Fri·Oct 26, 2001Friday·October 26, 2001

1. 01*

   The Maximal Abelian Gauge, Monopoles, and Vortices in SU(3) Lattice Gauge Theory

   John D. Stack🇺🇸 · William W. Tucker🇺🇸 · Roy J. Wensley🇺🇸

   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.

   hep-latNPB(2002)·44 citations
2. 02*

   The APENEXT project

   F. Bodin🇫🇷 · P. Boucaud🇫🇷 · N. Cabibbo🇮🇹 · F. Calvayrac🇫🇷 · M. Della Morte🇩🇪 · R. De Pietri🇮🇹 · P. De Riso🇮🇹 · F. Di Carlo🇮🇹 · F. Di Renzo🇮🇹 · W. Errico🇮🇹 · R. Frezzotti🇮🇹 · U. Gensch🇩🇪 and 22 other authors

   APENEXT is a new generation APE processor, optimized for LGT simulations. The project follows the basic ideas of previous APE machines and develops simple and cheap parallel systems with multi T-Flops processing power. This paper describes the main features of this new development.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·10 citations
3. 03*

   A comparative study of numerical methods for the overlap Dirac operator--a status report

   J. van den Eshof🇳🇱 · A. Frommer🇩🇪 · Th. Lippert🇩🇪 · K. Schilling🇩🇪 · H.A. van der Vorst🇳🇱

   Improvements of various methods to compute the sign function of the hermitian Wilson-Dirac matrix within the overlap operator are presented. An optimal partial fraction expansion (PFE) based on a theorem of Zolotarev is given. Benchmarks show that this PFE together with removal of converged systems within a multi-shift CG appears to approximate the sign function times a vector most efficiently. A posteriori error bounds are given.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·14 citations
4. 04*

   Scalar condensate and light quark masses from overlap fermions

   Pilar Hernandez🇨🇭 · Karl Jansen🇩🇪 · Laurent Lellouch🇫🇷 · Hartmut Wittig🇩🇪

   We have studied pseudoscalar correlation functions computed using the overlap operator. Within the accuracy of our calculation we find that the quark mass dependence agrees with the prediction of lowest-order Chiral Perturbation Theory (ChPT) for quark masses in the range of m ~ m_s/2-2m_s. We present the results of an analysis which assumes lowest-order ChPT to be valid to extract the low-energy constants Sigma and f_P, as well as the strange quark mass. Non-perturbative renormalization is implemented via a matching procedure with data obtained using Wilson fermions in the Schroedinger functional set-up. We find that the scalar condensate computed here agrees with the one obtained previously through a finite-size scaling analysis.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·27 citations
5. 05*

   PJLZ--gauge fixing approach in SU(2) lattice gauge theory

   V.K. Mitrjushkin (JINR, Dubna)🇷🇺 · A.I. Veselov (ITEP, Moscow)🇷🇺

   We study the SU(2) gauge theory with the interpolating gauge {\it a la} Parrinello--Jona-Lasinio--Zwanziger (PJLZ) with the gauge fixing functional $F={\sum }_{x\mu }1/2\text{tr}(U_{x\mu }{\sigma }_3{U}_{x\mu }^{†}{\sigma }_3)$. We find a strong indication of the non--analiticity with respect to the interpolating parameter $\lambda$ at ${\lambda }_c\sim 0.8$.

   hep-latJETP Lett.(2001)·3 citations
6. 06*

   The Schroedinger functional coupling in quenched QCD at low energies

   Jochen Heitger🇩🇪 · Hubert Simma🇩🇪 · Rainer Sommer🇩🇪 · Ulli Wolff🇩🇪

   Existing non-perturbative computations of the running coupling of quenched QCD in the Schroedinger functional scheme are extended to scales mu lying much deeper in the low-energy regime. We are able to reach 1/mu ~ 0.9 fm, where a significant deviation from its perturbative evolution is observed.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·18 citations
7. 07*

