analyse the results in terms of the force between $q\bar{q}$ pair as well as in terms of a {\em scaled second derivative} of the potential. We show that the data is accurate enough to distinguish between different string models and that it seems to favour the expression for ground state energy of a Nambu-Goto string. We conclude by discussing future plans.

   hep-latPoS(2006)·5 citations
3. 03*

   Landau gauge ghost and gluon propagators in SU(2) lattice gauge theory: Gribov ambiguity revisited

   I. L. Bogolubsky🇷🇺 · G. Burgio🇩🇪 · V. K. Mitrjushkin🇷🇺 · M. Mueller-Preussker

   We reinvestigate the problem of Gribov ambiguities within the Landau (or Lorentz) gauge for the ghost and gluon propagators in pure SU(2) lattice gauge theory. We make use of the full symmetry group of the action taking into account {\it large}, i.e. non-periodic $\mathbb{Z}(2)$ gauge transformations leaving lattice plaquettes invariant. Enlarging in this way the gauge orbits for any given gauge field configuration the Landau gauge can be fixed at higher local extrema of the gauge functional in comparison with standard (overrelaxation) techniques. This has a clearly visible effect not only for the ghost propagator at small momenta but also for the gluon propagator, in contrast to the common belief.

   hep-lathep-phPRD(2006)·85 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.