Internet Archive Search: creator:"R. Sugar"

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75 75

Update on the physics of light pseudoscalar mesons

Jul 20, 2013 07/13

by The MILC Collaboration; 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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We present an update of the MILC investigation of the properties of light pseudoscalar mesons using three flavors of improved staggered quarks. Results are presented for the $\pi$ and $K$ leptonic decay constants, the CKM matrix element $V_{us}$, the up, down and strange quark masses, and the coefficients of the $O(p^4)$ chiral lagrangian. We have new data for lattice spacing $a \approx 0.15$ fm with several values of the light quark mass down to one-tenth the strange quark mass, higher...
Source: http://arxiv.org/abs/hep-lat/0609053v1

Arxiv.org

51 51

Full nonperturbative QCD simulations with 2+1 flavors of improved staggered quarks

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

Arxiv.org

39 39

Neutral B-meson mixing from three-flavor lattice QCD: Determination of the SU(3)-breaking ratio ξ

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

eye 39

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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

Arxiv.org

34 34

Semileptonic decays of $D$ mesons in three-flavor lattice QCD

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

eye 34

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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

Arxiv.org

41 41

Electromagnetic splittings of hadrons from improved staggered quarks in full QCD

Sep 22, 2013 09/13

by S. Basak; 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

eye 41

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We present our initial study of the electromagnetic splittings of charged and neutral mesons, and the violation of Dashen's theorem. Hadron masses are calculated on MILC N_f=2+1 QCD ensembles at lattice spacing \approx 0.15fm, together with quenched non-compact U(1) configurations. The O(a^2) tadpole improved staggered quark (asqtad) action is used both for the sea quarks and for six different valence quark masses. Chiral extrapolations are performed using partially quenched chiral perturbation...
Source: http://arxiv.org/abs/0812.4486v1

Arxiv.org

31 31

Visualization of semileptonic form factors from lattice QCD

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

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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

Arxiv.org

34 34

Light hadron spectrum with Kogut-Susskind quarks

Sep 20, 2013 09/13

by MILC Collaboration; C. Bernard; C. DeTar; Steven Gottlieb; Urs M. Heller; J. E. Hetrick; C. McNeile; K. Rummukainen; R. Sugar; D. Toussaint

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We made an extensive study of the light hadron spectrum using the Wilson gauge action and Kogut-Susskind quarks. Using both dynamical quarks and the quenched approximation, we determine hadron masses for five and four gauge couplings respectively, with at least five quark masses at each coupling. In the continuum limit, we find a significant difference between two flavors of dynamical quarks and the quenched approximation for a range of quark masses.
Source: http://arxiv.org/abs/hep-lat/9810035v1

Arxiv.org

39 39

Exotic hybrid mesons from improved Kogut-Susskind fermions

Sep 19, 2013 09/13

by 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

Arxiv.org

36 36

High-Precision Lattice QCD Confronts Experiment

Sep 19, 2013 09/13

by C. T. H. Davies; E. Follana; A. Gray; G. P. Lepage; Q. Mason; M. Nobes; J. Shigemitsu; H. D. Trottier; M. Wingate; C. Aubin; C. Bernard; T. Burch; C. DeTar; Steven Gottlieb; E. B. Gregory; U. M. Heller; 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

eye 36

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We argue that high-precision lattice QCD is now possible, for the first time, because of a new improved staggered quark discretization. We compare a wide variety of nonperturbative calculations in QCD with experiment, and find agreement to within statistical and systematic errors of 3% or less. We also present a new determination of alpha_msbar(Mz); we obtain 0.121(3). We discuss the implications of this breakthrough for phenomenology and, in particular, for heavy-quark physics.
Source: http://arxiv.org/abs/hep-lat/0304004v1

Arxiv.org

46 46

Lattice results for the decay constant of heavy-light vector mesons

Sep 23, 2013 09/13

by 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

Arxiv.org

31 31

QCD Thermodynamics with Three Flavors of Improved Staggered Quarks

Sep 20, 2013 09/13

by The MILC Collaboration; C. Bernard; T. Burch; C. DeTar; Steven Gottlieb; E. B. Gregory; U. M. Heller; J. Osborn; R. Sugar; D. Toussaint

eye 31

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We report on a study of QCD thermodynamics with three flavors of quarks, using a Symanzik improved gauge action and the Asqtad O(a^2) improved staggered quark action. Simulations were carried out with lattice spacings 1/4T, 1/6T and 1/8T both for three degenerate quarks with masses less than or equal to the strange quark mass, m_s, and for degenerate up and down quarks with masses in the range 0.1 m_s \leq m_{u,d} \leq 0.6 m_s, and the strange quark mass fixed near its physical value. We...
Source: http://arxiv.org/abs/hep-lat/0405029v2

