Indexed on: 18 Oct '07Published on: 18 Oct '07Published in: Il Nuovo Cimento (1955-1965)
The study of the energy dependence of scattering and reaction cross sections near thresholds is performed by a method which has its basis in the construction of the effective potentials in every single channel. The formalism employed presents some advantage with respect to other kind of approaches in that it gives a simple physical description of the anomaly (cusp or rounded step) which appears in the scattering cross section at the opening up of a new channel. Furthermore, with this method it is effectively possible to give an explanation why the energy derivative of the scattering cross section is infinite when the threshold is approached from below. The effect is found to be purely quantum mechanical.