Cosmogenic Neutrinos from Cosmic Ray Interactions with Extragalactic   Infrared Photons
  We discuss the production of cosmogenic neutrinos on extragalactic infrared photons in a model of its cosmological evolution. The relative importance of these infrared photons as a target for proton interactions is significant, especially in the case of steep injection spectra of the ultrahigh energy cosmic rays. For an E$^{-2.5}$ cosmic ray injection spectrum, for example, the event rate of neutrinos of energy above 1 PeV is more than doubled. 
Daniel De Marco, Todor Stanev and F.W. Stecker