Quenched and Unquenched Chiral Perturbation Theory in the ε-Regime

Abstract

The chiral limit of finite-volume QCD is the $ε$-regime of the theory. We discuss how this regime can be used for determining low-energy observables of QCD by means of comparisons between lattice simulations and quenched and unquenched chiral perturbation theory. The quenched theory suffers in the $ε$-regime from ``quenched finite volume logs'', the finite-volume analogs of quenched chiral logs.