  High energy neutrinos can be produced by interactions of ultra-high energy
cosmic rays (UHECRs) in the dense radiation fields of their sources as well as
off the cosmic backgrounds when they propagate through the universe.
Multi-messenger interpretations of current measurements deeply rely on the
understanding of these interactions. In order to efficiently produce neutrinos
in the sources of UHECRs, at least a moderate level of interactions is needed,
which means that a nuclear cascade develops if nuclei are involved. On the
other hand, the available cross-section data and interaction models turn out to
make poor predictions for most nuclei heavier than protons. We show the impact
of these uncertainties in state-of-the-art photo-disintegration models and
motivate nuclear cross-section measurements. Further, we discuss extensions for
photo-meson models currently used in astrophysics and demonstrate the
importance of understanding the details of UHECR interaction with the Glashow
resonance.
