Properties of elementary excitations in spin-polarized liquidHe3

The structure of hole-line insertions and self-energy diagrams within the correlated-basis-functions (CBF) approach to strongly interacting Fermi systems is investigated. It is demonstrated that exact cancellations take place between diagrams of the Fermi-hypernetted-chain theory of the single-particle excitations and diagrammatic corrections to that theory within the CBF perturbation procedure. One important consequence of these cancellations is that the instability with respect to abnormal occupation in momentum space which plagued earlier microscopic studies of spin-polarized systems is, in fact, spurious. With this obstacle removed, predictions are made for the effective mass, the zero-sound dispersion relation, and other properties of elementary excitations in spin-polarized ${}_{}{}^3{}_{}{}^{}\mathrm{He}$.