INTERACTION BETWEEN COLOUR-SINGLET HADRONS FROM NONPERTURBATIVE QCD

We present a nonperturbative QCD contribution to interactions between separated coloursinglet hadrons, arising from the nontrivial topology of the QCD vacuum. We have calculated the effect of the structure of the vacuum (modelled here as a dilute gas of instantons) on hadron propagation, as a way of studying at least some nonperturbative effects. We find that a nonperturbative interaction arises which is familiar to us from our earlier studies of many-body potentials in multiquark systems. This interaction is distinct from those earlier perturbative QCD calculations which bear a direct analogy to the van der Waals interaction of atomic physics.