Arxiv.org

31 31

More evidence of localization in the low-lying Dirac spectrum

Sep 23, 2013 09/13

by 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

Arxiv.org

45 45

B meson form factors from HQET simulations

Sep 19, 2013 09/13

by C. Bernard; C. DeTar; Steven Gottlieb; U. M. Heller; J. Hetrick; B. Jegerlehner; C. McNeile; K. Rummukainen; R. Sugar; D. Toussaint; M. Wingate

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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

Arxiv.org

89 89

QCD thermodynamics with 2+1 flavors at nonzero chemical potential

Sep 23, 2013 09/13

by C. Bernard; C. DeTar; Steven Gottlieb; U. M. Heller; J. E. Hetrick; L. Levkova; R. Sugar; D. Toussaint

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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

Arxiv.org

48 48

B_s->D_s/B->D Semileptonic Form-Factor Ratios and Their Application to BR(B^0_s->μ^+μ^-)

Sep 23, 2013 09/13

by Jon A. Bailey; A. Bazavov; C. Bernard; C. M. Bouchard; C. DeTar; Daping Du; A. X. El-Khadra; J. Foley; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; Jongjeong Kim; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; Y. Meurice; E. Neil; M. B. Oktay; Si-Wei Qiu; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water; Ran Zhou

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We calculate form-factor ratios between the semileptonic decays \bar{B}->D^+\ell^-\bar{\nu} and \bar{B}_s->D_s^+\ell^-\bar{\nu} with lattice QCD. These ratios are a key theoretical input in a new strategy to determine the fragmentation fractions of the neutral B decays, which are needed for measurements of BR(B^0_s-> \mu^+\mu^-). We use the MILC ensembles of gauge configurations with 2+1 flavors of sea quarks at two lattice spacings of approximately 0.12 fm and 0.09 fm. We use the...
Source: http://arxiv.org/abs/1202.6346v2

Arxiv.org

41 41

Fluctuations and Correlations of net baryon number, electric charge, and strangeness: A comparison of lattice QCD results with the hadron resonance gas model

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

eye 41

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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

Arxiv.org

30 30

Lattice Calculation of Heavy-Light Decay Constants with Two Flavors of Dynamical Quarks

Sep 19, 2013 09/13

by The MILC Collaboration; C. Bernard; S. Datta; T. DeGrand; C. DeTar; Steven Gottlieb; Urs M. Heller; C. McNeile; K. Orginos; R. Sugar; D. Toussaint

eye 30

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We present results for $f_B$, $f_{B_s}$, $f_D$, $f_{D_s}$ and their ratios in the presence of two flavors of light sea quarks ($N_f=2$). We use Wilson light valence quarks and Wilson and static heavy valence quarks; the sea quarks are simulated with staggered fermions. Additional quenched simulations with nonperturbatively improved clover fermions allow us to improve our control of the continuum extrapolation. For our central values the masses of the sea quarks are not extrapolated to the...
Source: http://arxiv.org/abs/hep-lat/0206016v2

Arxiv.org

32 32

The scaling dimension of low lying Dirac eigenmodes and of the topological charge density

Sep 20, 2013 09/13

by MILC Collaboration; C. Aubin; C. Bernard; Steven Gottlieb; E. B. Gregory; Urs M. Heller; J. E. Hetrick; J. Osborn; R. Sugar; D. Toussaint; with; :; Ph. de Forcrand; O. Jahn

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As a quantitative measure of localization, the inverse participation ratio of low lying Dirac eigenmodes and topological charge density is calculated on quenched lattices over a wide range of lattice spacings and volumes. Since different topological objects (instantons, vortices, monopoles, and artifacts) have different co-dimension, scaling analysis provides information on the amount of each present and their correlation with the localization of low lying eigenmodes.
Source: http://arxiv.org/abs/hep-lat/0410024v1

Arxiv.org

42 42

Charmed meson decay constants in three-flavor lattice QCD

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

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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

