Influence of collective effects and the d charge-density wave on electronic Raman scattering in high-Tc 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 charge-density-wave 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