  In a recent experiment [E. Vogt et al., Phys. Rev. Lett. 108, 070404 (2012)],
quadrupole and breathing modes of a two-dimensional Fermi gas were studied. We
model these collective modes by solving the Boltzmann equation via the method
of phase-space moments up to fourth order, including in-medium effects on the
scattering cross section. In our analysis, we use a realistic Gaussian
potential deformed by the presence of gravity and magnetic field gradients. We
conclude that the origin of the experimentally observed damping of the
quadrupole mode, especially in the weakly interacting (or even non-interacting)
case, cannot be explained by these mechanisms.
