An eigenvalue estimate and its application to non-selfadjoint Jacobi and Schrödinger operators

Marcel Hansmann

For bounded linear operators $A,B$ on a Hilbert space $\mathcal{H}$ we show the validity of the estimate $$ \sum_{λ\in σ_d (B)} \dist(λ, \overline{\num}(A))^p \leq \| B-A \|_{\math…