Tue·Oct 16, 2001Tuesday·October 16, 2001

1. 01*

   A Two-Dimensional Lattice Model with Exact Supersymmetry

   S. Catterall🇺🇸 · S. Karamov🇺🇸

   Starting from a simple discrete model which exhibits a supersymmetric invariance we construct a local, interacting, two-dimensional Euclidean lattice theory which also admits an exact supersymmetry. This model is shown to correspond to the Wess-Zumino model with extended N=2 supersymmetry in the continuum. We have performed dynamical fermion simulations to check the spectrum and supersymmetric Ward identities and find good agreement with theory.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·32 citations
2. 02*

   Heavy-light decay constants with three dynamical flavors

   C. Bernard🇺🇸 · T. Burch🇺🇸 · S. Datta🇺🇸 · T. DeGrand🇺🇸 · C. DeTar🇺🇸 · Steven Gottlieb🇺🇸 · Urs M. Heller🇺🇸 · K. Orginos🇺🇸 · R. Sugar🇺🇸 · D. Toussaint🇺🇸

   We present preliminary results for the heavy-light leptonic decay constants in the presence of three light dynamical flavors. We generate dynamical configurations with improved staggered and gauge actions and analyze them for heavy-light physics with tadpole improved clover valence quarks. When the scale is set by $m_{\rho }$, we find an increase of approximately 23% in $f_B$ with three dynamical flavors over the quenched case. Discretization errors appear to be small (of order 3% or less) in the quenched case but have not yet been measured in the dynamical case.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·15 citations
3. 03*

   Continuum versus periodic lattice Monte Carlo approach to classical field theory

   Bogdan Mihaila🇺🇸 · John F. Dawson🇺🇸

   We compare the momentum space with the standard periodic lattice approach to Monte Carlo calculations in classical ${\varphi }^4$ field theory. We show that the mismatch in the initial value of ${\varphi }_{\text{cl}}^2(t)$, results in a shift in the ``thermalized'' value, at large times. The two approaches converge to the same result in the continuum limit.

   hep-latPRD(2002)·3 citations
4. 04*

   Chiral properties of domain wall fermions with improved gauge actions

   Konstantinos Orginos · RBC Collaboration

   We study the chiral properties of quenched domain wall fermions with several gauge actions. We demonstrate that the nearly translationally invariant modes in the fifth dimension that dominate the residual mass for Wilson gauge action can be substantially suppressed using improved gauge actions. In particular, we study the Symanzik action, the Iwasaki action, the DBW2 action and compare them to the Wilson action.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·31 citations
5. 05*

   Kaon Matrix Elements and CP-violation from Quenched Lattice QCD: (I) the 3-flavor case

   T. Blum · P. Chen · N. Christ · C. Cristian · C. Dawson · G. Fleming · R. Mawhinney · S. Ohta · G. Siegert · A. Soni · P. Vranas · M. Wingate and 3 other authors

   We report the results of a calculation of the K --> pi pi matrix elements relevant for the $\text{DIhalf}$ rule and $\text{epe}$ in quenched lattice QCD using domain wall fermions at a fixed lattice spacing $a^{-1}\sim 2$ GeV. Working in the three-quark effective theory, where only the u, d and s quarks enter and which is known perturbatively to next-to-leading order, we calculate the lattice K --> pi and K --> |0> matrix elements of dimension six, four-fermion operators. Through lowest order chiral perturbation theory these yield K --> pi pi matrix elements, which we then normalize to continuum values through a non-perturbative renormalization technique. For the ratio of isospin amplitudes |A_0|/|A_2| we find a value of $25.3\pm 1.8$ (statistical error only) compared to the experimental value of 22.2, with individual isospin amplitudes 10-20% below the experimental values. For $\text{epe}$, using known central values for standard model parameters, we calculate $(-4.0\pm 2.3)\times 10^{-4}$ (statistical error only) compared to the current experimental average of $(17.2\pm 1.8)\times 10^{-4}$. Because we find a large cancellation between the I = 0 and I = 2 contributions to $\text{epe}$, the result may be very sensitive to the approximations employed. Among these are the use of: quenched QCD, lowest order chiral perturbation theory and continuum perturbation theory below 1.3 GeV. We have also calculated the kaon B parameter, B_K and find $B_{K,\overline{MS}}(2\mathrm{GeV})=0.532(11)$. Although currently unable to give a reliable systematic error, we have control over statistical errors and more simulations will yield information about the effects of the approximations on this first-principles determination of these important quantities.

