SU(3) lattice gauge autocorrelations with anisotropic action

We report results of autocorrelation measurements in pure $SU(3)$ lattice gauge theory. The computations are performed on the {\sc convex spp1200} parallel platform within the {\sc canopy} programming environment. The focus of our analysis is on typical autocorrelation times and optimization of the mixing ratio between overrelaxation and pseudo-heatbath sweeps for generating gauge field configurations. We study second order tadpole-improved approximations of the Wilson action in the gluon sector, which offers the advantage of working on smaller lattices ($8^3~\times~16$ and $6^3~\times$~12~--~30). We also make use of anisotropic lattices, with temporal lattice spacing smaller than the spatial spacing, which prove useful for calculating noisy correlation functions with large spatial lattice discretization (of the order of 0.4 fm).Comment: 4 pages (LaTeX), 7 figures (PostScript), Talk presented at LATTICE96(improvement

Lattice HQET Calculation of the Isgur-Wise Function

We calculate the Isgur-Wise function on the lattice, simulating the light quark with the Wilson action and the heavy quark with a direct lattice implementation of the heavy-quark effective theory. Improved smearing functions produced by a variational technique, MOST, are used to reduce the statistical errors and to minimize excited-state contamination of the ground-state signal. Calculating the required matching factors, we obtain $\xi'(1)=-0.64(13)$ for the slope of the Isgur-Wise function in continuum-HQET in the \barMS scheme at a scale of $4.0$GeV.Comment: 3 Pages, LaTeX, Poster at Lattice '9

BB Meson Matrix Elements from Various Heavy Quark Effective Theories

Various properties of heavy-light mesons are determined, including decay constants, the $B_{B}$-parameter, and the Isgur-Wise function. The heavy (bottom) quark is simulated with the static, NRQCD and/or (fixed-velocity) lattice-HQET effective theories, using optimally-smeared sources as produced by the ``Maximal Operator Smearing Technique''.Comment: To appear in the proceedings of the Lattice '95 conference. 4 pages, uuencoded-compressed PostScript fil

NRQCD and Static Systems -- A General Variational Approach

We present initial results from Monte Carlo simulations of NRQCD-light, static-light, and NRQCD-NRQCD mesons, using a variational technique (MOST), as part of our ongoing calculation of the $f_{B}$ decay constant. The basis states for the variational calculation are quark-antiquark operators separated by all possible relative distances not equivalent under the cubic group (for example, for a $20^{3}$ lattice there are 286 operators). The efficacy of the method is demonstrated by the good plateaus obtained for the ground state and the clean extraction of the wave functions of the ground and first radially excited state.Comment: Contribution to the Lattice '94 conference, 3 pages, uuencoded-compressed PostScript fil

Chiral Limit of Nucleon Lattice Electromagnetic Form Factors

We calculate electric and magnetic form factors of protons and neutrons in quenched Monte Carlo lattice QCD on a $16^3\times 24$ lattice at $\beta = 6.0$ using Wilson fermions. We employ a method which characterizes one of the nucleon fields as a fixed zero-momentum secondary source. Extrapolating the overall data set to the chiral limit, we find acceptable fits for either dipole or monopole forms and extract proton and neutron magnetic moments, the magnitude of which are $10$ to $15\%$ low compared to experiment. In the extrapolation of the dipole fit of the form factors, we find that the dipole to nucleon mass ratio is about $7\%$ low compared to experiment. In addition, we obtain positive values of the neutron electric form factor, which, however, are poorly represented by a popular phenomenological form at intermediate to small $\kappa$ values. A zero-momentum technique for extracting hadron magnetic moments is briefly discussed and shown to yield unrealistically small magnetic moment values.Comment: 32 pages, figures not currently attache

A Study of the Static-Light BBB_B Parameter

We calculate the $B_B$ parameter, relevant for $\overline{B}^0$--$B^0$ mixing, from a lattice gauge theory simulation using the static approximation for the heavy quark and the Wilson action for the light quark and gauge fields. Improved sources, produced by an optimized variational technique, {\sc most}, reduce statistical errors and minimize excited-state contamination of the ground-state signal. Renormalization of four-fermion operator coefficients, using the Lepage-Mackenzie procedure for estimating typical momentum scales, is linearized to reduce order $\alpha_s^2$ uncertainties.Comment: 4 pages (LaTeX), Talk presented at LATTICE96(heavy quarks), Minor numerically-insignificant changes made and reference adde

Variational calculation of heavy-light meson properties

We present a new method for the study of heavy-light mesons in the static approximation of lattice QCD which is optimally effective in isolating ground and excited states. With ``MOST'' (Maximal Operator Smearing Technique), the heavy quark is smeared at all possible positions relative to the light quark, subject to the constraint of cubic symmetry. With correlation functions constructed using this set as a variational basis, eigenstates of the transfer matrix are projected out at very small time separations, where statistical errors are small. We illustrate the utility of the method with preliminary results for the meson decay constant $f_{B}^{\rm stat}$, binding energies and wave functions of the lowest states. The method produces dynamically-improved interpolating fields which can be used for matrix element calculations.Comment: 3pages, uuencode-compressed-tar Postscript file. (160 kbytes), preprint number uk/93-0