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96
Sep 17, 2013
09/13
by
A. Bazavov; C. Bernard; C. DeTar; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; J. E. Hetrick; A. X. El-Khadra; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; M. B. Oktay; M. Di Pierro; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water
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We present the leptonic decay constants fDs and fD+ 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 ~ 0:09, 0:12 and 0:15 fm. We have made several recent improvements in our analysis: a) we include terms in the fit...
Source: http://arxiv.org/abs/0912.5221v1
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51
Sep 23, 2013
09/13
by
A. Bazavov; C. Bernard; C. DeTar; Steven Gottlieb; U. M. Heller; J. E. Hetrick; J. Laiho; L. Levkova; P. B. Mackenzie; M. B. Oktay; R. Sugar; D. Toussaint; R. S. Van de Water
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Dramatic progress has been made over the last decade in the numerical study of quantum chromodynamics (QCD) through the use of improved formulations of QCD on the lattice (improved actions), the development of new algorithms and the rapid increase in computing power available to lattice gauge theorists. In this article we describe simulations of full QCD using the improved staggered quark formalism, ``asqtad'' fermions. These simulations were carried out with two degenerate flavors of light...
Source: http://arxiv.org/abs/0903.3598v2
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59
Sep 23, 2013
09/13
by
A. Bazavov; C. Bernard; C. DeTar; W. Freeman; Steven Gottlieb; U. M. Heller; J. E. Hetrick; J. Laiho; L. Levkova; J. Osborn; R. Sugar; D. Toussaint
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We report on recent progress in employing the Highly Improved Staggered Quark (HISQ) action introduced by the HPQCD/UKQCD collaboration in simulations with dynamical fermions. The HISQ action is an order $a^2$ Symanzik-improved action with further suppressed taste symmetry violations. The improvement in taste symmetry is achieved by introducing Fat7 smearing of the original gauge links and reunitarization (projection to an element of U(3) or SU(3)) followed by Asq-type smearing. Major...
Source: http://arxiv.org/abs/0903.0874v1
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44
Sep 21, 2013
09/13
by
A. Bazavov; C. Bernard; C. DeTar; X. Du; W. Freeman; Steven Gottlieb; U. M. Heller; J. E. Hetrick; J. Laiho; L. Levkova; M. B. Oktay; R. Sugar; D. Toussaint; R. S. Van de Water
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In the light pseudoscalar sector, we study rooted staggered chiral perturbation theory in the two-flavor case. The pion mass and decay constant are calculated through NLO for a partially-quenched theory. In the limit where the strange quark mass is large compared to the light quark masses and the taste splittings, we show that the SU(2) staggered chiral theory emerges from the SU(3) staggered chiral theory, as expected. Explicit relations between SU(2) and SU(3) low energy constants and...
Source: http://arxiv.org/abs/1011.1792v1
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34
Sep 19, 2013
09/13
by
A. Bazavov; C. Bernard; C. DeTar; X. Du; W. Freeman; Steven Gottlieb; Urs M. Heller; J. E. Hetrick; J. Laiho; L. Levkova; M. B. Oktay; J. Osborn; R. Sugar; D. Toussaint; R. S. Van de Water
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We present the status of the MILC collaboration's analysis of the light pseudoscalar meson sector with SU(3) chiral fits. The analysis includes data from new ensembles with smaller lattice spacing, smaller light quark masses and lighter than physical strange quark masses. Our fits include the NNLO chiral logarithms. We present results for decay constants, quark masses, Gasser-Leutwyler low energy constants, and condensates in the two- and three-flavor chiral limits.
Source: http://arxiv.org/abs/0910.3618v2
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42
Sep 19, 2013
09/13
by
A. Bazavov; C. Bernard; C. DeTar; X. Du; W. Freeman; Steven Gottlieb; Urs M. Heller; J. E. Hetrick; J. Laiho; L. Levkova; M. B. Oktay; J. Osborn; R. Sugar; D. Toussaint; R. S. Van de Water
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We present the latest preliminary results of the MILC collaboration's analysis of the light pseudoscalar meson sector. The analysis includes data from new ensembles with smaller lattice spacings, smaller light quark masses and lighter-than-physical strange quark masses. Both SU(2) and SU(3) chiral fits, including NNLO chiral logarithms, are shown. We give results for decay constants, quark masses, Gasser-Leutwyler low energy constants, and condensates in the two- and three-flavor chiral limits.
