Universal relations for the two-dimensional spin-1/2 Fermi gas with   contact interactions
  We present universal relations for a two-dimensional Fermi gas with pairwise contact interactions. The derivation of these relations is made possible by obtaining the explicit form of a generalized function -- selector -- in the momentum representation. The selector implements the short-distance boundary condition between two fermions in a straightforward manner, and leads to simple derivations of the universal relations, in the spirit of Tan's original method for the three-dimensional gas. 
Manuel Valiente, Nikolaj Zinner and Klaus Molmer
cond-mat.quant-gas quant-ph