HEP Lattice·hep-lat

Mon·Sep 13, 2004Monday·September 13, 2004

9 papers—7 primary·2 cross-listed·reconstructed*

01*
A Lattice Formulation of Super Yang-Mills Theories with Exact Supersymmetry
Fumihiko Sugino (Okayama Inst. for Quantum Phys.)🇯🇵
We construct SU( $N$ ) super Yang-Mills theories with extended supersymmetry on hypercubic lattices of various dimensions keeping one or two supercharges exactly. It is based on topological field theory formulation for the super Yang-Mills theories. Gauge fields are represented by compact unitary link variables, and the exact supercharges on the lattice are nilpotent up to gauge transformations. In particular, the lattice models are free from the vacuum degeneracy problem, which was encountered in earlier approaches. Thus, we do not need to introduce any supersymmetry breaking terms, and the exact supersymmetry is preserved wholly in the process of taking the continuum limit. Among the models, we show that the desired continuum theories are obtained without any fine tuning of parameters for the cases $N = 2, 4, 8$ in two-dimensions. Also, the cases $N = 4, 8$ in three-dimensions are investigated, and a problem arising in four-dimensional models is discussed.
hep-lathep-thNucl.Phys.B Proc.Suppl.(2005)·12 citations
02*
Remarks on the discretization of physical momenta in lattice QCD
Nazario Tantalo🇮🇹
The calculation on the lattice of cross--sections, form--factors and decay rates associated to phenomenologically relevant physical processes is complicated by the spatial momenta quantization rule arising from the introduction of limited box sizes in numerical simulations. A method to overcome this problem, based on the adoption of two distinct boundary conditions for two fermions species on a finite lattice, is here discussed and numerical results supporting the physical significance of this procedure are shown.
hep-latNucl.Phys.B Proc.Suppl.(2005)·1 citation
03*
Non-compact QED(3) coupled to a four-fermi interaction
J.B. Kogut🇺🇸 · C.G. Strouthos🇨🇾 · I.N. Tziligakis🇺🇸
We present preliminary numerical results for the three dimensional non-compact QED with a weak four-fermion term in the lattice action. Approaches based on Schwinger-Dyson studies, arguments based on thermodynamic inequalities and numerical simulations lead to estimates of the critical number of fermion flavors (below which chiral symmetry is broken) ranging from $N_{f c} = 1$ to $N_{f c} = 4$ . The weak four-fermion coupling provides the framework for an improved algorithm, which allows us to simulate the chiral limit of massless fermions and expose delicate effects.
hep-latcond-mat.supr-conhep-phNucl.Phys.B Proc.Suppl.(2005)·1 citation
04*
The Quenched Continuum Limit
C. T. H. Davies🇬🇧 · G. P. Lepage🇺🇸 · F. Niedermayer🇨🇭 · D. Toussaint🇺🇸
We show that all current formalisms for quarks in lattice QCD are consistent in the quenched continuum limit, as they should be. We improve on previous extrapolations to this limit, and the understanding of lattice systematic errors there, by using a constrained fit including both leading and sub-leading dependence on a.
hep-latNucl.Phys.B Proc.Suppl.(2005)·12 citations
05*
B Leptonic Decays and B- bar B Mixing with 2+1 Flavors of Dynamical Quarks
A. Gray🇺🇸 · C. Davies🇬🇧 · E. Gulez · G. P. Lepage🇺🇸 · J. Shigemitsu🇺🇸 · M. Wingate🇺🇸
Calculations of B leptonic decays and B- bar B mixing using NRQCD heavy and Asqtad light valence quarks on the MILC dynamical configurations are described. Smearing has been implemented to substantially reduce the statistical errors of the matrix elements needed for the determination of f_B. The four-fermion matrix elements needed for the determination of f_{B_s}^2B_{B_s} have been calculated and a preliminary result is given.
hep-latNucl.Phys.B Proc.Suppl.(2005)·11 citations
06*
Results for light pseudoscalars from three-flavor simulations
MILC Collaboration: C. Aubin🇺🇸 · C. Bernard🇺🇸 · C. DeTar🇺🇸 · Steven Gottlieb🇺🇸 · E.B. Gregory🇺🇸 · Urs M. Heller🇺🇸 · J.E. Hetrick🇺🇸 · J. Osborn🇺🇸 · R.L. Sugar🇺🇸 · D. Toussaint🇺🇸
We compute pseudoscalar meson masses and decay constants in partially quenched QCD with three dynamical flavors of improved staggered quarks. Fitting the lattice data to staggered chiral perturbation theory forms and extrapolating in quark mass and lattice spacing, we find: $f_{π} = 129.5 \pm 0.9 \pm 3.5$ MeV, $f_{K} = 156.6 \pm 1.0 \pm 3.6$ MeV, and $f_{K} / f_{π} = 1.210 (4) (13)$ . The value for $f_{K} / f_{π}$ implies $∣ V_{u s} ∣ = 0.2219 (26)$ . We also obtain $m_{u} / m_{d} = 0.43 (0) (1) (8)$ , or, with more input on electromagnetic effects from the continuum, $m_{u} / m_{d} = 0.41 (0) (1) (4)$ . Using the one-loop perturbative mass renormalization, we determine $m_{u}$ and $m_{d}$ in the MSbar scheme.
hep-lathep-phNucl.Phys.B Proc.Suppl.(2005)·15 citations
07*
QCD on the BlueGene/L Supercomputer
G. Bhanot🇺🇸 · D. Chen🇺🇸 · A. Gara🇺🇸 · J. Sexton🇮🇪 · P. Vranas🇺🇸
In June 2004 QCD was simulated for the first time at sustained speed exceeding 1 TeraFlops in the BlueGene/L supercomputer at the IBM T.J. Watson Research Lab. The implementation and performance of QCD in the BlueGene/L is presented.
hep-latNucl.Phys.B Proc.Suppl.(2005)·2 citations
08*
Renormalized thermodynamics from the 2PI effective action
J. Berges🇩🇪 · Sz. Borsanyi🇩🇪 · U. Reinosa🇦🇹 · J. Serreau🇩🇪
High-temperature resummed perturbation theory is plagued by poor convergence properties. The problem appears for theories with bosonic field content such as QCD, QED or scalar theories. We calculate the pressure as well as other thermodynamic quantities at high temperature for a scalar one-component field theory, solving a three-loop 2PI effective action numerically without further approximations. We present a detailed comparison with the two-loop approximation. One observes a strongly improved convergence behavior as compared to perturbative approaches. The renormalization employed in this work extends previous prescriptions, and is sufficient to determine all counterterms required for the theory in the symmetric as well as the spontaneously broken phase.
↳ hep-phhep-lathep-thnucl-thPRD(2005)·100 citations
09*
Bridges from Lattice QCD to Nuclear Physics
A. M. Green🇫🇮
A review is given of attempts to bridge the gap between everyday particle and nuclear physics - involving many quarks - and the basic underlying theory of QCD that can only be evaluated exactly for few quark systems. Even the latter requires the original theory of QCD to be discretised to give Lattice QCD - but this modification can still yield exact results for the original theory. These LQCD results can then be considered on a similar footing to experimental data - namely as cornerstones that must be fitted by phenomenological models. In this way, the hope is that "QCD inspired" models can become more and more "QCD based" models, by fixing - in the few-quark case where LQCD can be carried out - the form of these models in such a way that they can be extended to multi-quark systems.
↳ nucl-thhep-lathep-ph3 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.