GIANT-RESONANCES AS COLLECTIVE STATES WITH DISSIPATIVE COUPLING

We describe giant resonances as the collective coordinates of a harmon ic oscillator with dissipative coupling. Using a quantum master equati on, the energy and width of the first two levels are obtained as funct ions of temperature and of the dissipative coupling strength. On this basis, we evaluate the ratio of the two spectral Linewidths. The resul t agrees with available experimental data. We evaluate transition matr ix elements among particle excitations belonging to the environment an d find a weak dependence on temperature.