We present results for physical quantities computed in quenched chiral perturbation theory and compare them with the corresponding unquenched expressions. We also point out an apparent theoretical problem of the quenched approximation. 1.

spectroscopy of the scalar mesons. Because lattice QCD provides a first principal approach of hadron physics and allows us to study non-perturbative aspects of quark-gluon dynamics. We perform a quenched QCD calculation using the Wilson fermion, with the plaquette gauge action, on a relatively large lattice, i

The generating functional for hadronic weak

We use an effective low energy field theory to describe the coupling between glueballs and mesons as an analog of the quenched approximation in lattice QCD. This allows us to study the temperature dependence of mesonic screening masses at temperatures below the deconfinement phase transition.

. Problems for future study are described. I. Introduction and Motivation The quenched approximation1 to QCD, in which virtual quark loops are neglected, is a necessary evil in lattice QCD simulations and will be with us for the foreseeable future. Even with the proposed QCD Teraflop Machine, 2 the quenched

In the quenched approximation, loops of the light singlet meson (the η ′ ) give rise to a type of chiral logarithm absent in full QCD. These logarithms are singular in the chiral limit [1–3], throwing doubt upon the utility of the quenched approximation. In previous work, I summed a class

its quenched approximation

approximation is applied to the study of meson correlators, and the results compared with both naive quenched and full dynamical calculations of the same quantity. 1 1

Abstract not found

approximation is applied to the study of meson correlators, and the results compared with both naive quenched and full dynamical calculations of the same quantity. 1 1