The Infrared Limit of the QCD Dirac Spectrum

The distribution of the low-lying QCD Dirac spectrum is analyzed by means of partial quenched chiral perturbation theory. We identify an energy scale below which the valence quark mass dependence of the QCD partition function is given by chiral Random Matrix Theory. This is the the domain where the low-energy QCD partition function is dominated by the fluctuations of the mass term of the Goldstone bosons. In mesoscopic physics this domain is known the ergodic domain and the corresponding energy scale is the Thouless energy.