A two-dimensional Fermi liquid with attractive interactions
  We realize and study an attractively interacting two-dimensional Fermi liquid. Using momentum resolved 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. 
B. Fr\"ohlich, M. Feld, E. Vogt, M. Koschorreck, M. K\"ohl, C.   Berthod, T. Giamarchi
cond-mat.quant-gas