Spherical Stein spaces (Q1882777)

Let \(X\) be an irreducible reduced complex space on which a connected compact Lie group \(K\) acts by holomorphic automorphisms. The authors introduce the notion of spherical Stein space, give some interesting characterizations of such spaces (e.g. a connected Stein manifold \(X\) is spherical iff the algebra of \(K\)-invariant differential operators on \(X\) is commutative) and provide some useful examples for further study.