   Nonstandard Cutoff Effects in the Nonlinear Sigma Model

   Martin Hasenbusch🇩🇪 · Peter Hasenfratz🇨🇭 · Ferenc Niedermayer🇨🇭 · Bernhard Seefeld🇨🇭 · Ulli Wolff🇩🇪

   High precision measurements of the renormalized zero-momentum 4-point coupling g_R and of the Luscher-Weisz-Wolff running coupling gbar(L) = L*m(L) performed with two different lattice actions in the non-perturbative region confirm the earlier observations, that the cutoff effects look linear, in contrast to perturbative considerations. The use of different actions allows one to make a more reliable estimate on the continuum limit. The measurements were done for infinite volume correlation length up to 350.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·21 citations
8. 08*

   Numerical Quantum Field Theory on the Continuum and a New Look at Perturbation Theory

   P. Emirdag🇺🇸 · R. Easther🇺🇸 · G. S. Guralnik🇺🇸 · S. C. Hahn🇺🇸 · D. Petrov🇺🇸

   The Source Galerkin method finds approximate solutions to the functional differential equations of field theories in the presence of external sources. While developing this process, it was recognized that approximations of the spectral representations of the Green's functions by Sinc function expansions are an extremely powerful calculative tool. Specifically, this understanding makes it not only possible to apply the Source Galerkin method to higher dimensional field theories, but also leads to a new approach to perturbation theory calculations in scalar and fermionic field theories. This report summarizes the methodologies for solving quantum field theories with the Source Galerkin method and for performing perturbation theory calculations using Sinc approximations.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·1 citation
9. 09*

   Study of spatial meson correlators at finite temperature in quenched anisotropic lattice QCD

   K. Nomura🇯🇵 · O. Miyamura🇯🇵 · T. Umeda🇯🇵 · H. Matsufuru🇯🇵

   We analyze the meson correlator in the spatial direction at finite temperature. To achieve fine resolution in the spatial direction, we use an anisotropic lattice with the standard Wilson plaquette gauge action and the $O(a)$ improved Wilson quark action. Below and above $T_c$, properties of correlators are investigated by two methods: fits with ansatz for the spectral function, and direct reconstruction of the spectral function using the maximum entropy method.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·2 citations
10. 10*

    Generalized ensemble algorithm for U(1) gauge theory

    Tetsuya Takaishi🇯🇵

    Hybrid Monte Carlo simulations of the pure compact U(1) gauge theory are performed with the Tsallis weight. The simulations show that the use of the Tsallis weight enhances the tunneling rate between metastable states.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·2 citations
11. 11*

    Topological quantum memory

    Eric Dennis🇺🇸 · Alexei Kitaev🇺🇸 · Andrew Landahl🇺🇸 · John Preskill🇺🇸

    We analyze surface codes, the topological quantum error-correcting codes introduced by Kitaev. In these codes, qubits are arranged in a two-dimensional array on a surface of nontrivial topology, and encoded quantum operations are associated with nontrivial homology cycles of the surface. We formulate protocols for error recovery, and study the efficacy of these protocols. An order-disorder phase transition occurs in this system at a nonzero critical value of the error rate; if the error rate is below the critical value (the accuracy threshold), encoded information can be protected arbitrarily well in the limit of a large code block. This phase transition can be accurately modeled by a three-dimensional Z_2 lattice gauge theory with quenched disorder. We estimate the accuracy threshold, assuming that all quantum gates are local, that qubits can be measured rapidly, and that polynomial-size classical computations can be executed instantaneously. We also devise a robust recovery procedure that does not require measurement or fast classical processing; however for this procedure the quantum gates are local only if the qubits are arranged in four or more spatial dimensions. We discuss procedures for encoding, measurement, and performing fault-tolerant universal quantum computation with surface codes, and argue that these codes provide a promising framework for quantum computing architectures.

    ↳ quant-phcond-mat.stat-mechhep-lathep-thJ.Math.Phys.(2002)·2450 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.