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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, [......],
P B Mackenzie,
D Menscher,
F Maresca, M Nobes,
M Okamoto,
D Renner,
J Simone,
R Sugar,
D Toussaint,
H D Trottier
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ABSTRACT: 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(Ds)=249+/-3+/-16 MeV for the Ds meson.
Physical Review Letters 10/2005; 95(12):122002. · 7.37 Impact Factor
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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, [......],
D. Menscher, M. Nobes,
M. Okamoto,
M. B. Oktay,
J. Osborn,
D. Renner,
J. N. Simone,
R. Sugar,
D. Toussaint,
H. D. Trottier
[show abstract]
[hide abstract]
ABSTRACT: 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. Comment: v1: talk given at the International Conference on QCD and Hadronic Physics, Beijing, June 16-20, 2005; v2: poster presented at the XXIIIrd International Symposium on Lattice Field Theory, Dublin, July 25-30
09/2005;
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ABSTRACT: We obtain a new value for the QCD coupling constant by combining lattice QCD simulations with experimental data for hadron masses. Our lattice analysis is the first to (1) include vacuum polarization effects from all three light-quark flavors (using MILC configurations), (2) include third-order terms in perturbation theory, (3) systematically estimate fourth and higher-order terms, (4) use an unambiguous lattice spacing, and (5) use an [symbol: see text](a2)-accurate QCD action. We use 28 different (but related) short-distance quantities to obtain alpha((5)/(MS))(M(Z)) = 0.1170(12).
Physical Review Letters 08/2005; 95(5):052002. · 7.37 Impact Factor
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C Aubin,
C Bernard,
C Detar,
M Dipierro,
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
[show abstract]
[hide abstract]
ABSTRACT: We present the first three-flavor lattice QCD calculations for D-->pilnu and D-->Klnu 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. Our results for the form factors at q(2)=0 are f(D-->pi)(+)(0)=0.64(3)(6) and f(D-->K)(+)(0)=0.73(3)(7), where the first error is statistical and the second is systematic, added in quadrature. Combining our results with experimental branching ratios, we obtain the Cabibbo-Kobayashi-Maskawa matrix elements |V(cd)|=0.239(10)(24)(20) and |V(cs)|=0.969(39)(94)(24), where the last errors are from experimental uncertainties.
Physical Review Letters 01/2005; 94(1):011601. · 7.37 Impact Factor
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J. N. Simone,
C. Aubin,
C. Bernard,
C. DeTar,
M. Di Pierro,
A. X. El-Khadra,
Steven Gottlieb,
E. B. Gregory,
U. M. Heller,
J. E. Hetrick, [......],
D. P. Menscher, M. Nobes,
M. Okamoto,
M. B. Oktay,
J. Osborn,
R. Sugar,
D. Toussaint,
H. D. Trottier: The Fermilab Lattice,
MILC,
HPQCD Collaborations
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ABSTRACT: We determine the leptonic decay constants in three flavor unquenched lattice QCD. We use O(a^2)-improved staggered light quarks and O(a)-improved charm quarks in the Fermilab heavy quark formalism. Our preliminary results, based upon an analysis at a single lattice spacing, are f_Ds = 263(+5-9)(+/-24) MeV and f_D = 225(+11-13)(+/-21) MeV. In each case, the first reported error is statistical while the is the combined systematic uncertainty.
11/2004;
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M. Okamoto,
C. Aubin,
C. Bernard,
C. DeTar,
M. Di Pierro,
A. X. El-Khadra,
Steven Gottlieb,
E. B. Gregory,
U. M. Heller,
J. Hetrick,
A. S. Kronfeld,
P. B. Mackenzie,
D. P. Menscher, M. Nobes,
M. B. Oktay,
J. Osborn,
J. N. Simone,
R. Sugar,
D. Toussaint,
H. D. Trottier
[show abstract]
[hide abstract]
ABSTRACT: We present results for form factors of semileptonic decays of $D$ and $B$ mesons in 2+1 flavor lattice QCD using the MILC gauge configurations. With an improved staggered action for light quarks, we successfully reduce the systematic error from the chiral extrapolation. The results for $D$ decays are in agreement with experimental ones. The results for B decays are preliminary. Combining our results with experimental branching ratios, we then obtain the CKM matrix elements $|V_{cd}|$, $|V_{cs}|$, $|V_{cb}|$ and $|V_{ub}|$. We also check CKM unitarity, for the first time, using only lattice QCD as the theoretical input.