Source: http://arxiv.org/abs/0910.2966v1
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2.0
Jun 29, 2018
06/18
by
A. Bazavov; C. Bernard; C. M. Bouchard; C. C. Chang; C. DeTar; Daping Du; A. X. El-Khadra; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; A. S. Kronfeld; J. Laiho; P. B. Mackenzie; E. T. Neil; J. Simone; R. Sugar; D. Toussaint; R. S. Van de Water; Ran Zhou
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We calculate---for the first time in three-flavor lattice QCD---the hadronic matrix elements of all five local operators that contribute to neutral $B^0$- and $B_s$-meson mixing in and beyond the Standard Model. We present a complete error budget for each matrix element and also provide the full set of correlations among the matrix elements. We also present the corresponding bag parameters and their correlations, as well as specific combinations of the mixing matrix elements that enter the...
Topics: High Energy Physics - Phenomenology, High Energy Physics - Lattice
Source: http://arxiv.org/abs/1602.03560
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3.0
Jun 30, 2018
06/18
by
A. Bazavov; C. Bernard; C. M. Bouchard; C. DeTar; D. Du; A. X. El-Khadra; J. Foley; E. D. Freeland; E. Gámiz; Steven Gottlieb; U. M. Heller; J. Kim; J. Komijani; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; E. T. Neil; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water; R. Zhou
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We compute the leptonic decay constants $f_{D^+}$, $f_{D_s}$, and $f_{K^+}$, and the quark-mass ratios $m_c/m_s$ and $m_s/m_l$ in unquenched lattice QCD using the experimentally determined value of $f_{\pi^+}$ for normalization. We use the MILC highly improved staggered quark (HISQ) ensembles with four dynamical quark flavors---up, down, strange, and charm---and with both physical and unphysical values of the light sea-quark masses. The use of physical pions removes the need for a chiral...
Topics: High Energy Physics - Phenomenology, High Energy Physics - Lattice
Source: http://arxiv.org/abs/1407.3772
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53
Sep 23, 2013
09/13
by
A. Bazavov; C. Bernard; C. M. Bouchard; C. DeTar; M. Di Pierro; A. X. El-Khadra; R. T. Evans; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; J. E. Hetrick; R. Jain; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; E. T. Neil; M. B. Oktay; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water
texts
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We calculate the leptonic decay constants of B_{(s)} and D_{(s)} mesons in lattice QCD using staggered light quarks and Fermilab bottom and charm quarks. We compute the heavy-light meson correlation functions on the MILC asqtad-improved staggered gauge configurations which include the effects of three light dynamical sea quarks. We simulate with several values of the light valence- and sea-quark masses (down to ~m_s/10) and at three lattice spacings (a ~ 0.15, 0.12, and 0.09 fm) and extrapolate...
Source: http://arxiv.org/abs/1112.3051v1
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39
Sep 20, 2013
09/13
by
A. Bazavov; C. Bernard; C. M. Bouchard; C. DeTar; M. Di Pierro; A. X. El-Khadra; R. T. Evans; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; J. E. Hetrick; R. Jain; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; E. T. Neil; M. B. Oktay; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water
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We study SU(3)-breaking effects in the neutral B_d-\bar B_d and B_s-\bar B_s systems with unquenched N_f=2+1 lattice QCD. We calculate the relevant matrix elements on the MILC collaboration's gauge configurations with asqtad-improved staggered sea quarks. For the valence light-quarks (u, d, and s) we use the asqtad action, while for b quarks we use the Fermilab action. We obtain \xi=f_{B_s}\sqrt{B_{B_s}}/f_{B_d}\sqrt{B_{B_d}}=1.268+-0.063. We also present results for the ratio of bag parameters...
Source: http://arxiv.org/abs/1205.7013v1
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44
Sep 23, 2013
09/13
by
A. Bazavov; T. Bhattacharya; M. Cheng; C. DeTar; H. -T. Ding; Steven Gottlieb; R. Gupta; P. Hegde; U. M. Heller; F. Karsch; E. Laermann; L. Levkova; S. Mukherjee; P. Petreczky; C. Schmidt; R. A. Soltz; W. Soeldner; R. Sugar; D. Toussaint; W. Unger; P. Vranas
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We present results on the chiral and deconfinement properties of the QCD transition at finite temperature. Calculations are performed with 2+1 flavors of quarks using the p4, asqtad and HISQ/tree actions. Lattices with temporal extent N_tau=6, 8 and 12 are used to understand and control discretization errors and to reliably extrapolate estimates obtained at finite lattice spacings to the continuum limit. The chiral transition temperature is defined in terms of the phase transition in a theory...
