Out in the universe, when ultra-high energy charged cosmic rays (UHECRs) propagate from their source and/or acceleration site, they may interact with the environment (gas), producing high-energy gamma rays and neutrinos. One of the main uncertainties in the prediction of the flux of gamma rays and neutrinos from such UHECR interactions is due to the modeling of hadronic interactions.
Back here on Earth, the LHCb experiment at CERN employs a general-purpose forward spectrometer to primarily study heavy flavor physics at the Large Hadron Collider (LHC). The acceptance of the spectrometer covers the pseudorapidity range $2 < \eta < 5$ and the detector provides full tracking and particle identification down to very small transverse momenta. This makes LHCb ideal to study hadronic interactions similar to those undergone by UHECRs.
The modeling of different astrophysical source scenarios involves the transport of CRs through magnetic fields, generating secondary particles from CR interactions in the local environment and tracking these interaction products through the universe to Earth. All these processes are implemented in CRPropa. Since recently, it also provides an interface to the general-purpose hadronic event generators.
In this contribution, we summarize measurements of hadronic particle production done by LHCb and use them to evaluate the performance of the event generators employed in CRPropa. Based on these comparisons we determine which measurements could be performed by LHCb in the future to reduce the uncertainty in the hadronic interaction models and to provide better constraints on the modeling of astrophysical sources and transport.