Collisional damping and collisional coupling in the nuclear collective response - art. no. 024307

We show that the collision term in extended temperature-dependent Hartree-F ock not only induces a damping of collective states but also leads to a cou pling between random-phase approximation states. This coupling may reorgani ze the collective response and may induce a transition from zero to first s ound. Applying this formalism to the monopole and dipole responses in the c alcium nucleus, it is found that the coupling between collective states thr ough their decay channel remains small up to several MeV temperature. There fore, the computed effect appears not to be strong enough to bring the cons idered nucleus in the first sound regime.