Spectrum of a diffusion operator with coefficient changing sign over a small inclusion

Lucas Chesnel, Xavier Claeys, Sergei A. Nazarov

We study a spectral problem $({\mathcal{P}}^{\delta })$ for a diffusion like equation in a 3D domain $\Omega$. The main originality lies in the presence of a parameter ${\sigma }^{\delta }$, whose sign changes o…