Source: http://arxiv.org/abs/1111.1710v2
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42
Sep 23, 2013
09/13
by
A. Bazavov; T. Bhattacharya; M. Cheng; N. H. Christ; C. DeTar; S. Ejiri; Steven Gottlieb; R. Gupta; U. M. Heller; K. Huebner; C. Jung; F. Karsch; E. Laermann; L. Levkova; C. Miao; R. D. Mawhinney; P. Petreczky; C. Schmidt; R. A. Soltz; W. Soeldner; R. Sugar; D. Toussaint; P. Vranas
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We calculate the equation of state in 2+1 flavor QCD at finite temperature with physical strange quark mass and almost physical light quark masses using lattices with temporal extent Nt=8. Calculations have been performed with two different improved staggered fermion actions, the asqtad and p4 actions. Overall, we find good agreement between results obtained with these two O(a^2) improved staggered fermion discretization schemes. A comparison with earlier calculations on coarser lattices is...
Source: http://arxiv.org/abs/0903.4379v1
2
2.0
Jun 30, 2018
06/18
by
A. Bazavov; Tanmoy Bhattacharya; C. DeTar; H. -T. Ding; Steven Gottlieb; Rajan Gupta; P. Hegde; U. M. Heller; F. Karsch; E. Laermann; L. Levkova; Swagato Mukherjee; P. Petreczky; C. Schmidt; C. Schroeder; R. A. Soltz; W. Soeldner; R. Sugar; M. Wagner; P. Vranas
texts
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We present results for the equation of state in (2+1)-flavor QCD using the highly improved staggered quark action and lattices with temporal extent $N_{\tau}=6,~8,~10$, and $12$. We show that these data can be reliably extrapolated to the continuum limit and obtain a number of thermodynamic quantities and the speed of sound in the temperature range $(130-400)$ MeV. We compare our results with previous calculations, and provide an analytic parameterization of the pressure, from which other...
Topics: High Energy Physics - Phenomenology, High Energy Physics - Lattice, Nuclear Theory
Source: http://arxiv.org/abs/1407.6387
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41
Jul 20, 2013
07/13
by
A. Bazavov; Tanmoy Bhattacharya; C. E. DeTar; H. -T. Ding; Steven Gottlieb; Rajan Gupta; P. Hegde; Urs Heller; F. Karsch; E. Laermann; L. Levkova; Swagato Mukherjee; P. Petreczky; Christian Schmidt; R. A. Soltz; W. Soeldner; R. Sugar; Pavlos M. Vranas
texts
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We calculate the quadratic fluctuations of net baryon number, electric charge and strangeness as well as correlations among these conserved charges in (2+1)-flavor lattice QCD at zero chemical potential. Results are obtained using calculations with tree level improved gauge and the highly improved staggered quark (HISQ) actions with almost physical light and strange quark masses at three different values of the lattice cut-off. Our choice of parameters corresponds to a value of 160 MeV for the...
Source: http://arxiv.org/abs/1203.0784v2
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36
Sep 18, 2013
09/13
by
Andreas S. Kronfeld; I. F. Allison; C. Aubin; C. Bernard; C. T. H. Davies; C. DeTar; M. Di Pierro; E. D. Freeland; Steven Gottlieb; A. Gray; E. Gregory; U. M. Heller; J. E. Hetrick; A. X. El-Khadra; L. Levkova; P. B. Mackenzie; F. Maresca; D. Menscher; M. Nobes; M. Okamoto; M. B. Oktay; J. Osborn; D. Renner; J. N. Simone; R. Sugar; D. Toussaint; H. D. Trottier
texts
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In the past year, we calculated with lattice QCD three quantities that were unknown or poorly known. They are the $q^2$ dependence of the form factor in semileptonic $D\to Kl\nu$ decay, the decay constant of the $D$ meson, and the mass of the $B_c$ meson. In this talk, we summarize these calculations, with emphasis on their (subsequent) confirmation by experiments.
Source: http://arxiv.org/abs/hep-lat/0509169v2
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34
Sep 23, 2013
09/13
by
C. Aubin; C. Bernard; C. DeTar; M. Di Pierro; A. El-Khadra; Steven Gottlieb; E. B. Gregory; U. M. Heller; J. Hetrick; A. S. Kronfeld; P. B. Mackenzie; D. Menscher; M. Nobes; M. Okamoto; M. B. Oktay; J. Osborn; J. Simone; R. Sugar; D. Toussaint; H. D. Trottier
texts
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We present the first three-flavor lattice QCD calculations for $D\to \pi l\nu$ and $D\to K l\nu$ semileptonic decays. Simulations are carried out using ensembles of unquenched gauge fields generated by the MILC collaboration. With an improved staggered action for light quarks, we are able to simulate at light quark masses down to 1/8 of the strange mass. Consequently, the systematic error from the chiral extrapolation is much smaller than in previous calculations with Wilson-type light quarks....
