Thu·Sep 16, 2004Thursday·September 16, 2004

1. 01*

   Topological Charge Membranes in 2D and 4D Gauge Theory

   H. Thacker🇺🇸 · S. Ahmad🇺🇸 · J. Lenaghan🇺🇸

   Local topological charge structure in the 2D CP(N-1) sigma models is studied using the overlap Dirac operator. Long-range coherence of topological charge along locally 1D regions in 2D space-time is observed. We discuss the connection between these results and the recent discovery of coherent 3D sheets of topological charge in 4D QCD. In both cases, coherent regions of topological charge form along surfaces of approximmate codimension 1.

   hep-latNucl.Phys.B Proc.Suppl.(2005)·3 citations
2. 02*

   Baryonic sources using irreducible representations of the double-covered octahedral group

   LHP Collaboration: S. Basak🇺🇸 · R. Edwards🇺🇸 · R. Fiebig🇺🇸 · G. T. Fleming🇺🇸 · U. M. Heller🇺🇸 · C. Morningstar🇺🇸 · D. Richards🇺🇸 · I. Sato🇺🇸 · S. Wallace🇺🇸

   Irreducible representations (IRs) of the double-covered octahedral group are used to construct lattice source and sink operators for three-quark baryons. The goal is to achieve a good coupling to higher spin states as well as ground states. Complete sets of local and nonlocal straight-link operators are explicitly shown for isospin 1/2 and 3/2 baryons. The orthogonality relations of the IR operators are confirmed in a quenched lattice simulation.

   hep-latNucl.Phys.B Proc.Suppl.(2005)·5 citations
3. 03*

   Pion form factor using domain wall valence and asqtad sea quarks

   LHP Collaboration: George T. Fleming (1 and 2)🇺🇸 · Frederic D. R. Bonnet (2 and 3)🇨🇦 · Robert G. Edwards (1)🇺🇸 · Randy Lewis (3)🇨🇦 · David G. Richards (1) ((1) Jefferson Lab, (2) Yale University, (3) University of Regina)🇺🇸

   We compute the pion electromagnetic form factor in a hybrid calculation with domain wall valence quarks and improved staggered (asqtad) sea quarks. This method can easily be extended to rho-to-gamma-pi transition form factors.

   hep-latnucl-exnucl-thNucl.Phys.B Proc.Suppl.(2005)·5 citations
4. 04*

   Analysis of $N^{\star }$ spectra using matrices of correlation functions based on irreducible baryon operators

   LHP Collaboration: S. Basak🇺🇸 · I. Sato🇺🇸 · S. Wallace (UMD)🇺🇸 · R. Edwards🇺🇸 · G.T. Fleming🇺🇸 · D. Richards (JLab)🇺🇸 · R. Fiebig (FIU)🇺🇸 · U.M. Heller (APS)🇺🇸 · C. Morningstar (CMU)🇺🇸

   We present results for ground and excited-state nucleon masses in quenched lattice QCD using anisotropic lattices. Group theoretical constructions of local and nonlocal straight-link irreducible operators are used to obtain suitable sources and sinks. Matrices of correlation functions are diagonalized to determine the eigenvectors. Both chi-square fitting and Bayesian inference with an entropic prior are used to extract masses from the correlation functions in a given channel. We observe clear separation of the excited state masses from the ground state mass. States of spin >= 5/2 have been isolated by use of G_2 operators.

   hep-latNucl.Phys.B Proc.Suppl.(2005)·11 citations
5. 05*

   Confinement from Instantons or Merons

   J. W. Negele🇺🇸 · F. Lenz🇩🇪 · M. Thies🇩🇪

   In contrast to ensembles of singular gauge instantons, which are well known to fail to produce confinement, it is shown that effective theories based on ensembles of merons or regular gauge instantons do produce confinement. Furthermore, when the scale is set by the string tension, the action density, topological susceptibility, and glueball masses are similar to those arising in lattice QCD.

   hep-latNucl.Phys.B Proc.Suppl.(2005)·27 citations
6. 06*

   Status of International Lattice Data Grid -- An Overview --

   Akira Ukawa🇯🇵

   We report on the status of the International Lattice Data Grid.

