Dynamical susceptibility of a thermally excited neutral Fermi-liquid film

We perform a detailed study of the dynamical susceptibility of two-dimensional Fermi gases and liquids, in terms of the momentum and energy transferred to the system by an external probe, and both at zero and at finite temperatures. The response of a noninteracting system is computed and analyzed together with that of a liquid subjected to a monopole interaction, paying special attention to the Landau limit. The disappearance of Pauli blocking associated with thermal effects is examined in the frame of the collisional Landau regime. All results are compared to the equivalent ones obtained for a three-dimensional Fermi liquid.