54
54
Sep 23, 2013
09/13
by
K. Orginos; R. Sugar; D. Toussaint
texts
eye 54
favorite 0
comment 0
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
53
53
Sep 21, 2013
09/13
by
C. Bernard; T. Blum; T. DeGrand; C. Detar; S. Gottlieb; A. Krasnitz; R. Sugar; D. Toussaint
texts
eye 53
favorite 0
comment 0
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
43
43
Sep 17, 2013
09/13
by
C. DeTar; L. Levkova; Steven Gottlieb; U. M. Heller; J. E. Hetrick; R. Sugar; D. Toussaint
texts
eye 43
favorite 0
comment 0
We extend our work on QCD thermodynamics with 2+1 quark flavors at nonzero chemical potential to finer lattices with $N_t=6$. We study the equation of state and other thermodynamic quantities, such as quark number densities and susceptibilities, and compare them with our previous results at $N_t=4$. We also calculate the effects of the addition of the charm and bottom quarks on the equation of state at zero and nonzero chemical potential. These effects are important for cosmological studies of...
Source: http://arxiv.org/abs/1003.5682v2
51
51
Sep 19, 2013
09/13
by
C. Aubin; C. Bernard; C. DeTar; Steven Gottlieb; Urs M. Heller; K. Orginos; R. Sugar; D. Toussaint
texts
eye 51
favorite 0
comment 0
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
49
49
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
eye 49
favorite 0
comment 0
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
112
112
Sep 23, 2013
09/13
by
C. Bernard; C. DeTar; Steven Gottlieb; U. M. Heller; J. E. Hetrick; L. Levkova; R. Sugar; D. Toussaint
texts
eye 112
favorite 0
comment 0
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
54
54
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
texts
eye 54
favorite 0
comment 0
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
85
85
Sep 20, 2013
09/13
by
C. Bernard; T. Burch; C. DeTar; Steven Gottlieb; E. B. Gregory; U. M. Heller; J. Osborn; R. Sugar; D. Toussaint
texts
eye 85
favorite 0
comment 0
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
51
51
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
texts
eye 51
favorite 0
comment 0
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
51
51
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
texts
eye 51
favorite 0
comment 0
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
92
92
Sep 18, 2013
09/13
by
C. Bernard; T. Burch; C. DeTar; Steven Gottlieb; L. Levkova; U. M. Heller; J. E. Hetrick; R. Sugar; D. Toussaint
texts
eye 92
favorite 0
comment 0
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
41
41
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
texts
eye 41
favorite 0
comment 0
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
57
57
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
texts
eye 57
favorite 0
comment 0
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
60
60
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
texts
eye 60
favorite 0
comment 0
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
43
43
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
texts
eye 43
favorite 0
comment 0
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
90
90
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
eye 90
favorite 0
comment 0
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
51
51
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
texts
eye 51
favorite 0
comment 0
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
47
47
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
texts
eye 47
favorite 0
comment 0
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
48
48
Sep 22, 2013
09/13
by
MILC Collaboration; C. Bernard; T. Burch; C. DeTar; Steven Gottlieb; E. B. Gregory; U. M. Heller; J. Osborn; R. Sugar; D. Toussaint
texts
eye 48
favorite 0
comment 0
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
48
48
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
texts
eye 48
favorite 0
comment 0
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
47
47
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
eye 47
favorite 0
comment 0
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
52
52
Sep 20, 2013
09/13
by
Claude Bernard; Tom Blum; Carleton DeTar; Steven Gottlieb; Urs M. Heller; James E. Hetrick; K. Rummukainen; R. Sugar; D. Toussaint; Matthew Wingate
texts
eye 52
favorite 0
comment 0
Sigma models for the high temperature phase transition in quantum chromodynamics (QCD) suggest that at high temperature the SU(N_f) x SU(N_f) chiral symmetry becomes exact, but the anomalous axial U(1) symmetry need not be restored. In numerical lattice simulations, traditional methods for detecting symmetry restoration have sought multiplets in the screening mass spectrum. However, these methods were imprecise and the results, so far, incomplete. With improved statistics and methodology, we...
