# The essential spectrum of the Neumann--Poincare operator on a domain with corners

Research paper by Karl-Mikael Perfekt, Mihai Putinar

Indexed on: 12 Feb '16Published on: 12 Feb '16Published in: Mathematics - Functional Analysis

#### Abstract

Exploiting the homogeneous structure of a wedge in the complex plane, we compute the spectrum of the anti-linear Ahlfors-Beurling transform acting on the associated Bergman space. Consequently, the similarity equivalence between the Ahlfors-Beurling transform and the Neumann-Poincare operator provides the spectrum of the latter integral operator on a wedge. A localization technique and conformal mapping lead to the first complete description of the essential spectrum of the Neumann-Poincare operator on a planar domain with corners, with respect to the energy norm of the associated harmonic field.