Effects of Forward Scattering from Dopant Impurities in Overdoped Cuprates*

Many properties of overdoped cuprate superconductors can be explained by simple BCS and Landau Fermi liquid theory, supplemented by an appropriate description of disorder from dopant impurities. In addition to simply providing weaker scattering, out-of-plane dopants give rise to extended impurity potentials that scatter preferentially in the forward direction. Here we investigate the effects of such forward scattering on the optical conductivity and the penetration depth, and make specific quantitative comparisons with both LSCO and Tl-2201. We discuss previous work on forward scattering in ARPES in the same context.