  We study the renormalization of the Fermi-liquid parameters in the vicinity
of a density wave quantum phase transition, which should occur in MOSFET
systems at low densities. First, using a perturbative RPA treatment of
fluctuations, we calculate the electronic self-energy and show that the
effective mass diverges at the density wave transition point. Second, we go
beyond perturbation theory, making use of the exact Pitaevskii identities.
Within this exact analysis, we also find a divergence of the effective mass,
which occurs at higher densities in the fluctuation region, as compared to the
perturbation theory. This result signals the break-down of conventional
Fermi-liquid description in the vicinity of the transition point. The
divergence of the effective mass gives rise to a singular behavior of the
electronic compressibility. We suggest that the experimentally observed
enhancement of the effective mass is a precursor to a second order
thermodynamic phase transition into a glassy density wave state.
