What is the Pairing Glue in the Cuprates? Insights from Normal and   Anomalous Propagators
  Both the pairing and the pair-breaking modes lead to similar kinks of the electron dispersion curves in superconductors, and therefore the photoemission spectroscopy can not be straightforwardly applied in search for their pairing glue. If the momentum-dependence of the normal and anomalous self-energy can be neglected, manipulation with the data does allow us to extract the gap function $\Delta(\omega)$ and therefore also the pairing glue. However, in the superconducting cuprates such procedure may not be justified. In this paper we point out that the pairing glue is more directly visible in the spectral function of the Nambu-Gor'kov anomalous propagator and we demonstrate that this function is in principle experimentally observable. 
Tom\'a\v{s} Bzdu\v{s}ek, Richard Hlubina
cond-mat.supr-con