Speaker:	Mihály Weiner, Università di Roma "Tor Vergata"
Title:	Restrictions of positive energy representations of Diff+(S1)
Abstract:	Let Gn ⊂ Diff+(S1) be the stabilizer of n given points of S1. How much information we loose if we restrict a positive energy representation of Diff+(S1) to the subgroup Gn? If the (original) representation was irreducible, will the restriction remain so? The questions, and a part of the answers, originate in chiral conformal QFT. For example, by the modular theory of von Neumann algebras, we know that in a chiral conformal QFT Haag-duality always holds. Thus it easily follows that the 2-point restriction of an irreducible positive energy representation with zero lowest energy remains irreducible. However, the general situation seems to be much harder to tackle, and, as I will explain, it contains some surprises, too.