528 research outputs found

    Problems with the Quenched Approximation in the Chiral Limit

    Get PDF
    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

    Get PDF
    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

    Get PDF
    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
    • …