Chiara Esposito

Title: Obstructions of Drinfel'd twist deformations [pdf]
Abstract: Given a Drinfel'd twist on the universal enveloping algebra of a Lie algebra g one can write the correponding realization in terms of left- invariant bidi erential operators on the Lie group G and obtain a left- invariant star product on G. This procedure can be extended to any U(g)-module algebra A. The question we answer in this talk is in which conditions this is not possible. In other words, we study when a star prod- uct can not be induced by a twist. This is a joint work with P. Bieliavsky, S. Waldmann and T. Weber.