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Status of glueball mass calculations in lattice gauge theory

Description: The status of glueball spectrum calculations in lattice gauge theory is briefly reviewed, with focus on the comparison between Monte Carlo simulations and small-volume analytical calculations in SU(3). The agreement gives confidence that the large-volume Monte Carlo results are accurate, at least in the context of the pure gauge theory. An overview of some of the technical questions, which is aimed at non-experts, serves as an introduction. 19 refs., 1 fig.
Date: November 1, 1989
Creator: Kronfeld, A.S.
Partner: UNT Libraries Government Documents Department

Improved methods for computing masses from numerical simulations

Description: An important advance in the computation of hadron and glueball masses has been the introduction of non-local operators. This talk summarizes the critical signal-to-noise ratio of glueball correlation functions in the continuum limit, and discusses the case of (q{bar q} and qqq) hadrons in the chiral limit. A new strategy for extracting the masses of excited states is outlined and tested. The lessons learned here suggest that gauge-fixed momentum-space operators might be a suitable choice of interpolating operators. 15 refs., 2 tabs.
Date: November 22, 1989
Creator: Kronfeld, A.S.
Partner: UNT Libraries Government Documents Department

Numerical Tests of the Improved Fermilab Action

Description: Recently, the Fermilab heavy-quark action was extended to include dimension-six and -seven operators in order to reduce the discretization errors. In this talk, we present results of the first numerical simulations with this action (the OK action), where we study the masses of the quarkonium and heavy-light systems. We calculate combinations of masses designed to test improvement and compare results obtained with the OK action to their counterparts obtained with the clover action. Our preliminary results show a clear improvement.
Date: November 1, 2010
Creator: Detar, C.; Kronfeld, A.S. & Oktay, M.B.
Partner: UNT Libraries Government Documents Department

Three electroweak results from lattice QCD

Description: Quantum chromodynamics is needed to understand quarks and, hence, to determine the quarks` Yukawa couplings from experimental measurements. As a short illustration, the results of three lattice calculations are given.
Date: August 1, 1998
Creator: Kronfeld, A.S., FERMI
Partner: UNT Libraries Government Documents Department

Calculation of $K\to\pi l\nu$ Form Factors with $N_f = 2+1$ Flavors of Staggered Auarks

Description: We report on the status of the Fermilab-MILC calculation of the form factor f{sub +}{sup K}{pi}(q{sup 2} = 0), needed to extract the CKM matrix element |V{sub us}| from experimental data on K semileptonic decays. The HISQ formulation is used in the simulations for the valence quarks, while the sea quarks are simulated with the asqtad action (MILC N{sub f} = 2 + 1 configurations). We discuss the general methodology of the calculation, including the use of twisted boundary conditions to get values of the momentum transfer close to zero and the different techniques applied for the correlators fits. We present initial results for lattice spacings a {approx} 0.12 fm and a {approx} 0.09 fm, and several choices of the light quark masses.
Date: November 1, 2011
Creator: Gamiz, E.; DeTar, C.; El-Khadra, A. X.; Kronfeld, A. S.; Mackenzie, P. B. & Simone, J.
Partner: UNT Libraries Government Documents Department

The B {r{underscore}arrow} D*{ell}{nu} form factor at zero recoil

Description: The authors describe a model independent lattice QCD method for determining the deviation from unity for h{sub A{sub 1}}, the B {r{underscore}arrow} D*{ell}{nu} form factor at zero recoil. They extend the double ratio method previously used to determine the B {r{underscore}arrow} D{ell}{nu} form factor. The bulk of statistical and systematic errors cancel in the double ratios they consider, yielding form factors which promise to reduce present theoretical uncertainties in the determination of {vert{underscore}bar}V{sub cb}{vert{underscore}bar}. They present results from a prototype calculation at a single lattice spacing corresponding to {beta} = 5.7.
Date: January 26, 2000
Creator: Simone, J.N.; Hashimoto, S.; El-Khadra, A.X.; Kronfeld, A.S.; Mackenzie, P.B. & Ryan, S.M.
Partner: UNT Libraries Government Documents Department

