Strong-coupling theory of electronic Raman scattering in high-temperature superconductors

We have calculated the response function for electronic Raman scattering wi thin the fluctuation-exchange approximation for the two-dimensional Hubbard model. Below T-c. a large pair-breaking peak and a gap develop in the B-1g spectrum while the effect of superconductivity on the B-2g spectrum is muc h smaller, In order to investigate the underdoped regime we study the influ ence of a phenomenologically introduced pseudogap. In the normal state we f ind that this pseudogap leads for decreasing temperature to development of a d-wave gap structure in the density of states which merges continuously i nto the superconducting spectrum. A corresponding pair-breaking peak evolve s continuously in the B-1g Raman spectrum as T decreases in the normal stat e and below T-c. We discuss our results in connection with recent tunneling , optical conductivity, and Raman data on the cuprates. [S0163-1829(99)1372 1-4].