Anomaly at Delta_k in the ARPES spectrum of dirty superconductors
  Elastic forward scattering can lead to an anomaly in the ARPES spectrum of the cuprate superconductors. Here we discuss how this anomaly can be used to provide a measurement of the superconducting gap Delta_k for k values away from the Fermi surface. 
T. Dahm, P. J. Hirschfeld, L. Zhu, and D. J. Scalapino