Comment on ``Quasiparticle Decay Effects in the Superconducting Density of States: Evidence for d-Wave Pairing in the Cuprates''

Abstract

We comment on a letter publised in PRL by: D. Coffey and L. Coffey, Phys. Rev. Lett. {\bf 70}, 1529 (1993) where it is claimed that the dip structure above the gap is evidence for d-wave pairing. We show that the analysis in this letter is completely contradictory to all ARPES experiments (including those which are considered to be evidence for d-wave), since this letter predicts a dip structure in the direction in which the gap is absent (within the d-wave scenario) and the absence of the dip in the direction in which the gap is maximal. We point out a series of additional experimental facts that exclude the analysis of the previous letter and that can be naturally understool within a strong coupling s-wave analysis made by the author of this comment [Phys. Rev. B {\bf 51} (Rapid. Comm.), 1381 (1995)].