95 research outputs found

    Renormalization of Massive Lattice Fermions

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    The renormalization of a general action for massive lattice fermions is discussed. The analysis applies for all mqam_q a. Preliminary results for the self energy at one loop in perturbation theory are presented.Comment: 3 pages (you guessed it: to appear in Lattice '93), uuencoded PostScript file, FERMILAB-CONF-93/382-T and EFI 93-72. Regular PostScript file by anonymous ftp to fnth06.fnal.gov as pub/Fermilab-Pub/93.38

    A More Improved Lattice Action for Heavy Quarks

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    We extend the Fermilab formalism for heavy quarks to develop a more improved action. We give results of matching calculations of the improvement couplings at tree level. Finally, we estimate the discretization errors associated with the new action.Comment: 3 pages, 1 figure, Lattice 2003 Tsukuba Japa

    Application of heavy-quark effective theory to lattice QCD: III. Radiative corrections to heavy-heavy currents

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    We apply heavy-quark effective theory (HQET) to separate long- and short-distance effects of heavy quarks in lattice gauge theory. In this paper we focus on flavor-changing currents that mediate transitions from one heavy flavor to another. We stress differences in the formalism for heavy-light currents, which are discussed in a companion paper, showing how HQET provides a systematic matching procedure. We obtain one-loop results for the matching factors of lattice currents, needed for heavy-quark phenomenology, such as the calculation of zero-recoil form factors for the semileptonic decays B→D(∗)lÎœB\to D^{(*)}l\nu. Results for the Brodsky-Lepage-Mackenzie scale q∗q^* are also given.Comment: 35 pages, 17 figures. Program LatHQ2QCD to compute matching one-loop coefficients available at http://theory.fnal.gov/people/kronfeld/LatHQ2QCD

    First results from the asymmetric O(a) improved Fermilab action

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    We present first results from calculations using O(a) improved (FNAL) space-time asymmetric action on a 12^3 x 24 quenched lattice at \beta = 5.7 and c_SW = 1.57. The asymmetry parameter is determined non-perturbatively from the energy-momentum dispersion relation. This improvement scheme is mass dependent, and the calculations have been done in the charm and bottom quark mass sectors since it is at these heavier masses that the asymmetry is expected to be relevant.Comment: 3 pp. LaTeX2e, 6PostScript figures, uses espcrc2.sty. Contribution to Lattice99 (Pisa) proceedings (Improvement and Renormalisation

    Disappearance of the Abrikosov vortex above the deconfining phase transition in SU(2) lattice gauge theory

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    We calculate the solenoidal magnetic monopole current and electric flux distributions at finite temperature in the presence of a static quark antiquark pair. The simulation was performed using SU(2) lattice gauge theory in the maximal Abelian gauge. We find that the monopole current and electric flux distributions are quite different below and above the finite temperature deconfining phase transition point and agree with predictions of the Ginzburg-Landau effective theory.Comment: 12 pages, Revtex Latex, 6 figures - ps files will be sent upon reques

    Application of heavy-quark effective theory to lattice QCD: II. Radiative corrections to heavy-light currents

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    We apply heavy-quark effective theory to separate long- and short-distance effects of heavy quarks in lattice gauge theory. In this approach, the inverse heavy-quark mass and the lattice spacing are treated as short distances, and their effects are lumped into short-distance coefficients. We show how to use this formalism to match lattice gauge theory to continuum QCD, order by order in the heavy-quark expansion. In this paper, we focus on heavy-light currents. In particular, we obtain one-loop results for the matching factors of lattice currents, needed for heavy-quark phenomenology, such as the calculation of heavy-light decay constants, and heavy-to-light transition form factors. Results for the Brodsky-Lepage-Mackenzie scale q∗q^* are also given.Comment: 32 pages, 8 figures. v2 corrects Eqs. (4.9) and (4.10) and adds a reference. Program LatHQ2QCD to compute matching one-loop coefficients available at http://theory.fnal.gov/people/kronfeld/LatHQ2QCD

    Estimated Errors in |Vcd|/|Vcs| from Semileptonic D Decays

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    We estimate statistical and systematic errors in the extraction of the CKM ratio |Vcd|/|Vcs| from exclusive D-meson semileptonic decays using lattice QCD and anticipated new experimental results.Comment: LATTICE98(heavyqk), LaTeX, 3 pages, 2 postscript figures, uses espcrc2.sty and hyperbasics.te

    B Mixing in the Standard Model and Beyond: Lattice QCD

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    We give a brief overview and progress report on our lattice QCD calculation of neutral B mixing hadronic matrix elements needed for Standard Model and Beyond the Standard Model physics. Reference [1] contains more details and results.Comment: 3 pages, 0 figures, Proceedings of the 19th Particles and Nuclei International Conference (PANIC11), Cambridge, MA, U.S.A., July 201

    Effective Monopole Action at Finite Temperature in SU(2) Gluodynamics

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    Effective monopole action at finite temperature in SU(2) gluodynamics is studied on anisotropic lattices. Using an inverse Monte-Carlo method and the blockspin transformation for space directions, we determine 4-dimensional effective monopole action at finite temperature. We get an almost perfect action in the continuum limit under the assumption that the action is composed of two-point interactions alone. It depends on a physical scale bsb_s and the temperature TT. The temperature-dependence appears with respect to the spacelike monopole couplings in the deconfinement phase, whereas the timelike monopole couplings do not show any appreciable temperature-dependence. The dimensional reduction of the 4-dimensional SU(2) gluodynamics ((SU(2))4D_{4D}) at high temperature is the 3-dimensional Georgi-Glashow model ((GG)3D(GG)_{3D}). The latter is studied at the parameter region obtained from the dimensional red uction. We compare the effective instanton action of (GG)3D(GG)_{3D} with the timelike monopole action obtained from (SU(2))4D_{4D}. We find that both agree very well for T≄2.4TcT \ge 2.4T_c at large bb region. The dimensional reduction works well also for the effective action.Comment: 34 pages, 23 figure

    Continuum Gauge Fields from Lattice Gauge Fields

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    On the lattice some of the salient features of pure gauge theories and of gauge theories with fermions in complex representations of the gauge group seem to be lost. These features can be recovered by considering part of the theory in the continuum. The prerequisite for that is the construction of continuum gauge fields from lattice gauge fields. Such a construction, which is gauge covariant and complies with geometrical constructions of the topological charge on the lattice, is given in this paper. The procedure is explicitly carried out in the U(1)U(1) theory in two dimensions, where it leads to simple results.Comment: 16 pages, HLRZ 92-3
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