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10.0
Jun 28, 2018
06/18
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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
9
9.0
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
2
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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77
Sep 18, 2013
09/13
by
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
5
5.0
Jun 27, 2018
06/18
by
Fermilab Lattice; MILC Collaborations; :; 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; J. Komijani; A. S. Kronfeld; J. Laiho; L. Levkova; Yuzhi Liu; P. B. Mackenzie; Y. Meurice; E. T. Neil; Si-Wei Qiu; J. Simone; R. Sugar; D. Toussaint; R. S. Van de Water; Ran Zhou
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We present a lattice-QCD calculation of the $B\to\pi\ell\nu$ semileptonic form factors and a new determination of the CKM matrix element $|V_{ub}|$. We use the MILC asqtad 2+1-flavor lattice configurations at four lattice spacings and light-quark masses down to 1/20 of the physical strange-quark mass. We extrapolate the lattice form factors to the continuum using staggered chiral perturbation theory in the hard-pion and SU(2) limits. We employ a model-independent $z$ parameterization to...
Topics: High Energy Physics - Experiment, High Energy Physics - Phenomenology, High Energy Physics - Lattice
Source: http://arxiv.org/abs/1503.07839
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42
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
texts
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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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32
Sep 19, 2013
09/13
by
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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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
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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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31
Sep 24, 2013
09/13
by
E. T. Neil; Jon A. Bailey; A. Bazavov; C. Bernard; C. M. Bouchard; C. DeTar; M. Di Pierro; A. X. El-Khadra; R. T. Evans; E. Freeland; E. Gamiz; Steven Gottlieb; U. M. Heller; J. E. Hetrick; R. Jain; 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; for the Fermilab Lattice Collaboration; for the MILC Collaboration
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We give an update on simulation results for the decay constants f_B, f_{B_s}, f_D and f_{D_s}. These decay constants are important for precision tests of the standard model, in particular entering as inputs to the global CKM unitarity triangle fit. The results presented here make use of the MILC (2+1)-flavor asqtad ensembles, with heavy quarks incorporated using the clover action with the Fermilab method. Partially quenched, staggered chiral perturbation theory is used to extract the decay...
Source: http://arxiv.org/abs/1112.3978v1
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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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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
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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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48
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
texts
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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
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112
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
3
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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41
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
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34
Sep 19, 2013
09/13
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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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31
Sep 22, 2013
09/13
by
MILC Collaboration; Claude Bernard; Tom Blum; Carleton DeTar; Steven Gottlieb; Urs M. Heller; James E. Hetrick; Craig McNeile; K. Rummukainen; R. Sugar; D. Toussaint
texts
eye 31
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We calculate the light quark spectrum of lattice QCD in the quenched approximation using Kogut-Susskind quarks. By combining results for different lattice spacings, several volumes and five quark masses, we are able to take the light quark mass, infinite volume, continuum limit. When we use non-linear chiral extrapolations, we find that the nucleon to rho mass ratio is 1.254 +- 0.018 +- 0.027, where the errors are statistical and systematic (within the quenched approximation), respectively....
Source: http://arxiv.org/abs/hep-lat/9805004v2
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40
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
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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
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42
Sep 23, 2013
09/13
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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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eye 42
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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
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42
Sep 22, 2013
09/13
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MILC Collaboration; C. Bernard; T. Burch; C. DeTar; Steven Gottlieb; E. B. Gregory; U. M. Heller; J. Osborn; R. Sugar; D. Toussaint
texts
eye 42
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We report on preliminary results from multi-particle fits to meson propagators with three flavors of light dynamical quarks. We are able to measure excited states in propagators with pion quantum numbers, which we interpret as the pion 2S state, and is evidence of locality of the action. In the a_0 (0^{++}) propagators we find evidence for excited states which are probably the expected decay channels, pi+eta and K+Kbar.
