Spectral functions and momentum distribution of fully polarized liquid sup 3 He

We study the effects of short-range correlations on single-particle properties in fully spin-polarized liquid {sup 3}He ({sup 3}He{sup {up arrow}}). By calculating the full frequency dependence of the self-energy, we are able to obtain the spectral functions, quasiparticle strength, momentum distribution, {omega} mass, and {ital k} mass. We start from the He-He interatomic potential and use the Galitskii-Feynman-Hartree-Fock (GFHF) approximation for the self-energy. In the GFHF approximation, the vertex is represented by the Galitskii-Feynman {ital T} matrix, which includes particle-particle and hole-hole scattering to all orders, and thus is a good representation of the short-range correlation effects brought about by the strong core repulsion of the He-He potential. We find large departures from independent-particle behavior, indicating that the system is highly correlated. In particular, we find that the quasiparticle pole takes up only about 50% of the strength of the spectral functions for a wide range of momenta near {ital k}{sub {ital F}}. There is a substantial depletion of the occupation of states within the Fermi sea, the {ital k}=0 state being only 83% occupied. We comment on the relevance of these results for a description of neutron scattering from normal {sup 3}He. Approximations for the ground-state energy are investigated.