From BCS to BEC Superconductivity: Spectroscopic Consequences
  The evolution from BCS to BEC superconductivity in the s-wave and d-wave channels is analyzed at zero temperature for a two-dimensional superconductor. Spectroscopic quantities for s-wave and d-wave systems present fundamental differences when particle density and attraction strength are varied. A detailed analysis of single quasiparticle properties (excitation spectrum, momentum distribution, spectral function and density of states) indicates that the evolution of these spectroscopic quantities in the d-wave case is not smooth, unlike the situation encountered for the s-wave system. 
L.S. Borkowski and C.A.R. Sa de Melo