Source: http://arxiv.org/abs/hep-lat/0309117v1
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38
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
texts
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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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40
Sep 18, 2013
09/13
by
C. Bernard; T. DeGrand; C. DeTar; Steven Gottlieb; U. M. Heller; J. Hetrick; C. McNeile; R. Sugar; D. Toussaint
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We repeat our original simulations of the hybrid meson spectrum using the clover action, as a check on lattice artifacts. Our results for the 1-+ masses do not substantially change. We present preliminary results for the wave function of the 1-+ state in Coulomb gauge.
Source: http://arxiv.org/abs/hep-lat/9809087v1
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28
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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31
Sep 20, 2013
09/13
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HPQCD collaboration; MILC collaboration; UKQCD collaboration; C. Aubin; C. Bernard; C. Davies; C. DeTar; Steven Gottlieb; A. Gray; E. Gregory; J. Hein; U. Heller; J. Hetrick; G. Lepage; Q. Mason; J. Osborn; J. Shigemitsu; R. Sugar; D. Toussaint; H. Trottier; M. Wingate
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We compute the strange quark mass $m_s$ and the average of the $u$ and $d$ quark masses $\hat m$ using full lattice QCD with three dynamical quarks combined with experimental values for the pion and kaon masses. The simulations have degenerate $u$ and $d$ quarks with masses $m_u=m_d\equiv \hat m$ as low as $m_s/8$, and two different values of the lattice spacing. The bare lattice quark masses obtained are converted to the $\msbar$ scheme using perturbation theory at $O(alpha_s)$. Our results...
Source: http://arxiv.org/abs/hep-lat/0405022v3
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41
Jul 20, 2013
07/13
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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
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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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51
Sep 23, 2013
09/13
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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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Sep 23, 2013
09/13
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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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58
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
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30
Sep 18, 2013
09/13
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MILC Collaboration; C. Bernard; T. DeGrand; C. DeTar; Steven Gottlieb; Urs M. Heller; J. Hetrick; N. Ishizuka; C. McNeile; R. Sugar; D. Toussaint; M. Wingate
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We report on the results of a MILC collaboration calculation of $f_B$, $f_{B_s}$, $f_D$, $f_{D_s}$ and their ratios. We discuss the most important errors in more detail than we have elsewhere.
Source: http://arxiv.org/abs/hep-lat/9809109v2
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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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36
Sep 19, 2013
09/13
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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
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Sep 19, 2013
09/13
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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; 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
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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
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Sep 23, 2013
09/13
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K. Orginos; R. Sugar; D. Toussaint
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We study improved Kogut-Susskind fermion actions focusing on flavor symmetry restoration. Several variants of fat actions suitable for dynamical simulations are considered, including an action with no tree level order a-squared errors. The spectrum of all the pions is computed and used as a measure of flavor symmetry violation. Finally, the Naik term is introduced to restore rotational symmetry.
Source: http://arxiv.org/abs/hep-lat/9909087v1
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Sep 18, 2013
09/13
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E. Gamiz; J. A. Bailey; A. Bazavov; C. Bernard; C. Bouchard; C. DeTar; D. Du; A. X. El-Khadra; J. Foley; E. D. Freeland; Steven Gottlieb; U. M. Heller; J. Kim; A. S. Kronfeld; J. Laiho; L. Levkova; P. B. Mackenzie; E. T. Neil; M. B. Oktay; Si-Wei Qiu; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water; R. Zhou
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We report on the status of our kaon semileptonic form factor calculations using the highly-improved staggered quark (HISQ) formulation to simulate the valence fermions. We present results for the form factor f_+^{K \pi}(0) on the asqtad N_f=2+1 MILC configurations, discuss the chiral-continuum extrapolation, and give a preliminary estimate of the total error. We also present a more preliminary set of results for the same form factor but with the sea quarks also simulated with the HISQ action;...
Source: http://arxiv.org/abs/1211.0751v1
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2.0
Jun 29, 2018
06/18
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E. Gamiz; A. Bazavov; C. Bernard; C. DeTar; D. Du; A. X. El-Khadra; E. D. Freeland; Steven Gottlieb; U. M. Heller; J. Komijani; A. S. Kronfeld; J. Laiho; P. B. Mackenzie; E. T. Neil; T. Primer; J. N. Simone; R. Sugar; D. Toussaint; R. S. Van de Water; Ran Zhou
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We discuss the reduction of errors in the calculation of the form factor $f_+^{K \pi}(0)$ with HISQ fermions on the $N_f=2+1+1$ MILC configurations from increased statistics on some key ensembles, new data on ensembles with lattice spacings down to 0.042 fm and the study of finite-volume effects within staggered ChPT. We also study the implications for the unitarity of the CKM matrix in the first row and for current tensions with leptonic determinations of $\vert V_{us}\vert$.
