The interior transmission problem and bounds on transmission eigenvalues
Michael Hitrik, Katsiaryna Krupchyk, Petri Ola, Lassi Païvärinta · Mathematical Research Letters · 2011
We study the interior transmission eigenvalue problem for sign-definite multiplicative perturbations of the Laplacian in a bounded domain.We show that all but finitely many complex transmission eigenvalues are confined to a parabolic neighborhood of the positive real axis.