Influence of collective effects and the d-CDW on electronic Raman   scattering in high-T$_c$ superconductors
  Electronic Raman scattering in high-T$_c$ superconductors is studied within the t-J model. It is shown that the A$_{1g}$ and B$_{1g}$ spectra are dominated by amplitude fluctuations of the superconducting and the d-wave CDW order parameters, respectively. The B$_{2g}$ spectrum contains no collective effects and its broad peak reflects vaguely the doping dependence of T$_c$, similarly to the pronounced peak in the A$_{1g}$ spectrum. The agreement of our theory with the experiment supports the picture of two different, competing order parameters in the underdoped regime of high-T$_c$ superconductors. 
R. Zeyher and A. Greco