Alpha-like resonances in nuclei

We investigate normal dipole oscillations in a system of protons, neutrons and -particles within the Brink approach. We introduce an effective mass of -clusters in terms of the spectroscopic factor. The Pauli exclusion principle is taken into account by using the Wildermuth rule. The ratio between alpha and giant resonance energy weighted sum rule (EWSR) is investigated for N = Z and N > Z systems. In both cases we notice an unexpected decrease of this ratio versus the increase of the spectroscopic factor. Due to this fact the possibility to experimentally detect -like oscillations is enhanced in nuclei above 100Sn. The occurrence of the pygmy mode in N > Z systems decreases the EWSR for the -like oscillations.