Bosonization of Fermi liquids

We bosonize a Fermi liquid in any number of dimensions in the limit of long wavelengths. From the bosons we construct a set of coherent states which are related to the displacement of the Fermi surface due to particle-hole excitations. We show that an interacting Hamiltonian in terms of the original fermions is quadratic in the bosons. We obtain a path-integral representation for the generating function, which, in real time, in the semiclassical limit, gives the Landau equation for sound waves and in the imaginary time gives us the correct form of the specific heat for a Fermi liquid even with the corrections due to the interactions between the fermions. We also discuss the similarities between our results and the physics of quantum crystals.