THEORY OF FERMION LIQUIDS

We develop a general theory of fermion liquids in spatial dimensions g reater than 1. The principal method, bosonization, is applied to the c ases of short- and long-range longitudinal interactions and to transve rse gauge interactions. All the correlation functions of the system ma y be obtained with the use of a generating functional. Short-range and Coulomb interactions do not destroy the Landau-Fermi fixed point. Non -Fermi liquid fixed points are found, however, in the cases of a super -long-range longitudinal interaction in two dimensions and transverse gauge interactions in two and three spatial dimensions. We consider in some detail the (2+1)-dimensional problem of a Chern-Simons gauge act ion combined with a longitudinal two-body interaction V(q) proportiona l to \q\(y-1), which controls the density, and hence gauge, fluctuatio ns. For y < 0 we find that the gauge interaction is irrelevant and the Landau fixed point is stable, while for y > 0 the interaction is rele vant and the fixed point cannot be accessed by bosonization. Of specia l importance is the case y = 0 (Coulomb interaction), which describes the Halperin-Lee-Read theory of the half-filled Landau level. We obtai n the full quasiparticle propagator, which is of a marginal Fermi-liqu id form. Using Ward identities, we show that neither the inclusion of nonlinear terms in the fermion dispersion nor vertex corrections alter s our results: the fixed point is accessible by bosonization. As the t wo-point fermion Green's function is not gauge invariant, we also inve stigate the gauge-invariant density response function. Near momentum Q = 2k(F), in addition to the Kohn anomaly we find other nonanalytic be havior. In the appendixes we present a numerical calculation of the sp ectral function for a Fermi-liquid with Landau parameter f(0) not equa l 0. We also show how Kohn's theorem is satisfied within the bosonizat ion framework.