Source: http://arxiv.org/abs/hep-ph/0408306v1
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42
Sep 20, 2013
09/13
by
C. Aubin; C. Bernard; C. DeTar; M. Di Pierro; E. D. Freeland; Steven Gottlieb; U. M. Heller; J. E. Hetrick; A. X. El-Khadra; A. S. Kronfeld; L. Levkova; P. B. Mackenzie; D. Menscher; F. Maresca; M. Nobes; M. Okamoto; D. Renner; J. Simone; R. Sugar; D. Toussaint; H. D. Trottier
texts
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We present the first lattice QCD calculation with realistic sea quark content of the D^+ meson decay constant f_{D^+}. We use the MILC Collaboration's publicly available ensembles of lattice gauge fields, which have a quark sea with two flavors (up and down) much lighter than a third (strange). We obtain f_{D^+} = 201 +/- 3 +/- 17 MeV, where the errors are statistical and a combination of systematic errors. We also obtain f_{D_s} = 249 +/- 3 +/- 16 MeV for the D_s meson.
Source: http://arxiv.org/abs/hep-lat/0506030v2
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30
Sep 21, 2013
09/13
by
C. Aubin; C. Bernard; C. DeTar; Steven Gottlieb; E. B. Gregory; U. M. Heller; J. E. Hetrick; J. Osborn; R. Sugar; D. Toussaint
texts
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We have extended our program of QCD simulations with an improved Kogut-Susskind quark action to a smaller lattice spacing, approximately 0.09 fm. Also, the simulations with a approximately 0.12 fm have been extended to smaller quark masses. In this paper we describe the new simulations and computations of the static quark potential and light hadron spectrum. These results give information about the remaining dependences on the lattice spacing. We examine the dependence of computed quantities on...
Source: http://arxiv.org/abs/hep-lat/0402030v1
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35
Sep 19, 2013
09/13
by
C. Aubin; C. Bernard; C. DeTar; Steven Gottlieb; Urs M. Heller; K. Orginos; R. Sugar; D. Toussaint
texts
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We compute chiral logarithms in the presence of "taste" symmetry breaking of staggered fermions. The lagrangian of Lee and Sharpe is generalized and then used to calculate the logs in $\pi$ and $K$ masses. We correct an error in Ref. [1] [C. Bernard, hep-lat/0111051]; the issue turns out to have implications for the comparison with simulations, even at tree level. MILC data with three light dynamical flavors can be well fit by our formulas. However, two new chiral parameters, which...
Source: http://arxiv.org/abs/hep-lat/0209066v1
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77
Sep 18, 2013
09/13
by
C. Bernard T. Blum; C. DeTar; Steven Gottlieb; Urs M. Heller; J. Hetrick; K. Rummukainen; R. Sugar; D. Toussaint; M. Wingate
texts
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Previous work at $6/g^2=5.7$ with quenched staggered quarks is extended with new calculations at 5.85 and 6.15 on lattices up to $32^3\times 64$. These calculations allow a more detailed study of extrapolation in quark mass, finite volume and lattice spacing than has heretofore been possible. We discuss how closely the quenched spectrum approaches that of the real world.
Source: http://arxiv.org/abs/hep-lat/9509076v1
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42
Sep 23, 2013
09/13
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C. Bernard; B. Billeter; C. DeTar; L. Levkova; Steven Gottlieb; U. M. Heller; J. E. Hetrick; J. Osborn; D. B. Renner; D. Toussaint; R. Sugar
texts
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We report new data for the topological susceptibility computed on 2+1 flavor dynamical configurations with lattice spacing 0.06 fm, generated with the asqtad action. The topological susceptibility is computed by HYP smearing and compared with rooted staggered chiral perturbation theory as the pion mass goes to zero. At 0.06 fm, the raw data is already quite close to the continuum extrapolated values obtained from coarser lattices. These results provide a further test of the asqtad action with...
Source: http://arxiv.org/abs/0710.3124v1
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113
Sep 17, 2013
09/13
by
C. Bernard; C. Davies; C. DeTar; Steven Gottlieb; U. M. Heller; J. E. Hetrick; L. Levkova; J. Osborn; D. B. Renner; R. Sugar; D. Toussaint
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The MILC collaboration's simulations with improved staggered quarks are being extended with runs at a lattice spacing of 0.06 fm with quark masses down to one tenth the strange quark mass. We give a brief introduction to these new simulations and the determination of the lattice spacing. Then we combine these new runs with older results to study the masses of the nucleon and the Omega minus in the continuum and chiral limits.
