Wed·Oct 17, 2001Wednesday·October 17, 2001

1. 01*

   The Static Potential to O(\alpha^2) in Lattice Perturbation Theory

   Peter Boyle🇬🇧 · Gunnar S Bali🇬🇧

   We present a calculation of Wilson loops, and the static inter-quark potential to $O({\alpha }^2)$ in lattice perturbation theory. This is carried out with the Wilson, Symanzik-Weisz, and Iwasaki gauge actions and the Wilson, Sheikholeslami-Wohlert, and Kogut-Susskind dynamical fermion action for small Wilson loops, and with the Wilson gauge action and each of the dynamical quark actions in the case of the static potential.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·2 citations
2. 02*

   Finite-size scaling of interface free energies in the 3d Ising model

   M. Pepe (Paris-Sud U.)🇫🇷 · Ph. de Forcrand (ETH and CERN)🇨🇭

   We perform a study of the universality of the finite size scaling functions of interface free energies in the 3d Ising model. Close to the hot/cold phase transition, we observe very good agreement with the same scaling functions of the 4d SU(2) Yang--Mills theory at the deconfinement phase transition.

   hep-latcond-matNucl.Phys.B Proc.Suppl.(2002)·20 citations
3. 03*

   Nonperturbative tuning of $O(a^2)$ improved staggered fermions

   Massimo Di Pierro🇺🇸 · Paul Mackenzie🇺🇸

   We perform a nonperturbative tuning of the coefficients in the $O(a^2)$ improved action for staggered fermions. The mass splitting for the pions of different doubler flavor is used as a measure of the symmetry breaking effects introduced by $O(a^2)$ discretization errors. We find that the flavor nondegeneracy can be somewhat reduced but not eliminated by such a tuning, indicating the need for new terms in the action to reduce the nondegeneracy.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·1 citation
4. 04*

   Physical Observables from Lattice QCD at Fixed Topology

   R. Brower🇺🇸 · S. Chandrasekharan🇺🇸 · J. W. Negele🇺🇸 · U.-J. Wiese🇺🇸

   Because present Monte Carol algorithms for lattice QCD may become trapped in a given topological charge sector when one approaches the continuum limit, it is important to understand the effect of calculating at fixed topology. In this work, we show that although the restriction to a fixed topological sector becomes irrelevant in the infinite volume limit, it gives rise to characteristic finite size effects due to contributions from all $\theta$-vacua. We calculate these effects and show how to extract physical results from numerical data obtained at fixed topology.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·3 citations
5. 05*

   Measuring infrared contributions to the QCD pressure

   K. Kajantie (Univ. Helsinki)🇫🇮 · M. Laine (CERN)🇨🇭 · K. Rummukainen (NORDITA)🇸🇪 · Y. Schroder (Univ. Helsinki & MIT)🇫🇮

   For the pressure (or free energy) of QCD, four-dimensional (4d) lattice data is available at zero baryon density up to a few times the critical temperature $T_c$. Perturbation theory, on the other hand, has serious convergence problems even at very high temperatures. In a combined analytical and three-dimensional (3d) lattice method, we show that it is possible to compute the QCD pressure from about $2T_c$ to infinity. The numerical accuracy is good enough to resolve in principle, e.g., logarithmic contributions related to 4-loop perturbation theory.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·8 citations
6. 06*

   Vortex waistlines and vortex gas

   T.G. Kovács (NIC/DESY Zeuthen & Pecs U.)🇩🇪 · E.T. Tomboulis (UCLA)🇺🇸

   We investigate the manner in which a linear potential arises from fluctuations due to vortices linked with the Wilson loop. In particular, the customary naive picture is critically reexamined.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·2 citations
7. 07*

   Status of the QCDOC project

   P.A. Boyle🇬🇧 · D. Chen🇺🇸 · N.H. Christ🇺🇸 · C. Cristian🇺🇸 · Z. Dong🇺🇸 · A. Gara🇺🇸 · B. Joó🇬🇧 · C. Kim🇺🇸 · L. Levkova🇺🇸 · X. Liao🇺🇸 · G. Liu🇺🇸 · R.D. Mawhinney🇺🇸 and 3 other authors

