Stephan Güsken

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We illustrate the current status of heavy quark physics on the lattice. Special emphasis is paid to the question of systematic uncertainties and to the connection of lattice computations to continuum physics. Latest results are presented and discussed with respect to the progress in methods, statistical accuracy and reliability.
A parallelizable SSOR preconditioning scheme for Krylov subspace iterative solvers in lattice QCD applications involving Wilson fermions is presented. In actual Hybrid Monte Carlo simulations and quark propagator calculations it helps to reduce the number of iterations by a factor of 2 compared to conventional odd-even preconditioning. This corresponds to a(More)
We present the final analysis of the light and strange hadron spectra from a full QCD lattice simulation with two degenerate dynamical sea quark flavours at β = 5.6 on a 163 × 32 lattice. Four sets of sea quark masses corresponding to the range .69 ≤ mπ/mρ ≤ .83 are investigated. For reference we also ran a quenched simulation at βeff = 6.0, which is the(More)
The computational effort in the calculation of Wilson fermion quark propagators in Lattice Quantum Chromodynamics can be considerably reduced by exploiting the Wilson fermion matrix structure in inversion algorithms based on the non-symmetric Lanczos process. We consider two such methods: QMR (quasi minimal residual) and BCG (biconjugate gradients). Based(More)
Th. Lippert, G. Bali, N. Eicker, L. Giusti, U. Glässner, S. Güsken, H. Hoeber, P. Lacock, G. Martinelli, F. Rapuano, G. Ritzenhöfer, K. Schilling, G. Siegert, A. Spitz, P. Ueberholz, and J. Viehoff HLRZ, c/o Jülich Research Center and DESY, Hamburg, D-52425-Jülich, Germany Physics Department, The University, Southampton SO17 1JB, UK INFN, University “La(More)
The investigation of light sea-quark effects in lattice QCD with dynamical Wilson fermions requires both larger physical volumes and finer lattice resolutions than achieved previously. As high-end supercomputers like the 512-node APE Tower provide the compute power to perform a major step towards the chiral limit (TχL), we have launched a feasibility study(More)
In order to compute physical quantities in lattice quantum chromodynamics huge systems of linear equations have to be solved. The availability of eecient parallel Krylov subspace solvers plays a vital role in the solution of these systems. We present a detailed analysis of the performance of the stabilized biconjugate gradient (BiCGStab) algorithm with(More)
Flavor singlet combinations of quark operators OΓ S = ūΓu+ d̄Γd+ s̄Γs contribute to many important physical observables in the low energy region of QCD. Experimentally one finds the values of some of these observables to be in sharp contrast to the naive (perturbative) theoretical expectations. This indicates that non perturbative vacuum properties might(More)
Disconnected diagrams are expected to be sensitive to the inclusion of dynamical fermions. We present a feasibility study for the observation of such effects on the nucleonic matrix elements of the axial vector current, using SESAM full QCD vacuum configurations with Wilson fermions on 16 × 32 lattices, at β = 5.6. Starting from the standard methods(More)