Source: http://arxiv.org/abs/0711.0021v1
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66
Sep 23, 2013
09/13
by
C. Bernard; C. DeTar; M. Di Pierro; A. X. El-Khadra; R. T. Evans; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; J. E. Hetrick; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; J. Simone; R. Sugar; D. Toussaint; R. S. Van de Water
texts
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We present an update of our calculations of the decay constants of the D, D_s, B, and B_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.
Source: http://arxiv.org/abs/0904.1895v1
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39
Sep 21, 2013
09/13
by
C. Bernard; C. DeTar; M. Di Pierro; A. X. El-Khadra; R. T. Evans; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; J. E. Hetrick; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; M. Okamoto; J. Simone; R. Sugar; D. Toussaint; R. S. Van de Water
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We present the first lattice QCD calculation of the form factor for B-> D* l nu with three flavors of sea quarks. We use an improved staggered action for the light valence and sea quarks (the MILC configurations), and the Fermilab action for the heavy quarks. The form factor is computed at zero recoil using a new double ratio method that yields the form factor more directly than the previous Fermilab method. Other improvements over the previous calculation include the use of much lighter...
Source: http://arxiv.org/abs/0808.2519v2
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31
Sep 22, 2013
09/13
by
C. Bernard; C. DeTar; M. Di Pierro; A. X. El-Khadra; R. T. Evans; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; J. E. Hetrick; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; M. Okamoto; M. B. Oktay; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water
texts
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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...
Source: http://arxiv.org/abs/0906.2498v2
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103
Sep 17, 2013
09/13
by
C. Bernard; C. DeTar; M. Di Pierro; A. X. El-Khadra; R. T. Evans; E. D. Freeland; E. Gámiz; Steven Gottlieb; U. M. Heller; J. E. Hetrick; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water
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We report the non-perturbative tuning of parameters--- kappa_c, kappa_b, and kappa_crit ---that determine the heavy-quark mass in the Fermilab action. This requires the computation of the masses of Ds^(*) and Bs^(*) mesons comprised of a Fermilab heavy quark and a staggered light quark. Additionally, we report the hyperfine splittings for Ds and Bs mesons as a cross-check of our simulation and analysis methods. We find a splitting of 145 +/- 15 MeV for the Ds system and 40 +/- 9 MeV for the Bs...
Source: http://arxiv.org/abs/1003.1937v2
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37
Sep 22, 2013
09/13
by
C. Bernard; C. DeTar; Steven Gottlieb; E. Gregory; Urs Heller; C. McNeile; J. Osborn; R. Sugar; D. Toussaint
texts
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We present preliminary results of a determination of the semileptonic form factor for the decay of pseudoscalar heavy-light mesons to pseudoscalar light-light mesons in full QCD. In this preliminary study we focus on the effects of dynamical quark loops. Accordingly, we compare results of simulations with matched quenched and Asqtad dynamical gauge configurations. The latter include three flavors of light quarks. Our simulation uses clover Wilson valence quarks, treated in the Fermilab...
Source: http://arxiv.org/abs/hep-lat/0309055v1
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29
Sep 18, 2013
09/13
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C. Bernard; C. DeTar; Steven Gottlieb; U. Heller; J. E. Hetrick; L. Levkova; F. Maresca; D. Renner; R. Sugar; D. Toussaint
texts
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The fourth root approximation in LQCD simulations with dynamical staggered fermions requires justification. We test its validity numerically in the interacting theory in a renormalization group framework.
Source: http://arxiv.org/abs/hep-lat/0509176v1
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35
Sep 18, 2013
09/13
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C. Bernard; C. DeTar; Steven Gottlieb; U. M. Heller; J. E. Hetrick; L. Levkova J. Osborn; D. Renner; R. Sugar; D. Toussaint
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Based on ongoing simulations, we update our results for low energy constants, decay constants, and light quark masses. The simulations employ three dynamical flavors of improved staggered quarks.
Source: http://arxiv.org/abs/hep-lat/0611024v1
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Sep 23, 2013
09/13
by
C. Bernard; C. DeTar; Steven Gottlieb; U. M. Heller; J. E. Hetrick; L. Levkova; J. Osborn; D. Renner; R. Sugar; D. Toussaint
texts
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We discuss the current status of our calculation of the physics of pi and K mesons using three dynamical flavors of improved staggered quarks. This year, we have a new ensemble with a lattice spacing of 0.06 fm and a light sea mass of 0.2 m_s, as well as significant increases in statistics at several coarser lattice spacings and/or heavier sea masses. Results for decay constants, quark masses, low energy constants, condensates, and V_{us} are presented.
