Instanton-Induced Correlations in Hadrons

Abstract

QCD instantons generate non-perturbative spin- and flavor- dependent forces between quarks. We review the results of a series of studies on instanton-induced correlations in hadrons. We first present some evidence for instanton-mediated interactions in QCD, based on lattice simulations. Then we show that the Instanton Liquid Model can reproduce the available data on proton and pion form factors at large momentum transfer and explain the delay of the onset of the perturbative regime in several hard reactions. We also show that instantons generate a deeply bound scalar color anti-triplet diquark, with a mass of about 450 MeV and size comparable with that of the proton. The strong attraction in the anti-triplet scalar diquark channel leads to a quantitative description of non-leptonic weak decays of hyperons and provides a microscopic dynamical explanation of the Delta I=1/2 rule.Comment: Summary of the results presented at the "8th Workshop on Non-perturbative Quantum Chromodynamics", Paris 7-11 June 2003, the "26th International School on Nuclear Physics", Erice 16-24 September 2004, and the "X Convegno sui Problemi della Fisica Nucleare Teorica", Cortona, 6-9 October 200