The Dicke model as the contraction limit of a pseudo-deformed   Richardson-Gaudin model
  The Dicke model is derived in the contraction limit of a pseudo-deformation of the quasispin algebra in the su(2)-based Richardson-Gaudin models. Likewise, the integrability of the Dicke model is established by constructing the full set of conserved charges, the form of the Bethe Ansatz state, and the associated Richardson-Gaudin equations. Thanks to the formulation in terms of the pseudo-deformation, the connection from the su(2)-based Richardson-Gaudin model towards the Dicke model can be performed adiabatically. 
Pieter W. Claeys, Stijn De Baerdemacker, Mario Van Raemdonck and   Dimitri Van Neck
math-ph math.MP quant-ph