   hep-latNucl.Phys.B Proc.Suppl.(2005)·11 citations
7. 07*

   Non-perturbative determination of heavy quark action coefficients

   Huey-Wen Lin🇺🇸

   We propose to determine the coefficients in the Fermilab heavy quark action by matching the finite-volume, off-shell, gauge-fixed propagator and vertex functions with those determined in the exact, relativistic theory. The matching relativistic amplitudes may be determined either from short-distance perturbation theory or from finite-volume step-scaling recursion. Tree-level matching and non-perturbative off-shell amplitudes are presented.

   hep-latNucl.Phys.B Proc.Suppl.(2005)·3 citations
8. 08*

   Charmed meson spectra and decay constants with one-loop $O(a)$ improved relativistic heavy quark action

   Y. Kayaba🇯🇵 · S. Aoki🇯🇵 · M. Fukugita🇯🇵 · K-I. Ishikawa🇯🇵 · Y. Iwasaki🇯🇵 · K. Kanaya🇯🇵 · T. Kaneko🇯🇵 · Y. Kuramashi🇯🇵 · M. Okawa🇯🇵 · A. Ukawa🇯🇵 · T. Yoshié🇯🇵

   We calculate charmed meson spectra and decay constants in lattice QCD employing one-loop $O(a)$ improved heavy quark action and axial-vector currents. In quenched simulations at $a\sim 0.1$ fm with the plaquette gauge action as well as a renormalization-group improved one, it is shown that the deviation from the continuum dispersion relation and the violation of space-time symmetry for the pseudoscalar meson decay constants are substantially reduced, once the $O(a)$ improvement is applied. Preliminary results with two flavors of dynamical quarks are also presented.

   hep-latNucl.Phys.B Proc.Suppl.(2005)·8 citations
9. 09*

   Excited S- and P-wave B mesons from the lattice

   J. Koponen · for UKQCD Collaboration

   The energies of different angular momentum states of a heavy-light meson were measured on a lattice in Michael and Peisa, Phys. Rev. D 58, 34506 (1998). We have now repeated this study using several different lattices, quenched and unquenched, that have different physical lattice sizes, clover coefficients and quark-gluon couplings. The heavy quark is taken to be infinitely heavy, whereas the light quark mass is approximately that of the strange quark. By interpolating and extrapolating in the light quark mass we can thus compare the lattice results with B and B_s meson experiments. Most interesting is the lowest P-wave B_s state, since it is possible that it lies below the $BK$ threshold and hence is very narrow. Unfortunately, there are no experimental results on P-wave B or B_s mesons available at present. In addition to the energy spectrum, we measured earlier also vector (charge) and scalar (matter) radial distributions of the light quark in the S-wave states of a heavy-light meson on a lattice (Phys. Rev. D 65, 014512 (2002) and Eur. Phys. J. C 28, 79 (2003)). Now we are extending the study of radial distributions to P-wave states.

   hep-latNucl.Phys.B Proc.Suppl.(2005)·2 citations
10. 10*

    The heavy quark's self energy from moving NRQCD on the lattice

    A. Dougall🇬🇧 · C. T. H. Davies🇬🇧 · K. M. Foley🇺🇸 · G. P. Lepage🇺🇸

    We present a calculation of the heavy quark's self energy in moving NRQCD to one-loop in perturbation theory. Results for the energy shift and external momentum renormalisation are discussed and compared with non-perturbative results. We show that the momentum renormalisation is small, which is the result of a remnant of re-parameterisation invariance on the lattice.

    hep-latNucl.Phys.B Proc.Suppl.(2005)·6 citations
11. 11*

    The charm quark mass with dynamical fermions

    UKQCD Collaboration · A. Dougall · C.M. Maynard · C. McNeile

    We compute the charm quark mass in lattice QCD and compare different formulations of the heavy quark, and quenched data to that with dynamical sea quarks. We take the continuum limit of the quenched data by extrapolating from three different lattice spacings, and compare to data with two flavours of dynamical sea quarks with a mass around the strange at the coarsest lattice spacing. Both the FNAL and ALPHA formalism are used. We find the different heavy quark formulations have the same continuum limit in the quenched approximation, and limited evidence that this approximation overestimates the charm quark mass.

