Semiclassical description of the scissors mode: Possible improvements and intrinsic limitations

It is shown that the quantitative description within the two-rotor model of the low-lying, moderately collective {ital M}1 excitation observed in deformed nuclei and known as the scissors mode can be drastically improved by properly computing the relevant physical quantities that determine the properties of such a mode. A two-fluid formulation of the model in which only the nuclear mass external to a rotational invariant inner core of each rotor takes part in the motion is also presented and discussed, especially in relation to the algebraic interacting boson model and to the random phase approximation. The importance of dynamical correlations is stressed in this connection.