Effective interactions, elementary excitations, and transport in the helium liquids

Polarization potentials, the self-consistent fields that describe the primary consequences of the strong atom–atom interaction in the helium liquids, are developed for liquid 4He and 3He. Emphasis is placed on the common physical origin of the effective interactions in all helium liquids, and the hierarchy of physical effects (very short-range atomic correlations, zero-point motion, and the Pauli principle) that determine their strength is reviewed. An overview is then given of the application of polarization potential theory to experiment, including the phonon–maxon–roton spectra of 4He and 3He–4He mixtures, the phonon–maxon spectrum of normal and spin-polarized 3He, and the transport properties of superfluid 4He and of normal and spin-polarized 3He.