Dynamical polarization potential due to the excitation of collective states

Abstract

Within the Feshbach formalism we calculate the nucleus-nucleus dynamical polarization potential arising from the coupling of the elastic channel to the collective vibrational states, described by the random-phase approximation. Calculations for the systems O16+40Ca and Ca40+40Ca show the importance of the high-lying states. They give the main contribution to the real part of the polarization potential at every incident energy, while they dominate the imaginary part only at very high energy. At low energy the absorption is given by the low-lying states. The real and imaginary parts of the potential are shown to obey a dispersion relation. Calculations of elastic cross section give a good description of the experimental data.