Topics: High Energy Physics - Phenomenology, High Energy Physics - Lattice, High Energy Physics - Experiment
Source: http://arxiv.org/abs/1611.04118
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Sep 19, 2013
09/13
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The MILC Collaboration; C. Bernard; S. Datta; T. DeGrand; C. DeTar; Steven Gottlieb; Urs M. Heller; C. McNeile; K. Orginos; R. Sugar; D. Toussaint
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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
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Sep 23, 2013
09/13
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MILC Collaboration; C. Bernard; T. DeGrand; C. DeTar; Steven Gottlieb; Urs M. Heller; J. E. Hetrick; N. Ishizuka; C. McNeile; R. Sugar; D. Toussaint; M. Wingate
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We report on the MILC collaboration's calculation of $f_B$, $f_{B_s}$, $f_D$, $f_{D_s}$, and their ratios. Our central values come from the quenched approximation, but the quenching error is estimated from $N_F=2$ dynamical staggered lattices. We use Wilson light valence quarks and Wilson and static heavy quarks. We find, for example, $f_B=157 \pm 11 {}^{+25}_{-9} {}^{+23}_{-0} \MeV$, $f_{B_s}/f_B = 1.11 \pm 0.02 {}^{+0.04}_{-0.03} \pm 0.03$, $f_{D_s} = 210 \pm 9 {}^{+25}_{-9} {}^{+17}_{-1}...
Source: http://arxiv.org/abs/hep-ph/9806412v2
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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 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 20, 2013
09/13
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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; A. S. Kronfeld; P. B. Mackenzie; 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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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.
Source: http://arxiv.org/abs/hep-lat/0410030v1
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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 20, 2013
09/13
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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
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Sep 21, 2013
09/13
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C. Aubin; C. Bernard; C. DeTar; Steven Gottlieb; E. B. Gregory; U. M. Heller; J. E. Hetrick; J. Osborn; R. Sugar; D. Toussaint
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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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Sep 21, 2013
09/13
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MILC Collaboration; C. Aubin; C. Bernard; C. DeTar; Steven Gottlieb; E. B. Gregory; U. M. Heller; J. E. Hetrick; J. Osborn; R. Sugar; D. Toussaint
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As part of our program of lattice simulations of three flavor QCD with improved staggered quarks, we have calculated pseudoscalar meson masses and decay constants for a range of valence quark masses and sea quark masses on lattices with lattice spacings of about 0.125 fm and 0.09 fm. We fit the lattice data to forms computed with staggered chiral perturbation theory. Our results provide a sensitive test of the lattice simulations, and especially of the chiral behavior, including the effects of...
Source: http://arxiv.org/abs/hep-lat/0407028v3
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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 19, 2013
09/13
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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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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 20, 2013
09/13
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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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Sep 22, 2013
09/13
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MILC Collaboration; C. Aubin; C. Bernard; C. DeTar; Steven Gottlieb; E. B. Gregory; Urs M. Heller; J. E. Hetrick; J. Osborn; R. Sugar; D. Toussaint
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We compute pseudoscalar meson masses and decay constants using staggered quarks on lattices with three flavors of sea quarks and lattice spacings $\approx 0.12$ fm and $\approx 0.09$ fm. We fit partially quenched results to ``staggered chiral perturbation theory'' formulae, thereby taking into account the effects of taste-symmetry violations. Chiral logarithms are observed. From the fits we calculate $f_\pi$ and $f_K$, extract Gasser-Leutwyler parameters of the chiral Lagrangian, and (modulo...
Source: http://arxiv.org/abs/hep-lat/0309088v1
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Sep 18, 2013
09/13
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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; 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
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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
