INSTANTONS AND THE LARGE NC LIMIT OF QCD

We summarize our current understanding of instantons in the large Nc limit of QCD. We also present some recent results from simulations of the instanton liquid in QCD for Nc> 3. 1 Historical Overview Both instantons and the large Nc expansion are important corner stones in our attempts to understand non-perturbative aspects of QCD. Instantons are related to topological aspects of QCD and play and important role in understanding the U(1)A anomaly. There is also a growing body of evidence that the mechanism for chiral symmetry breaking in QCD is intimately connected with instantons. The large Nc expansion is based on the idea that 1/Nc can be used as expansion parameter in QCD. The main assumption is that QCD with many colors is a theory that exhibits confinement and chiral symmetry breaking, and that this theory is smoothly connected to the real world, in which Nc is equal to three. There is an impressive amount of evidence, mainly of phenomenological nature, but also from the lattice, that this assumption is