   hep-lathep-phPRD(2003)·236 citations
6. 06*

   Efficient computation of low-lying eigenmodes of non-Hermitian Wilson-Dirac type matrices

   H. Neff🇩🇪

   A polynomial transformation for non-Hermitian matrices is presented, which provides access to wedge-shaped spectral windows. For Wilson-Dirac type matrices this procedure not only allows the determination of the physically interesting low-lying eigenmodes but also provides a substantial acceleration of the eigenmode algorithm employed.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·9 citations
7. 07*

   A New Approach to eta' on the Lattice

   K. Schilling🇩🇪 · H. Neff🇩🇪 · N. Eicker🇩🇪 · Th. Lippert🇩🇪 · J.W. Negele🇺🇸

   We perform an eta' mass analysis based on a total of 1130 dynamical gauge field configurations, with 5 different quark mass values on lattices of size 16^3*32 (SESAM) and 24^3*40 (TkL) at beta = 5.6. We employ the stochastic estimator technique and spectral methods to deal with the disconnected piece of the flavour singlet correlation function. We demonstrate that very early plateau formation in the local eta' mass can be achieved by first ground state projecting the connected piece of its correlator.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·6 citations
8. 08*

   The Berry Phase and Monopoles in Gluodynamics

   F.V. Gubarev🇷🇺 · V.I. Zakharov🇩🇪

   We introduce a gauge invariant definition of a monopole on the lattice. The construction is based on the observation that for each Wilson loop there exists an extra U(1) group which leaves the loop invariant. Since the lattice formulation utilizes the language of Wilson loops, the definition of the monopole charge in terms of this plaquette dependent U(1) is gauge invariant. The explicit construction of gauge invariant monopoles is presented both in continuum and on the lattice.

   hep-latNucl.Phys.B Proc.Suppl.(2002)·2 citations
9. 09*

   A Simulation of the 't Hooft Model at finite N_c with the Overlap Dirac Operator

   F. Berruto🇺🇸 · L. Giusti🇺🇸 · C. Hoelbling🇺🇸 · C. Rebbi🇺🇸

   We present some results of a numerical investigation of the 't Hooft model with 2,3 and 4 colors, regularized on the lattice with overlap fermions.

   hep-lathep-thNucl.Phys.B Proc.Suppl.(2002)·1 citation
10. 10*

    Aspects of the thermal phase transition of QCD with small chemical potential

    S. Ejiri🇬🇧 · C.R. Allton🇬🇧 · S.J. Hands🇬🇧 · O. Kaczmarek🇩🇪 · F. Karsch🇩🇪 · E. Laermann🇩🇪 · L. Scorzato🇬🇧

    We propose a new method to investigate the thermal properties of QCD with a small chemical potential $(\mu )$. The derivatives of the phase transition point with respect to $\mu$ are computed for 2 flavors of p4-improved staggered fermions. We moreover comment on the complex phase of the fermion determinant in finite-density QCD.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·7 citations
11. 11*

    Lattice Quark Propagator in Landau and Laplacian Gauges

    P.O. Bowman🇺🇸 · U.M. Heller🇺🇸 · A.G. Williams🇦🇺

    We present results for the lattice quark propagator in both Landau and Laplacian gauges using standard and improved staggered quark actions. The standard Kogut-Susskind action has errors of \oa{2} while the improved ``Asqtad'' action has \oa{4}, \oag{2}{2} errors. This improvement is seen in the quark propagator. We demonstrate the application of tree-level corrections to these actions and see that Landau and Laplacian gauges produce very similar results.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·18 citations
12. 12*

    Super Yang-Mills Theory on Lattice and the Transformation

    K. Itoh🇯🇵 · M. Kato🇯🇵 · H. Sawanaka🇯🇵 · H. So🇯🇵 · N. Ukita🇯🇵

    We present a new lattice super Yang-Mills theory and its SUSY transformation. After our formulation of the model in a fundamental lattice, it is extended to the whole lattice with a substructure of modulo 2.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·1 citation
13. 13*

