Do Instantons of the CP(N-1) Model Melt?
  In the two-dimensional CP(N-1) model one can parametrize exact many-instanton solutions via N `constituents' (called `zindons'). This parameterization allows, in principle, a complete `melting' of individual instantons. The model is therefore well suited to study whether dynamics prefers a dilute or a strongly overlapping ensemble of instantons. We study the statistical mechanics of instantons both analytically and numerically. We find that at N=2 the instanton system collapses into zero-size instantons. At N=3,4 we find that well-isolated instantons are dynamically preferred though 15-25% of instantons have a considerable overlap with others. 
M. Maul and D. Diakonov