Long-wave fluctuation kinetics and quasi-linear relaxation for zero-point sound in a normal Fermi liquid

A universal phenomenological approach to studying macroscopic fluctuations is proposed and general kinetic equations for long-wave fluctuations in a normal Fermi liquid are derived. These kinetic equations form the basis of the theory of quasi-linear relaxation for zero-point sound in a normal Fermi liquid in the paired fluctuation approximation. The conditions for the existence of the quasi-linear approximation are considered.