Two-Dimensional Fermi Liquid with Attractive Interactions

We realize and study an attractively interacting two-dimensional Fermi liquid. Using momentumresolved photoemission spectroscopy, we measure the self-energy, determine the contact parameter of the short-range interaction potential, and find their dependence on the interaction strength. We successfully compare the measurements to a theoretical analysis, properly taking into account the finite temperature, harmonic trap, and the averaging over several two-dimensional gases with different peak densities.