TRANSVERSE SPIN DYNAMICS IN SPIN-POLARIZED FERMI LIQUIDS

A microscopic framework for a generalized Landau theory is established in the form of two coupled equations in "partial transverse densities". The 4-component effective interaction is related to the irreducible vertex, and not to the full vertex. The results explain the zero-temperature transverse relaxation and attenuation of spin waves. The spectrum of spin waves is expressed via harmonics of the interaction operator and its derivatives at arbitrary polarization. Our exact equations differ from previous semi-phenomenological ones, and reproduce all proper limiting cases like spin-polarized quantum gases or the Silin-Leggett low field equations.