Effects of low-lying fermion modes in the epsilon regime

Abstract

We investigate the effects of low-lying fermion modes on the QCD partition function in the epsilon-regime. With the overlap Dirac operator we calculate several tens of low-lying fermion eigenvalues on the quenched lattice. By partially incorporating the fermion determinant through the truncated determinant approximation, we calculate the partition function and other related quantities for Nf = 1 and compare them with the theoretical predictions obtained by Leutwyler and Smilga.