    The Index and Axial Anomaly of a lattice Dirac operator

    Ting-Wai Chiu🇹🇼

    A remarkable feature of a lattice Dirac operator is discussed. Unlike the Dirac operator for massless fermions in the continuum, this Ginsparg-Wilson lattice Dirac operator does not possess topological zero modes for any topologically-nontrivial background gauge fields, even though it is exponentially-local, doublers-free, and reproduces correct axial anomaly for topologically-trivial gauge configurations.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·2 citations
14. 14*

    Heavy monopole potential in gluodynamics

    M.N. Chernodub🇷🇺 · F.V. Gubarev🇷🇺 · M.I. Polikarpov🇷🇺 · V.I. Zakharov🇩🇪

    We discuss predictions for the interaction energy of the fundamental monopoles in gluodynamics introduced via the 't Hooft loop. At short distances, the heavy monopole potential is calculable from first principles. At larger distances, we apply the Abelian dominance models. We discuss the measurements which would be crucial to distinguish between various models. Non-zero temperatures are also considered. Our predictions are in qualitative agreement with the existing lattice data. We discuss further measurements which would be crucial to check the model.

    hep-lathep-phhep-thNucl.Phys.B Proc.Suppl.(2002)·1 citation
15. 15*

    One-loop renormalization of heavy-light currents

    J. Harada🇯🇵 · S. Hashimoto🇯🇵 · K.-I. Ishikawa🇯🇵 · A. S. Kronfeld🇺🇸 · T. Onogi🇯🇵 · N. Yamada🇯🇵

    We calculate the mass dependent renormalization factors of heavy-light bilinears at one-loop order of perturbation theory, when the heavy quark is treated with the Fermilab formalism. We present numerical results for the Wilson and Sheikholeslami-Wohlert actions, with and without tree-level rotation. We find that in both cases our results smoothly interpolate from the static limit to the massless limit. We also calculate the mass dependent Brodsky-Lepage-Mackenzie scale $q^{\ast }$, with and without tadpole-improvement.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·0 citations
16. 16*

    Improved Hamiltonian Lattice Gauge Theory

    J. Carlsson🇦🇺 · J. A. L. McIntosh🇦🇺 · B. H. J. McKellar🇦🇺 · L. C. L. Hollenberg🇦🇺

    We derive an improved lattice Hamiltonian for pure gauge theory, coupling arbitrarily distant links in the kinetic term. The level of improvement achieved is examined in variational calculations of the SU(2) specific heat in 2+1 dimensions.

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

    B meson B-parameters and the decay constant in two-flavor dynamical QCD

    JLQCD Collaboration: N.Yamada🇯🇵 · S.Aoki🇯🇵 · R.Bulkhalter🇯🇵 · M.Fukugita🇯🇵 · S.Hashimoto🇯🇵 · K-I.Ishikawa🇯🇵 · N.Ishizuka🇯🇵 · Y.Iwasaki🇯🇵 · K.Kanaya🇯🇵 · T.Kaneko🇯🇵 · Y.Kuramashi🇯🇵 · M.Okawa🇯🇵 and 5 other authors

    We present a two-flavor dynamical QCD calculation of the B meson B parameters and decay constant. We use NRQCD for heavy quark and the nonperturbatively O(a)-improved Wilson action for light quark at $\beta$=5.2 on a $20^3\times 48$ lattice. We confirm that the sea quark effect increases the heavy-light decay constant, while estimate of its magnitude depends significantly on the fitting form in the chiral extrapolation. For the B parameters, on the other hand, we do not find a significant sea quark effect. The chiral extrapolation with logarithmic term is examined for both quantities and compared with the prediction of ChPT.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·64 citations
18. 18*

    Non-trivial phase structure of $N_f=3$ QCD with $O(a)$-improved Wilson fermion at zero temperature

    JLQCD Collaboration: S. Aoki🇯🇵 · R. Burkhalter🇯🇵 · M. Fukugita🇯🇵 · S. Hashimoto🇯🇵 · K-I. Ishikawa🇯🇵 · N. Ishizuka🇯🇵 · Y. Iwasaki🇯🇵 · K. Kanaya🇯🇵 · T. Kaneko🇯🇵 · Y. Kuramashi🇯🇵 · M. Okawa🇯🇵 · T. Onogi🇯🇵 and 5 other authors