Source: http://arxiv.org/abs/0710.1118v2
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90
Sep 23, 2013
09/13
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C. Bernard; C. DeTar; Steven Gottlieb; U. M. Heller; J. E. Hetrick; L. Levkova; R. Sugar; D. Toussaint
texts
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We present results for the QCD equation of state, quark densities and susceptibilities at nonzero chemical potential, using 2+1 flavor asqtad ensembles with $N_t=4$. The ensembles lie on a trajectory of constant physics for which $m_{ud}\approx0.1m_s$. The calculation is performed using the Taylor expansion method with terms up to sixth order in $\mu/T$.
Source: http://arxiv.org/abs/0710.1330v4
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45
Sep 19, 2013
09/13
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C. Bernard; C. DeTar; Steven Gottlieb; U. M. Heller; J. Hetrick; B. Jegerlehner; C. McNeile; K. Rummukainen; R. Sugar; D. Toussaint; M. Wingate
texts
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We use simulations of heavy quark effective field theory to calculate the Isgur-Wise function, and we demonstrate the feasibility of calculating the matrix element for the $B \to \pi + \leptons$ decay in the lattice heavy quark effective theory (HQET).
Source: http://arxiv.org/abs/hep-lat/9709134v1
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Sep 23, 2013
09/13
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C. Bernard; P. Williams; S. Datta; Steven Gottlieb; C. DeTar; Urs M. Heller; C. McNeile; K. Orginos; R. Sugar; D. Toussaint
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We compute the leptonic decay constants of heavy-light vector mesons in the quenched approximation. The reliability of lattice computations for heavy quarks is checked by comparing the ratio of vector to pseudoscalar decay constant with the prediction of Heavy Quark Effective Theory in the limit of infinitely heavy quark mass. Good agreement is found. We then calculate the decay constant ratio for B mesons: $f_{B^*}/f_B= 1.01(0.01)(^{+0.04}_{-0.01})$. We also quote quenched $f_{B^*}=177(6)(17)$...
Source: http://arxiv.org/abs/hep-lat/0109015v2
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Sep 23, 2013
09/13
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C. Bernard; Ph. de Forcrand; Steven Gottlieb; U. M. Heller; J. E. Hetrick; O. Jahn; L. Levkova; F. Maresca; D. B. Renner; R. Sugar; D. Toussaint
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We have extended our computation of the inverse participation ratio of low-lying (asqtad) Dirac eigenvectors in quenched SU(3). The scaling dimension of the confining manifold is clearer and very near 3. We have also computed the 2-point correlator which further characterizes the localization.
Source: http://arxiv.org/abs/hep-lat/0510025v1
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Sep 22, 2013
09/13
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C. Bernard; S. Datta; C. DeTar; S. Gottlieb; U. M. Heller; J. Hetrick; C. Mcneile; K. Orginos; R. Sugar; D. Toussaint
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We present results for pseudoscalar decay constants of heavy-light mesons using both quenched and N_f = 2 dynamical fermion configurations. A variety of fermion actions is investigated : Wilson, nonperturbative clover, and fat-link clover. For heavy quarks the Fermilab formalism is applied. In the quenched approximation, results with the nonperturbatively improved clover action of the Alpha collaboration allow us to study the systematic error of the continuum extrapolation from the Wilson...
Source: http://arxiv.org/abs/hep-lat/0011029v1
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Jul 20, 2013
07/13
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C. Bernard; T. Blum; A. De; T. DeGrand; C. DeTar; Steven Gottlieb; U. M. Heller; N. Ishizuka; L. Kärkkäinen; J. Labrenz; A. Soni; R. Sugar; D. Toussaint
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Preliminary results from the MILC collaboration for $f_B$, $f_{B_s}$, $f_D$, $f_{D_s}$ and their ratios are presented. We compute in the quenched approximation at $\beta=6.3$, 6.0 and 5.7 with Wilson light quarks and static and Wilson heavy quarks. We attempt to quantify systematic errors due to finite volume, finite lattice spacing, large $am$, and fitting and extrapolation uncertainties. The hopping parameter approach of Henty and Kenway is used to treat the heavy quarks; the sources are...
Source: http://arxiv.org/abs/hep-lat/9411080v1
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Sep 18, 2013
09/13
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C. Bernard; T. Blum; A. De; T. DeGrand; C. DeTar; Steven Gottlieb; Urs M. Heller; J. Hetrick; N. Ishizuka; J. Labrenz; K. Rummukainen; A. Soni; R. Sugar; D. Toussaint; M. Wingate
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Results for $f_B$, $f_{B_s}$, $f_D$, $f_{D_s}$, and their ratios are presented. High statistics quenched runs at $\beta=5.7$, $5.85$, $6.0$, and $6.3$, plus a run still in progress at $\beta=6.52$ make possible a preliminary extrapolation to the continuum. The data allows good control of all systematic errors except for quenching, although not all of the error estimates have been finalized. Results from configurations which include effects of dynamical quarks show a significant deviation from...