Arxiv.org

29 29

Finite-size and quark mass effects on the QCD spectrum with two flavors

Sep 21, 2013 09/13

by 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

Arxiv.org

38 38

$Status and prospect for determining $f_B$, $f_{B_s}$, $f_{B_s} / f_B$ on the lattice$

Status and prospect for determining $f_B$, $f_{B_s}$, $f_{B_s} / f_B$ on the lattice

Sep 22, 2013 09/13

by The MILC Collaboration; C. Bernard; T. Blum; A. De; T. DeGrand; C. DeTar; Steven Gottlieb; Urs M. Heller; N. Ishizuka; L. Kärkkäinen; J. Labrenz; K. Rummukainen; A. Soni; R. Sugar; D. Toussaint

eye 38

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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 all systematic errors other than quenching, and have a first indication of the size of quenching errors.
Source: http://arxiv.org/abs/hep-ph/9503336v1

Arxiv.org

11 11

$$B\to Kl^+l^-$ decay form factors from three-flavor lattice QCD$

$B\to Kl^+l^-$ decay form factors from three-flavor lattice QCD

Jun 28, 2018 06/18

by Jon A. Bailey; A. Bazavov; C. Bernard; C. M. Bouchard; C. DeTar; Daping Du; A. X. El-Khadra; J. Foley; E. D. Freeland; E. Gámiz; Steven Gottlieb; U. M. Heller; R. D. Jain; J. Komijani; A. S. Kronfeld; J. Laiho; L. Levkova; Yuzhi Liu; P. B. Mackenzie; Y. Meurice; E. T. Neil; Si-Wei Qiu; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water; Ran Zhou

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We compute the form factors for the $B \to Kl^+l^-$ semileptonic decay process in lattice QCD using gauge-field ensembles with 2+1 flavors of sea quark, generated by the MILC Collaboration. The ensembles span lattice spacings from 0.12 to 0.045 fm and have multiple sea-quark masses to help control the chiral extrapolation. The asqtad improved staggered action is used for the light valence and sea quarks, and the clover action with the Fermilab interpretation is used for the heavy $b$ quark. We...
Topics: High Energy Physics - Phenomenology, High Energy Physics - Lattice
Source: http://arxiv.org/abs/1509.06235

Arxiv.org

10 10.0

$$B\to\pi\ell\ell$ form factors for new-physics searches from lattice QCD$

$B\to\pi\ell\ell$ form factors for new-physics searches from lattice QCD

Jun 28, 2018 06/18

by Jon A. Bailey; A. Bazavov; C. Bernard; C. M. Bouchard; C. DeTar; Daping Du; A. X. El-Khadra; E. D. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; A. S. Kronfeld; J. Laiho; L. Levkova; Yuzhi Liu; E. Lunghi; P. B. Mackenzie; Y. Meurice; E. Neil; Si-Wei Qiu; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water; Ran Zhou

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The rare decay $B\to\pi\ell^+\ell^-$ arises from $b\to d$ flavor-changing neutral currents and could be sensitive to physics beyond the Standard Model. Here, we present the first $ab$-$initio$ QCD calculation of the $B\to\pi$ tensor form factor $f_T$. Together with the vector and scalar form factors $f_+$ and $f_0$ from our companion work [J. A. Bailey $et~al.$, Phys. Rev. D 92, 014024 (2015)], these parameterize the hadronic contribution to $B\to\pi$ semileptonic decays in any extension of the...
Topics: High Energy Physics - Phenomenology, High Energy Physics - Lattice
Source: http://arxiv.org/abs/1507.01618

Arxiv.org

35 35

Status of the MILC light pseudoscalar meson project

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

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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

Arxiv.org

37 37

Heavy-light meson decay constants with N_f=3

Sep 19, 2013 09/13

by MILC Collaboration; C. Bernard; T. Burch; S. Datta; C. DeTar; Steven Gottlieb; E. Gregory; Urs M. Heller; R. Sugar; D. Toussaint

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During the past year the MILC Collaboration has continued its study of heavy-light meson decay constants with three dynamical quarks. Calculations have been extended to a second lattice spacing of about 0.09 fm. At this lattice spacing, there are results in the quenched approximation and for three sets of dynamical quark mass: m_l=m_s; m_l=0.4 m_s and m_l=0.2 m_s, where m_l is the light mass for the u and d quarks and m_s is the strange quark mass. At the coarser lattice spacing, for which...
Source: http://arxiv.org/abs/hep-lat/0209163v1

