On Spectral Representation For Selfadjoint Operators

Analytic Methods of Spectral Representations of Non-Selfadjoint (Non-Unitary) Operators

This book is concerned with the theory of model representations of linear non-selfadjoint and non-unitary operators. This booming area of functional analysis owes its origins to the fundamental works of M. S. Livšic on the theory of characteristic functions, the deep studies of B. S.-Nagy and C. Foias on dilation theory, and also to the Lax–Phillips scattering theory. Here, a uniform conceptual approach is developed which organically unites all these theories. New analytic methods are introduced which make it possible to solve some important problems from the theory of spectral representations. Aimed at specialists in functional analysis, the book will also be accessible to senior mathematics students.

Spectral Theory of Families of Self-Adjoint Operators

Stochastic Spectral Theory for Selfadjoint Feller Operators

A beautiful interplay between probability theory (Markov processes, martingale theory) on the one hand and operator and spectral theory on the other yields a uniform treatment of several kinds of Hamiltonians such as the Laplace operator, relativistic Hamiltonian, Laplace-Beltrami operator, and generators of Ornstein-Uhlenbeck processes. For such operators regular and singular perturbations of order zero and their spectral properties are investigated. A complete treatment of the Feynman-Kac formula is given. The theory is applied to such topics as compactness or trace class properties of differences of Feynman-Kac semigroups, preservation of absolutely continuous and/or essential spectra and completeness of scattering systems. The unified approach provides a new viewpoint of and a deeper insight into the subject. The book is aimed at advanced students and researchers in mathematical physics and mathematics with an interest in quantum physics, scattering theory, heat equation, operator theory, probability theory and spectral theory.