Title: Some automorphism invariance properties for multicontractions

Authors: Dan Timotin and Chafiq Benhida

Issue: Volume 56 (2007), Issue 1, 481-500

Abstract: In the theory of row contractions on a Hilbert space, as initiated by Popescu, two important objects are the Poisson kernel and the characteristic function. We determine their behaviour with respect to the action of the group of unitarily implemented automorphisms of the algebra generated by creation operators on the Fock space. The case of noncommutative varieties, introduced recently by Popescu, is also discussed.