Limit behaviour of Weyl coefficients

Abstract

We study the sets of radial or nontangential limit points towards $i\infty$ of a Nevanlinna function q. Given a nonempty, closed, and connected subset L of $C_+$ , we explicitly construct a Hamiltonian H such that the radial- and outer angular cluster sets towards $i\infty$ of the Weyl coefficient q H are both equal to L. Our method is based on a study of the continuous group action of rescaling operators on the set of all Hamiltonians.