Molecular signatures in the structure factor of an interacting Fermi gas

The static and dynamic structure factors of an interacting Fermi gas along the BCS-BEC crossover are calculated at momentum transfer $\mathrm{\hslash }\mathbf{k}$ higher than the Fermi momentum. The spin structure factor is found to be very sensitive to the correlations associated with the formation of molecules. On the BEC side of the crossover, even close to unitarity, clear evidence is found for a molecular excitation at ${\mathrm{\hslash }}^2{k}^2\mathrm{/}4m$, where $m$ is the atomic mass. Both quantum Monte Carlo and dynamic mean-field results are presented.