Spectral functions and momentum distribution of fully polarized liquid 3He

We study the effects of short-range correlations on single-particle properties in fully spin-polarized liquid 3He (3He↑). By calculating the full frequency dependence of the self-energy, we are able to obtain the spectral functions, quasiparticle strength, momentum distribution, ω mass, and 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 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 kF. There is a substantial depletion of the occupation of states within the Fermi sea, the k=0 state being only 83% occupied. We comment on the relevance of these results for a description of neutron scattering from normal 3He. Approximations for the ground-state energy are investigated