  Using the bosonization approach we study fermionic systems with a nonlinear
dispersion relation in dimension d>2. We explicitly show how the band curvature
gives rise to interaction terms in the bosonic version of the model. Although
these terms are perturbatively irrelevant in relation to the Landau Fermi
liquid fixed point, they become relevant perturbations when instabilities take
place. Using a coherent state path integral technique we built up the effective
action that governs the dynamics of the Fermi surface fluctuations. We consider
the combined effect of fermionic interactions and band curvature on possible
anisotropic phases triggered by negative Landau parameters. In particular we
study in some detail the phase diagram for the isotropic/nematic/hexatic
quantum phase transition.