    JLQCD collaboration recently started the $N_f=3$ QCD simulations with the $O(a)$-improved Wilson fermion action employing an exact fermion algorithm developed for odd number of quark flavors. It is found that this theory has an unexpected non-trivial phase structure in the $(\beta ,\kappa )$ plane even at zero temperature. A detailed study is made to understand the nature of the observed phase transitions and to find the way of avoiding untolerably large lattice artifacts associated with the phase transition.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·30 citations
19. 19*

    Chemical potential response of pseudoscalar meson masses in the Nambu--Jona-Lasinio model

    O. Miyamura🇯🇵 · S. Choe🇯🇵

    Using the Nambu--Jona-Lasinio (NJL) model we study chemical potential response of the pion and kaon masses as a function of temperature and chemical potential, i.e., dm/d\mu (T, \mu). First, we obtain the responses assuming the vector-axial vector coupling is zero (g_V=0). Then, we include a non-zero g_V and study the effects of g_V on the responses. We find that the behavior of dm/d\mu for the pion is quite different from that for the kaon. It means that dm/d\mu is much dependent on the mass difference between the two quarks, i.e., the u and s quarks (or even between the u and d quarks). Our results may give a clue to future studies of dm/d\mu on the lattice.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·1 citation
20. 20*

    Diquark condensation in dense SU(2) matter

    Simon Hands🇬🇧 · Istvan Montvay🇩🇪 · Luigi Scorzato🇬🇧 · Jonivar Skullerud🇩🇪

    We report on a lattice study of two-color QCD with adjoint staggered fermions at high density. We find that the model has no early onset and we report on results for diquark condensation, from simulations with and without a diquark source term.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·3 citations
21. 21*

    B-parameters of the complete set of matrix elements of (Delta B = 2) operators from the lattice

    D.Becirevic🇮🇹 · V.Gimenez🇪🇸 · G.Martinelli🇮🇹 · M.Papinutto🇮🇹 · J.Reyes🇮🇹

    We compute on the lattice the ``bag'' parameters of the five (Delta B = 2) operators of the supersymmetric basis, by combining their values determined in full QCD and in the static limit of HQET. The extrapolation of the QCD results from the accessible heavy-light meson masses to the B-meson mass is constrained by the static result. The matching of the corresponding results in HQET and in QCD is for the first time made at NLO accuracy in the MSbar(NDR) renormalization scheme. All results are obtained in the quenched approximation.

    hep-lathep-exhep-phJHEP(2002)·225 citations
22. 22*

    Real--time dynamics of a hot Yang-Mills theory: a numerical analysis

    J. Ambjorn🇩🇰 · K. N. Anagnostopoulos🇬🇷 · A. Krasnitz🇵🇹

    We discuss recent results obtained from simulations of high temperature, classical, real time dynamics of SU(2) Yang-Mills theory at temperatures of the order of the electroweak scale. Measurements of gauge covariant and gauge invariant autocorrelations of the fields indicate that the ASY-Bodecker scenario is irrelevant at these temperatures.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·1 citation
23. 23*

    New Initial Conditions for Quantum Field Simulations after a Quench

    M. Salle🇳🇱 · J. Smit🇳🇱 · J.C. Vink🇳🇱

    We investigate a new way of using the quantum fluctuations in the vacuum as initial conditions for subsequent classical field dynamics. This method avoids problems with renormalization and leads to better thermalization.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·10 citations
24. 24*

    On the Quantum Geometry of String Theory

    J. Ambjorn🇩🇰 · K.N. Anagnostopoulos🇬🇷 · W. Bietenholz🇩🇪 · F. Hofheinz🇩🇪 · J. Nishimura🇩🇰

    The IKKT or IIB matrix model has been proposed as a non-perturbative definition of type IIB superstring theories. It has the attractive feature that space--time appears dynamically. It is possible that lower dimensional universes dominate the theory, therefore providing a dynamical solution to the reduction of space--time dimensionality. We summarize recent works that show the central role of the phase of the fermion determinant in the possible realization of such a scenario.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·0 citations
25. 25*

    Equation of state for pure SU(3) gauge theory 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🇯🇵 · Y.Namekawa🇯🇵 and 5 other authors

