On the Trace Formula of Perturbation Theory. II
Peter Jonas · Mathematische Nachrichten · 1999
Abstract In a previous paper for a class of pairs of operators in a Hilbert space with nuclear difference or under a more general nuclearity condition there was introduced a spectral shift functional. Here we consider the local integrability of this spectral shift functional, i.e., the problem when this functional can locally be represented by an integrable function. The general results are then applied to pairs of definitizable and locally definitizable unitary operators in a Krein space.