Scattering Rate Anisotropy in the Pseudogap State of BSCCO

We study quasi-particle lifetime anisotropy in BSCCO as a function of temperature and doping by relaxational analysis of symmetrized Raman response functions. For moderately underdoped BSCCO the pseudogap behavior manifests itself in anisotropic suppression of the low-frequency scattering rates, sharper in the vicinity of (pi, 0) and equivalent points of the Brillouin zone, or the hot spots, and milder in the vicinity of (pi/2,pi/2) points, or the cold spots. With stronger underdoping the scattering rate suppression becomes more pronounced and isotropic.