Invariant Star Products of Wick Type: Classification and Quantum Momentum Mappings

Abstract

We extend our investigations on $\mathfrak g$-invariant Fedosov star products and quantum momentum mappings \cite{MN03a} to star products of Wick type on pseudo-K\"ahler manifolds. Star products of Wick type can be completely characterized by a local description as given by Karabegov in \cite{Kar96} for star products with separation of variables. We separately treat the action of a Lie group $G$ on $\Cinf{M}[[\nu]]$ by (pull-backs with) diffeomorphisms and the action of a Lie algebra $\mathfrak g$ on $\Cinf{M}[[\nu]]$ by (Lie derivatives with respect to) vector fields. Within Karabegov's framework we prove necessary and sufficient conditions for a given star product of Wick type to be invariant in the respective sense. Moreover, our results yield a complete classification of invariant star products of Wick type. We also prove a necessary and sufficient condition for (the Lie derivative with respect to) a vector field to be even a quasi-inner derivation of a given star product of Wick type. We then transfer our former results about quantum momentum mappings for $\mathfrak g$-invariant Fedosov star products to the case of invariant star products of Wick type.