   A status report is given of the QCDOC project, a massively parallel computer optimized for lattice QCD using system-on-a-chip technology. We describe several of the hardware and software features unique to the QCDOC architecture and present performance figures obtained from simulating the current VHDL design of the QCDOC chip with single-cycle accuracy.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·13 citations
8. 08*

   Superconductivity and Chiral Symmetry Breaking with Fermion Clusters

   Shailesh Chandrasekharan🇺🇸

   Cluster variables have recently revolutionized numerical work in certain models involving fermionic variables. This novel representation of fermionic partition functions is continuing to find new applications. After describing results from a study of a two dimensional Hubbard type model that confirm a superconducting transition in the Kosterlitz-Thouless universality class, we show how a cluster type algorithm can be devised to study the chiral limit of strongly coupled lattice gauge theories with staggered fermions.

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

   Chiral property of domain-wall fermion from eigenvalues of 4D Wilson-Dirac Operator

   CP-PACS Collaboration : S. Aoki🇯🇵 · Y. Aoki🇯🇵 · R. Burkhalter🇯🇵 · S. Ejiri🇯🇵 · M. Fukugita🇯🇵 · S. Hashimoto🇯🇵 · N. Ishizuka🇯🇵 · Y. Iwasaki🇯🇵 · T. Izubuchi🇯🇵 · K. Kanaya🇯🇵 · T. Kaneko🇯🇵 · Y. Kuramashi🇯🇵 and 6 other authors

   We investigate a chiral property of the domain-wall fermion (DWF) system using the four-dimensional hermitian Wilson-Dirac operator $H_W$. A formula expressing the Ward-Takahashi identity quark mass $m_{5q}$ with eigenvalues of this operator is derived, which well explains the $N_5$ dependence of $m_{5q}$ observed in previous numerical simulations. We further discuss the chiral property of DWF in the large volume in terms of the spectra of $H_W$.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·7 citations
10. 10*

    Maximum entropy analysis of hadron spectral functions and excited states in quenched lattice QCD

    CP-PACS Collaboration: S. Aoki🇯🇵 · R. Burkhalter🇯🇵 · M. Fukugita🇯🇵 · S. Hashimoto🇯🇵 · N. Ishizuka🇯🇵 · Y. Iwasaki🇯🇵 · K. Kanaya🇯🇵 · T. Kaneko🇯🇵 · Y. Kuramashi🇯🇵 · M. Okawa🇯🇵 · Y. Taniguchi🇯🇵 · A. Ukawa🇯🇵 · T. Yamazaki🇯🇵 · T. Yoshié🇯🇵

    Employing the maximum entropy method we extract the spectral functions from meson correlators at four lattice spacings in quenched QCD with the Wilson quark action. We confirm that the masses and decay constants, obtained from the position and the area of peaks, agree well with the results from the conventional exponential fit. For the first excited state, we obtain $m_{{\pi }_1}=660(590)$ MeV, $m_{{\rho }_1}=1540(570)$ MeV, and $f_{{\rho }_1}=0.085(36)$ in the continuum limit.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·1 citation
11. 11*

    Non-perturbative renormalization for a renormalization group improved gauge action

    CP-PACS Collaboration: S.Aoki🇯🇵 · R.Burkhalter🇯🇵 · M.Fukugita🇯🇵 · S.Hashimoto🇯🇵 · K.Ide🇯🇵 · N.Ishizuka🇯🇵 · Y.Iwasaki🇯🇵 · K.Kanaya🇯🇵 · T.Kaneko🇯🇵 · Y.Kuramashi🇯🇵 · V.Lesk🇯🇵 · M.Okawa🇯🇵 and 3 other authors

