Momentum-dependent scattering-amplitude model for liquidHe3

A model to calculate the quasiparticle interaction and the scattering amplitude is presented. The quasiparticle interaction can be separated into two pieces: the direct and the induced. The direct term is an effective potential which can be characterized by three parameters. The s-wave component of this potential is fixed by a general sum rule and the experimentally determined Landau parameters. The other two parameters are independent of density. The induced term includes the exchange of the virtual collective excitations of the medium. The structure of the induced interaction is a direct consequence of the antisymmetrization of the scattering amplitudes. The resulting integral equations self-consistently sum the particle-hole reducible diagrams. The agreement with experiment is very good over the entire pressure range of liquid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$.