Superconductivity, d Charge-Density Wave and Electronic Raman Scattering in High-T_c Superconductors

The competition of superconductivity and a d charge-density wave (CDW) is studied in the t-J model as a function of temperature at large N where N is the number of spin components. Applying the theory to electronic Raman scattering the temperature dependence of the $B_{1g}$ and the $A_{1g}$ spectra are discussed for a slightly underdoped case.