    Renormalization constants of vector ($Z_V$) and axial-vector ($Z_A$) currents are determined non-perturbatively in quenched QCD for a renormalization group improved gauge action and a tadpole improved clover quark action using the Schrödinger functional method. Non-perturbative values of $Z_V$ and $Z_A$ turn out to be smaller than the one-loop perturbative values by $O(10$ at $a^{-1}\approx 1$ GeV. A sizable scaling violation of meson decay constants $f_{\pi }$ and $f_{\rho }$ observed with the one-loop renormalization factors remains even with non-perturbative renormalization.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·5 citations
12. 12*

    Charmonium spectrum from quenched QCD on anisotropic lattices

    CP-PACS Collaboration : S. Aoki🇯🇵 · R. Burkhalter🇯🇵 · S. Ejiri🇯🇵 · M. Fukugita🇯🇵 · S. Hashimoto🇯🇵 · N. Ishizuka🇯🇵 · Y. Iwasaki🇯🇵 · K. Kanaya🇯🇵 · T. Kaneko🇯🇵 · Y. Kuramashi🇯🇵 · V. Lesk🇯🇵 · K. Nagai🇯🇵 and 5 other authors

    We present our final results of the charmonium spectrum in quenched QCD on anisotropic lattices. Simulations are made with the plaquette gauge action and a tadpole improved clover quark action employing $\xi =a_s/a_t=3$. We calculate the spectrum of S- and P-states and their excitation, and study the scaling behavior of mass splittings. Comparison is made with the experiment and previous lattice results. The issue of hyperfine splitting for different choices of the clover coefficients obtained by Klassen is discussed.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·2 citations
13. 13*

    QCD spectroscopy with three light quarks

    F. Farchioni🇩🇪 · C. Gebert🇩🇪 · I. Montvay🇩🇪 · W. Schroers🇩🇪

    We report about a simulation using three dynamical Wilson quarks and on the progress in going to small quark masses.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·8 citations
14. 14*

    The Charm Quark Mass to Two-Loop Order

    K.J. Juge🇺🇸

    The truncation of the perturbative series at one loop order for the mass renormalization constants remain a significant systematic uncertainty in the determination of heavy quark masses in lattice QCD. We present here a high beta Monte Carlo calculation of the two loop mass renormalization constant for clover-improved fermions near the charm mass in the Fermilab heavy quark formalism. A preliminary value for the charm quark mass in the MS-bar scheme at two loop order is reported.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·10 citations
15. 15*

    Meson Spectral Functions at finite Temperature

    I. Wetzorke🇩🇪 · F. Karsch🇩🇪 · E. Laermann🇩🇪 · P. Petreczky🇩🇪 · S. Stickan🇩🇪

    The Maximum Entropy Method provides a Bayesian approach to reconstruct the spectral functions from discrete points in Euclidean time. The applicability of the approach at finite temperature is probed with the thermal meson correlation function. Furthermore the influence of fuzzing/smearing techniques on the spectral shape is investigated. We present first results for meson spectral functions at several temperatures below and above $T_c$. The correlation functions were obtained from quenched calculations with Clover fermions on large isotropic lattices of the size $(24-64{)}^3\times 16$. We compare the resulting pole masses with the ones obtained from standard 2-exponential fits of spatial and temporal correlation functions at finite temperature and in the vacuum. The deviation of the meson spectral functions from free spectral functions is examined above the critical temperature.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·72 citations
16. 16*

    Larger physical volume with a noncompact lattice regularization of SU(N) theories

    Giuseppe Di Carlo🇮🇹 · Fabrizio Palumbo🇮🇹 · Roberto Scimia🇮🇹

    Recently it has been found that in a noncompact formulation of the SU(2) gauge theory on a lattice the physical volume is larger than in the Wilson theory with the same number of sites. In its original formulation such noncompact regularization is directly applicable to U(N) theories for any N and to SU(N) theories for N=2 only. In this work we extend it to SU(N) for any N and investigate some of its properties.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·2 citations
17. 17*

