Dynamic correlations in Fermi fluids

We consider dynamic correlations in normal liquid He3 following the kinetic theory approach introduced in earlier work. The connection between the kinetic theory formalism and the Landau and polarization potential theories is discussed in detail and the approximations implicit in the latter approach are pointed out. We present a phenomenological approach to the dynamic memory function which incorporates finite frequency and wave-vector effects. This form of the dynamic kernel is used to evaluate the shear viscosity, including contributions from nonlocal effects. Estimates of these contributions indicate that they are non-negligible. The consequences of our method and its future application to the evaluation of collisional broadening of collective modes observed in neutron scattering experiments are discussed.