    We present results for the equation of state for pure SU(3) gauge theory obtained on anisotropic lattices with the anisotropy $\xi \equiv a_s/a_t=2$. The pressure and energy density are calculated on $N_t/\xi =4,5$ and 6 lattices with the integral method. They are found to satisfy the leading $1/N_t^2$ scaling from our coarsest lattice $N_t/\xi =4$. This enables us to carry out well controlled continuum extrapolations. We find that the pressure and energy density agree with those obtained using the isotropic plaquette action, but have smaller and more reliable errors.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·1 citation
26. 26*

    An explicit example of HQET at one-loop order of perturbation theory

    Martin Kurth🇬🇧 · Rainer Sommer🇩🇪

    As an explicit example of HQET, we construct correlation functions containing a heavy-light axial current, both in the static approximation and in full QCD. This enables us to investigate the size of finite mass effects. As we use the lattice regularisation, we can also check the mass dependence of discretisation errors.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·3 citations
27. 27*

    K0-K0bar mixing from the Schroedinger functional and twisted mass QCD

    M.Guagnelli🇮🇹 · J.Heitger🇩🇪 · C.Pena🇮🇹 · S.Sint🇨🇭 · A.Vladikas🇮🇹

    We describe how the Schroedinger functional and twisted mass QCD can be used to compute the kaon B-parameter B_K on the lattice with Wilson fermions. This new approach is expected to reduce the systematic uncertainties on B_K through a better control of its (nonperturbative) renormalisation. Preliminary results for the bare matrix element in a physical volume of (1.5^3 x 4.5) fm^4 are presented. The renormalisation of the matrix element in a Schroedinger functional scheme is also discussed.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·24 citations
28. 28*

    Vortices in the SU(2)-Higgs model -- Vortices and the covariant adjoint Laplacian

    Roman Bertle🇦🇹 · Manfried Faber🇦🇹 · Albert Hirtl🇦🇹

    Vortices in the SU(2)--Higgs model: The presence of a fundamental Higgs in the SU(N)-Higgs model yields color screening at some finite distance. Whereas the transition to the Higgs "phase" is accompanied by a suppression of projected center vortices, there is nearly no influence of color screening on the vortex properties in the confined "phase". Hence the behavior of the Wilson loop can be described in both phases within the vortex picture of confinement. Vortices and the covariant adjoint Laplacian: Laplacian center gauge is a method to localize center vortices in SU(N) gauge theory. We show that the eigenvectors of the covariant adjoint Laplacian identify vortices for a special class of gauge field configurations. However, for Monte Carlo generated configurations, modified approaches are required.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·3 citations
29. 29*

    Constrained fitting of three-point functions

    M. Gurtler🇬🇧 · C.T.H. Davies🇬🇧 · J. Hein🇬🇧 · J. Shigemitsu🇺🇸 · G. P. Lepage🇺🇸

    We determine matrix elements for $B\to D$ semileptonic decay. The use of the constrained fitting method and multiple smearings for both two- and three-point correlators allows an improved calculation of the form factors.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·1 citation
30. 30*

    Fat and Thin Fisher Zeroes

    W. Janke (ITP, Universitat Leipzig)🇩🇪 · D. Johnston🇬🇧 · M. Stathakopoulos (Heriot-Watt University, Edinburgh)🇬🇧

    We show that it is possible to determine the locus of Fisher zeroes in the thermodynamic limit for the Ising model on planar (``fat'') phi4 random graphs and their dual quadrangulations by matching up the real part of the high- and low-temperature branches of the expression for the free energy. Similar methods work for the mean-field model on generic, ``thin'' graphs. Series expansions are very easy to obtain for such random graph Ising models.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·0 citations
31. 31*

    Spectrum of k-string tensions in SU(N) gauge theories

    L. Del Debbio🇮🇹 · H. Panagopoulos🇨🇾 · P. Rossi🇮🇹 · E. Vicari🇮🇹

    We compute, for the four-dimensional SU(4) and SU(6) gauge theories formulated on a lattice, the string tensions sigma_k related to sources with Z_N charge k, using Monte Carlo simulations. Our results are compatible with sigma_k \propto sin (k pi/N), and show sizeable deviations from Casimir scaling.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·4 citations
32. 32*

    Lattice QCD at finite T and \mu and the critical point of QCD

    Z. Fodor🇭🇺 · S.D. Katz🇭🇺

    We propose a method to study lattice QCD at finite T and \mu. We compare it with direct results and with the Glasgow method by using n_f=4 QCD at Im(\mu)\neq 0. We locate the critical endpoint (E) of QCD on the Re(\mu)-T plane. In this study we use n_f=2+1 dynamical staggered quarks with semi-realistic masses on L_t=4 lattices.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·23 citations
33. 33*

