Dynamics of nuclear fluid. VII. Isovector, spin-vector, and spin-isovector giant multipole resonances as elastic vibrations

Abstract

Previously, we studied the isoscalar giant resonances as the elastic vibration of a nucleus, the peculiar properties of elasticity being a manifestation of the quantum stress tensor. We examine here the other types of collective vibrations involving elastic spin and isospin waves. Relevant electric and magnetic multipole states for the isovector, the spin vector, and the spin-isovector modes are determined. We find that for a given electric or magnetic state with multipolarity l different from zero, the lowest eigenenergies for the different modes of giant resonances (isoscalar, isovector, spin-vector, and spin-isovector) are approximately degenerate. On the other hand, the l/sup ..pi../ = 0/sup +/ states depend on the nuclear incompressibility and the symmetry energy coefficients. Their eigenenergies can be quite different. The theoretical eigenenergies for the giant isovector electric multipole states compare well with experimental data.