Gauge invariance of the beta-function in nonrelativistic quantum   electrodynamics
  Recently there has been much interest in gauge theories applied to condensed matter physics. I show that for a system of nonrelativistic electrons coupled to a U(1) gauge field in the presence of a Fermi surface, the beta-function to one-loop order is, for a particular family of gauge-choices, independent of the gauge-choice. 
Olav F. Syljuasen (UCLA)