Light hadron physics from the lattice

Abstract

Two aspects of chiral dynamics are explored using lattice QCD. The first is calculation of low-energy hadronic parameters and a brief survey of recent lattice results is presented, including meson decay constants, the quark condensate, pion and nucleon scattering lengths and the nucleon σ-term. The second is a demonstration of the dominant role of instantons in determining light hadron structure and quark propagation in the QCD vacuum. The instanton content of gluon fields sampling the Wilson action is extracted using cooling as a filter to selectively remove essentially all fluctuations of the gluon field except for instantons. Close agreement is demonstrated between quenched lattice QCD results including all gluonic contributions and including only instantons for vacuum correlation functions of hadronic currents and for density-density correlation functions in hadronic bound states.