“…If ( ) f k r , is decreasing exponentially at infinity for > k Im 0, then one gets a regular square-integrable wave function and consequently an eigen value. Therefore, zeros of the Jost function for > k Im 0 reproduce bound state energies [1,2,[4][5][6][7] while resonant states with zeros in the lower momentum half-plane and negative of the phase of the Jost function gives the scattering phase shift [1,2,[8][9][10][11][12]. This suggests that resonances are indeed bound states with complex energies and therefore decay in time.…”