    hep-latNucl.Phys.B Proc.Suppl.(2005)·5 citations
12. 12*

    A precise determination of the Bc mass from dynamical lattice QCD

    I. F. Allison🇬🇧 · C.T.H Davies🇬🇧 · A.Gray🇺🇸 · A.S. Kronfeld🇺🇸 · P.B. Mackenzie🇺🇸 · J.N. Simone🇺🇸

    We perform a precise calculation of the mass of the B_c meson using unquenched configurations from the MILC collaboration including 2+1 flavours of improved staggered quarks. Lattice NRQCD and the Fermilab formalism are used to describe the b and c quarks respectively. We find the mass of the B_c meson to be 6.304(16) GeV

    hep-latNucl.Phys.B Proc.Suppl.(2005)·19 citations
13. 13*

    Non-perturbative tests of HQET in small-volume quenched QCD

    Jochen Heitger🇩🇪 · Andreas Juttner🇩🇪 · Rainer Sommer🇩🇪 · Jan Wennekers🇩🇪

    We quantitatively investigate the quark mass dependence of current matrix elements and energies, calculated over a wide range of quark masses in the continuum limit of small-volume quenched lattice QCD. By a precise comparison of these observables as functions of the heavy quark mass with the predictions of HQET we are able to verify that their large quark mass behaviour is described by the effective theory.

    hep-latNucl.Phys.B Proc.Suppl.(2005)·0 citations
14. 14*

    Twisted N=2 exact SUSY on the lattice for BF and Wess-Zumino

    Alessandro D'Adda🇮🇹 · Issaku Kanamori🇯🇵 · Noboru Kawamoto🇯🇵 · Kazuhiro Nagata🇯🇵

    We formulate exact supersymmetric models on a lattice. We introduce noncommutativity to ensure the Leibniz rule. With the help of superspace formalism, we give supertransformations which keep the N=2 twisted SUSY algebra exactly. The action is given as a product of (anti)chiral superfields on the lattice. We present BF and Wess-Zumino models as explicit examples of our formulation. Both models have exact N=2 twisted SUSY in 2 dimensional space at a finite lattice spacing. In component fields, the action has supercharge exact form.

    hep-latNucl.Phys.B Proc.Suppl.(2005)·24 citations
15. 15*

    Group-theoretical construction of extended baryon operators

    S.Basak🇺🇸 · R.Edwards🇺🇸 · R.Fiebig🇺🇸 · G.T.Fleming🇺🇸 · U.M.Heller🇺🇸 · C.Morningstar🇺🇸 · D.Richards🇺🇸 · I.Sato🇺🇸 · S.Wallace🇺🇸

    The design and implementation of large sets of spatially extended baryon operators for use in lattice simulations are described. The operators are constructed to maximize overlaps with the low-lying states of interest, while minimizing the number of sources needed in computing the required quark propagators.

    hep-latNucl.Phys.B Proc.Suppl.(2005)·8 citations
16. 16*

    Eigenvalue correlations in QCD with a chemical potential

    James C. Osborn🇺🇸

    We discuss a new Random Matrix Model for QCD with a chemical potential that is based on the symmetries of the Dirac operator and can be solved exactly for all eigenvalue correlations for any number of flavors. In the microscopic limit of small energy levels the results should be an accurate description of QCD. This new model can also be scaled so that all physical observables remain at their $\mu =0$ values until a first order chiral restoration transition is reached. This gives a more realistic model for the QCD phase diagram than previous RMM. We also mention how the model might aid in determining the phase diagram of QCD from future numerical simulations.

