113 research outputs found
The Eta-prime and Cooling with Staggered Fermions
We present a calculation of the mass of the eta-prime meson using quenched
and dynamical staggered fermions. We also discuss the effects of "cooling" and
suggest its use as a quantitative tool.Comment: 4 pages, LaTeX with 7 EPS figs, contribution to Lattice 9
Effect of Improving the Lattice Gauge Action on QCD Topology
We use lattice topology as a laboratory to compare the Wilson action (WA)
with the Symanzik-Weisz (SW) action constructed from a combination of (1x1) and
(1x2) Wilson loops, and the estimate of the renormalization trajectory (RT)
from a renormalization group transformation (RGT) which also includes higher
representations of the (1x1) loop. Topological charges are computed using the
geometric (L\"uscher's) and plaquette methods on the uncooled lattice, and also
by using cooling to remove ultraviolet artifacts. We show that as the action
improves by approaching the RT, the topological charges for individual
configurations computed using these three methods become more highly
correlated, suggesting that artificial lattice renormalizations to the
topological susceptibility can be suppressed by improving the action.Comment: 4 pages, 4 figures, poster presented at LATTICE96(improvement
Delta I=1/2 rule from staggered fermions
We present our latest results for the Delta I=1/2 rule, obtained on quenched
ensembles with beta=6.0 and 6.2, and a set of N_f=2 configurations with
beta=5.7. The statistical noise is quite under control. We observe an
enhancement of the Delta I=1/2 amplitude consistent with experiment, although
the systematic errors are still large. We also present a non-perturbative
determination of Z_P, Z_S and the strange quark mass. We briefly discuss our
progress in calculating epsilon-prime.Comment: LATTICE98(matrixelement
Weak matrix elements for CP violation
We present preliminary results of matrix elements of four-fermion operators
relevant to the determination of e and e'/e using staggered fermions.Comment: 3 pages, 4 figures, Lattice 2001 (Hadronic Matrix Elements
Staggered fermion matrix elements using smeared operators
We investigate the use of two kinds of staggered fermion operators, smeared
and unsmeared. The smeared operators extend over a hypercube, and tend to
have smaller perturbative corrections than the corresponding unsmeared
operators. We use these operators to calculate kaon weak matrix elements on
quenched ensembles at , 6.2 and 6.4. Extrapolating to the continuum
limit, we find . The
systematic error is dominated by the uncertainty in the matching between
lattice and continuum operators due to the truncation of perturbation theory at
one-loop. We do not include any estimate of the errors due to quenching or to
the use of degenerate and quarks. For the
electromagnetic penguin operators we find
and . We also use the ratio of unsmeared to
smeared operators to make a partially non-perturbative estimate of the
renormalization of the quark mass for staggered fermions. We find that tadpole
improved perturbation theory works well if the coupling is chosen to be
\alpha_\MSbar(q^*=1/a).Comment: 22 pages, 1 figure, uses eps
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