Thu·Sep 2, 2004Thursday·September 2, 2004

1. 01*

   On-shell improvement of the massive Wilson quark action

   S. Aoki🇯🇵 · Y. Kayaba🇯🇵 · Y. Kuramashi🇯🇵 · N. Yamada🇺🇸

   We review a relativistic approach to the heavy quark physics in lattice QCD by applying a relativistic $O(a)$ improvement to the massive Wilson quark action on the lattice. After explaining how power corrections of $m_{Q}a$ can be avoided and remaining uncertainties are reduced to be of order $(a{\Lambda }_{\mathrm{QCD}}{)}^2$, we demonstrate a determination of four improvement coefficients in the action up to one-loop level in a mass dependent way. We also show a perturbative determination of mass dependent renormalization factors and $O(a)$ improvement coefficients for the vector and axial vector currents. Some preliminary results of numerical simulations are also presented.

   hep-lat2 citations
2. 02*

   Finite size mass shift formula for stable particles revisited

   Yoshiaki Koma🇩🇪 · Miho Koma🇩🇪

   Luescher's finite size mass shift formula in a periodic finite volume, involving forward scattering amplitudes in the infinite volume, is revisited for the two stable distinguishable particle system. The generalized mass shift formulae for the boson and fermion are derived in the boson-boson and fermion-boson systems, respectively. The nucleon mass shift is discussed in the nucleon-pion system.

   hep-latNucl.Phys.B Proc.Suppl.(2005)·6 citations
3. 03*

   The Chroma Software System for Lattice QCD

   Robert G. Edwards🇺🇸 · Balint Joo🇬🇧

   We describe aspects of the Chroma software system for lattice QCD calculations. Chroma is an open source C++ based software system developed using the software infrastructure of the US SciDAC initiative. Chroma interfaces with output from the BAGEL assembly generator for optimised lattice fermion kernels on some architectures. It can be run on workstations, clusters and the QCDOC supercomputer.

   hep-latNucl.Phys.B Proc.Suppl.(2005)·1136 citations
4. 04*

   Unquenched simulations with N_f=2 light quark flavours

   qq+q Collaboration · F. Farchioni · I. Montvay · E. Scholz

   The quark mass dependence of meson masses and decay constants in N_f=2 QCD is studied at a fixed gauge coupling with different dynamical quark masses. Partially Quenched Wilson Chiral Perturbation Theory (PQWchiPT) is applied to obtain the extrapolation to zero quark mass. It is shown, that in our analysis NNLO-terms play a more important role than O(a)-terms, which can be neglected. Also we compare our results with recent CP-PACS results.

   hep-latNucl.Phys.B Proc.Suppl.(2005)·1 citation
5. 05*

   Cutoff-effects in the spectrum of dynamical Wilson fermions

   M. Della Morte🇩🇪 · R. Hoffmann🇩🇪 · F. Knechtli🇩🇪 · U. Wolff🇩🇪

   We investigate the low-lying eigenvalues of the improved Wilson-Dirac operator in the Schroedinger functional with two dynamical quark flavors. At a lattice spacing of approximately 0.1 fm we find more very small eigenvalues than in the quenched case. These cause problems with HMC-type algorithms and in the evaluation of fermionic correlation functions. Through a simulation at a finer lattice spacing we are able to establish their nature as cutoff-effects

   hep-latNucl.Phys.B Proc.Suppl.(2005)·2 citations
6. 06*

   Twisted-mass QCD, O(a) improvement and Wilson chiral perturbation theory

   Sinya Aoki🇯🇵 · Oliver Baer

   We point out a caveat in the proof for automatic O(a) improvement in twisted mass lattice QCD at maximal twist angle. With the definition for the twist angle previously given by Frezzotti and Rossi, automatic O(a) improvement can fail unless the quark mass satisfies m_q >> a^2 Lambda_QCD^3. We propose a different definition for the twist angle which does not require a restriction on the quark mass for automatic O(a) improvement. In order to illustrate explicitly automatic O(a) improvement we compute the pion mass in the corresponding chiral effective theory. We consider different definitions for maximal twist and show explicitly the absence or presence of the leading O(a) effect, depending on the size of the quark mass.

   hep-latPRD(2004)·90 citations
7. 07*

   Are there Local Minima in the Magnetic Monopole Potential in Compact QED?

   H. Bozkaya🇦🇹 · M. Faber🇦🇹 · P. Koppensteiner🇦🇹 · M. Pitschmann🇦🇹

   We investigate the influence of the granularity of the lattice on the potential between monopoles. Using the flux definition of monopoles we introduce their centers of mass and are able to realize continuous shifts of the monopole positions. We find periodic deviations from the $1/r$-behavior of the monopole-antimonopole potential leading to local extrema. We suppose that these meta-stabilities may influence the order of the phase transition in compact QED.

   hep-latInt.J.Mod.Phys.A(2004)·2 citations
8. 08*

   Next-to-Leading-Order Staggered Chiral Perturbation Theory

   Stephen R. Sharpe🇺🇸 · Ruth S. Van de Water🇺🇸

   We have extended staggered chiral perturbation theory to O(a^2 p^2), O(a^4), and O(a^2 m), the orders necessary for a full next-to-leading order calculation of pseudo-Goldstone boson masses and decay constants including taste-symmetry violations. We present predictions relating SO(4) taste-breaking splittings in masses, pseudoscalar decay constants, and dispersion relations. These can be used to test the fourth-root trick.

   hep-latNucl.Phys.B Proc.Suppl.(2005)·0 citations
9. 09*

   Singlet Free Energies of a Static Quark-Antiquark Pair

   Konstantin Petrov🇺🇸

   We study the singlet part of the free energy of a static quark anti-quark pair at finite temperature in three flavor QCD with degenerate quark masses using $N_{\tau }=4$ and 6 lattices with Asqtad staggered fermion action. We look at thermodynamics of the system around phase transition and study its scaling with lattice spacing and quark masses.

   hep-lat0 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.