Source: http://arxiv.org/abs/hep-lat/9611031v1
50
50
Sep 19, 2013
09/13
by
C. Bernard; T. Burch; T. DeGrand; C. DeTar; Steven Gottlieb; E. B. Gregory; U. M. Heller; J. Osborn; R. Sugar; D. Toussaint
texts
eye 50
favorite 0
comment 0
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
41
41
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
texts
eye 41
favorite 0
comment 0
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
54
54
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
texts
eye 54
favorite 0
comment 0
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
54
54
Sep 19, 2013
09/13
by
C. Bernard; T. Burch; C. DeTar; Steven Gottlieb; L. Levkova; U. M. Heller; J. E. Hetrick; D. B. Renner; D. Toussaint; R. Sugar
texts
eye 54
favorite 0
comment 0
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
44
44
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
eye 44
favorite 0
comment 0
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
76
76
Sep 19, 2013
09/13
by
C. Bernard; T. DeGrand; C. DeTar; Steven Gottlieb; U. M. Heller; J. Hetrick; C. McNeile; K. Rummukainen; R. Sugar; D. Toussaint; M. Wingate
texts
eye 76
favorite 0
comment 0
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
39
39
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
texts
eye 39
favorite 0
comment 0
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
43
43
Sep 18, 2013
09/13
by
C. Bernard; T. Blum; C. DeTar; Steven Gottlieb; U. M. Heller; J. E. Hetrick; L. Karkkainen; K. Rummukainen; R. Sugar; D. Toussaint; M. Wingate
texts
eye 43
favorite 0
comment 0
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
46
46
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 46
favorite 0
comment 0
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
55
55
Sep 22, 2013
09/13
by
C. Bernard; T. DeGrand; C. DeTar; Steven Gottlieb; E. Gregory; A. Hart; A. Hasenfratz; Urs Heller; J. Hetrick; J. Osborn; R. Sugar; D. Toussaint
texts
eye 55
favorite 0
comment 0
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
91
91
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
texts
eye 91
favorite 0
comment 0
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
42
42
Sep 18, 2013
09/13
by
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
texts
eye 42
favorite 0
comment 0
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
47
47
Sep 23, 2013
09/13
by
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
eye 47
favorite 0
comment 0
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
132
132
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
texts
eye 132
favorite 0
comment 0
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
58
58
Sep 21, 2013
09/13
by
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
texts
eye 58
favorite 0
comment 0
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
38
38
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
texts
eye 38
favorite 0
comment 0
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
88
88
Sep 18, 2013
09/13
by
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
texts
eye 88
favorite 0
comment 0
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
47
47
Sep 22, 2013
09/13
by
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
texts
eye 47
favorite 0
comment 0
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
45
45
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
texts
eye 45
favorite 0
comment 0
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
67
67
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
texts
eye 67
favorite 0
comment 0
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
43
43
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
texts
eye 43
favorite 0
comment 0
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
59
59
Sep 23, 2013
09/13
by
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
texts
eye 59
favorite 0
comment 0
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
137
137
Jul 20, 2013
07/13
by
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
texts
eye 137
favorite 0
comment 0
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
47
47
Sep 18, 2013
09/13
by
The MILC Collaboration; C. Bernard; T. Blum; T. A. DeGrand; C. DeTar; S. Gottlieb; U. M. Heller; J. Hetrick; C. McNeile; K. Rummukainen; R. Sugar; D. Toussaint
texts
eye 47
favorite 0
comment 0
We present an update on the MILC Collaboration's light hadron spectrum calculation with two flavors of dynamical, staggered quarks. We present extrapolations of the nucleon to rho mass ratio to the continuum limit for fixed values of the pi to rho mass ratio including the physical one.
Source: http://arxiv.org/abs/hep-lat/9710063v1
52
52
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
texts
eye 52
favorite 0
comment 0
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
45
45
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
texts
eye 45
favorite 0
comment 0
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
46
46
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
texts
eye 46
favorite 0
comment 0
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
53
53
Sep 19, 2013
09/13
by
The MILC Collaboration; 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
texts
eye 53
favorite 0
comment 0
We present our new results for the QCD equation of state at nonzero chemical potential at N_t=6 and compare them with N_t=4. We use the Taylor expansion method with terms up to sixth order in simulations with 2+1 flavors of improved asqtad quarks along a line of constant physics with m_l=0.1 m_s and approximately physical strange quark mass m_s.
Source: http://arxiv.org/abs/0910.0276v1
Live Music Archive
Librivox Free Audio
Metropolitan Museum
Cleveland Museum of Art
Internet Arcade
Console Living Room
Books to Borrow
Open Library
TV News
Understanding 9/11