$D$ semileptonic form factors and $|V_{cs(d)}|$ from 2+1 flavor lattice QCD

Description: The measured partial widths of the semileptonic decays D {yields} K{ell}{nu} and D {yields} {pi}{ell}{nu} can be combined with the form factors calculated on the lattice to extract the CKM matrix elements |V{sub cs}| and |V{sub cd}|. The lattice calculations can be checked by comparing the form factor shapes from the lattice and experiment. We have generated a sizable data set by using heavy clover quarks with the Fermilab interpretation for charm and asqtad staggered light quarks on 2+1 flavor MILC ensembles with lattice spacings of approximately 0.12, 0.09, 0.06, and 0.045 fm. Preliminary fits to staggered chiral perturbation theory suggest that we can reduce the uncertainties in the form factors at q{sup 2} = 0 to below 5%.
Date: November 1, 2011
Creator: Bailey, Jon A.; Bazavov, A.; El-Khadra, A.X.; Gottlieb, Steven; Jain, R.D.; Kronfeld, A.S. et al.
Partner: UNT Libraries Government Documents Department

B and D Meson Decay Constants

Description: We present an update of our calculations of the decay constants of the D, D{sub s}, B, and B{sub s} mesons in unquenched 2+1 flavor QCD. We use the MILC library of improved staggered gauge ensembles at lattice spacings 0.09, 0.12, and 0.15 fm, clover heavy quarks with the Fermilab normalizations, and improved staggered light valence quarks.
Date: April 1, 2009
Creator: Bernard, C.; DeTar, C.; Di Pierro, M.; El-Khadra, A. X.; Evans, R. T.; Freeland, Elizabeth Dawn et al.
Partner: UNT Libraries Government Documents Department

Visualization of semileptonic form factors from lattice QCD

Description: Comparisons of lattice-QCD calculations of semileptonic form factors with experimental measurements often display two sets of points, one each for lattice QCD and experiment. Here we propose to display the output of a lattice-QCD analysis as a curve and error band. This is justified, because lattice-QCD results rely in part on fitting, both for the chiral extrapolation and to extend lattice-QCD data over the full physically allowed kinematic domain. To display an error band, correlations in the fit parameters must be taken into account. For the statistical error, the correlation comes from the fit. To illustrate how to address correlations in the systematic errors, we use the Becirevic-Kaidalov parametrization of the D {yields} {pi}{ell}{nu} and D {yields} K{ell}{nu} form factors, and a analyticity-based fit for the B {yields} {pi}{ell}{nu} form factor f{sub +}.
Date: June 1, 2009
Creator: Bernard, C.; DeTar, C.; Di Pierro, M.; El-Khadra, A. X.; Evans, R. T.; Freeland, E. D. et al.
Partner: UNT Libraries Government Documents Department

The Ds and D+ Leptonic Decay Constants from Lattice QCD

Description: We present the leptonic decay constants f{sub D{sub s}} and f{sub D{sup +}} computed on the MILC collaboration's 2+1 flavor asqtad gauge ensembles. We use clover heavy quarks with the Fermilab interpretation and improved staggered light quarks. The simultaneous chiral and continuum extrapolation, which determines both decay constants, includes partially-quenched lattice results at lattice spacings a {approx} 0.09, 0.12 and 0.15 fm. We have made several recent improvements in our analysis: (a) we include terms in the fit describing leading order heavy-quark discretization effects, (b) we have adopted a more precise input r{sub 1} value consistent with our other D and B meson studies, (c) we have retuned the input bare charm masses based upon the new r{sub 1}. Our preliminary results are f{sub D{sub s}} = 260 {+-} 10 MeV and f{sub D{sup +}} = 217 {+-} 10 MeV.
Date: December 1, 2009
Creator: Bazavov, A.; Bernard, C.; DeTar, C.; Freeland, E. D.; Gamiz, E.; Gottlieb, Steven et al.
Partner: UNT Libraries Government Documents Department

$B^0_s$ and $B^0$ Mixing in the Standard Model and Beyond: A Progress Report

Description: We give a progress report on the calculation of B meson mixing matrix elements, focusing on contributions that could arise beyond the Standard Model. The calculation uses asqtad (light quark) and Fermilab (heavy quark) valence actions and MILC ensembles with 2+1 flavors of asqtad sea quarks. We report preliminary B{sub s}{sup 0} fit results, at a lattice spacing of 0.12 fm, for the SUSY basis of effective four-quark mixing operators and include an estimate for the final error budget.
Date: November 1, 2010
Creator: Bouchard, C.; /Illinois U., Urbana /Fermilab; El-Khadra, A.X.; /Illinois U., Urbana; Freeland, E.D.; /Illinois U., Urbana /Washington U., St. Louis et al.
Partner: UNT Libraries Government Documents Department