On the Energy-Momentum Spectrum of a Homogeneous Fermi Gas

摘要: We consider translation-invariant quantum systems in thermodynamic limit. argue that their energy-momentum spectra should have shapes consistent with effective models involving quasiparticles. Our main example is second quantized homogeneous interacting Fermi gas a large cubic box periodic boundary conditions, at zero temperature. expect its spectrum has positive energy gap and critical velocity.