On spectral properties of the resonances for ed potential scattering systems.
The resonances (poles of the scattering matrix) of quantum mechanical
scattering by central-symmetric potentials
with compact support and zero angular momentum are spectrally characterized directly
in terms of the Hamiltonian
by a (generalized) eigenvalue problem distinguished by
an additional condition (called boundary condition).
The connection between the (generalized) eigenspace of a resonance and
corresponding Gamov vectors is pointed out. A condition is presented such that a
special transition probabilities and infinite sums of residual terms for
all complex-conjugated pairs of resonances can be proved. In the case of the
square well potential the condition is satisfied.