On the BCS gap equation for superfluid fermionic gases
  We present a rigorous derivation of the BCS gap equation for superfluid fermionic gases with point interactions. Our starting point is the BCS energy functional, whose minimizer we investigate in the limit when the range of the interaction potential goes to zero. 
Gerhard Br\"aunlich and Christian Hainzl and Robert Seiringer
math-ph cond-mat.quant-gas cond-mat.supr-con math.MP