Arxiv.org

29 29

The locality of the fourth root of staggered fermion determinant in the interacting case

Sep 18, 2013 09/13

by C. Bernard; C. DeTar; Steven Gottlieb; U. Heller; J. E. Hetrick; L. Levkova; F. Maresca; D. Renner; R. Sugar; D. Toussaint

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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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44 44

The chiral and deconfinement aspects of the QCD transition

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 42

B -> D* l nu at zero recoil: an update

Sep 21, 2013 09/13

by Jon A. Bailey; A. Bazavov; C. Bernard; C. M. Bouchard; C. DeTar; A. X. El-Khadra; E. D. Freeland; E. Gámiz; Steven Gottlieb; U. M. Heller; J. E. Hetrick; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; M. B. Oktay; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water

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We present an update of our calculation of the form factor for B -> D* l nu at zero recoil, with higher statistics and finer lattices. As before, we use the Fermilab action for b and c quarks, the asqtad staggered action for light valence quarks, and the MILC ensembles for gluons and light quarks (L\"uscher-Weisz married to 2+1 rooted staggered sea quarks). In this update, we have reduced the total uncertainty on F(1) from 2.6% to 1.7%. At Lattice2010 we presented a still-blinded...
Source: http://arxiv.org/abs/1011.2166v1

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39 39

The B -> D* l nu form factor at zero recoil from three-flavor lattice QCD: A model independent determination of |V_cb|

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

eye 39

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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

Arxiv.org

43 43

The equation of state with nonzero chemical potential for 2+1 flavors

Sep 23, 2013 09/13

by 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

Arxiv.org

112 112

Baryon masses with improved staggered quarks

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

Arxiv.org

59 59

HISQ action in dynamical simulations

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

Arxiv.org

103 103

Tuning Fermilab Heavy Quarks in 2+1 Flavor Lattice QCD with Application to Hyperfine Splittings

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

Arxiv.org

42 42

Equation of state and QCD transition at finite temperature

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

Arxiv.org

44 44

f_B for Various Actions : Approaching the Continuum Limit with Dynamical Fermions

Sep 22, 2013 09/13

by 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

Arxiv.org

31 31

Heavy-light decay constants with three dynamical flavors

Sep 18, 2013 09/13

by 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

Arxiv.org

39 39

Semileptonic D->pi/K and B->pi/D decays in 2+1 flavor lattice QCD

Sep 22, 2013 09/13

by 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

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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 $|V_{cd}|$,...
Source: http://arxiv.org/abs/hep-lat/0409116v1

Arxiv.org

32 32

Update on pi and K Physics

Sep 18, 2013 09/13

by MILC Collaboration; C. Bernard; C. DeTar; Steven Gottlieb; U. M. Heller; J. E. Hetrick; L. Levkova; F. Maresca; J. Osborn; D. Renner; R. Sugar; D. Toussaint

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We present an update of the MILC studies of the physics of light pseudoscalars using improved staggered fermions. New runs at lighter quark mass, as well as increased statistics for older sets, are enabling us to improve the results for decay constants in full QCD. In addition, we have analyzed quenched runs at two different lattice spacings. This makes possible a test of the applicability of staggered chiral perturbation theory in a different context.
Source: http://arxiv.org/abs/hep-lat/0509137v1

Arxiv.org

36 36

Update on $f_B$

Sep 23, 2013 09/13

by The MILC Collaboration; C. Bernard; T. Blum; T. DeGrand; C. DeTar; Steven Gottlieb; U. M. Heller; J. Hetrick; C. McNeile; K. Rummukainen; A. Soni; R. Sugar; D. Toussaint; M. Wingate

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We describe the current status of the MILC collaboration computation of $f_B$, $f_{B_s}$, $f_D$, $f_{D_s}$ and their ratios. Progress over the past year includes: better statistics and plateaus at $\beta=6.52$ (quenched), $\beta=5.6$ ($N_F=2$) and $\beta=5.445$ ($N_F=2$), new runs with a wide range of dynamical quark masses at $\beta=5.5$ ($N_F=2$), an estimate of the systematic errors due to the chiral extrapolation, and an improved analysis which consistently takes into account both the...
Source: http://arxiv.org/abs/hep-lat/9608092v1

Arxiv.org

35 35

Low energy constants from the MILC Collaboration

Sep 18, 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

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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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