    Light Quark Masses with $N_f=2$ Wilson Fermions

    N. Eicker🇩🇪 · Th. Lippert🇩🇪 · B. Orth🇩🇪 · K. Schilling🇩🇪

    We present new data on the mass of the light and strange quarks from SESAM/T$\chi$L. The results were obtained on lattice-volumes of $16^3\times 32$ and $24^3\times 40$ points, with the possibility to investigate finite-size effects. Since the SESAM/T$\chi$L ensembles at $\beta =5.6$ have been complemented by configurations with $\beta =5.5$, moreover, we are now able to attempt the continuum extrapolation (CE) of the quark masses with standard Wilson fermions.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·14 citations
18. 18*

    't Hooft loops and consistent order parameters for confinement

    Philippe de Forcrand (1)🇨🇭 · Lorenz von Smekal (2) ((1) ETH Zurich and CERN, (2) University Erlangen-Nuremberg)🇩🇪

    We study ratios of partition functions in two types of sectors of SU(2), with fixed temporal center flux and with static fundamental charge. Both can be used as bona fide order parameters for the deconfinement transition.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·26 citations
19. 19*

    Application of Maximum Entropy Method to Dynamical Fermions

    Jonathan Clowser🇬🇧 · Costas Strouthos (Univ. of Wales Swansea)🇬🇧

    The Maximum Entropy Method is applied to dynamical fermion simulations of the (2+1)-dimensional Nambu-Jona-Lasinio model. This model is particularly interesting because at T=0 it has a broken phase with a rich spectrum of mesonic bound states and a symmetric phase where there are resonances, and hence the simple pole assumption of traditional fitting procedures breaks down. We present results extracted from simulations on large lattices for the spectral functions of the elementary fermion, the pion, the sigma, the massive pseudoscalar meson and the symmetric phase resonances.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·5 citations
20. 20*

    Evidence for a BKT transition and a pseudogap phase in three-dimensional Gross-Neveu model at nonzero temperature

    Costas Strouthos (Univ. of Wales Swansea)🇬🇧

    We present results from Monte Carlo simulations of the three-dimensional Gross-Neveu model with a U(1) chiral symmetry at nonzero temperature. We provide evidence that the model undergoes a Berezinskii-Kosterlitz-Thouless transition in accordance with the dimensional reduction scenario. We also identify a regime in the high temperature phase in which the fermions acquire nonzero dynamical mass, analogous to the pseudogap behaviour observed in cuprate superconductors.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·1 citation
21. 21*

    Testing Dimensional Reduction in SU(2) Gauge Theory

    Slavo Kratochvila (ETH Zurich)🇨🇭 · Philippe de Forcrand (ETH Zurich and CERN)🇨🇭

    At high temperature, every $(d+1)$-dimensional theory can be reformulated as an effective theory in $d$ dimensions. We test the numerical accuracy of this Dimensional Reduction for (3+1)-dimensional SU(2) by comparing perturbatively determined effective couplings with lattice results as the temperature is progressively lowered. We observe an increasing disagreement between numerical and perturbative values from $T=4T_c$ downwards, which may however be due to somewhat different implementations of dimensional reduction in the two cases.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·3 citations
22. 22*

    Finite temperature phase transition, adjoint Polyakov loop and topology in SU(2) LGT

    A Barresi🇩🇪 · G. Burgio🇩🇪 · M. Muller-Preussker🇩🇪

    We investigate the phase structure of pure SU(2) LGT at finite temperature in the mixed fundamental and adjoint representation modified with a Z2 monopole chemical potential. The decoupling of the finite temperature phase transition from unphysical zero temperature bulk phase transitions is analyzed with special emphasis on the continuum limit. The possible relation of the adjoint Polyakov loop to an order parameter for the finite temperature phase transition and to the topological structure of the theory is discussed.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·15 citations
23. 23*