    Short distance physics with heavy quark potentials

    F. Zantow🇩🇪 · O. Kaczmarek🇩🇪 · F. Karsch🇩🇪 · P. Petreczky🇩🇪

    We present lattice studies of heavy quark potentials in the quenched approximation of QCD at finite temperatures. Both, the color singlet and color averaged potentials are calculated. While the potentials are well known at large distances, we give a detailed analysis of their short distance behavior (from 0.015 fm to 1 fm) near the critical temperature. At these distances we expect that the T-dependent potentials go over into the zero temperature potential. Indeed, we find evidences that the temperature influence gets suppressed and the potentials starts to become a unique function of the underlying distance scale. We use this feature to normalize the heavy quark potentials at short distances and extract the free energy of the quark system in a gluonic heat bath.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·14 citations
34. 34*

    Quenched charmonium near the continuum limit

    QCD-TARO Collaboration: S. Choe🇯🇵 · Ph. de Forcrand🇨🇭 · M. Garcia Perez🇨🇭 · S. Hioki🇯🇵 · Y. Liu🇯🇵 · H. Matsufuru🇯🇵 · O. Miyamura🇯🇵 · A. Nakamura🇯🇵 · I.-O. Stamatescu🇩🇪 · T. Takaishi🇯🇵 · T. Umeda🇯🇵

    We study relativistic charmonium on very fine quenched lattices (beta=6.4 and 6.6). We concentrate on the calculation of the hyperfine splitting between eta_c and J/psi, aiming for a controlled continuum extrapolation of this quantity. Results for the eta_c and J/psi wave functions are also presented.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·7 citations
35. 35*

    Where do perturbative and non-perturbative QCD meet?

    G.S. Bali🇬🇧 · P. Boyle🇬🇧 · C.T.H. Davies🇬🇧

    We computed the static potential and Wilson loops to $O({\alpha }^2)$ in perturbation theory for different lattice quark and gluon actions. In general, we find short distance lattice data to be well described by ``boosted perturbation theory''. For Wilson-type fermions at present-day quark masses and lattice spacings agreement within 10% between measured ``$\beta$-shifts'' and those predicted by perturbation theory is found. We comment on prospects for a determination of the real world QCD running coupling.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·1 citation
36. 36*

    An new order parameter with renormalized Polyakov loops

    F. Zantow🇩🇪 · O. Kaczmarek🇩🇪 · F. Karsch🇩🇪 · P. Petreczky🇩🇪

    It is well established that physical quantities like the heavy quark potentials get temperature independent at sufficiently short distances. As a first application of this feature we suggest a new order parameter for the confinement/deconfinement phase transition. Our investigations are based on recent lattice studies.

    hep-lat6 citations
37. 37*

    An exact algorithm for three-flavor QCD with $O(a)$-improved Wilson fermions

    JLQCD Collaboration: S. Aoki🇯🇵 · R. Burkhalter🇯🇵 · M. Fukugita🇯🇵 · S. Hashimoto🇯🇵 · K-I. Ishikawa🇯🇵 · N. Ishizuka🇯🇵 · Y. Iwasaki🇯🇵 · K. Kanaya🇯🇵 · T. Kaneko🇯🇵 · Y. Kuramashi🇯🇵 · M. Okawa🇯🇵 · T. Onogi🇯🇵 and 5 other authors

    We present an exact dynamical QCD simulation algorithm for the $O(a)$-improved Wilson fermion with odd number of flavors. Our algorithm is an extension of the non-Hermitian polynomials HMC algorithm proposed by Takaishi and de Forcrand previously. In our algorithm, the systematic errors caused by the polynomial approximation of the inverse of Dirac operator is removed by a noisy-Metropolis test. For one flavor quark it is achieved by taking the square root of the correction matrix explicitly. We test our algorithm for the case of $N_f=1+1$ on a moderately large lattice size ($16^3\times 48$). The $N_f=2+1$ case is also investigated.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·5 citations
38. 38*

