نتایج جستجو برای: milc
تعداد نتایج: 185 فیلتر نتایج به سال:
The scaling corrections that affected previous staggered calculations of BK have been proved to be reduced by using improved actions (HYP, Asqtad) in the quenched approximation. This improved behaviour allows us to perform a reliable dynamical calculation of BK including quark vacuum polarization effects using the MILC (2+1) flavour dynamical configurations. We report here on the results from s...
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 error...
We report on heavy quark mass calculations using Fermilab heavy quarks. Lattice calculations of heavy-strange meson masses are combined with one-loop (automated) lattice perturbation theory to arrive at the quark mass. Mesons are constructed from Fermilab heavy quarks and staggered light quarks. We use the MILC ensembles at three lattice spacings and sea quark mass ratios of mu,d/ms = 0.1 to 0....
We have greatly extended an earlier calculation of the charmonium spectrum on three flavor dy-namical quark ensembles by using more recent ensembles generated by the MILC collaboration. The heavy quarks are treated using the Fermilab formulation. The charmonium state masses are in reasonable agreement with the observed spectrum; however, some of the spin splittings may still be too small. c Cop...
We determine the radial excitation energy (2S-1S splitting)in the Upsilon spectrum using NRQCD b quarks on MILC configurations. We have statistical fitting errors of around 1% across a range of lattice spacing values using random wall sources, and this allows us to give improved determinations of the physical value of the heavy quark potential parameter r1. We also show improved results for the...
We present the current status of the MILC collaboration’s calculations of the properties of the light pseudoscalar meson sector. We use asqtad staggered ensembles with 2+1 dynamical flavors down to a≈ 0.045 fm and light quark mass down to 0.05ms. Here we describe fits to the data using chiral forms from SU(3) chiral perturbation theory, including all staggered taste violations at NLO and the co...
I describe a new way of constructing a gauge action that eliminates scaling artifacts, by writing the continuum formalism in terms of “gauge links” (Schwinger line integrals) and using the optimal SLAC representation of the lattice derivative. Computational performance can be maintained by implementing the action as a “stochastic” operator, as has been recently implemented in the MILC code for ...
Recently, we have benchmarked and tuned the MILC code on a number of architectures including Intel Itanium and Pentium IV (PIV), dual-CPU Athlon, and the latest Compaq Alpha nodes. Results will be presented for many of these, and we shall discuss some simple code changes that can result in a very dramatic speedup of the KS conjugate gradient on processors with more advanced memory systems such ...
One-loop matching of heavy-light currents is carried out for a highly improved lattice action, including the effects of mixings with dimension 4 O(1/M) and O(a) operators. We use the NRQCD action for heavy quarks, the Asqtad improved naive action for light quarks, and the Symanzik improved glue action. These results are being used in recent heavy meson decay constant and semileptonic form facto...
We discuss prospects for improving the q 2 extrapolation of the B → πlν form factors with model-independent constraints based on unitarity and heavy quark power-counting. As an illustration, we apply the method to preliminary results of calculations of the form factors, which we generated using the MILC gauge configurations and the Fermilab action for the heavy b-quark. Unitarity, the heavy qua...
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