10/2004;
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C T H Davies,
E Follana,
A Gray,
G P Lepage,
Q Mason, M Nobes,
J Shigemitsu,
H D Trottier,
M Wingate,
C Aubin, [......],
J E Hetrick,
J Osborn,
R Sugar,
D Toussaint,
M Di Pierro,
A El-Khadra,
A S Kronfeld,
P B Mackenzie,
D Menscher,
J Simone
[show abstract]
[hide abstract]
ABSTRACT: The recently developed Symanzik-improved staggered-quark discretization allows unquenched lattice-QCD simulations with much smaller (and more realistic) quark masses than previously possible. To test this formalism, we compare experiment with a variety of nonperturbative calculations in QCD drawn from a restricted set of "gold-plated" quantities. We find agreement to within statistical and systematic errors of 3% or less. We discuss the implications for phenomenology and, in particular, for heavy-quark physics.
Physical Review Letters 02/2004; 92(2):022001. · 7.37 Impact Factor
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C Davies,
A. Gray,
M. Alford,
E. Follana,
J. Hein,
P. Lepage,
Q. Mason, M. Nobes,
J. Shigemit su,
H. Trottier,
M. Wingate
[show abstract]
[hide abstract]
ABSTRACT: We describe the first lattice determination of the strong coupling constant with 3 flavors of dynamical quarks. The method follows previous analyses in using a perturbative expansion for the plaquette and Upsilon spectroscopy to set the scale. Using dynamical configurations from the MILC collaboration with 2+1 flavors of dynamical quarks we are able to avoid previous problems of having to extrapolate to 3 light flavors from 0 and 2. Our results agree with our previous work: alpha_s_MSbar(M_Z) = 0.121(3).
10/2002;
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A. Gray,
C Davies,
M. Alford,
E. Follana,
J. Hein,
G. P. Lepage,
Q. Mason, M. Nobes,
J. Shigemitsu,
H. Trottier,
M. Wingate
[show abstract]
[hide abstract]
ABSTRACT: We describe the bottomonium spectrum obtained on the MILC configurations which incorporate 2+1 flavors of dynamical quarks. We compare to quenched and 2 flavor results also on MILC configurations. We show that the lattice spacing determination using different quantities shows clear signs of convergence with 2+1 flavors and give results for the leptonic width and hyperfine splitting, in the form of the ratio of the 1st excited state of the Upsilon to that of the ground state.
10/2002;
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ABSTRACT: We present the results of our perturbative calculations of the static quark potential, small Wilson loops, the static quark self energy, and the mean link in Landau gauge. These calculations are done for the one loop Symanzik improved gluon action, and the improved staggered quark action.
11/2001;
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P B Mackenzie,
C Aubin,
C Bernard,
C Detar,
M Di Pierro,
Steven Gottlieb,
E Gregory,
U M Heller,
J E Hetrick,
A X El-Khadra, [......],
D Menscher, M Nobes,
M Okamoto,
M B Oktay,
J Osborn,
D Renner,
J N Simone,
R Sugar,
D Toussaint,
H D Trottier
[show abstract]
[hide abstract]
ABSTRACT: Fermilab Lattice, MILC, and HPQCD Collaborations We have calculated the semileptonic form factors of B and D mesons using unquenched, im-proved staggered light quarks, and improved clover heavy quarks. We discuss the use of unitarity constraints to bound the form factors in the high recoil momentum region.
01/2002;
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C Davies,
A. Gray,
M. Alford,
E. Follana,
J. Hein,
P. Lepage,
Q. Mason, M. Nobes,
J. Shigemitsu,
H. Trottier,
M. Wingate
[show abstract]
[hide abstract]
ABSTRACT: We describe the first lattice determination of the strong coupling constant with 3 flavors of dynamical quarks. The method follows previous analyses in using a perturbative expansion for the plaquette and Upsilon spectroscopy to set the scale. Using dynamical configurations from the MILC collaboration with 2+1 flavors of dynamical quarks we are able to avoid previous problems of having to extrapolate to 3 light flavors from 0 and 2. Our result agrees with our previous work: alpha /sub theta //sup MS/(Mz) = 0.121(3).