    hep-latNucl.Phys.B Proc.Suppl.(2005)·2 citations
17. 17*

    Phenomenology of static-light mesons from unquenched lattice QCD calculations

    UKQCD Collaboration: Craig McNeile🇬🇧 · Chris Michael🇬🇧 · Gavin Thompson🇬🇧

    We present results for the static-light meson from unquenched lattice QCD. The unquenched gauge configurations were generated using the non-perturbatively improved clover action. At the fixed lattice spacing of 0.1 fm the lightest sea quark mass used is a third of the strange quark mass. A comparison is made between heavy-light chiral perturbation theory and the f_B^(static) decay constant. The mass of the bottom quark is also reported: m_b(m_b) = 4.25(2)(11) GeV, where the first error is statistical and the last error is the systematic uncertainty.

    hep-latNucl.Phys.B Proc.Suppl.(2005)·0 citations
18. 18*

    Effects of large field cutoffs in scalar and gauge models

    L. Li🇺🇸 · Y. Meurice🇺🇸

    We discuss the notion of a large field cutoff for lattice gauge models with compact groups. We propose and compare gauge invariant and gauge dependent (in the Landau gauge) criteria to sort the configurations into ``large-field'' and ``small-field'' configurations. We show that the correlations between volume average of field size indicators and the behavior of the tail of the distribution are very different in the gauge and scalar cases. We show that the effect of discarding the large field configurations on the plaquette average is very different above, below and near beta=5.6 for a pure SU(3) LGT.

    hep-latNucl.Phys.B Proc.Suppl.(2005)·4 citations
19. 19*

    Three Flavor QCD at High Temperatures

    The MILC Collaboration: C. Bernard🇺🇸 · T. Burch🇩🇪 · C. DeTar🇺🇸 · Steven Gottlieb🇺🇸 · E.B. Gregory🇺🇸 · U.M. Heller🇺🇸 · J. Osborn🇺🇸 · R.L. Sugar🇺🇸 · D. Toussaint🇺🇸

    We have continued our study of the phase diagram of high temperature QCD with three flavors of improved staggered quarks. We are performing simulations with three degenerate quarks with masses less than or equal to the strange quark mass m_s and with degenerate up and down quarks with masses m_{u,d} less than the strange quark mass. For the quark masses studied to date, we find a crossover that strengthens as m_{u,d} decreases, rather than a bona fide phase transition. We present new results for the crossover temperature extrapolated to the physical value of m_{u,d}, and for quark number susceptibilities.

    hep-latNucl.Phys.B Proc.Suppl.(2005)·6 citations
20. 20*

    Glueball Regge trajectories and the Pomeron -- a lattice study --

    Harvey B. Meyer🇬🇧 · Michael J. Teper🇬🇧

    We perform lattice calculations of the lightest J=0,2,4,6 glueball masses in the D=3+1 SU(3) gauge theory and extrapolate to the continuum limit. Assuming that these masses lie on linear Regge trajectories we find a leading glueball trajectory alpha(t)=0.93(24) + 0.28(2)alpha'_R t, where alpha'_R ~ 0.9 GeV^{-2} is the slope of the usual mesonic Regge trajectory. This glueball trajectory has an intercept and slope similar to that of the Pomeron trajectory. We contrast this with the situation in D=2+1 where the leading glueball Regge trajectory is found to have too small an intercept to be important for high-energy cross-sections. We interpret the observed states and trajectories in terms of open and closed string models of glueballs. We discuss the large-N limit and perform an SU(8) calculation that hints at new states based on closed strings in higher representations.

    ↳ hep-phhep-lathep-thPLB(2005)·170 citations
21. 21*

    Chiral Symmetry Breaking in QCD

    Yu.A.Simonov🇷🇺

    Chiral Symmetry Breaking (CSB) is derived in QCD starting from the QCD Lagrangian and using Field Correlators Method (FCM). The kernel in the resulting equations responsible for CSB is directly connected to confinement, and therefore both phenomena occur and vanish together as supported by lattice data. Chiral Lagrangian and quark-meson Lagrangian are derived with explicit coefficients and compared to standard expressions. Spectrum of Nambu-Goldstone mesons and their radial excitations is calculated in good agreement with experiment.

    ↳ hep-phhep-lathep-th2 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.