A New Method for Measuring the Pion-Air Cross Section at Multi-TeV Energies Using Muon Bundle Properties in Deep Underground Detectors

The interaction cross section of charged pions with air nuclei is a critical parameter for accurately simulating extensive air showers. Improving the modeling of high-energy pion interactions is essential for addressing the muon puzzle-the observed deficit of muons in simulations compared to indirect experimental estimates. As collider experiments cannot directly probe these interactions, we propose a novel measurement approach using muon bundles detected in deep-underground water Cherenkov detectors, such as IceCube and KM3NeT. This method aims to constrain the pion-air inelastic cross section, thereby reducing uncertainties in air shower simulations and advancing our understanding of cosmic ray interactions.