On the complexification of $ q $-deformations of compact semisimple Lie groups

Abstract

For the quantised algebra of functions on a simply connected compact semisimple Lie group, we study the relationship between the primitive spectrum, topologically irreducible representations by bounded operators on Hilbert spaces, and quantum holomorphic evaluations induced via the Drinfeld double. In terms of the Joseph stratification of the primitive spectrum, we prove a sharp dichotomy: primitive ideals in homogeneous strata always arise as kernels of topologically irreducible representations by bounded operators on a Hilbert space, whereas those in inhomogeneous strata do not admit any such realisations. We further show that, unlike in the classical situation, quantum holomorphic evaluations typically fail to be topologically irreducible, and that their kernels do not determine the primitive spectrum. Finally, we describe the Iwasawa decomposition of the Drinfeld double in terms of polynomial functions, extending work by Podleś-Woronowicz for the quantum Lorentz group to all complex semisimple quantum groups, and clarifying the structure of quantum holomorphic evaluations.