    Hadron spectroscopy of twisted mass lattice QCD at beta = 6.0

    UKQCD collaboration: Craig McNeile🇬🇧 · Chris Michael🇬🇧

    Simulations that use the clover action in quenched QCD calculations have a lower limit to the quark mass that can be reached, because of the fluctuations caused by exceptional configurations. From this low statistics study, we find that the twisted clover action, recently introduced by the ALPHA collaboration, can be used to simulate quenched QCD at quark masses below those attainable by simulations that use the clover action.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·6 citations
39. 39*

    Nonequilibrium Aspects of Quantum Field Theory

    Travis R. Miller🇺🇸 · Michael C. Ogilvie🇺🇸

    We have developed a method for extracting equilibrium observables from non-equilibrium simulations by rapidly changing the temperature and recording the subsequent evolution of the Polyakov loop. Both nucleation and spinodal decomposition are observed to occur. In the latter case the Polyakov loop correlation function shows exponential growth for wavenumbers less than or equal to the critical wavenumber k_c. We have constructed the bare as wee as the effective potential for the Polyakov loop, from which k_c and m_D/k_c can be extracted as a function of temperature. The shift from spinodal decomposition to nucleation as the dominant equilibration mechanism occurs at the spinodal temperature that separates these two regimes.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·8 citations
40. 40*

    Lattice supersymmetric Ward identities

    F. Farchioni🇩🇪 · A. Feo🇩🇪 · T. Galla🇬🇧 · C. Gebert🇩🇪 · R. Kirchner🇩🇪 · I. Montvay🇩🇪 · G. Münster🇩🇪 · A. Vladikas🇮🇹

    SUSY Ward identities for the N=1 SU(2) SUSY Yang-Mills theory are studied on the lattice in a non-perturbative numerical approach. As a result a determination of the subtracted gluino mass is obtained.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·7 citations
41. 41*

    Temporal quark and gluon propagators: measuring the quasiparticle masses

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

    We calculate the Coulomb gauge temporal quark and gluon propagators in quenched QCD. From the temporal quark and gluon propagators, dispersion relations and quasiparticle masses are determined by means of the Maximum Entropy Method.

    hep-lathep-phNucl.Phys.B Proc.Suppl.(2002)·87 citations
42. 42*

    Is the Up Quark Massless?

    Daniel R. Nelson (1)🇺🇸 · George T. Fleming (1)🇺🇸 · Greg W. Kilcup (1) ((1) The Ohio State University)🇺🇸

    Several lattice calculations of a combination of the low energy constants of the chiral Lagrangian, 2\alpha_8-\alpha_5, are presented. This combination is critical for the preclusion of a massless up quark. The result found is 2\alpha_8-\alpha_5 = 0.115 \pm 0.051^{stat} \pm 0.25^{syst}, which is well outside of the range allowed by a massless up quark.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·9 citations
43. 43*

    SUSY Ward identities in 1-loop perturbation theory

    Federico Farchioni🇩🇪 · Alessandra Feo🇩🇪 · Tobias Galla🇬🇧 · Claus Gebert🇩🇪 · Robert Kirchner🇩🇪 · Istvan Montvay🇩🇪 · Gernot Muenster🇩🇪 · Roland Peetz🇩🇪 · Anastassios Vladikas🇮🇹

    We present preliminary results of a study of the supersymmetric (SUSY) Ward identities (WIs) for the N=1 SU(2) SUSY Yang-Mills theory in the context of one-loop lattice perturbation theory. The supersymmetry on the lattice is explicitly broken by the gluino mass and the lattice artifacts. However, the renormalization of the supercurrent can be carried out in a scheme that restores the nominal continuum WIs. The perturbative calculation of the renormalization constants and mixing coefficients for the local supercurrent is presented.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·13 citations
44. 44*

    Non-perturbative parton mass for the gluon

    O. Philipsen (MIT)🇺🇸

    A gauge invariant, non-local observable is constructed in pure gauge theory, which is identical to the gluon propagator in a particular gauge, permitting to define a non-perturbative parton mass for the gluon. This mass can be shown to be related to the 1P-1S mass splitting of heavy quarkonia. Preliminary numerical results for 3d SU(2) yield m_A=0.37(6)g^2, while from the \bar{b}b spectrum one infers m_A\approx 420 MeV for QCD.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·8 citations
45. 45*

