Correlated Instanton Orientations in the SU(2) Yang-Mills Vacuum and   Pair Formation in the Deconfined Phase
  Using the renormalization group motivated smoothing technique we study the semiclassical structure of the pure Yang-Mills vacuum. We carefully check that identified clusters of topological charge behave like instantons around their centers. Looking at distance distributions of clusters we find instanton-antiinstanton pair formation in the deconfined phase. We use suitably normalized gauge invariant field strength correlators to obtain first quantitative information on the relative color orientation of instantons. We give further evidence for a modified instanton profile in the confined phase and present a simple alternative model for it. 
E.-M. Ilgenfritz, S. Thurner