A simulation study for one-pion exchange contribution on very forward neutron productions in ATLAS-LHCf common events

Interpretations of the mass composition of ultra-high energy cosmic rays are unclear owing to uncertainties in the hadronic interaction models. Therefore, validations of hadronic interaction models via experiments are required. Recently, the LHCf experiment demonstrated differences in very forward neutron productions between data and predictions using hadronic interaction models for pseudo-rapidity 𝜂 > 10.76. Contributions of the one-pion exchange process, diffractive collisions, and non-diffractive collisions are possible sources of these differences. These three contributions exhibit different effects on the mass-sensitive observables of ultra-high energy cosmic-ray experiments; hence, it is crucial to measure these contributions separately. In this study, we present a method for separating the contribution of the one-pion exchange process from contributions of diffractive and non-diffractive collisions in ATLAS and LHCf detectors, considering detector resolutions in LHC-Run2 and Run3.