    Some remarks on O(a) improved twisted mass QCD

    Roberto Frezzotti🇮🇹 · Stefan Sint🇨🇭

    Twisted mass QCD (tmQCD) has been introduced as a solution to the problem of unphysical fermion zero modes in lattice QCD with quarks of the Wilson type. We here argue that O(a) improvement of the tmQCD action and simple quark bilinear operators can be more economical than in the standard framework. In particular, an improved and renormalized estimator of the pion decay constant in two-flavour QCD is available, given only the Sheikholeslami-Wohlert coefficient c_sw and an estimate of the critical mass m_c.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·29 citations
24. 24*

    Hadronic Correlators from All-point Quark Propagators

    A. Duncan🇺🇸 · E. Eichten🇺🇸 · J. Yoo🇺🇸

    A method for computing all-point quark propagators is applied to a variety of processes of physical interest in lattice QCD. The method allows, for example, efficient calculation of disconnected parts and full momentum-space 2 and 3 point functions. Examples discussed include: extraction of chiral Lagrangian parameters from current correlators, the pion form factor, and the unquenched eta-prime.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·3 citations
25. 25*

    Calculation of $K\to \pi \pi$ decay amplitudes from $K\to \pi$ matrix elements in quenched domain-wall QCD

    CP-PACS Collaboration: S.Aoki🇯🇵 · Y.Aoki🇯🇵 · R.Burkhalter🇯🇵 · S.Ejiri🇯🇵 · M.Fukugita🇯🇵 · S.Hashimoto🇯🇵 · N.Ishizuka🇯🇵 · Y.Iwasaki🇯🇵 · T.Izubuchi🇯🇵 · K.Kanaya🇯🇵 · T.Kaneko🇯🇵 · Y.Kuramashi🇯🇵 and 7 other authors

    We present a calculation of the $K\to \pi \pi$ decay amplitudes from the $K\to \pi$ matrix elements using leading order relations derived in chiral perturbation theory. Numerical simulations are carried out in quenched QCD with the domain-wall fermion action and the renormalization group improved gluon action. Our results show that the I=2 amplitude is reasonably consistent with experiment whereas the I=0 amplitude is sizably smaller. Consequently the $\Delta I=1/2$ enhancement is only half of the experimental value, and ${ϵ}^{\prime }/ϵ$ is negative.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·9 citations
26. 26*

    Hadron Spectrum for Quenched Domain-Wall Fermions with DBW2 Gauge Action

    Yasumichi Aoki · RBC collaboration

    We investigate basic physical quantities for quenched simulation with domain-wall fermions and the DBW2 gauge action. Masses and decay constant of pseudoscalar mesons are measured. Scaling properties are tested.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·10 citations
27. 27*

    Re $A_0$ and Re $A_2$ from Quenched Lattice QCD

    Calin R. Cristian · RBC Collaboration

    We have used domain wall fermions to calculate $K\to \pi$ and $K\to 0$ matrix elements which can be used to study the $\Delta I=1/2$ rule for K decays in the Standard Model. Nonlinearities in the $\Delta I=3/2$ matrix elements due to chiral logarithms are explored and the subtractions needed for the $\Delta I=1/2$ matrix elements are discussed. Using renormalization factors calculated using non-perturbative renormalization then yields values for real $A_0$ and $A_2$. We present the details of our quenched $16^3\times 32\times 16$, $\beta =6.0$, $M_5=1.8$ simulation, where a previous calculation showed that the finite $L_s$ chiral symmetry breaking effects are small ($m_{\mathrm{res}}\approx 4\mathrm{MeV}$).

    hep-latNucl.Phys.B Proc.Suppl.(2002)·2 citations
28. 28*

    1/M correction to quenched QCD with non-zero baryon density

    Gert Aarts🇩🇪 · Olaf Kaczmarek🇩🇪 · Frithjof Karsch🇩🇪 · Ion-Olimpiu Stamatescu🇩🇪

    We study the \kappa^2 corrections to the quenched limit of \mu>0 QCD. We use an improved reweighting procedure.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·22 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.