530 research outputs found
Problems with the Quenched Approximation in the Chiral Limit
In the quenched approximation, loops of the light singlet meson (the )
give rise to a type of chiral logarithm absent in full QCD. These logarithms
are singular in the chiral limit throwing doubt upon the utility of the
quenched approximation. In previous work, I summed a class of diagrams, leading
to non-analytic power dependencies such as \cond\propto
m_q^{-\delta/(1+\delta)}. I suggested, however, that these peculiar results
could be redefined away. Here I give an alternative derivation of the results,
based on the renormalization group, and argue that they cannot be redefined
away. I discuss the evidence (or lack thereof) for such effects in numerical
data.Comment: (talk given at Lattice '92), 4 pages latex, 3 postscript figures,
uses espcr2.sty and psfig.tex (all included) UW/PT-92-2
Physical Results from Partially Quenched Simulation
We describe how one can use chiral perturbation theory to obtain results for
physical quantities, such as quark masses, using partially quenched
simulations.Comment: Written version of two talks at DPF 2000. 6 pages, 2 figure
Using Staggered Fermions: An Update
Improved results for are discussed. Scaling corrections are argued to
be of , leading to a reduction in the systematic error. For a kaon
composed of degenerate quarks, the quenched result is .Comment: (poster presented at Lattice '93), 7 pages latex (it's in preprint
format!), 1 postscript figure, bundled with uufiles. Uses psfig.tex.
UW/PT-93-2
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