Source: http://arxiv.org/abs/hep-lat/9509045v1
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Sep 18, 2013
09/13
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C. Bernard; T. Blum; C. DeTar; Steven Gottlieb; U. M. Heller; J. E. Hetrick; L. Karkkainen; K. Rummukainen; R. Sugar; D. Toussaint; M. Wingate
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We improve the calculation of the equation of state for two flavor QCD by simulating on $N_t=6$ lattices at appropriate values of the couplings for the deconfinement/chiral symmetry restoration crossover. For $am_q=0.0125$ the energy density rises rapidly to approximately 1 ${\rm GeV/fm^3}$ just after the crossover($m_\pi/m_\rho\approx 0.4$ at this point). Comparing with our previous result for $N_t=4$~\cite{eos}, we find large finite $N_t$ corrections as expected from free field theory on...
Source: http://arxiv.org/abs/hep-lat/9509093v1
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Sep 19, 2013
09/13
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C. Bernard; T. Blum; T. DeGrand; C. DeTar; Steven Gottlieb; U. M. Heller; J. Hetrick; C. McNeile; K. Rummukainen; R. Sugar; D. Toussaint; M. Wingate
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The MILC collaboration computation of heavy-light decay constants is described. Results for $f_B$, $f_{B_s}$, $f_D$, $f_{D_s}$ and their ratios are presented. These results are still preliminary, but the analysis is close to being completed. Sources of systematic error, both within the quenched approximation and from quenching itself, are estimated, although the latter estimate is rather crude. A sample of our results is: $f_B=153 \pm 10 {}^{+36}_{-13} {}^{+13}_{-0} MeV$, $f_{B_s}/f_B = 1.10...
Source: http://arxiv.org/abs/hep-ph/9709328v1
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Sep 21, 2013
09/13
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C. Bernard; T. Blum; T. DeGrand; C. Detar; S. Gottlieb; A. Krasnitz; R. Sugar; D. Toussaint
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We have carried out spectrum calculations with two flavors of dynamical Kogut-Susskind quarks on four lattice sizes from $8^3\times 24$ to $16^3\times24$ at couplings that correspond to chiral symmetry restoration for a lattice with 6 time slices. We estimate that the linear spatial sizes of the lattices range from 1.8 to 3.6 fm. We find significant finite size effects for all particles between the smallest and largest volume with the larger quark mass that we study, $am_q=0.025$, where $a$ is...
Source: http://arxiv.org/abs/hep-lat/9305023v1
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Sep 23, 2013
09/13
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C. Bernard; T. Burch; C. DeTar; L. Levkova; Steven Gottlieb; U. M. Heller; J. E. Hetrick; R. Sugar; D. Toussaint
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We present results for the QCD equation of state with nonzero chemical potential using the Taylor expansion method with terms up to sixth order in the expansion. Our calculations are performed on asqtad 2+1 quark flavor lattices at $N_t=4$.
Source: http://arxiv.org/abs/0710.2520v1
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Sep 20, 2013
09/13
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C. Bernard; T. Burch; C. DeTar; Steven Gottlieb; E. B. Gregory; U. M. Heller; J. Osborn; R. Sugar; D. Toussaint
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We report on a lattice determination of the mass of the exotic $1^{-+}$ hybrid meson using an improved Kogut-Susskind action. Results from both quenched and dynamical quark simulations are presented. We also compare with earlier results using Wilson quarks at heavier quark masses. The results on lattices with three flavors of dynamical quarks show effects of sea quarks on the hybrid propagators which probably result from coupling to two meson states. We extrapolate the quenched results to the...
Source: http://arxiv.org/abs/hep-lat/0301024v2
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Sep 19, 2013
09/13
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C. Bernard; T. Burch; C. DeTar; Steven Gottlieb; E. B. Gregory; U. M. Heller; J. Osborn; R. Sugar; D. Toussaint
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We summarize our measurement of the mass of the exotic $1^{-+}$ hybrid meson using an improved Kogut-Susskind action. We show results from both quenched and dynamical quark simulations and compare with results from Wilson quarks. Extrapolation of these results to the physical quark mass allows comparison with experimental candidates for the $1^{-+}$ hybrid meson.
