528 research outputs found

    Problems with the Quenched Approximation in the Chiral Limit

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    In the quenched approximation, loops of the light singlet meson (the η′\eta') 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

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    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

    BKB_K Using Staggered Fermions: An Update

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    Improved results for BKB_K are discussed. Scaling corrections are argued to be of O(a2)O(a^2), leading to a reduction in the systematic error. For a kaon composed of degenerate quarks, the quenched result is B^K=0.825±0.027±0.023{\widehat{B}_K} = 0.825 \pm 0.027 \pm 0.023.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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