    Static three- and four-quark potentials

    C. Alexandrou (Univ. of Cyprus)🇨🇾 · Ph.de Forcrand (ETH-Zurich and CERN)🇨🇭 · A. Tsapalis (Univ. of Athens)🇬🇷

    We present results for the static three- and four-quark potentials in SU(3) and SU(4) respectively. Using a variational approach, combined with multi-hit for the time-like links, we determine the ground state of the baryonic string with sufficient accuracy to test the $Y-$ and $\Delta -$ ansätze for the baryonic Wilson area law. Our results favor the $\Delta$ ansatz, where the potential is the sum of two-body terms.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·9 citations
46. 46*

    FermiQCD: A tool kit for parallel lattice QCD applications

    Massimo Di Pierro🇺🇸

    We present here the most recent version of FermiQCD, a collection of C++ classes, functions and parallel algorithms for lattice QCD, based on Matrix Distributed Processing. FermiQCD allows fast development of parallel lattice applications and includes some SSE2 optimizations for clusters of Pentium 4 PCs.

    hep-latNucl.Phys.B Proc.Suppl.(2002)·17 citations
47. 47*

    Combined Relativistic and static analysis for all Delta B=2 operators

    D. Becirevic🇮🇹 · V. Gimenez🇪🇸 · G. Martinelli🇮🇹 · M. Papinutto🇮🇹 · J. Reyes🇮🇹

    We analyse matrix elements of Delta B=2 operators by combining QCD results with the ones obtained in the static limit of HQET. The matching of all the QCD operators to HQET is made at NLO order. To do that we have to include the anomalous dimension matrix up to two loops, both in QCD and HQET, and the one loop matching for all the Delta B=2 operators. The matrix elements of these operators are relevant for the prediction of the B-\bar B mixing, B_s meson width difference and supersymmetric effects in Delta B=2 transitions.

    hep-lathep-phNucl.Phys.B Proc.Suppl.(2002)·31 citations
48. 48*

    Exact Finite-Size-Scaling Corrections to the Critical Two-Dimensional Ising Model on a Torus. II. Triangular and hexagonal lattices

    J. Salas (Zaragoza U.)🇪🇸

    We compute the finite-size corrections to the free energy, internal energy and specific heat of the critical two-dimensional spin-1/2 Ising model on a triangular and hexagonal lattices wrapped on a torus. We find the general form of the finite-size corrections to these quantities, as well as explicit formulas for the first coefficients of each expansion. We analyze the implications of these findings on the renormalization-group description of the model.

    ↳ cond-mat.stat-mechhep-lathep-thJ.Phys.A(2002)·12 citations
49. 49*

    Strangeness-changing scalar form factors

    Matthias Jamin🇩🇪 · Jose Antonio Oller🇩🇪 · Antonio Pich🇪🇸

    We derive expressions for strangeness-changing scalar form factors, which incorporate known theoretical constraints both at low and high energies. Their leading behaviour in the limit of a large number of colours is calculated from the resonance chiral Lagrangian. A set of short-distance constraints on the scalar resonance couplings is obtained, imposing the form factors to vanish at infinite momentum transfer. Making use of previous results on S-wave KPi scattering [1], and a coupled--channel dispersion-relation analysis, the KPi, KEta and KEta' scalar form factors are calculated up to 2 GeV. These scalar form factors are a key ingredient in the determination of the corresponding scalar spectral function which is important in the extraction of the mass of the strange quark from QCD sum rules as well as hadronic tau decays.

    ↳ hep-phhep-exhep-latnucl-thNPB(2002)·227 citations
50. 50*

    Light quark masses from scalar sum rules

    Matthias Jamin🇩🇪 · Jose Antonio Oller🇩🇪 · Antonio Pich🇪🇸

    In this work, the mass of the strange quark is calculated from QCD sum rules for the divergence of the strangeness-changing vector current. The phenomenological scalar spectral function which enters the sum rule is determined from our previous work on strangeness-changing scalar form factors [1]. For the running strange mass in the MS_bar scheme, we find m_s(2 GeV) = 99 +- 16 MeV. Making use of this result and the light-quark mass ratios obtained from chiral perturbation theory, we are also able to extract the masses of the lighter quarks m_u and m_d. We then obtain m_u(2 GeV) = 2.9 +- 0.6 MeV and m_d(2 GeV) = 5.2 +- 0.9 MeV. In addition, we present an updated value for the light quark condensate.

    ↳ hep-phhep-exhep-latnucl-thEPJC(2002)·139 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.