Source: http://arxiv.org/abs/hep-lat/0209097v1
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Sep 19, 2013
09/13
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C. Bernard; T. Burch; C. DeTar; Steven Gottlieb; L. Levkova; U. M. Heller; J. E. Hetrick; D. B. Renner; D. Toussaint; R. Sugar
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We report on our result for the equation of state (EOS) with a Symanzik improved gauge action and the asqtad improved staggered fermion action at $N_t=4$ and 6. In our dynamical simulations with 2+1 flavors we use the inexact R algorithm and here we estimate the finite step-size systematic error on the EOS. Finally we discuss the non-zero chemical potential extension of the EOS and give some preliminary results.
Source: http://arxiv.org/abs/hep-lat/0610017v1
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Sep 18, 2013
09/13
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C. Bernard; T. Burch; C. DeTar; Steven Gottlieb; L. Levkova; U. M. Heller; J. E. Hetrick; R. Sugar; D. Toussaint
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We report results for the interaction measure, pressure and energy density for nonzero temperature QCD with 2+1 flavors of improved staggered quarks. In our simulations we use a Symanzik improved gauge action and the Asqtad $O(a^2)$ improved staggered quark action for lattices with temporal extent $N_t=4$ and 6. The heavy quark mass $m_s$ is fixed at approximately the physical strange quark mass and the two degenerate light quarks have masses $m_{ud}\approx0.1 m_s$ or $0.2 m_s$. The calculation...
Source: http://arxiv.org/abs/hep-lat/0611031v3
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Sep 18, 2013
09/13
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C. Bernard; T. Burch; C. DeTar; Steven Gottlieb; U. M. Heller; J. E. Hetrick; L. Levkova; F. Maresca; D. B. Renner; R. Sugar; D. Toussaint
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We report results for the interaction measure, pressure and energy density for nonzero temperature QCD with 2+1 flavors of improved staggered quarks. In our simulations we use a Symanzik improved gauge action and the Asqtad $O(a^2)$ improved staggered quark action for lattices with temporal extent $N_t=4$ and 6. The heavy quark mass $m_s$ is fixed at approximately the physical strange quark mass and the two degenerate light quarks have masses $m_{ud} =0.1m_s$ or $0.2m_s$. The calculation of the...
Source: http://arxiv.org/abs/hep-lat/0509053v1
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Sep 18, 2013
09/13
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C. Bernard; T. Burch; S. Datta; T. DeGrand; C. DeTar; Steven Gottlieb; Urs M. Heller; K. Orginos; R. Sugar; D. Toussaint
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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...
Source: http://arxiv.org/abs/hep-lat/0110072v1
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Sep 19, 2013
09/13
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C. Bernard; T. Burch; T. DeGrand; C. DeTar; Steven Gottlieb; E. B. Gregory; U. M. Heller; J. Osborn; R. Sugar; D. Toussaint
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Preliminary results from simulations with 2+1 dynamical quark flavors at a lattice spacing of 0.09 fm are combined with earlier results at a=0.13 fm. We examine the approach to the continuum limit and investigate the dependence of the pseudoscalar masses and decay constants as the sea and valence quark masses are separately varied.
Source: http://arxiv.org/abs/hep-lat/0208041v1
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Sep 22, 2013
09/13
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C. Bernard; T. DeGrand; C. DeTar; Steven Gottlieb; E. Gregory; A. Hart; A. Hasenfratz; Urs Heller; J. Hetrick; J. Osborn; R. Sugar; D. Toussaint
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Chiral perturbation theory predicts that in quantum chromodymamics light dynamical quarks suppress the topological (instanton) susceptibility. We investigate this suppression through direct numerical simulation using the Asqtad improved lattice fermion action. This action holds promise for carrying out nonperturbative simulations over a range of quark masses for which chiral perturbation theory is expected to converge. To test the effectiveness of the action in capturing instanton physics, we...
Source: http://arxiv.org/abs/hep-lat/0308019v2
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Sep 19, 2013
09/13
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C. Bernard; T. DeGrand; C. DeTar; Steven Gottlieb; U. M. Heller; J. Hetrick; C. McNeile; K. Rummukainen; R. Sugar; D. Toussaint; M. Wingate
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MILC collaboration results for \fB, \fBs, \fD, \fDs and their ratios are presented. These results are still preliminary, but the analysis is close to being completed. Sources of systematic error, both within the quenched approximation and from quenching itself, are estimated. We find, for example, $f_B=153\pm 10 {}^{+36}_{-13} {}^{+13}_{-0} MeV$, and $f_{B_s}/f_B = 1.10 \pm 0.02 {}^{+0.05}_{-0.03} {}^{+0.03}_{-0.02}$, where the errors are statistical, systematic (within the quenched...
Source: http://arxiv.org/abs/hep-lat/9709142v1
