Finitely many δ-interactions with supports on concentric spheres

Using the theory of self-adjoint extensions of symmetric operators we give the precise mathematical definition of the quantum Hamiltonian describing a finite number of δ-interactions with supports on concentric spheres. We also derive its resolvent, describe its spectral properties and show how this Hamiltonian can be obtained as a norm resolvent limit of a family of local scaled short-range Hamiltonians. (author). 15 refs